Anatomy & Physiology · Study Guide

Exam 1 Study Guide

Four chapters, one ladder. You start with the whole body and the words that place its parts. Then you drop to atoms and water. Then to the cell. Then back up to the four tissues. Work one chapter at a time. Read the "what to know" list first. Copy each table out by hand. Then try the reasoning walk-throughs with the answers covered. Finish each chapter with its ten self-test items. The cram sheet at the end holds every list and value in one place.

Chapter 1 Chapter 2 Chapter 3 Chapter 4 Cram sheet

What this guide covers

Chapter 1 · the six levels, the eleven organ systems, homeostasis and feedback, direction words, planes, cavities and the belly map.
Chapter 2 · atoms and elements, the three bonds, reaction types and enzymes, water, pH and buffers, and the molecules of life.
Chapter 3 · the cell membrane, transport, the organelles, gene to protein, the cell cycle, and tonicity.
Chapter 4 · the four tissues, naming an epithelium, the connective tissue family, the three muscles, the neuron, and tissue repair.

Chapter 1An Introduction to the Human Body

What to know

Anatomy asks what a part is and where it sits. Physiology asks what it does. The two go together, because structure always fits function. A lung air sac is as thin as tissue paper, so gas crosses it fast. The wall of the heart's main pumping chamber is thick, so it can push hard.

The body is built in six nested levels. Each level is made from the one below it. The cell is the smallest living unit. It is the line between chemistry and life. You can also read the ladder downward. A heart attack is an organ problem, but it starts in cells with too little oxygen.

Eleven organ systems share the work of staying alive. Know each one's main job and one key organ. They never work alone. One breath uses five of them at once. A few organs serve two systems. The pancreas is both digestive and endocrine.

Homeostasis is the one big idea. It means the inside of the body stays steady while the world outside changes. Values wobble around a set point. For temperature the set point is near 37 °C. Most disease is a failure of homeostasis.

Negative feedback keeps values steady. It has three parts, always in the same order. A receptor senses the change. A control center compares the reading to the set point. An effector carries out the fix. The response pushes against the first change, so it is called negative.

Positive feedback is the rare one. It makes a change bigger until an event ends it. Childbirth, blood clotting and milk release all work this way. Each one has a built-in stop.

Every direction word starts from the anatomical position. The body stands upright and faces forward. The feet are a little apart. The arms hang at the sides with the palms forward. Right and left always mean the patient's own right and left.

Three planes slice the body, and each one is at a right angle to the other two. Organs sit in cavities. The dorsal cavity holds the brain and the spinal cord. The diaphragm splits the ventral cavity into the chest and the belly. Thin serous membranes line those spaces so organs do not rub.

Lock these in

The six levels run chemical, cellular, tissue, organ, organ system, organism.
There are eleven organ systems. The cell is the smallest living unit.
A negative feedback loop is receptor, then control center, then effector.
Negative feedback reverses a change. Positive feedback builds on it.
Right and left mean the patient's sides, not yours.
The parietal layer lines the wall. The visceral layer hugs the organ.

Worth memorizing

Start with the ladder. Say it out loud in order, then write it from memory.

Chemical — atoms join into molecules, such as water or a protein.
Cellular — molecules build a cell, such as a muscle cell or a neuron.
Tissue — alike cells doing one job, such as heart muscle tissue.
Organ — two or more tissue types in one part, such as the heart.
Organ system — organs on a shared job, such as heart, vessels and blood.
Organism — all the systems together. One living person.

System	Main job	Key organs
Integumentary	Covers and protects; helps control temperature; senses touch; makes vitamin D	Skin, hair, nails
Skeletal	Holds the body up; protects organs; levers for movement; makes blood cells; stores minerals	Bones, cartilage, joints
Muscular	Moves the body; holds posture; makes heat	Skeletal muscles
Nervous	Fast control and messages	Brain, spinal cord, nerves
Endocrine	Slow control using hormones	Thyroid, pancreas, adrenal, pituitary
Cardiovascular	Carries blood, O₂, nutrients and wastes	Heart, blood vessels, blood
Lymphatic / immune	Returns fluid to the blood and fights germs	Lymph nodes, spleen, thymus, lymph vessels
Respiratory	Gas exchange: O₂ in, CO₂ out	Lungs, airways
Digestive	Breaks down food, takes in nutrients, gets rid of waste	Stomach, intestines, liver, pancreas
Urinary	Cleans the blood; balances water, salts and pH; makes urine	Kidneys, ureters, bladder
Reproductive	Makes offspring and sex hormones	Ovaries and uterus; testes

Direction words come in opposite pairs. Learn them two at a time, and always use them to compare two parts.

Pair	Meaning	Example from the book
Superior / inferior	Above / below (toward the head / toward the feet)	The heart is superior to the stomach
Anterior / posterior	Front / back (also ventral / dorsal)	The sternum is anterior to the heart
Medial / lateral	Toward the midline / away from it	The nose is medial to the eyes
Proximal / distal	Closer to / farther from the trunk, for arms and legs	The elbow is proximal to the wrist
Superficial / deep	Toward the surface / away from it	The skin is superficial to the muscle

Direction words and the three planes. Every word is read from this one pose. Proximal and distal are measured along a limb from where it joins the trunk.

Plane	Splits the body into	Note
Sagittal	Left and right	A cut down the midline is midsagittal. A cut off to one side is parasagittal.
Frontal (coronal)	Front and back (anterior and posterior)	An up-and-down plane seen from the front
Transverse (horizontal)	Top and bottom (superior and inferior)	The slice view used on a CT scan

Now the cavities. Learn them as a tree, not a list.

