Biology · Unit 10 · Quick reference

Anatomy & Physiology

Grades 10–12+8 pages

Anatomical language, homeostasis and normal values; cells and tissues; the skin, skeleton and muscles; neurons, brain, cranial nerves and special senses; hormones; heart, blood and vessels; lymphatic and immune defense; breathing, digestion, kidneys and acid–base; reproduction and development.

1Anatomical terms2Homeostasis & values3Cells & tissues4Integumentary5Skeletal6Muscular7Neurons8Brain & nerves9Special senses10Endocrine11Heart12Blood & immunity13Respiratory14Digestive15Urinary & acid–base16Reproduction & development

1Anatomical Language

Anatomical position

Upright, facing forward, arms at the sides, palms forward.
Directions are the patient’s: “left” means the patient’s left.

Directional terms
Term	Means	Opposite
Superior (cranial)	toward the head	inferior (caudal)
Anterior (ventral)	toward the front	posterior (dorsal)
Medial	toward the midline	lateral
Proximal	nearer a limb’s attachment	distal
Superficial	toward the surface	deep

EX: the wrist is proximal to the fingers; skin is superficial to muscle.

Body planes
Plane	Divides into
Sagittal (median = midsagittal)	right and left
Frontal (coronal)	front and back
Transverse (axial)	upper and lower

Body cavities
Cavity	Holds
Cranial; vertebral canal	brain; spinal cord
Thoracic: pleural ×2	lungs
Thoracic: mediastinum	heart (pericardial cavity), trachea, esophagus, great vessels
Abdominal	stomach, intestines, liver, spleen, pancreas
Pelvic	bladder, rectum, internal reproductive organs

The diaphragm divides thoracic from abdominopelvic.

Nine abdominopelvic regions (solid) and four quadrants (dashed), facing the patient.

What lies where
Quadrant	Main organs
RUQ	liver, gallbladder, duodenum, pancreas head
LUQ	stomach, spleen, pancreas tail
RLQ	cecum, appendix, right ovary
LLQ	sigmoid colon, left ovary

Appendicitis pain often starts at the navel, then settles in the RLQ.

2Organization, Homeostasis & Normal Values

Levels of organization

Chemical → cell → tissue → organ → organ system → organism. Eleven systems: integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, reproductive.

“I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well” (Psalm 139:14, KJV).

Homeostasis

A stable internal state. Stimulus → receptor → control center → effector → response.
Negative feedback (most) reverses a change: temperature, glucose, blood pressure.
Positive feedback amplifies until an end event: labor (oxytocin), platelet plug, LH surge.

Negative keeps you normal

Negative feedback nudges back to normal; positive feedback pushes on until something ends it (a birth, a clot).

Resting vitals, chemistry and gases
Measure	Typical adult
Temperature	36.5–37.3 °C (97.7–99.1 °F)
Heart rate	60–100/min
Breathing rate	12–18/min
Blood pressure	< 120/80 mm Hg
O₂ saturation	95–100 %
Sodium	136–144 mEq/L
Potassium	3.5–5.0 mEq/L
Bicarbonate	22–28 mEq/L
Calcium (total)	8.5–10.2 mg/dL
Glucose (fasting)	70–99 mg/dL
Creatinine	0.8–1.2 mg/dL
Arterial pH	7.35–7.45
PaCO₂; PaO₂	35–45; 80–100 mm Hg

Blood counts
CBC	Male	Female
Hemoglobin (g/dL)	13–18	12–16
Hematocrit (%)	40–55	36–48
WBC (per µL)	4,500–11,000	same
Platelets (per µL)	150,000–400,000	same

Typical values (MedlinePlus, Merck Manual); each lab sets its own range.

Body fluids
Fluid	Share	70 kg
Total body water	≈ 60 % of mass (men)	42 L
Intracellular	⅔ of water	28 L
Extracellular	⅓: ¾ interstitial, ¼ plasma	14 L

Plasma osmolality ≈ 2 Na⁺ + glucose ÷ 18 + BUN ÷ 2.8 = 2(140) + 90 ÷ 18 + 14 ÷ 2.8 = 290 mOsm/kg (normal ≈ 275–295).

