Comprehensive Human Anatomy and Physiology Study Guide: Chapters 11-20

Pheromones and the Human Sense of Smell

• Hormones: Biochemicals that spread messages within an individual.
• Pheromones: Chemical signals sent between individuals of a species, often stimulating mating behavior in insects and rodents.
• Rodent Mate Selection: Mice/rats choose mates with dissimilar genes for immunity to prevent inbreeding and strengthen offspring immune systems. Receptors in the olfactory epithelium (trace amine-associated receptors) detect these signals in urine.
• Human Study: Researchers in Switzerland typed DNA of 49 women and 44 men. Women preferred the scent of tee shirts from men genetically dissimilar to them.
• Androstadienone: A male sweat component that acts as a potential human pheromone, causing mood elevation/sexual arousal in women and increasing salivary cortisol levels ($cortisol$ raises blood pressure and blood sugar).

11.1 Introduction to the Endocrine System

• Homeostasis: Maintained by the nervous system (nerve impulses) and the endocrine system (hormones).
• Endocrine Glands: Secrete hormones into the internal environment; hormones diffuse into the bloodstream to act on distant target cells.
• Local Hormones (Non-traditional secretions):     * Paracrine: Affects neighboring cells.     * Autocrine: Affects only the secreting cell itself.
• Exocrine Glands: Secrete outside the body through tubes/ducts (e.g., sweat glands).
• Aids to Understanding Words:     * -crin [to secrete]     * diuret- [to pass urine]     * endo- [within]     * exo- [outside]     * hyper- [above]     * hypo- [below]     * para- [beside]     * toc- [birth]     * -tropic [influencing]

11.2 General Characteristics

• Comparison with Nervous System:     * Cells: Neurons vs. Glandular epithelium.     * Signal: Neurotransmitter vs. Hormone.     * Speed: Seconds vs. Seconds to hours.     * Duration: Very brief vs. Brief to days.
• Specificity: Determined by specific receptors (proteins or glycoproteins) on target cells.
• Major Glands: Pituitary, thyroid, parathyroid, adrenal, pancreas, pineal, thymus, and reproductive glands.

11.3 Hormone Action

• Chemical Classification:     * Steroids (from cholesterol): Estrogen, testosterone, aldosterone, cortisol.     * Amines (from amino acids): Norepinephrine, epinephrine.     * Peptides: $ADH$, oxytocin, $TRH$.     * Proteins: $PTH$, growth hormone ($GH$), prolactin ($PRL$).     * Glycoproteins: $FSH, LH, TSH$.
• Steroid Hormone Mechanism:     1. Lipid-soluble hormone diffuses through the cell membrane.     2. Binds a specific protein receptor.     3. Complex binds target cell $DNA$, activating transcription of mRNA.     4. mRNA directs synthesis of specific proteins (enzymes, transport proteins).
• Nonsteroid Hormone Mechanism (Signal Transduction):     1. Hormone (first messenger) binds receptor.     2. Complex activates G protein.     3. G protein activates adenylate cyclase.     4. Adenylate cyclase converts $ATP$ into cyclic adenosine monophosphate ($cAMP$, second messenger).     5. $cAMP$ activates protein kinases, which phosphorylate substrates to alter cellular processes.     6. Phosphodiesterase quickly inactivates $cAMP$.
• Prostaglandins: Lipids synthesized from arachidonic acid; potent, act locally, not stored. Effects include smooth muscle relaxation/contraction and inhibiting acid secretion.

11.4 Control of Hormonal Secretions

• Controlled via negative feedback in three ways:     1. Hypothalamus regulates anterior pituitary stimulation of peripheral glands.     2. Nervous system stimulates glands directly (e.g., adrenal medulla response to sympathetic impulses).     3. Glands respond directly to changes in internal environment (e.g., pancreas response to blood glucose).