Dorsal (posterior) cavity — holds the nervous system.
- Cranial cavity — the brain.
- Vertebral cavity — the spinal cord.
Ventral (anterior) cavity — the diaphragm splits it in two.
- Thoracic cavity — the chest, with the heart and lungs.
- Abdominopelvic cavity — the belly and hip area, with the digestive organs.

Serous membrane	Wraps	Disease when it is inflamed
Pleura	The lungs	Pleuritis
Pericardium	The heart	Pericarditis
Peritoneum	The belly organs	Peritonitis

Each of those three has two layers with paired names. The parietal layer lines the cavity wall. The visceral layer hugs the organ. The slippery fluid between them cuts down on rubbing.

The belly surface is mapped two ways. The quick map uses four quadrants: right upper, left upper, right lower, left lower. The detailed map uses nine regions, like a tic-tac-toe grid. The umbilical region sits in the center. The epigastric region is above it. The hypogastric region is below it. Saying "right lower quadrant pain" narrows the cause fast, because the appendix sits there.

How to reason through it

Walk-through 1 · "X is ___ to Y" items

These items hand you two parts and ask for one word. Work the same three steps every time.

Step 1 · stand the body upPut the body in the anatomical position in your head. Upright, facing you, palms forward.

Step 2 · pick the axisAsk which way the two parts differ. Up and down calls for superior or inferior. Front and back calls for anterior or posterior. Near or far from the midline calls for medial or lateral. Along a limb calls for proximal or distal. In or out from the surface calls for superficial or deep.

Step 3 · name the first partThe word describes the first part, not the second. The wrist is distal to the elbow. Flip the order and the word flips too. The elbow is proximal to the wrist.

Try it"The thumb is ___ to the shoulder." The two differ along a limb, so use proximal or distal. The thumb is farther from the trunk, so the answer is distal.

Walk-through 2 · feedback loop items

An item gives you a story and asks for the part, the loop type, or what happens next.

Step 1 · label the three partsWhat senses the change is the receptor. What compares and decides is the control center. What acts is the effector. In the cold, skin receptors sense, the hypothalamus compares, and blood vessels and muscles act.

Step 2 · check the directionDoes the response undo the change or add to it? Undoing means negative feedback. Adding means positive feedback.

Step 3 · find the stopPositive feedback needs an event that ends it. A birth ends labor. A sealed clot ends clotting. If nothing ends it, the loop is not positive feedback.

Try itBlood sugar climbs after a meal, insulin goes out, and sugar falls. The response reversed the climb, so this is negative feedback. The pancreas is the control center, and body cells are the effectors.

Walk-through 3 · plane, cavity and quadrant items

Scan and pain items both reward one habit: name the space first.

Step 1 · for an image, name the planeTwo halves, left and right, means sagittal. Front and back means frontal. A round slice across means transverse.

Step 2 · for an organ, climb the cavity treeIs it nervous tissue? Then it is dorsal, either cranial or vertebral. Is it above the diaphragm? Then it is thoracic. Below it? Then it is abdominopelvic.

Step 3 · for pain, use the patient's sidesRight means the patient's right. Then pick the quadrant or the region.

Try itA round slice through the belly shows the organs cut straight across. That is a transverse image of the abdominopelvic cavity.

Traps people fall into

Using your own right and left. Right always means the patient's right side.
Using proximal and distal on the trunk. Save that pair for the arms and legs.
Calling every sagittal cut midsagittal. Only a cut down the midline makes equal halves.
Swapping parietal and visceral. Parietal lines the wall. Visceral is on the organ.
Thinking positive feedback means helpful. Positive only means the change gets bigger.
Putting the spinal cord in the ventral cavity. It sits in the vertebral cavity, which is dorsal.
Naming the second part. The word always describes the first part named.

Chapter 1 self-test · ten items

1. Put the six levels of organization in order from smallest to largest.

Chemical, cellular, tissue, organ, organ system, organism. Each level is built from the one below it. The cell is the smallest level that is alive.

2. Name the three parts of a negative feedback loop in order.

Receptor, control center, effector. The receptor senses. The control center compares the reading to the set point. The effector acts. The action pushes against the first change.

3. The knee is ___ to the ankle.

Proximal. Both parts sit on a limb, so use the proximal and distal pair. The knee is closer to the trunk. Superior would also be true here, but proximal is the pair built for limbs.

4. Which plane makes the slice view you see on a CT scan?

The transverse plane. It splits the body into top and bottom. Sagittal splits left from right. Frontal splits front from back.

5. Which cavity holds the spinal cord, and which larger cavity is it part of?

The vertebral cavity, part of the dorsal cavity. The dorsal cavity has two parts. The cranial cavity holds the brain, and the vertebral cavity holds the cord.

6. Which layer of a serous membrane lines the wall of the cavity?

The parietal layer. The visceral layer hugs the organ itself. Fluid between the two layers lets the organ slide.

7. Labor contractions get stronger and stronger until the baby is born. Which kind of feedback is that?

Positive feedback. The stretch sets off oxytocin, which makes the squeeze stronger, which stretches more. The birth is the built-in stop. Clotting and milk release work the same way.

8. Which structure splits the ventral cavity into the thoracic and abdominopelvic cavities?

The diaphragm. It is a sheet of muscle. Above it sit the heart and lungs. Below it sit the digestive organs.

9. Which organ belongs to two organ systems, and which two?

The pancreas, in the digestive and the endocrine systems. It sends enzymes into the gut and it sends hormones into the blood. Systems overlap all the time.

10. Pain in the right lower quadrant points first to which organ, and why?

The appendix, because it sits in that quadrant. The four-quadrant map is the quick way to narrow a cause. The nine-region map is the detailed version, with the umbilical region in the center.