Anatomy & PhysiologyBiology · Unit 10 · continued

3Cells & Tissues

Cell parts
Cell part	Job	Cell part	Job
Plasma membrane	phospholipid bilayer with proteins; controls entry	Golgi apparatus	modifies, packages and ships proteins
Nucleus; nucleolus	holds DNA; builds ribosomes	Mitochondria	make most ATP (aerobic respiration)
Ribosomes; rough ER	make proteins	Lysosomes	digest worn parts and microbes
Smooth ER	lipids; detoxification; Ca²⁺ store (muscle)	Cilia; flagellum	move fluid (airway); move a sperm

Crossing the membrane
Process	ATP?	Example
Diffusion; osmosis	no	O₂ into blood; water toward more solute
Facilitated diffusion	no	glucose by carriers
Active transport	yes	Na⁺/K⁺ pump: 3 Na⁺ out, 2 K⁺ in
Exocytosis	yes	releasing neurotransmitter

Red cells: isotonic (0.9 % NaCl) no change; hypotonic swell and burst; hypertonic shrink.

Connective tissues
Connective tissue	Where
Areolar; adipose	under epithelia; hypodermis
Dense regular	tendons, ligaments
Dense irregular	dermis, joint capsules
Hyaline cartilage	joint surfaces, trachea, costal cartilage
Elastic cartilage	external ear, epiglottis
Fibrocartilage	intervertebral discs, menisci

The four tissue types
Tissue	Features	Examples
Epithelial	cell sheets on a basement membrane; no vessels; covers, lines, forms glands	epidermis, gut lining
Connective	cells in matrix of fibers and ground substance	tendon, bone, fat, blood
Muscle	contracts	skeletal, cardiac, smooth
Nervous	neurons signal; glia support	brain, nerves

Junctions and glands

Tight junctions seal; desmosomes anchor; gap junctions pass ions cell to cell (heart, smooth muscle).
Exocrine glands use ducts (sweat, saliva); endocrine glands release hormones into the blood.

Epithelia
Epithelium	Where
Simple squamous	alveoli, capillary endothelium
Simple cuboidal	kidney tubules, gland ducts
Simple columnar	stomach, intestine
Pseudostratified ciliated	trachea, bronchi
Stratified squamous	epidermis, mouth, esophagus
Transitional	bladder, ureters (stretch)

Muscle tissue
	Skeletal	Cardiac	Smooth
Striated	yes	yes	no
Control	voluntary	involuntary	involuntary
Nuclei	many, peripheral	1–2, central	1, central
Special	long cylinders	branched; intercalated discs	spindle-shaped

4Integumentary System

Jobs of the skin

Barrier to water loss, microbes and UV; temperature control; makes vitamin D₃ with UVB; senses touch, pain and temperature.

Layers
Layer	Made of; notes
Epidermis	keratinized stratified squamous epithelium; no vessels; renews ≈ every 4 weeks
Dermis	papillary (areolar; fingerprints) over reticular (dense irregular; glands, follicles)
Hypodermis	fat and areolar tissue; not part of the skin

Glands and hair

Eccrine sweat glands cool the body; apocrine (armpit, groin) start at puberty; sebaceous glands oil hair and skin.
Melanin from melanocytes shields DNA from UV.

Epidermis
Stratum (deep → surface)	Notes
Basale	stem cells divide; melanocytes, tactile (Merkel) cells
Spinosum	desmosomes; dendritic (Langerhans) immune cells
Granulosum	keratin fills cells; they die
Lucidum	thick skin only (palms, soles)
Corneum	dead, flat keratin cells that flake off

Come, Let’s Get Sun Burned

Corneum, Lucidum, Granulosum, Spinosum, Basale: surface to deep. (Traditional.)

Skin cancer warning signs

ABCDE of a mole (Traditional): Asymmetry, Border irregular, Color varied, Diameter > 6 mm, Evolving. Basal cell carcinoma is most common; melanoma is most deadly.

Burns
Burn depth	Damage; look
Superficial (1st degree)	epidermis; red, painful
Partial thickness (2nd)	into dermis; blisters, very painful
Full thickness (3rd)	whole dermis; white or leathery, little pain

Rule of nines (Traditional)
Adult area	%
Head and neck	9
Each arm	9
Front of trunk	18
Back of trunk	18
Each leg	18
Perineum	1

The patient’s palm with fingers ≈ 1 %. Children need a separate chart.

Estimate a burn Worked

whole right arm + front of trunk: 9 + 18 = 27 %partial and full thickness only

Anatomy & PhysiologyBiology · Unit 10 · continued

5Skeletal System

Adult skeleton. Bones support, protect, store 99 % of body calcium and make blood cells. Vesalius drew it from his own dissections (Fabrica, 1543).

