Anatomy & Physiology Study Guide: Ch. 13-16

Respiratory System

Epiglottis and Vocal Folds

The upper respiratory tract includes structures that protect the airway and produce sound.

• Epiglottis: A flap of cartilage that covers the trachea during swallowing, preventing food from entering the airway.

• Vocal Folds (Vocal Cords): Bands of muscle and connective tissue in the larynx that vibrate to produce sound when air passes through.

Alveoli and Gas Exchange

The alveoli are the primary sites of gas exchange in the lungs.

• Function of Alveoli: Tiny air sacs where oxygen diffuses into the blood and carbon dioxide diffuses out.

• Intrapulmonary vs. Atmospheric Pressure: Gas exchange depends on pressure gradients between the alveoli (intrapulmonary pressure) and the atmosphere.

• Pleural Cavity Pressure: The pressure in the pleural cavity is always slightly negative relative to atmospheric pressure, preventing lung collapse.

Respiratory Physiology

Respiratory processes involve the movement of gases and the regulation of breathing.

• Pulmonary Ventilation: The process of moving air into and out of the lungs (breathing).

• External Respiration: Exchange of gases between alveoli and blood.

• Internal Respiration: Exchange of gases between blood and tissues.

• Oxygen and Carbon Dioxide Transport: Oxygen is mainly transported bound to hemoglobin; carbon dioxide is transported as bicarbonate ions, dissolved in plasma, or bound to hemoglobin.

• Role of Carbon Dioxide in Ventilation: CO2 levels in the blood influence the rate and depth of breathing by affecting blood pH and stimulating chemoreceptors.

Digestive System

Overview of Digestion

Digestion involves mechanical and chemical processes that break down food into absorbable nutrients.

• Major Digestive Processes: Ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation.

• Enzymatic Digestion: Specific enzymes break down carbohydrates (amylase), proteins (pepsin, trypsin), and fats (lipase).

• Accessory Organs: Liver, pancreas, and gallbladder contribute enzymes and bile for digestion.

Digestive Hormones and Enzymes

Hormones and enzymes regulate and facilitate digestion.

• Gastrin: Stimulates gastric acid secretion.

• Secretin: Stimulates bicarbonate secretion from the pancreas.

• Cholecystokinin (CCK): Stimulates bile release from the gallbladder and enzyme secretion from the pancreas.

Digestive Tract Sphincters

Sphincters control the passage of food and prevent backflow.

• Pyloric Sphincter: Regulates passage of chyme from the stomach to the duodenum.

• Ileocecal Sphincter: Controls flow from the small to the large intestine.

ATP Production and Metabolism

Cells metabolize nutrients to produce ATP, the energy currency of the cell.

• ATP Production Steps: Glycolysis, Krebs cycle (citric acid cycle), and electron transport chain.

• ATP Yield: Complete oxidation of one glucose molecule yields approximately 36-38 ATP molecules.

• Glucose Metabolism: Glucose is broken down to pyruvate, then to CO2 and H2O, producing ATP.

Urinary System

Organs and Functions

The urinary system removes waste and regulates fluid and electrolyte balance.

• Kidneys: Filter blood, remove waste, regulate electrolyte balance, and produce urine.

• Ureters: Transport urine from kidneys to bladder.

• Bladder: Stores urine until excretion.

• Urethra: Conducts urine out of the body.

Nephron Structure and Function

The nephron is the functional unit of the kidney.

• Filtration: Occurs in the glomerulus; blood plasma is filtered into the nephron.

• Reabsorption: Useful substances are reabsorbed into the blood in the tubules.

• Secretion: Additional wastes are secreted into the tubule for excretion.

• Countercurrent Mechanism: Maintains concentration gradients in the medulla, allowing urine concentration.

Hormonal Regulation

Hormones regulate kidney function and fluid balance.

• Aldosterone: Increases sodium reabsorption and potassium secretion.

• Antidiuretic Hormone (ADH): Increases water reabsorption in the collecting ducts.

Reproductive System

Male and Female Reproductive Anatomy

The reproductive systems produce gametes and support fertilization and development.

• Male Structures: Testes (produce sperm and testosterone), epididymis, vas deferens, seminal vesicles, prostate gland, penis.

• Female Structures: Ovaries (produce eggs and hormones), fallopian tubes, uterus, cervix, vagina.

Gametogenesis

Gametogenesis is the process of forming gametes (sperm and eggs).

• Spermatogenesis: Production of sperm in the testes.

• Oogenesis: Production of eggs in the ovaries.

Hormonal Regulation

Reproductive hormones control gamete production and secondary sexual characteristics.

• Luteinizing Hormone (LH): Stimulates testosterone production in males and ovulation in females.

• Follicle-Stimulating Hormone (FSH): Stimulates spermatogenesis in males and follicle development in females.

• Testosterone: Promotes male secondary sexual characteristics and sperm production.

• Estrogen and Progesterone: Regulate female reproductive cycle and secondary sexual characteristics.

Fertilization and Development

Fertilization leads to embryonic development and pregnancy.

• Fertilization: Fusion of sperm and egg to form a zygote.

• Cleavage and Implantation: Early cell divisions (cleavage) produce a blastocyst, which implants in the uterine wall.

• Germ Layers: Ectoderm (forms skin and nervous system), mesoderm (forms muscles, bones, circulatory system), endoderm (forms digestive and respiratory tracts).

• Trimesters: Pregnancy is divided into three trimesters, each with specific developmental milestones.

• Labor Stages: Dilation of cervix, delivery of baby, delivery of placenta.

Summary Table: Key Hormones in Digestion and Reproduction

Hormone	Source	Main Function
Gastrin	Stomach	Stimulates gastric acid secretion
Secretin	Duodenum	Stimulates bicarbonate secretion from pancreas
Cholecystokinin (CCK)	Duodenum	Stimulates bile and pancreatic enzyme release
Luteinizing Hormone (LH)	Pituitary	Stimulates ovulation/testosterone production
Follicle-Stimulating Hormone (FSH)	Pituitary	Stimulates gamete production
Testosterone	Testes	Male secondary sex characteristics, spermatogenesis
Estrogen	Ovaries	Female secondary sex characteristics, menstrual cycle
Progesterone	Ovaries	Maintains uterine lining for pregnancy

Key Equations

• Gas Exchange (Fick's Law):

$\text{Rate of diffusion} = \frac{(P_1 - P_2) \times A \times D}{T}$

• ATP Yield from Glucose Oxidation:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + 36-38\ \text{ATP}$

• Glomerular Filtration Rate (GFR):

$\text{GFR} = K_f \times [(P_{GC} - P_{BS}) - (\pi_{GC} - \pi_{BS})]$

Additional info: Some explanations and context have been expanded for clarity and completeness based on standard Anatomy & Physiology curricula.