Chapter 2The Chemical Level of Organization

What to know

Matter is made of elements. The smallest unit of an element is an atom. An atom has a nucleus of protons and neutrons, with electrons in shells around it. Protons are positive. Neutrons have no charge. Electrons are negative and weigh almost nothing.

The atomic number is the number of protons. It tells you which element you have. The mass number is protons plus neutrons added together. Isotopes are the same element with a different number of neutrons. Carbon-12 and carbon-14 both have 6 protons.

Chemistry comes from the outer shell, the valence shell. Atoms bond to fill it. For most atoms in the body, full means eight electrons. That is the octet rule. A full shell does not react.

There are three bonds. An ionic bond passes an electron from one atom to another, which leaves two ions with opposite charges. A covalent bond shares a pair of electrons, and it is the strongest bond in the body. Equal sharing is nonpolar. Unequal sharing is polar. A hydrogen bond is a weak pull between polar molecules, and many of them together are strong.

Reactions come in three patterns. Synthesis builds. Decomposition breaks apart. Exchange swaps partners. Every reaction must first get over its activation energy. Enzymes lower that hill. They are almost always proteins, each one fits one substrate, and they are not used up.

Water is polar, and that one fact explains the rest. It is the universal solvent. It has a high heat capacity, so body temperature holds near 37 °C. Evaporating water carries heat away, which is why sweating cools you. Water also takes part in reactions.

pH measures free hydrogen ions. Below 7 is acidic. Above 7 is basic. The scale is logarithmic, so one unit is a tenfold change. Blood must stay between 7.35 and 7.45. Too low is acidosis. Too high is alkalosis. Buffers, mainly the bicarbonate system, soften the swings.

Four families of big molecules build the body. Carbohydrates are fuel. Lipids store energy and build membranes. Proteins do the work, and their shape sets their job. Nucleic acids hold the instructions. ATP powers it all.

Lock these in

Six elements make about 99% of body mass: O, C, H, N, Ca, P.
Atomic number is protons. Mass number is protons plus neutrons.
Covalent bonds are the strongest in the body. Hydrogen bonds are the weakest.
Blood pH is 7.35 to 7.45. One pH unit is a tenfold change in H⁺.
Enzymes lower activation energy and can be used again.
Dehydration synthesis takes water out to build. Hydrolysis adds water to break.

Worth memorizing

Element	Symbol	About % of body mass	A job it does
Oxygen	O	65%	Part of water; takes the electrons at the last step of making energy from food
Carbon	C	18%	The backbone of every organic molecule
Hydrogen	H	10%	Part of water; as H⁺ it sets pH
Nitrogen	N	3%	In every protein and nucleic acid
Calcium	Ca	1.5%	Bone mineral; helps muscles and nerves send signals
Phosphorus	P	1%	Bone; the energy-rich bonds of ATP; the backbone of DNA

Particle	Charge	Where it is	Relative mass
Proton	+1	Nucleus	1 (heavy)
Neutron	0	Nucleus	1 (heavy)
Electron	−1	Shells around the nucleus	About 1/1800 (almost nothing)

Bond	How it forms	Strength	Example
Ionic	One atom gives an electron to another; the opposite charges attract	Strong, but weak once it dissolves in water	Na⁺Cl⁻, table salt
Covalent, nonpolar	Electrons are shared equally	Strongest in the body	O₂; the C–H bonds in fats
Covalent, polar	Electrons are shared unequally, so each end gets a partial charge	Strongest in the body	Water, H₂O
Hydrogen	A pull between a partial plus and a partial minus on polar molecules	Weak alone, strong in large numbers	Between water molecules; between DNA strands

Reaction type	Pattern	What it does	Body example
Synthesis (anabolic)	A + B → AB	Builds bigger molecules	Amino acids joined into a protein
Decomposition (catabolic)	AB → A + B	Breaks molecules apart	Digesting starch into glucose
Exchange	AB + CD → AC + BD	Swaps partners	Buffers trading H⁺ in the blood

The pH scale is worth drawing from memory. Mark the five fluids the book gives you, then check the gap between each one.

The pH scale. Below 7.35 in blood is acidosis. Above 7.45 is alkalosis. Past about 6.8 or 7.8, proteins lose their shape and enzymes fail.

Property of water	Why, from polarity	What it does for you
Solvent	Its charged ends pull solutes apart	Carries nutrients, wastes and ions in the blood
High heat capacity	Hydrogen bonds soak up heat	Keeps body temperature steady near 37 °C
Cooling by evaporation	Breaking hydrogen bonds carries heat away	Sweating cools the body
Cohesion and lubrication	Water molecules stick to each other	Slippery films in joints, membranes and airways
Reactant	Can be added or taken out in reactions	Builds and breaks big molecules

Family	Monomer or unit	Example	Main job
Carbohydrate	Monosaccharide (glucose)	Glycogen, starch	Quick energy; short-term fuel storage
Lipid	Fatty acids plus glycerol	Triglyceride, phospholipid, cholesterol	Energy storage, keeping warm, membranes, hormones
Protein	Amino acid, 20 kinds	Enzymes, keratin, hemoglobin	Structure, speeding reactions, carrying, signaling
Nucleic acid	Nucleotide	DNA, RNA	Store and use genetic information

How to reason through it

Walk-through 1 · counting the parts of an atom

You get two of the three numbers and must find the third.

Step 1 · protons name the elementThe atomic number is the proton count. It never changes for an element. Carbon always has 6.

Step 2 · subtract for neutronsNeutrons equal mass number minus atomic number.

Step 3 · a neutral atom has matched chargesElectrons equal protons when there is no overall charge.