11.5 Pituitary Gland

• Stucture: $1\,cm$ diameter; attached to hypothalamus by infundibulum; sits in sella turcica of sphenoid bone. Divided into anterior and posterior lobes.
• Anterior Pituitary Hormones:     * Growth Hormone ($GH$): Stimulates size/division rate of cells; enhances amino acid movement; speeds carbohydrate/fat utilization. Regulated by $GH$-releasing and release-inhibiting hormones.     * Prolactin ($PRL$): Sustains milk production after birth.     * Thyroid-stimulating hormone ($TSH$): Controls thyroid secretions. Regulated by $TRH$.     * Adrenocorticotropic hormone ($ACTH$): Controls adrenal cortex hormones. Regulated by $CRH$; increased by stress.     * Gonadotropins ($FSH, LH$): Act on gonads (testes/ovaries).
• Anterior Pituitary Clinical Conditions:     * Hypopituitary dwarfism: Insufficient $GH$ during childhood; proportional body.     * Gigantism: Oversecretion of $GH$ during childhood; often due to tumor.     * Acromegaly: Overproduction of $GH$ in adulthood; enlarged heart, bones, facial features.
• Posterior Pituitary Hormones: Produced in hypothalamus; stored in axon ends.     * Antidiuretic hormone ($ADH$): Regulates water concentration by reducing kidney excretion. Regulated by osmoreceptors sensing osmotic pressure.     * Oxytocin ($OT$): Contracts uterine walls; ejection of milk; weak antidiuretic effects.
• Posterior Pituitary Clinical Conditions:     * Diabetes insipidus: Too little $ADH$; patient produces $25\text{--}30\,liters$ of dilute urine/day.

11.6 Thyroid Gland

• Structure: Below larynx, in front of trachea; two lobes connected by isthmus. Contains follicles lined with cuboidal epithelium filled with colloid.
• Thyroid Hormones: Thyroxine ($T_4$) and Triiodothyronine ($T_3$).     * Function: Regulate metabolism of carbs, lipids, proteins; increase energy release and protein synthesis.     * Determinants of Basal Metabolic Rate ($BMR$).     * Follicular cells require iodine salts (iodides); thyroid contains $80\%$ of body iodine.
• Calcitonin: Produced by extrafollicular cells; lowers blood $Ca^{+2}$ and phosphate ions by inhibiting osteoclasts and increasing kidney excretion.
• Thyroid Disorders:     * Cretinism: Infantile hypothyroidism; stunted growth, retardation.     * Hyperthyroidism: Goiter (bulge in neck), exophthalmia (eye protrusion), elevated metabolic rate.

11.7 Parathyroid Glands

• Structure: Four small glands on posterior of thyroid.
• Parathyroid Hormone ($PTH$): Increases blood calcium; decreases phosphate.     * Mechanisms: Stimulates osteoclasts to resorb bone; kidneys to conserve $Ca^{+2}$ and excrete phosphate; intestines to absorb $Ca^{+2}$ via vitamin D activation.
• Clinical:     * Hyperparathyroidism: Often due to tumor; softens bones; causes kidney stones.     * Hypoparathyroidism: Muscle tetany, decreased $Ca^{+2}$.

11.8 Adrenal Glands

• Structure: Sit atop kidneys. Outer cortex (three zones) and inner medulla.
• Adrenal Medulla Hormones: Epinephrine ($80\%$) and Norepinephrine. Sympathetic "fight-or-flight" response; increase heart rate, breathing, glucose levels; decrease digestion.
• Adrenal Cortex Hormones (Steroids):     * Aldosterone: A mineralocorticoid; conserves sodium ($Na^+$) and excretes potassium ($K^+$). Regulates blood volume/pressure.     * Cortisol: A glucocorticoid; affects glucose metabolism. Inhibits protein synthesis; promotes fatty acid release; stimulates glucose synthesis (gluconeogenesis). Regulated by $CRH \rightarrow ACTH$ negative feedback.     * Adrenal Sex Hormones: Androgens; some convert to estrogens in skin/liver.
• Adrenal Disorders:     * Addison disease: Hyposecretion; low sodium, high potassium, hypoglycemia, skin pigmentation.     * Cushing syndrome: Hypersecretion; high glucose, sodium retention ("puffy"), masculinizing effects in females.

11.9 Pancreas

• Structure: Elongated organ posterior to stomach. Dual nature (exocrine/endocrine).
• Islets of Langerhans (Endocrine portion):     * Alpha cells: Secrete Glucagon. Stimulates liver to break down glycogen and convert amino acids to glucose (raises blood sugar).     * Beta cells: Secrete Insulin. Promotes facilitated diffusion of glucose into cells (cardiac, adipose, resting skeletal muscle); stimulates glycogen formation (lowers blood sugar).
• Nerve cells: Obtain glucose by facilitated diffusion without requiring insulin.