The 206 adult bones
Division	Bones	Count
Axial: 80	skull (8 cranial + 14 facial)	22
	ossicles 6, hyoid 1	7
	vertebrae	26
	24 ribs + sternum	25
Appendicular: 126	pectoral girdles (clavicle, scapula ×2)	4
	upper limbs	60
	hip bones	2
	lower limbs	60

Arm (30): humerus, radius, ulna, 8 carpals, 5 metacarpals, 14 phalanges. Leg (30): femur, patella, tibia, fibula, 7 tarsals, 5 metatarsals, 14 phalanges.

Sally Left The Party To Take Cathy Home

Carpals, lateral to medial: scaphoid, lunate, triquetrum, pisiform; trapezium, trapezoid, capitate, hamate. (Traditional.)

Vertebrae (26) and ribs

Cervical 7 (C1 atlas nods; C2 axis turns), thoracic 12, lumbar 5, sacrum, coccyx. Breakfast at 7, lunch at 12, dinner at 5. (Traditional.) Ribs 1–7 true; 8–12 false (11–12 floating).

Bone tissue

Diaphysis (shaft): compact bone, yellow marrow. Epiphysis (end): spongy bone, red marrow. Growth plate between.
Osteoblasts build; osteoclasts carve; osteocytes maintain. (Traditional.)

Synovial joints (move freely)
Synovial joint	Examples
Hinge	elbow, fingers; knee (modified)
Pivot	atlas on axis; radius on ulna
Saddle	thumb base
Ball-and-socket	shoulder, hip

Fibrous: sutures. Cartilaginous: pubic symphysis, discs.

6Muscular System

Major muscles
Muscle	Action	Muscle	Action
Sternocleidomastoid	flexes, turns neck	Rectus abdominis	flexes trunk
Trapezius	moves scapula	Iliopsoas	flexes hip
Deltoid	abducts arm	Gluteus maximus	extends hip
Pectoralis major	flexes, adducts arm	Gluteus medius	abducts hip
Latissimus dorsi	extends, adducts arm	Quadriceps	extends knee
Biceps brachii	flexes elbow, supinates	Hamstrings	flex knee
Triceps brachii	extends elbow	Gastrocnemius	plantar flexes
Diaphragm	inspiration	Tibialis anterior	dorsiflexes

“C3, 4, 5 keeps the diaphragm alive”: the phrenic nerve’s roots. (Traditional.)

Terms

Origin fixed, insertion moves. Agonist acts, antagonist opposes, synergist helps.
Muscle → fascicle → fiber → myofibril → sarcomere.

Filaments slide; none changes length.

Sliding filament steps

Motor neuron releases acetylcholine at the neuromuscular junction.
Action potential runs along the sarcolemma and T tubules.
Sarcoplasmic reticulum releases Ca²⁺; Ca²⁺ binds troponin, moving tropomyosin off actin.
Myosin binds actin and pulls (power stroke); ATP releases and re-cocks it.
Relax: ACh broken down; Ca²⁺ pumped back.

Proposed in 1954 by H. E. Huxley and J. Hanson and by A. F. Huxley and R. Niedergerke.

Calcium unlocks, ATP lets go

Ca²⁺ uncovers actin; ATP releases the grip. No ATP after death: rigor mortis.

SITS

Rotator cuff: Supraspinatus, Infraspinatus, Teres minor, Subscapularis. (Traditional.)

Movements and energy

Flexion/extension close/open a joint; abduction/adduction move from/to the midline; pronation/supination turn the palm back/forward.
ATP: creatine phosphate (≈ 10–15 s), anaerobic glycolysis, aerobic respiration (hours).

Anatomy & PhysiologyBiology · Unit 10 · continued

7Neurons & Nerve Signals

Organization

CNS: brain, spinal cord. PNS: 12 cranial and 31 spinal nerve pairs.
Afferent (sensory) fibers carry signals in; efferent (motor) carry them out: somatic to skeletal muscle, autonomic to heart, smooth muscle, glands.

Myelin: the signal jumps node to node (saltatory).

Neuroglia

CNS: astrocytes, oligodendrocytes (myelin), microglia, ependymal cells. PNS: Schwann cells (myelin).

One action potential lasts ≈ 1–2 ms.

The action potential

Resting ≈ −70 mV; the Na⁺/K⁺ pump keeps Na⁺ out, K⁺ in.
Threshold ≈ −55 mV: Na⁺ channels open → depolarization to ≈ +30 mV.
K⁺ channels open → repolarization, brief hyperpolarization.
All-or-none; the refractory period keeps it one-way.