Try itCarbon-14 has a mass number of 14. Carbon has 6 protons. So it holds 14 − 6 = 8 neutrons and 6 electrons. It is still carbon, because the proton count did not change. It just has two extra neutrons, and it is radioactive.

Walk-through 2 · naming the bond

Three questions sort any bond in the book.

Step 1 · is an electron handed over?If yes, you get two ions with opposite charges. That is ionic. In water it splits into electrolytes.

Step 2 · is a pair shared?Then it is covalent. Now ask if the sharing is even. Even is nonpolar. Uneven is polar.

Step 3 · is the pull between whole molecules?Then it is a hydrogen bond. It is weak, and it forms and breaks again easily.

Try itWhat holds the two strands of DNA together? The pull is between separate strands, not inside one molecule. So the answer is hydrogen bonds, many of them at once.

Walk-through 3 · pH and buffer items

These items test one idea: the scale is logarithmic.

Step 1 · count the stepsEach whole pH unit is a tenfold change in free H⁺. Two units is ten times ten, or a hundredfold.

Step 2 · check the directionLower pH means more H⁺. Higher pH means less.

Step 3 · name the problemBlood below 7.35 is acidosis. Above 7.45 is alkalosis.

Try itHow much more H⁺ does a fluid at pH 3 hold than one at pH 5? Two steps down, so a hundred times more. A buffer would soften that swing, but it does not make the acid go away. The lungs blow off CO₂ and the kidneys get rid of H⁺ to fix the balance.

Traps people fall into

Mixing up the two numbers. Atomic number is protons. Mass number adds the neutrons.
Thinking an isotope is a new element. Only the neutron count changes.
Calling a hydrogen bond covalent. It is a pull between molecules, and it is weak.
Reading pH as a straight line. Each unit is a tenfold step.
Saying a buffer removes acid. It only softens the swing and buys time.
Thinking an enzyme is used up. It is free to work again right away.
Flipping the two water reactions. Taking water out builds. Adding water breaks.

Chapter 2 self-test · ten items

1. Name the six elements that make up about 99% of body mass.

Oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus. Oxygen alone is about 65%, carbon 18% and hydrogen 10%.

2. An atom has 11 protons and a mass number of 23. How many neutrons and electrons does it have when neutral?

12 neutrons and 11 electrons. Neutrons are 23 − 11 = 12. A neutral atom matches electrons to protons, so 11 electrons.

3. Why do atoms form bonds at all?

To fill the outer, or valence, shell. For most atoms in the body, full means eight electrons. That is the octet rule. Atoms with a full shell, like helium and neon, do not react.

4. Which bond type is strongest in the body, and which is weakest?

Covalent is strongest. Hydrogen is weakest. Ionic bonds are strong when dry but weak once they dissolve in water. Many hydrogen bonds together still hold water, DNA and folded proteins.

5. Digesting starch into glucose is which type of reaction?

Decomposition, also called catabolic. One big molecule becomes smaller pieces, so the pattern is AB → A + B. Joining amino acids into a protein would be synthesis.

6. What does an enzyme do to a reaction, and is the enzyme used up?

It lowers the activation energy, and it is not used up. That lets the reaction run fast at a safe 37 °C. Each enzyme has an active site shaped for one substrate. High fever or the wrong pH can unfold it and stop it working.

7. Give the normal pH range of blood and name the two problems outside it.

7.35 to 7.45. Below is acidosis, above is alkalosis. Past about 6.8 or 7.8, proteins lose their shape and enzymes fail.

8. Which buffer system is the body's first line of defense in the blood?

The bicarbonate system. Carbonic acid and the bicarbonate ion trade hydrogen ions back and forth. The lungs then breathe off CO₂ and the kidneys get rid of H⁺.

9. Which property of water explains sweating, and which explains why your temperature holds steady?

Cooling by evaporation explains sweating. High heat capacity holds the temperature steady. Both trace back to hydrogen bonds, and those come from water being polar.

10. Which molecule family has amino acids as its unit, and what sets a member's job?

Proteins, and the folded shape sets the job. Twenty kinds of amino acid link into a chain that folds. Unfold it with heat or the wrong pH and it stops working, like egg white in a hot pan.

Chapter 3The Cellular Level of Organization

What to know

Every cell is wrapped in a plasma membrane. It does three jobs. It separates inside from outside. It controls traffic, which makes it selectively permeable. And it carries receptors and ID tags, so the cell can sense signals.

The fluid mosaic model describes it. Mosaic means a patchwork of fats, proteins and sugars. Fluid means the pieces drift sideways. The base is a phospholipid bilayer, two layers of fat lined up tail to tail. Water-loving heads face out. Water-fearing tails hide in the middle. That oily middle is why the membrane is picky.

Transport splits in two on one question: does it cost energy? Passive transport goes down the gradient for free. Active transport goes up a gradient and costs ATP. The sodium and potassium pump moves 3 Na⁺ out and 2 K⁺ in for each ATP. It runs in every cell and sets up the charge that nerves and muscles use.

Inside, the organelles share the work like the departments of a factory. The nucleus stores DNA and runs the cell. The protein path runs ribosome, then rough ER, then Golgi, then vesicle. Mitochondria make ATP. Lysosomes break down junk. The cytoskeleton gives shape.

A gene is the recipe for one protein. The flow is DNA, then RNA, then protein. Transcription happens in the nucleus and copies a gene into mRNA. RNA uses uracil where DNA would use thymine. Translation happens at a ribosome. It reads mRNA three bases at a time. Each three-base codon stands for one amino acid, and tRNA brings it in.

The cell cycle is a long interphase plus a short mitosis. Interphase runs G₁, then S, then G₂. DNA is copied in S phase. Mitosis runs in four stages you can remember as PMAT. Then cytokinesis splits the rest of the cell. The result is two identical daughter cells.