11.10 Other Endocrine Glands

• Pineal Gland: Deep between cerebral hemispheres. Secretes Melatonin in the dark to regulate circadian rhythms (24-hour cycles).
• Thymus: Gland in mediastinum; shrinks with age. Secretes Thymosins for lymphocyte differentiation/immunity.
• Reproductive Organs: Ovaries (estrogen/progesterone), testes (testosterone), placenta (estrogen, progesterone, gonadotropin).
• Heart: Atrial natriuretic peptide ($ANP$) for sodium excretion.
• Kidney: Erythropoietin for red blood cell growth.

Topic of Interest: Diabetes Mellitus

• Definition: Insulin deficiency or cell inability to recognize insulin.
• Consequences: Hyperglycemia, glycosuria (glucose in urine), dehydration (polydipsia/extreme thirst), acidosis (ketone buildup), tissue wasting.
• Type 1: Juvenile; autoimmune destruction of beta cells. Treated with human insulin from genetically modified bacteria.
• Edmonton protocol: Islet transplantation into liver vein.
• Type 2: Maturity-onset; cells lose insulin recognition. Linked to weight/inactivity.

11.11 Stress and Health

• Stressor: Factor stimulating the response (physical or psychological).
• Stress Response (General Adaptation Syndrome):     * Alarm stage: Hypothalamus triggers sympathetic impulses; increases glucose, heart rate, blood pressure, epinephrine.     * Resistance stage: $CRH \rightarrow ACTH \rightarrow$ Cortisol release. Cortisol increases amino acids and glucose for stress recovery. Excess cortisol lowers immune resistance.
• Clinical: Post-traumatic Stress Disorder (PTSD) involves overactivity of the amygdala and vivid flashbacks due to stress hormones strengthening memory consolidation.

Chronobiology: Biological Rhythms

• Types: Ultradian ($< 24\,hours$), Infradian ($> 24\,hours$), Circadian ($\approx 24\,hours$).
• Endogenous control: Suprachiasmatic nuclei and "clock" genes (e.g., "period" gene mutation causing advanced sleep phase syndrome).
• Jet Lag: Melatonin responding to day length. Studies showed melatonin supplements had no effect on 257 doctors traveling Norway to NY.

12.1 Introduction to Blood

• Function: Transports nutrients, oxygen, wastes, hormones; maintains interstitial fluid stability; distributes heat.
• Composition: Connective tissue ($45\%$ formed elements, $55\%$ plasma).
• Volume: Adult average is $5\,liters$ ($5.3\,quarts$). Men ($5\text{--}6\,L$) have more than women ($4\text{--}5\,L$).
• Hematocrit ($HCT$): The percentage of red blood cells by volume (approx. $45\%$).
• Buffy coat: Thin layer of WBCs and platelets between plasma and RBCs after centrifugation.

12.2 Blood Cells

• Red Blood Cells (Erythrocytes):     * Shape: Biconcave discs; increases surface area for gas diffusion.     * Hemoglobin: Encompasses $1/3$ of cell volume. Oxyhemoglobin (red) vs. Deoxyhemoglobin (dark/bluish).     * Structure: Lack nuclei and mitochondria; produce ATP via glycolysis only.     * Counts ($RBCC$): Male $4,600,000\text{--}6,200,000/\mu L$; Female $4,200,000\text{--}5,400,000/\mu L$.
• RBC Life Cycle:     * Erythropoiesis: Initially in yolk sac, liver, spleen; after birth, in red bone marrow.     * Control: Negative feedback via Erythropoietin (from kidneys/liver) sensitive to low blood oxygen.     * Dietary factors: Vitamin $B_{12}$ and Folic acid (DNA synthesis); Iron (hemoglobin synthesis).     * Lifespan: $120\,days$. Destroyed by macrophages in liver/spleen.     * Breakdown: Hemoglobin ightarrow Heme ( ightarrow iron + biliverdin) + Globin. Biliverdin ightarrow Bilirubin (bile pigment).
• Sickle Cell Disease: DNA base change causes crystallized hemoglobin; sickle-shaped cells block vessels. Treatment includes hydroxyurea (fetal hemoglobin activation).
• White Blood Cells (Leukocytes):     * Granulocytes ($12\,hour$ life):         * Neutrophils ($54\text{--}62\%$): Lobed nucleus; active phagocytes.         * Eosinophils ($1\text{--}3\%$): Bilobed; kill parasites; control inflammation/allergies.         * Basophils ($< 1\%$): Blue granules; release heparin (blood thinner) and histamine (blood flow).     * Agranulocytes:         * Monocytes ($3\text{--}9\%$): Largest cells; become macrophages.         * Lymphocytes ($25\text{--}33\%$): Round nucleus; vital for immunity (T and B cells).
• Leukocyte Behavior:     * Diapedesis: Squeezing between blood vessel wall cells.     * Amoeboid motion: Self-propulsion outside blood.
• Clinical WBC Counts:     * Normal: $4,500\text{--}10,000\,cells/\mu L$.     * Leukocytosis: $> 10,000$ (infection).     * Leukopenia: $< 5,000$ (influenza, AIDS).
• Platelets (Thrombocytes): Fragments of megakaryocytes released from red bone marrow via Thrombopoietin. Count: $130,000\text{--}360,000/\mu L$. Role in clotting.