Hodgkin and Huxley measured these currents in squid axons (1952).

Synapse

Ca²⁺ enters terminal → transmitter released → binds receptors → cleared.
ACh (muscle, parasympathetic); norepinephrine (sympathetic); dopamine (movement); GABA inhibits; glutamate excites.

Tendon reflexes
Reflex	Level
Biceps	C5–C6
Triceps	C7–C8
Patellar (knee)	L3–L4
Calcaneal (ankle)	S1–S2

Arc: receptor → sensory neuron → cord → motor neuron → effector.

Buckle my shoe

“S1, 2, buckle my shoe; L3, 4, kick the door; C5, 6, pick up sticks; C7, 8, lay them straight.” (Traditional.)

8Brain, Cranial Nerves & Autonomic System

Cranial nerves (S sensory, M motor, B both)
#	Nerve		Main job	#	Nerve		Main job
I	Olfactory	S	smell	VII	Facial	B	facial expression; taste, front ⅔; tears, saliva
II	Optic	S	vision	VIII	Vestibulocochlear	S	hearing, balance
III	Oculomotor	M	most eye movements, eyelid, pupil constriction	IX	Glossopharyngeal	B	taste, back ⅓; swallowing; parotid; carotid sinus
IV	Trochlear	M	superior oblique	X	Vagus	B	throat, voice; parasympathetic to heart, lungs, gut
V	Trigeminal	B	face sensation; chewing	XI	Accessory	M	sternocleidomastoid, trapezius
VI	Abducens	M	lateral rectus	XII	Hypoglossal	M	tongue

Left hemisphere, cerebellum and brainstem.

Protection

Meninges, brain outward: Pia, Arachnoid, Dura (“PAD,” Traditional). CSF (≈ 150 mL; ≈ 500 mL/day from choroid plexus) fills the subarachnoid space.
Spinal cord ends near L1–L2.

Brain regions
Region	Main jobs
Frontal	planning; motor cortex; Broca area (speech, usually left)
Parietal	body sensation (postcentral gyrus)
Temporal	hearing; Wernicke area (language); memory
Occipital	vision
Thalamus	sensory relay to cortex
Hypothalamus	temperature, thirst, hunger; runs the pituitary
Brainstem	midbrain, pons, medulla: breathing, heart rate
Cerebellum	balance, coordination

Oh Oh Oh To Touch And Feel Very Good Velvet, AH

Cranial nerves I to XII. (Traditional.)

Some Say Marry Money, But My Brother Says Big Brains Matter More

Sensory, motor or both, I to XII. (Traditional.)

Autonomic nervous system
	Sympathetic	Parasympathetic
Called	fight or flight	rest and digest
Leaves CNS	T1–L2	CN III, VII, IX, X; S2–S4
Final transmitter	norepinephrine	acetylcholine
Pupils; heart	dilate; faster	constrict; slower
Airways; gut	dilate; slows	constrict; speeds

Sympathetic also triggers adrenal epinephrine; sweat glands use ACh. The vagus carries ≈ 75 % of parasympathetic fibers.

Anatomy & PhysiologyBiology · Unit 10 · continued

9Special Senses

The eye
Eye layer	Parts
Fibrous	sclera; cornea (most focusing)
Vascular (uvea)	choroid, ciliary body (shapes lens), iris
Neural	retina: rods, cones

Light: cornea → aqueous humor → pupil → lens → vitreous humor → retina → optic nerve → thalamus → occipital cortex.

Receptors
Retina	Notes
Rods (≈ 120 million)	dim light; gray scale
Cones (≈ 6 million)	color, detail
Fovea centralis	cones only; sharpest
Optic disc	no receptors: blind spot

Pupil and pathway

Near focus: ciliary muscle contracts, lens rounds, pupil constricts (parasympathetic, CN III). Dim light or alarm: pupil dilates (sympathetic).
At the optic chiasm the nasal half of each retina crosses, so each side of the brain sees the opposite visual field.

Cones for color

Cones see color and detail; rods work in dim rooms.

Focus problems

Myopia: image in front of retina; concave lens. Hyperopia: behind; convex lens.
Presbyopia: stiff lens with age. Cataract: cloudy lens. Glaucoma: optic-nerve damage, often high eye pressure.