Osmosis is water moving across the membrane toward the side with more solute. Tonicity tells you what a fluid will do to a cell. Isotonic keeps it normal. Hypotonic makes it swell and maybe burst. Hypertonic makes it shrivel. Water always follows the solute, so find the saltier side.

Lock these in

The membrane is a fluid phospholipid bilayer with proteins, cholesterol and sugars in it.
Passive is free and downhill. Active is uphill and costs energy.
The sodium and potassium pump sends 3 out and brings 2 in per ATP.
DNA is copied in S phase, not during mitosis.
Mitosis order is prophase, metaphase, anaphase, telophase.
Water moves toward the saltier side. Nothing else about osmosis matters more.

Worth memorizing

Membrane part	What it is	Main job
Phospholipid bilayer	Two layers of phospholipids, tails inward	The basic wall; blocks water-loving molecules, passes small fat-soluble ones
Integral proteins	Proteins that span the whole membrane	Channels, carriers and pumps; receptors
Peripheral proteins	Proteins stuck to one surface	Enzymes, anchors and support for cell shape
Cholesterol	Fat molecules tucked between phospholipids	Keeps the membrane from getting too stiff or too runny
Glycocalyx	Sugar chains on the outer face	Cells know each other and stick together; marks "self"

Transport method	Energy?	Direction and example
Simple diffusion	No, passive	Downhill, right through the fat layer: O₂, CO₂
Facilitated diffusion	No, passive	Downhill, through a protein: glucose, ions
Osmosis	No, passive	Water moves toward the saltier side
Primary active transport	Yes, uses ATP directly	Uphill by a pump: 3 Na⁺ out, 2 K⁺ in
Secondary active transport	Yes, uses an ion gradient	Rides another ion's gradient: glucose with Na⁺ in the gut
Bulk transport	Yes, active	Cargo wrapped in membrane: endocytosis in, exocytosis out

Organelle	Job	Memory hook
Nucleus	Stores DNA; runs the cell	The control room
Nucleolus	Builds ribosomes	Ribosome factory inside the nucleus
Ribosome	Builds proteins by reading mRNA	The 3-D printer
Rough ER	Makes and packs proteins; studded with ribosomes	Protein assembly line
Smooth ER	Makes fats, breaks down harmful substances, stores Ca²⁺	Fat and cleanup lab
Golgi apparatus	Changes, sorts and ships proteins in vesicles	The post office
Mitochondrion	Makes ATP from food and O₂	The powerhouse
Lysosome	Breaks down junk and worn-out parts	The recycling crew
Cytoskeleton	Shape, support and moving cargo	The inside frame

Step	Where	What happens
Transcription	Nucleus	RNA polymerase copies a gene from DNA into mRNA
mRNA leaves	Nuclear pore	The working copy moves out to the cytoplasm
Translation	Ribosome	Codons are read three bases at a time; tRNA anticodons bring the matching amino acids
Product	Cytoplasm or ER	Amino acids link into a chain that folds into a working protein

Phase	Part of cycle	What happens
G₁	Interphase	Cell grows and does its normal work
S	Interphase	All the DNA is copied
G₂	Interphase	Last growth; DNA is checked for mistakes
Prophase	Mitosis	Chromatin packs into chromosomes; the spindle forms
Metaphase	Mitosis	Chromosomes line up across the middle
Anaphase	Mitosis	Chromosome copies are pulled to opposite ends
Telophase	Mitosis	Two new nuclei form; cytokinesis splits the cell

Tonicity is the one topic here that is easiest to learn as a picture. Draw these three cells, then label which way the water goes.

Tonicity in three pictures. 0.9% normal saline is isotonic. Pure water into a vein is hypotonic, and red cells would burst, so it is never given.

How to reason through it

Walk-through 1 · tonicity items

A cell goes into a fluid, and you must say what happens.

Step 1 · find the saltier sideCompare solute outside the cell to solute inside. More solute outside means the outside is saltier.

Step 2 · send the water thereWater follows the solute, so it moves toward the saltier side.

Step 3 · name the resultWater in means swelling, and maybe bursting, which is lysis. Water out means shriveling, which is crenation. Equal means no change.

Try itA red cell is dropped into pure water. There is no solute outside, so the inside is saltier. Water rushes in. The cell swells and bursts. That fluid is hypotonic, and the bursting of a red cell is hemolysis.

Walk-through 2 · passive or active?

Do not start with the name of the method. Start with the gradient.

Step 1 · which way is the gradient?From a lot to a little is downhill. From a little to a lot is uphill.

Step 2 · downhill is freeDownhill is passive, with no ATP, even if a protein is used. That is why facilitated diffusion is still passive.

Step 3 · uphill always costsUphill is active. Either ATP is spent directly, or a gradient a pump already built is spent instead.

Try itGlucose moves into a cell from blood that holds more of it. That is downhill, through a carrier protein. So it is facilitated diffusion, and it is passive. The protein does not make it active.

Walk-through 3 · gene to protein items

Items here ask for the place, the step or a count of bases.

Step 1 · place the stepTranscription is in the nucleus. Translation is at a ribosome. The mRNA travels out through a nuclear pore.

Step 2 · match the basesC pairs with G. DNA's A calls for U in the RNA, because RNA uses uracil in place of thymine.

Step 3 · count in threesThree mRNA bases make one codon, and one codon stands for one amino acid.

Try itHow many mRNA bases does a chain of 30 amino acids need? Three bases per amino acid, so 90 bases, plus a stop codon to end the chain.