12.3 Blood Plasma

• Constituents: $92\%$ water; solutes (proteins, gases, nutrients, electrolytes).
• Plasma Proteins (Not energy sources):     * Albumins ($60\%$): Establish colloid osmotic pressure (holds water in capillaries). Deficiency cause edema.     * Globulins ($36\%$): Alpha/Beta (transport lipids); Gamma (antibodies from lymphatic tissue).     * Fibrinogen ($4\%$): Key role in coagulation.
• Nonprotein Nitrogenous Substances: Amino acids, Urea, Uric acid.
• Electrolytes: $Na^+$ and $Cl^-$ are most abundant. Bicarbonate ($HCO_3^-$) maintains pH.

12.4 Hemostasis

• 1. Blood Vessel Spasm: Vasospasm (smooth muscle contraction) lasts up to $30\,minutes$. Platelets release serotonin to help.
• 2. Platelet Plug Formation: Platelets adhere to rough surfaces and collagen; form small plug.
• 3. Blood Coagulation: Fibrinogen (soluble) ightarrow Fibrin (insoluble threads).     * Factors: Prothrombin activator (needs $Ca^{+2}$) converts Prothrombin ightarrow Thrombin.     * Thrombin converts Fibrinogen ightarrow Fibrin.     * Blood clot = mass of fibrin threads trapping cells.     * Serum: Plasma minus clotting factors.     * Dissolution: Plasminogen becomes Plasmin (digests fibrin).
• Clot Pathology:     * Thrombus: Abnormal clot in a vessel.     * Embolus: Dislodged clot movement. Infarction results if blood flow is blocked to vital organs.     * Treatment: $tPA$, streptokinase, urokinase.
• Genetic Disorders:     * Hemophilia A: Lack of Factor VIII; mostly males.     * von Willebrand disease: Common; lack of protein for platelet adhesion.     * ITP: Immune system attacks platelets.

12.5 Blood Groups and Transfusions

• ABO Group: Based on Presence of Antigens A and B.     * Type A: Antigen A, Anti-B antibody.     * Type B: Antigen B, Anti-A antibody.     * Type AB: Antigens A and B, neither antibody (Universal Recipient).     * Type O: Neither antigen, both antibodies (Universal Donor).
• Rh Group: Based on Antigen D.     * Rh-positive: Antigen present.     * Rh-negative: Lacks antigen. Anti-Rh antibodies form only after sensitization.     * Erythroblastosis fetalis: Rh-negative mother has second Rh-positive baby; anti-Rh antibodies ($hemolysins$) destroy fetal RBCs. Prevented with RhoGAM injections within $72\,hours$ of contact.

13.1 cardiovascular introduction

• Circuits:     * Pulmonary circuit: Deoxygenated blood to lungs (eliminates $CO_2$; gains $O_2$).     * Systemic circuit: Oxygenated blood/nutrients to body cells (eliminates waste).

13.2 Heart Structure

• Dimensions: $14\,cm$ long, $9\,cm$ wide. Base beneath 2nd rib; Apex at 5th intercostal space.
• Coverings:     * Pericardium: Fibrous (outer) and Serous (inner).     * Visceral pericardium (Epicardium) covers heart.     * Parietal pericardium lines fibrous bag.     * Pericardial cavity: Serous fluid reduces friction.
• Heart Wall layers: Epicardium (outer), Myocardium (muscle), Endocardium (inner lining).
• Chambers/Valves:     * Atria (upper) receive blood; Ventricles (lower) pump blood out.     * Tricuspid valve: Right A-V; Mitral (bicuspid) valve: Left A-V.     * Chordae tendineae: Fibrous strings attached to papillary muscles hold A-V valves shut.     * Pulmonary and Aortic valves: Semilunar; prevent backflow into ventricles.
• Blood Flow Path: Venae Cavae ightarrow Rt Atrium ightarrow Tricuspid ightarrow Rt Ventricle ightarrow Pulmonary Valve ightarrow Pulmonary Trunk ightarrow Lungs ightarrow Pulmonary Veins ightarrow Lt Atrium ightarrow Mitral ightarrow Lt Ventricle ightarrow Aortic Valve ightarrow Aorta.