The ear
Ear	Structures	Job
Outer	auricle, canal, eardrum	collect sound
Middle	malleus, incus, stapes; auditory tube	amplify; equalize pressure
Inner	cochlea (spiral organ)	hearing
	vestibule; semicircular canals	tilt and straight motion; rotation

Sound: eardrum → ossicles → oval window → cochlear fluid → hair cells → CN VIII → temporal lobe. Hearing ≈ 20–20,000 Hz.

Smell and taste

Smell: CN I; the one sense that reaches cortex without passing the thalamus first.
Taste: sweet, sour, salty, bitter, umami; CN VII, IX, X.

10Endocrine System

Glands and hormones
Gland	Hormones → main effect
Hypothalamus	releasing hormones (TRH, CRH, GnRH, GHRH) for the pituitary; makes ADH, oxytocin
Anterior pituitary	GH → growth; TSH → thyroid; ACTH → adrenal cortex; FSH, LH → gonads; prolactin → milk
Posterior pituitary	releases ADH (kidneys keep water) and oxytocin (labor, milk let-down)
Thyroid	T₄, T₃ (iodine) → metabolic rate; calcitonin → lowers Ca²⁺
Parathyroids	PTH → raises Ca²⁺ (bone, kidney, vitamin D)
Adrenal cortex	aldosterone → keep Na⁺, lose K⁺; cortisol → stress, glucose; androgens
Adrenal medulla	epinephrine, norepinephrine → fight or flight
Pancreatic islets	insulin (β) lowers glucose; glucagon (α) raises it
Pineal; thymus	melatonin (sleep); thymosins (T cells)
Gonads	testosterone; estrogen and progesterone
Kidney; heart	EPO (red cells); ANP (lose Na⁺ and water)

Two kinds of hormones

Steroids (cortisol, aldosterone, sex hormones) and thyroid hormone enter cells and change gene expression.
Peptides and amines (insulin, ADH, epinephrine) bind membrane receptors; second messengers such as cAMP.

FLAT PiG

Anterior pituitary: FSH, LH, ACTH, TSH, Prolactin, (i), GH. (Traditional.)

Feedback axis

Low T₄ → TRH → TSH → thyroid makes T₄; rising T₄ shuts off TRH and TSH.
Same pattern: CRH → ACTH → cortisol; GnRH → FSH/LH → sex hormones.

Salt, sugar, sex hormones

Adrenal cortex, outer to inner: aldosterone, cortisol, androgens. (Traditional.)

Glucose criteria
Fasting glucose	A1C	ADA category
70–99 mg/dL	< 5.7 %	normal
100–125	5.7–6.4 %	prediabetes
≥ 126	≥ 6.5 %	diabetes (repeat to confirm)

Glucagon when glucose is gone

Glucagon answers glucose gone; insulin puts glucose in. (Traditional.)

Blood glucose

High → insulin → cells take up glucose; liver stores glycogen.
Low → glucagon → liver releases glucose.
Type 1: autoimmune loss of β cells. Type 2: insulin resistance (most common).

Banting and Best isolated insulin in Toronto (1921).

Too much, too little

Thyroid: hyper (Graves): fast pulse, heat intolerance, weight loss; hypo (Hashimoto): fatigue, cold intolerance, weight gain.
Cortisol: excess = Cushing syndrome; adrenal failure = Addison disease. GH excess: gigantism in children, acromegaly in adults.

Anatomy & PhysiologyBiology · Unit 10 · continued

11The Heart

Blue: oxygen-poor (right heart). Red: oxygen-rich (left heart).

Path of blood

Venae cavae → RA → tricuspid → RV → pulmonary valve → lungs (pulmonary circuit) → pulmonary veins → LA → mitral → LV (thickest wall) → aortic valve → aorta → body (systemic circuit).

Harvey showed the blood circulates (De Motu Cordis, 1628).

Tri before you bi

Blood passes the tricuspid before the bicuspid (mitral). (Traditional.)

Conduction system
Conduction	Own rate
SA node (pacemaker)	60–100/min
AV node (delay lets ventricles fill)	40–60/min
AV bundle → bundle branches → Purkinje fibers	20–40/min

P: atria depolarize. QRS: ventricles depolarize. T: ventricles repolarize.