Traps people fall into

Thinking solute moves in osmosis. The membrane holds the solute back, so water moves instead.
Calling facilitated diffusion active. A protein doorway is still a free ride downhill.
Putting DNA copying in mitosis. It happens in S phase, during interphase.
Treating mitosis and cytokinesis as one step. Mitosis splits the nucleus. Cytokinesis splits the cell.
Giving RNA a thymine. RNA uses uracil in its place.
Putting ribosomes on the smooth ER. Only the rough ER has them.
Reversing the pump count. It is 3 sodium out and 2 potassium in.

Chapter 3 self-test · ten items

1. What do the two words in "fluid mosaic model" each tell you?

Mosaic means a patchwork of fats, proteins and sugars. Fluid means the pieces drift sideways. So the membrane acts more like a thin film of oil than a hard wall.

2. Why do ions need a protein to cross the membrane while oxygen does not?

The middle of the bilayer is oily, and ions are charged. Small molecules with no charge, like O₂ and CO₂, slip straight through. Charged and water-loving molecules need a channel or a carrier.

3. How many sodium and potassium ions does the pump move, and what does it cost?

3 Na⁺ out and 2 K⁺ in for each ATP. It is primary active transport. It runs in every cell and sets up the charge that nerve and muscle signals use.

4. Trace a protein that will be sent out of the cell, naming the organelles in order.

Ribosome, then rough ER, then Golgi, then a vesicle. The Golgi changes, sorts and packs it. The smooth ER is not on this path. It makes fats, handles harmful substances and stores calcium.

5. Which organelle breaks down worn-out parts and germs?

The lysosome. It is a sac of digestive enzymes. Peroxisomes are the other cleanup organelle, and they make harmful by-products safe.

6. Where does transcription happen, and what does it make?

In the nucleus, and it makes mRNA. RNA polymerase unzips the gene and builds a matching strand. The copy then slips out through a nuclear pore to find a ribosome.

7. What is a codon, and what does one codon stand for?

Three mRNA bases, and it stands for one amino acid. A tRNA with a matching three-base anticodon brings that amino acid in. A stop codon releases the finished chain.

8. In which phase is DNA copied, and which part of the cycle is that phase in?

S phase, which is part of interphase. Interphase runs G₁, S, G₂. Checkpoints guard each step so damaged cells do not divide.

9. Give the four stages of mitosis in order and say what lines up in the middle.

Prophase, metaphase, anaphase, telophase. The chromosomes line up in metaphase. Remember PMAT. Anaphase pulls the copies apart, and telophase builds two new nuclei.

10. A cell is put in a fluid with more solute than its inside. What happens, and what is that called?

Water leaves and the cell shrivels. That shriveling is crenation, and the fluid is hypertonic. Water follows the solute to the saltier side every time.

Chapter 4The Tissue Level of Organization

What to know

A tissue is a group of similar cells that work together on a shared job. The study of tissues under the microscope is histology. The whole body is built from just four primary tissues.

Epithelial tissue covers surfaces, lines spaces and forms glands. Its cells are tightly packed, so almost nothing crosses without going through a cell. It has polarity, which means a top and a bottom. The apical surface faces the open space. The basal surface sits on a basement membrane. It is avascular, so it has no blood vessels of its own, yet it has plenty of nerves. It regrows fast.

Connective tissue binds, supports, protects, stores and carries. Its cells are few and far apart in an extracellular matrix. The matrix has fibers and ground substance. Change the matrix and you change the tissue. A rubbery gel gives cartilage. Calcium salts give bone. A liquid gives blood.

Muscle tissue contracts. Actin and myosin threads slide past each other to shorten the cell. Neat rows of threads catch the light, which is why some muscle looks striped. There are exactly three muscle tissues.

Nervous tissue senses, sorts out and sends electrical signals. Its star cell is the neuron, and its shape is a map of the signal. Traffic goes one way: dendrite, then cell body, then axon. Neuroglia are the support crew. Counts show about one glial cell per neuron across the whole brain.

Hurt tissue heals two ways. Regeneration replaces the lost cells with the same kind, and the tissue goes back to normal. Fibrosis fills the gap with scar, which is strong but cannot do the old job. Which path a tissue takes depends mostly on how well its cells divide and on its blood supply.

Lock these in

The four tissues cover and line, bind and support, move, and communicate.
Epithelial cells are crowded. Connective cells are spread out in a matrix.
Name an epithelium by layers plus the shape of the surface cells.
A name ending in -blast builds matrix. A name ending in -cyte keeps it up.
Both striated muscles are skeletal and cardiac. Only skeletal is voluntary.
Repair runs hemostasis, inflammation, proliferation, remodeling.

Worth memorizing

Tissue	What it does	Where you find it
Epithelial	Covers surfaces, lines spaces, forms glands; protects, absorbs, releases	Skin surface, gut lining, kidney tubes, gland cells
Connective	Binds, supports, protects, stores, carries; the body's packing material	Bone, fat, tendon, cartilage, blood
Muscle	Contracts to make movement and force; also makes heat	Skeletal muscles, heart wall, walls of hollow organs
Nervous	Senses, sorts out and quickly sends electrical signals	Brain, spinal cord, nerves in the rest of the body

The naming rule for epithelium is the best deal in this chapter. Two words, and you can name a tissue you have never seen. The first word gives the layers. The second gives the shape of the cells at the surface.

Layers plus shape. One layer of flat cells is simple squamous. Many stacked flat layers are stratified squamous. One row of tall cells is simple columnar.