13.3 Heart Actions

• Cardiac Cycle: Atrial systole (valves open, ventricles fill $70\%$ passively, $30\%$ pushed by contraction) then Ventricular systole (pressure rises, A-V valves close, semilunars open).
• Heart Sounds: Lubb (A-V valves closing during systole); Dupp (Semilunar valves closing during diastole).
• Functional Syncytium: Mass of cells acting as a unit (atrial and ventricular).
• Conduction System: S-A Node (Pacemaker, $70\text{--}80\,bpm$) ightarrow Atria ightarrow A-V Node (delay) ightarrow A-V Bundle (His) ightarrow Bundle Branches ightarrow Purkinje Fibers (ventricular contraction).
• ECG (Electrocardiogram):     * P Wave: Atrial depolarization.     * QRS Complex: Ventricular depolarization (hides atrial repolarization).     * T Wave: Ventricular repolarization.
• Regulation: Parasympathetic (Vagus nerve) secretes acetylcholine (slows HR); Sympathetic secretes norepinephrine (increases HR).     * Baroreceptor reflex: Aorta/Carotid receptors detect stretch; signal BP changes to medulla.     * Ions: Hyperkalemia (excess $K^+$) slows contractions; Hypercalcemia (excess $Ca^{+2}$) prolongs contraction.

13.4 Blood Vessels

• Arteries: Tunica interna (endothelium), media (smooth muscle/elastic fiber), externa (connective). Vasoconstriction/Vasodilation via vasomotor fibers.
• Atherosclerosis: Plaque (cholesterol) in artery walls. Treatment: statins, angioplasty, stents, bypass surgery.
• Capillaries: Smallest vessels; single-layer squamous epithelium (semipermeable).     * Density relates to metabolism (Cartilage/cornea lack capillaries).     * Precapillary sphincters control distribution.     * Exchanges: Diffusion; Filtration (via blood pressure); Osmosis (via colloid osmotic pressure).     * Net filtration at arteriolar end ($11\,mm\,Hg$); Net reabsorption at venular end ($8\,mm\,Hg$).
• Veins: Thinner walled; lower pressure; contain valves to prevent backflow; act as blood reservoirs (hold up to $25\%$ volume).

13.5 Blood Pressure ($BP$)

• Measurement: Systolic pressure (maximum during contraction); Diastolic pressure (lowest before next contraction). Normal approx. $120/80\,mm\,Hg$.
• Arterial BP Factors:     * Cardiac Output ($CO$): Stroke Volume ($SV$) $imes$ Heart Rate ($HR$). Normal $SV ext{ is } 70\,mL$.     * Blood Volume ($5\,L$ average; $8\%$ body weight).     * Peripheral Resistance ($PR$): Friction against walls.     * Viscosity: Resistance to flow (blood cells/proteins).
• Starling's Law ($Frank ext{-}Starling$): Fiber length (stretch) determines force of contraction ($CO$ matches venous return).
• Hypertension: PERSISTENTLY elevated pressure. Essential (unknown) vs. Secondary (caused by disease).
• Venous Return: Aided by skeletal muscle contraction, respiratory movements (thoracic pressure drop), and venoconstriction.

14.1–14.6 Lymphatic System

• Functions: Returns excess fluid to blood; absorbs dietary fats via lacteals; immunity via lymphocytes/macrophages.
• Pathway: Lymph capillaries ightarrow Vessels (with valves) ightarrow Nodes ightarrow Trunks ightarrow Collecting Ducts.     * Thoracic Duct: Drains most of body into left subclavian vein.     * Right Lymphatic Duct: Drains upper right side into right subclavian vein.
• Lymph Formation: Filtration from plasma exceeds reabsorption; excess tissue fluid enters lymphatic capillaries.
• Lymph Nodes: Filter lymph; perform immune surveillance. Functional units are nodules containing B cells/macrophages. Hilum is exit for efferent vessels.
• Thymus: Mediastinum; secretes Thymosins for T-cell maturation. Shrinks after puberty.
• Spleen: Largest lymphatic organ. White pulp (lymphocytes); Red pulp (RBCs/macrophages). Filters blood.