Resting adult Worked

EDV 120, ESV 50 mL: SV = 70 mL; EF = 58 %normal ≈ 50–70 %

CO = 70/min × 70 mL = 4.9 L/min

Coronary arteries
Coronary artery	Supplies
LAD	front of left ventricle; front ⅔ of septum
Circumflex	side and back of left ventricle
Right coronary	right ventricle; usually SA and AV nodes

Reading the ECG Worked

PR 0.12–0.20 s; QRS < 0.12 s; big box 0.20 sat 25 mm/s

R to R = 4 big boxes = 0.80 s → 60 ÷ 0.80 = 75/minor 300 ÷ 4

Output

Frank–Starling: more filling → stronger beat. S1: AV valves close; S2: semilunar valves close.

CO = HR × SV

SV = EDV − ESV

EF = SV ÷ EDV

12Blood, Vessels & Immunity

Blood (≈ 5 L)
Part	Facts
Plasma ≈ 55 %	≈ 92 % water; albumin, globulins, fibrinogen
Red cells ≈ 45 %	the hematocrit; no nucleus; live ≈ 120 days; kidney EPO drives production
White cells, platelets < 1 %	platelets: cell fragments; 7–10 days

“For the life of the flesh is in the blood” (Leviticus 17:11, KJV).

White cells, most to fewest
White cell	%	Job
Neutrophils	40–60	first responders; bacteria
Lymphocytes	20–40	B, T and NK cells
Monocytes	2–8	become macrophages
Eosinophils	1–4	parasites, allergy
Basophils	0.5–1	histamine

Order: Never Let Monkeys Eat Bananas. (Traditional.)

Hemostasis

Spasm → platelet plug → coagulation: thrombin turns fibrinogen into fibrin (needs Ca²⁺, vitamin K).

ABO types (Landsteiner, 1901)
Type	Antigens	Antibodies	Receives
A	A	anti-B	A, O
B	B	anti-A	B, O
AB	A, B	none	all
O	none	anti-A, B	O

Rh⁺ = D antigen. O⁻: universal donor; AB⁺: universal recipient.

Adult blood pressure (mm Hg)
2025 AHA/ACC	Systolic		Diastolic
Normal	< 120	and	< 80
Elevated	120–129	and	< 80
Stage 1	130–139	or	80–89
Stage 2	≥ 140	or	≥ 90

Arteries carry blood away from the heart; veins hold ≈ 60–70 % of it.

Mean arterial pressure Worked

120/80: 80 + ⅓(120 − 80) = 93 mm HgMAP ≈ D + ⅓(S − D)

Lymphatic system

Returns ≈ 3 L/day of tissue fluid (lymph); absorbs fat (lacteals). Organs: red marrow, thymus (T cells mature), lymph nodes, spleen (filters blood). Thoracic duct → left subclavian vein; right lymphatic duct drains the upper right quarter.

Lines of defense
Defense	Examples
Innate: barriers	skin, mucus, cilia, stomach acid
Innate: inside	phagocytes, NK cells, inflammation, fever, complement
Adaptive	specific, with memory: B cells (antibodies), T cells

Inflammation: redness, heat, swelling, pain (rubor, calor, tumor, dolor).

Lymphocytes

Helper T (CD4) directs; cytotoxic T (CD8) kills infected cells; plasma cells (from B cells) make antibodies; memory cells speed a second response.

GAMED

Antibodies: IgG (most; crosses placenta), IgA (tears, milk), IgM (first made), IgE (allergy, parasites), IgD (B-cell receptor). (Traditional.)

Acquired immunity
Immunity	Natural	Artificial
Active (lasting)	having the disease	vaccination
Passive (weeks)	via placenta, milk	antibody shot

Jenner vaccinated against smallpox with cowpox (1796).

Anatomy & PhysiologyBiology · Unit 10 · continued

13Respiratory System

Airway

Nasal cavity → pharynx → larynx (epiglottis, vocal folds) → trachea → main bronchi → bronchioles → alveoli (≈ 300–500 million, ≈ 70 m²).
Type I alveolar cells: gas exchange. Type II: surfactant.

Lungs

Right: 3 lobes; left: 2 (cardiac notch).
Right main bronchus is wider and more vertical: inhaled objects usually go right.

Lung volumes
Volume	Typical (male)
Tidal (TV)	500 mL
Inspiratory reserve	3100 mL
Expiratory reserve	1200 mL
Residual (RV)	1200 mL
Vital capacity = TV + IRV + ERV	4800 mL
Total = VC + RV	6000 mL

Women’s are ≈ 20–25 % smaller.

Breathing (Boyle’s law)

Inhale: diaphragm contracts and flattens, external intercostals lift ribs → volume up, pressure down → air in.
Quiet exhale is passive recoil.