Epithelium	Build	Best-known job and place
Simple squamous	One layer of flat cells	Fast diffusion: lung air sacs, lining of capillaries and vessels
Simple cuboidal	One layer of cube cells	Releasing and absorbing: kidney tubes, gland ducts
Simple columnar	One layer of tall cells	Absorbing and releasing: lining of the stomach and intestines
Stratified squamous	Many stacked flat layers	Protection from rubbing: skin surface, mouth, esophagus, vagina
Pseudostratified columnar	One layer that looks layered	Lining of the airways, with cilia that sweep mucus upward
Transitional	Stretchy layers that change shape	Bladder and ureters: stretches as they fill

Connective tissue	Matrix	Job and place
Loose (areolar)	Soft and gel-like, with loosely woven fibers	All-purpose packing and cushion; under epithelia everywhere
Adipose (fat)	Cells so full of fat that there is little matrix	Stores energy, holds in heat, pads organs
Dense regular	Tightly packed collagen, all lined up the same way	Strong pull in one direction: tendons and ligaments
Cartilage	Firm, rubbery gel	Bendable support: nose, ears, joint surfaces, discs in the spine
Bone (osseous)	Collagen hardened with calcium salts	Stiff support and protection; stores minerals
Blood	Liquid matrix, called plasma	Carries cells, gases, nutrients and wastes

Three fibers run through that whole family. Collagen is rope-like and resists pulling. Elastic fibers stretch and snap back. Reticular fibers are thin and form a mesh that holds things up.

Feature	Skeletal	Cardiac	Smooth
Stripes	Striated	Striated	Non-striated
Control	Voluntary	Involuntary	Involuntary
Cell shape	Long tubes	Short, branched	Tapered spindles
Nuclei per cell	Many	One, or two	One
Where	Attached to bones	Heart wall only	Walls of hollow organs

One more detail for cardiac muscle. Its branched cells are joined end to end by intercalated discs, so the whole heart squeezes as one team.

The neuron is a map of its own signal. Dendrites in, cell body in the middle, axon out. Nervous tissue is defined by excitability and conductivity.

Body membrane	What it is made of	Where
Cutaneous	Stratified squamous epithelium on dense irregular connective tissue	The skin; the only dry membrane
Mucous	An epithelium on a loose layer called the lamina propria	Any space open to the outside: airway, gut, urinary and reproductive tracts
Serous	Simple squamous mesothelium on a thin areolar layer	Closed spaces in the front of the trunk: pleura, pericardium, peritoneum
Synovial	Connective tissue only, with no epithelium	The spaces inside joints

Repair stage	What happens	Purpose
1. Hemostasis	Blood clots seal the broken vessels, and a scab forms	Stop the bleeding
2. Inflammation	Vessels widen, and immune cells arrive to clear junk and germs	Clean up the wound
3. Proliferation	New tiny vessels and collagen build pink granulation tissue; epithelium spreads across the top	Rebuild the tissue
4. Remodeling	Collagen is rearranged and strengthened; the scar matures and shrinks	Make the area strong again over weeks to months

The four visible signs of stage two are redness, heat, swelling and pain. They feel like the problem, but they are the repair getting started.

How to reason through it

Walk-through 1 · naming an epithelium

You get a description or a place and must give the two-word name.

Step 1 · count the layersOne layer is simple. Two or more stacked layers are stratified.

Step 2 · read the surface cellsFlat is squamous. Cube-shaped is cuboidal. Tall is columnar.

Step 3 · sanity-check against the jobThin and simple fits fast crossing. Thick and stratified fits protection. If the two do not agree, re-read the description.

Try itA lung air sac needs gas across in a split second. That calls for the thinnest build, one layer of flat cells. So it is simple squamous.

Walk-through 2 · the three-question muscle sort

Any muscle item falls to the same three questions, in this order.

Step 1 · striped?Non-striated leaves only smooth muscle, and you are done.

Step 2 · voluntary?Striped and voluntary is skeletal. Striped and involuntary is cardiac.

Step 3 · check the cell shapeLong tubes with many nuclei means skeletal. Short branched cells with intercalated discs means cardiac. Tapered spindles means smooth.

Try itA slide shows short branched cells joined end to end, with stripes and one nucleus each. Striped rules out smooth. Branched with discs settles it: cardiac muscle, from the heart wall.

Walk-through 3 · will it regrow or scar?

Repair items reward one question asked first.

Step 1 · can the cells divide?Skin and gut cells divide fast, so those tissues regenerate well. Heart muscle and neurons barely divide, so they tend to scar.

Step 2 · check the blood supplyGood blood flow brings the cells and the building blocks that repair needs.

Step 3 · name the four stages in orderHemostasis, inflammation, proliferation, remodeling. The stage names rarely change, only the outcome.

Try itWhat fills the gap after a heart attack, and what can it not do? Heart muscle cells hardly divide, so the gap fills with scar tissue by fibrosis. Scar is strong, but it cannot beat.

Traps people fall into

Counting pseudostratified as many layers. Every cell touches the basement membrane. Only the nuclei sit at different heights.
Forgetting that adipose is the odd one. Its fat fills the cells, not the matrix.
Calling cardiac muscle voluntary. It is striped, but the heart runs on its own.
Giving the synovial membrane an epithelium. It is connective tissue only.
Saying epithelium has no nerves. It has no blood vessels, but plenty of nerves.
Treating inflammation as the injury. Redness, heat, swelling and pain are the repair at work.
Expecting scar to do the old job. It brings back strength, not function.

Chapter 4 self-test · ten items

1. Name the four primary tissues and the basic need each one meets.

Epithelial covers and lines. Connective binds and supports. Muscle moves. Nervous communicates. Every organ in the body is built from these four.

2. What is the fastest way to tell epithelial from connective tissue on a slide?

Look at how much room the cells give each other. Epithelial cells are crowded with almost no space between them. Connective cells are few and spread out in a matrix they made.