14.8–14.9 Immunity

• Innate (Nonspecific) Defenses:     * Species resistance; Mechanical (skin/mucus); Chemical (Pepsin/HCl/Lysozyme); Interferon (antiviral pepides); Complement (cascades); Natural Killer cells (perforins); Inflammation; Phagocytosis (Neutrophils/Monocytes); Fever.
• Adaptive (Specific) Defenses:     * Antigens: Large/complex molecules ($Nonself$). Haptens: small molecules needing carriers to stimulate immune response.     * T Cells ($70 ext{--}80\%$ lymphocytes): Cellular immune response. Activated by antigen-presenting cells ($APCs$) with MHC proteins. Helper T cells release cytokines; Cytotoxic T cells release perforins to cut pores into cells.     * B Cells ($20 ext{--}30\%$): Humoral immune response. Produce antibodies/immunoglobulins. Clones include memory cells.
• Antibody Types:     * $IgG$ ($80\%$): Plasma; crosses placenta.     * $IgA$: Exocrine secretions (milk, tears).     * $IgM$: Plasma; anti-A/anti-B antibodies.     * $IgD$: B cell surfaces.     * $IgE$: Allergic reactions.
• Antibody Actions: Agglutination, precipitation, neutralization, complement activation (opsonization, chemotaxis, lysis).
• Immunity Classification:     * Naturally acquired active: Disease exposure.     * Artificially acquired active: Vaccines/Toxoids.     * Artificially acquired passive: Gamma globulin/antiserum injection.     * Naturally acquired passive: Placental IgG/Colostrum $IgA$.

15.1–15.10 Digestive System

• Alimentary Canal: $8\,meters$ long. Wall Layers: Mucosa, Submucosa, Muscular (circular/longitudinal), Serosa.
• Mouth: Mastication (chewing). Primary teeth ($20$); Secondary teeth ($32$). Crown (enamel/dentin), Root (cementum/periodontal ligament).
• Salivary Glands: Amylase (starch breakdown), Mucus. Parotid (largest/watery), Submandibular (viscous), Sublingual (stringy).
• Stomach: Cardiac, fundic, body, pyloric regions. Pyloric sphincter controls emptying.     * Gastric Juice: Pepsinogen (inactive) ightarrow Pepsin (active, protein digestion) via $HCl$ from Parietal cells. Intrinsic factor for $B_{12}$.     * Chyme: Semifluid paste of food and gastric juice. Emptying takes $3 ext{--}6\,hours$.
• Pancreas: Pancreatic amylase (carbs), lipase (fats), nucleases (nucleic acids), proteolytic enzymes (Trypsin, Chymotrypsin, Carboxypeptidase). Secretin (neutralizes acidity); $CCK$ (enzyme release).
• Liver: Hepatic lobules (functional unit) with sinusoids and Kupffer cells. Functions: Carbohydrate/Lipid/Protein metabolism; deamination; bile secretion.
• Bile: Bile salts (emulsification); pigments (bilirubin/biliverdin). Stored in Gallbladder.
• Small Intestine: Duodenum ($25\,cm$), Jejunum, Ileum. Villi increase surface area. Absorption of monosaccharides, amino acids, fatty acids (via chylomicrons/lacteals), electrolytes.
• Large Intestine: Cecum, Colon (Ascending, Transverse, Descending, Sigmoid), Rectum, Anal Canal. Absorbs water/electrolytes. Intestinal flora produce vitamins K and $B_{12}$.

15.11 Nutrition

• Macronutrients: Carbohydrates ($4\,cal/g$), Lipids ($9\,cal/g$), Proteins ($4\,cal/g$).
• Micronutrients: Vitamins and Minerals.
• Vitamins: Fat-soluble ($A, D, E, K$); Water-soluble ($B, C$).
• Minerals: Major ($Ca, P, K, S, Na, Cl, Mg$); Trace ($Fe, Mn, Cu, I, Co, Zn, F, Se, Cr$).
• BMI: weight in $kg / height^2$ in $meters$.