Ventilation Worked

500 mL × 12/min = 6.0 L/minminute

(500 − 150 dead space) × 12 = 4.2 L/minalveolar

Partial pressures (mm Hg)
Site	PO₂	PCO₂
Air at sea level	0.21 × 760 ≈ 160	≈ 0.3
Alveoli	≈ 104	40
Arterial	80–100	35–45
Venous	≈ 40	≈ 46

Control

Rhythm from the medulla (with the pons).
Main drive: CO₂ sensed centrally (CSF H⁺). Carotid and aortic bodies add a low-O₂ drive (PaO₂ below ≈ 60).

Transport

O₂: ≈ 98.5 % on hemoglobin. CO₂: ≈ 70 % as HCO₃⁻, ≈ 23 % on hemoglobin, ≈ 7 % dissolved.
More O₂ unloads when CO₂, H⁺ or temperature rise (Bohr effect).

Oxygen content Worked

CaO₂ = 1.34 × Hb × SaO₂ + 0.003 × PaO₂

1.34(15)(0.98) + 0.003(100) = 20.0 mL/dL

Common lung problems
Problem	What goes wrong
Asthma	reversible airway narrowing; wheeze
COPD	emphysema (alveoli destroyed), chronic bronchitis; mostly smoking
Pneumonia	infected alveoli fill with fluid
Pneumothorax	air in the pleural space; lung collapses
Pulmonary embolism	clot (usually from leg veins) blocks a pulmonary artery

14Digestive System

The GI tract

Mouth → pharynx → esophagus → stomach → duodenum, jejunum, ileum → cecum (appendix) → ascending, transverse, descending, sigmoid colon → rectum → anus.
Accessory: salivary glands, liver, gallbladder, pancreas.

Teeth and swallowing

Adult 32: in each quarter 2 incisors, 1 canine, 2 premolars, 3 molars. Children 20: 2 incisors, 1 canine, 2 molars per quarter.
Swallowing: the epiglottis covers the larynx; peristalsis moves food; the lower esophageal and pyloric sphincters guard the stomach.

Gastric glands
Stomach cell	Secretes
Parietal	HCl (pH ≈ 1.5–3.5); intrinsic factor (for B₁₂)
Chief	pepsinogen
G cell	gastrin
D cell	somatostatin (brakes acid)

Enzymes
Enzyme	Source	Breaks
Salivary amylase	mouth	starch
Pepsin	stomach	protein
Pancreatic amylase	pancreas	starch
Trypsin, chymotrypsin	pancreas	protein
Lipase	pancreas	fat → monoglycerides, fatty acids
Lactase, sucrase, peptidases	brush border	disaccharides, peptides

Bile salts (liver, stored in the gallbladder) emulsify fat; bile has no enzymes.

GI hormones
Hormone	Trigger → effect
Gastrin	food in stomach → acid
Secretin	acid in duodenum → pancreatic bicarbonate
CCK	fat in duodenum → gallbladder contracts, enzymes

Secretin sends soda

Secretin sends bicarbonate (baking soda); CCK calls bile and enzymes for fat.

Absorption
Where	Absorbed
Duodenum	iron, calcium
Jejunum	most nutrients
Terminal ileum	B₁₂, bile salts
Colon	water, salts; bacteria make vitamin K

Fats enter lacteals as chylomicrons; the rest goes to the liver by the hepatic portal vein.

Common digestive problems
Problem	Cause; sign
GERD	acid backs up past the lower esophageal sphincter; heartburn
Peptic ulcer	mostly H. pylori infection or NSAIDs
Gallstones	pain after fatty meals (CCK)
Lactose intolerance	low lactase; gas, diarrhea after milk
Celiac disease	gluten damages small-intestine villi

Liver (≈ 1.5 kg)

Makes bile (bilirubin from old red cells), albumin and clotting factors; stores glycogen, iron, vitamins; turns ammonia into urea; detoxifies drugs.

Beaumont studied digestion through Alexis St. Martin’s stomach opening (1822–1833).

Anatomy & PhysiologyBiology · Unit 10 · continued

15Urinary System & Acid–Base

Organs and jobs

Kidneys (retroperitoneal, ≈ T12–L3) → ureters → bladder → urethra. Kidneys filter blood, balance water, ions and pH, and make renin, EPO and active vitamin D.

About 1 million nephrons per kidney.