3. Name the epithelium that lines the bladder, and say why that build suits the job.

Transitional epithelium. Its cells slide over each other and flatten as the bladder fills, then bunch back up as it empties.

4. What does "avascular" mean for epithelium, and how does it get fed?

It has no blood vessels of its own, and it is fed by diffusion from the tissue underneath. It still has plenty of nerves, and it regrows fast because surface cells are always wearing away.

5. Give the two parts of an extracellular matrix and the three fiber types.

Fibers and ground substance. The fibers are collagen, elastic and reticular. Collagen resists pulling. Elastic stretches and snaps back. Reticular forms a fine mesh.

6. What does a cell name ending in -blast do, and what does one ending in -cyte do?

A -blast is a young builder that makes matrix. A -cyte is a grown-up cell that keeps it in good shape. So a fibroblast builds and a fibrocyte maintains. The same rule works for bone and cartilage.

7. Which two muscle tissues are striated, and which one of the three is voluntary?

Skeletal and cardiac are striated. Only skeletal is voluntary. The two striped ones are the fast, strong pair. Smooth muscle is the slow, steady one.

8. Trace a signal through a neuron, naming the parts in order.

Dendrites, then the cell body, then the axon, then the axon terminals. The traffic only goes that way. A fatty myelin sheath on the axon lets the signal jump along faster.

9. Which of the four body membranes is dry, and which has no epithelium?

The cutaneous membrane, the skin, is the dry one. The synovial membrane has no epithelium. Mucous membranes line spaces open to the outside. Serous membranes line closed spaces in the front of the trunk.

10. Put the four stages of tissue repair in order and say what stage two looks like.

Hemostasis, inflammation, proliferation, remodeling. Stage two shows redness, heat, swelling and pain. Stage three builds pink granulation tissue. Stage four strengthens the scar over weeks to months.

One pageCram sheet

Everything from chapters 1 to 4 in one place. Cover the right side of each row and try to rebuild it.

Sequences, in order

Sequence	The order
Levels of organization	Chemical → cellular → tissue → organ → organ system → organism
Negative feedback loop	Receptor → control center → effector
Cavity tree	Dorsal (cranial, vertebral); ventral, split by the diaphragm into thoracic and abdominopelvic
Central dogma	DNA → RNA → protein
Protein synthesis	Transcription in the nucleus → mRNA out a pore → translation at a ribosome
Secreted protein path	Ribosome → rough ER → Golgi → vesicle
Cell cycle	G₁ → S (DNA copied) → G₂ → mitosis → cytokinesis
Mitosis (PMAT)	Prophase → metaphase → anaphase → telophase
Neuron signal	Dendrites → cell body → axon → axon terminals
Tissue repair	Hemostasis → inflammation → proliferation → remodeling

Numbers and values

Item	Value from the book
Levels of organization	6
Organ systems	11
Primary tissues	4
Body membranes	4: cutaneous, mucous, serous, synovial
Temperature set point	About 37 °C
Blood pH	7.35 to 7.45; acidosis below, alkalosis above
Danger pH	Past about 6.8 or 7.8, proteins unfold and enzymes fail
Stomach acid / urine / water / pancreatic juice	About 2 / about 6 / 7 / about 8
One pH unit	A tenfold change in free H⁺
Octet rule	A full outer shell is 8 electrons for most body atoms
Six main elements	O 65%, C 18%, H 10%, N 3%, Ca 1.5%, P 1%; about 99% together
Body water	About 60% of you
Sodium and potassium pump	3 Na⁺ out, 2 K⁺ in, per ATP
Codon	3 mRNA bases = 1 amino acid
Amino acid kinds	20
Normal saline	0.9%, and it is isotonic
Glial cells to neurons	About one to one across the whole brain

Rules that decide an answer

Topic	The rule
Direction words	Read from the anatomical position. The word describes the first part named. Right and left are the patient's.
Proximal and distal	Limbs only, measured from where the limb joins the trunk.
Planes	Sagittal = left and right. Frontal = front and back. Transverse = top and bottom.
Serous layers	Parietal lines the wall. Visceral hugs the organ.
Feedback type	Response undoes the change = negative. Response adds to it = positive, and it needs a stop.
Atom counts	Protons = atomic number. Neutrons = mass number − atomic number. Neutral means electrons = protons.
Bond type	Electron handed over = ionic. Pair shared = covalent, even or uneven. Pull between molecules = hydrogen.
Reaction type	A + B → AB = synthesis. AB → A + B = decomposition. AB + CD → AC + BD = exchange.
Enzymes	Lower activation energy, fit one substrate, are not used up, and fail if unfolded.
Building and breaking	Dehydration synthesis takes water out to build. Hydrolysis adds water to break.
Transport	Downhill = passive and free, protein or not. Uphill = active and costs energy.
Osmosis	Water follows the solute. Find the saltier side and send the water there.
Tonicity	Isotonic = no change. Hypotonic = swell, maybe lysis. Hypertonic = shrivel, crenation.
RNA bases	C pairs with G. DNA's A calls for U, because RNA uses uracil for thymine.
Naming an epithelium	Layers (simple or stratified) + surface cell shape (squamous, cuboidal, columnar).
Epithelium exceptions	Pseudostratified is really one layer. Transitional stretches in the urinary tract.
Connective tissue	Spread-out cells in a matrix of fibers + ground substance. Change the matrix, change the tissue.
Cell name endings	-blast builds matrix. -cyte maintains it.
Muscle sort	Striped? Voluntary? Cell shape? Only skeletal is voluntary; only cardiac has intercalated discs.
Healing path	Cells divide well = regeneration. Cells barely divide = fibrosis, which is strong but cannot do the old job.