16.1–16.6 Respiratory System

• Tracts: Upper (nose, nasal cavity, sinuses, pharynx); Lower (larynx, trachea, bronchial tree, lungs).
• Mechanics: Atmospheric pressure ($760\,mm\,Hg$). Inspiration via Diaphragm/Intercostals contraction (pressure drops $758\,mm\,Hg$). Surfactant reduces surface tension.
• Volumes: $TV = 500\,mL$; $IRV = 3,000\,mL$; $ERV = 1,100\,mL$; $RV = 1,200\,mL$.
• Capacities: $VC = TV + IRV + ERV = 4,600\,mL$; Total Lung Capacity $ext{ (TLC) } = 5,800\,mL$.
• Gas Exchange: Respiratory membrane (alveolar and capillary walls). $PO_2 ext{ in alveolar air is } 104\,mm\,Hg$. Oxygen transport via Hemoglobin ($Oxyhemoglobin$).
• $CO_2$ Transport: $7\%$ dissolved, $23\%$ carbaminohemoglobin, $70\%$ bicarbonate ions ($HCO_3^-$). Carbonic anhydrase speeds the reaction (CO_2 + H_2O ightarrow H_2CO_3).

17.1–17.4 Urinary System

• Organs: Kidneys, Ureters, Urinary Bladder, Urethra.
• Kidney Functional Unit: Nephron ($1\,million$ per kidney). Corpuscle (Glomerulus + Capsule) and Tubule.
• Urine Formation:     1. Filtration: $180\,liters/24\,h$. Net filtration pressure approx $10\,mm\,Hg$.     2. Reabsorption: Proximal convoluted tubule ($70\%$ $Na^+, H_2O, glucose$ reclaimed).     3. Secretion: Removal of penicillin, $H^+, K^+$.
• Renin-Angiotensin: Renin ightarrow Angiotensin I ightarrow Angiotensin II (vasoconstrictor, stimulates Aldosterone).
• Micturition: Refex center in spinal cord; detrusor muscle contracts, external sphincter (voluntary) relaxes.

18.1–18.6 Balance

• Body Fluid: $52\%$ weight in females, $63\%$ in males. $63\%$ Intracellular; $37\%$ Extracellular.
• Buffers:     * Bicarbonate: H^+ + HCO_3^- ightleftharpoons H_2CO_3.     * Phosphate: H^+ + HPO_4^{-2} ightleftharpoons H_2PO_4^-.     * Protein: Amino groups accept $H^+$, carboxyl groups release them.
• Acid-Base Imbalances:     * Respiratory Acidosis: $CO_2$ accumulation (emphysema).     * Metabolic Acidosis: Lack of bases or excess non-respiratory acid (diabetes).     * Alkalosis: Loss of acids or gain of bases.

19.1–19.7 Reproductive Systems

• Male: Testes produce sperm in seminiferous tubules via Spermatogenesis (Meiosis I and II result in 4 haploid sperm). Testosterone from Interstitial cells (Leydig). Semen contains sperm plus secretions from Seminal Vesicles ($alkaline/fructose/prostaglandins$) and Prostate ($milky/alkaline$).
• Female: Ovaries produce oocytes via Oogenesis (results in 1 secondary oocyte and polar bodies). Reproductive cycle: $FSH$ matures follicle ightarrow Estrogen thickens endometrium ightarrow $LH$ surge triggers Ovulation (Day 14) ightarrow Corpus luteum secretes Progesterone ightarrow lining sloughs (Menses) if no fertilization.
• Birth Control: Hormonal (Pill/Depo-Provera) prevents $LH$ surge. IUD prevents implantation. Sterilization (Vasectomy/Tubal Ligation).

20.1–20.5 Development and Genetics

• Prenatal: Zygote ightarrow Cleavage ightarrow Morula ($16\,cells$) ightarrow Blastocyst (implants) ightarrow Gastrula (3 germ layers).     * Layers: Ectoderm (nervous); Mesoderm (muscle/bone); Endoderm (epithelial linings).
• Fetal Circulation: Umbilical vein (oxygenated); Ductus venosus (liver bypass); Foramen ovale (lung bypass atrial septum); Ductus arteriosus (pulmonary trunk to aorta bypass).
• Genetics: $23\,pairs$ chromsomes ($22\,autosomes$, $1\,sex$). Punnett Squares/Pedigrees predict outcomes. Multifactorial traits (genes + environment) like height/skin color.