Along the nephron
Part	What happens
Glomerulus, capsule	filtration of water and small solutes
PCT	≈ 65 % of Na⁺, water back; all glucose
Descending limb	water out
Ascending limb	NaCl out; water stays
DCT	aldosterone: Na⁺ in, K⁺ out
Collecting duct	ADH inserts aquaporins: water back

How much is reabsorbed? Worked

GFR 125 mL/min × 1440 = 180 L/day

urine 1.5 L/day: 1.5 ÷ 180 ≈ 0.8 % → ≈ 99 % reabsorbed

RAAS

Low pressure → renin → angiotensin I → ACE (lungs) → angiotensin II: vasoconstriction, aldosterone, ADH, thirst. ANP (heart) opposes it.

Acid–base

Normal: 24 ÷ (0.03 × 40) = 20; 6.1 + log 20 = 7.40. Lungs fix CO₂ in minutes; kidneys fix HCO₃⁻ over days.

pH = 6.1 + log [HCO₃⁻ ÷ (0.03 × PaCO₂)]

Acid–base disorders
Disorder	pH	Primary	Example
Resp. acidosis	↓	CO₂ ↑	slow breathing
Resp. alkalosis	↑	CO₂ ↓	fast breathing
Metab. acidosis	↓	HCO₃⁻ ↓	ketoacidosis, diarrhea
Metab. alkalosis	↑	HCO₃⁻ ↑	vomiting

ROME

Respiratory Opposite (pH vs CO₂); Metabolic Equal (pH with HCO₃⁻). (Traditional.)

16Reproduction & Development

Sex is set at fertilization

The sperm carries X or Y: XX female, XY male.
The SRY gene on the Y starts testis development (≈ week 7); testosterone shapes male anatomy.

Male system
Male	Job
Testes (≈ 2–3 °C below core)	tubules make sperm (FSH); Leydig cells make testosterone (LH)
Epididymis	sperm mature, are stored
Ductus (vas) deferens	carries sperm
Seminal vesicles	≈ 60–70 % of semen; fructose
Prostate	≈ 25–30 %; PSA
Bulbourethral glands	neutralizing mucus

SEVEN UP

Sperm path: Seminiferous tubules, Epididymis, Vas deferens, Ejaculatory duct, (Nothing), Urethra, Penis. (Traditional.)

Making gametes (meiosis)

Sperm: from puberty on; 4 per cell; ≈ 64–74 days. Eggs: begun before birth, paused in prophase I; 1 ovum + polar bodies; meiosis II ends at fertilization.

Female system
Female	Job
Ovaries	oocytes; estrogen, progesterone
Uterine tubes	fertilization, usually in the ampulla
Uterus	endometrium (lining), myometrium (muscle); cervix
Vagina; vulva	birth canal; external genitalia

A 28-day cycle
Day	Ovary	Uterus
1–5	follicles start (FSH)	menstrual: lining sheds
6–13	follicular: estrogen rises	proliferative
≈ 14	ovulation after the LH surge
15–28	luteal: corpus luteum, progesterone	secretory

Rising estrogen triggers the LH surge (positive feedback); 21–35-day cycles are normal. hCG, which pregnancy tests detect, keeps the corpus luteum.

First two weeks

Fertilization: a new human organism, the zygote, with 46 chromosomes and its own DNA. Morula (day 3–4) → blastocyst (inner cell mass → embryo; trophoblast → placenta) → implantation begins ≈ day 6–7.

“For thou hast possessed my reins: thou hast covered me in my mother’s womb” (Psalm 139:13, KJV).

Gastrulation (week 3)
Germ layer	Becomes
Ectoderm	epidermis; brain, spinal cord, nerves
Mesoderm	muscle, bone, heart, blood, kidneys, gonads
Endoderm	gut and airway linings, liver, pancreas, thyroid

Timeline
From fertilization	Milestone
Day ≈ 22	heart beats
Week 4	neural tube closes (folic acid helps)
Weeks 3–8	embryo: organs form
Week 9 on	fetus: growth
≈ 38 weeks	birth (≈ 40 weeks from LMP)

Due date (Naegele, Traditional) Worked

LMP + 1 yr − 3 mo + 7 days ≈ LMP + 280 days

LMP March 1, 2026 → December 8, 2026 by the rule (about 280 days)

Fetal circulation
Fetal shunt	Route	Becomes
Ductus venosus	skips liver	ligamentum venosum
Foramen ovale	RA → LA	fossa ovalis
Ductus arteriosus	pulmonary trunk → aorta	ligamentum arteriosum

Umbilical vein (1) brings O₂-rich blood; 2 arteries return it. Maternal and fetal blood do not mix.