Study Guide: Respiratory, Digestive, Urinary, and Reproductive Systems

Respiratory System

Overview and Functions

The respiratory system is essential for gas exchange, supplying oxygen to the body and removing carbon dioxide. It also plays roles in regulating blood pH and protecting against pathogens.

• Purpose: To obtain oxygen and eliminate carbon dioxide.

• Importance: Oxygen is vital for cellular metabolism; removal of CO2 prevents acidification of blood.

• Functions: Gas exchange, regulation of blood pH, voice production, olfaction, and protection.

Anatomy of the Respiratory System

• Upper respiratory tract: Nose, nasal cavity, pharynx, larynx.

• Lower respiratory tract: Trachea, bronchi, bronchioles, lungs, alveoli.

• Pathway of air: Air enters through the nose/mouth → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

Structure and Function

• Tracheal cartilage: C-shaped rings keep the airway open.

• Bronchi and bronchioles: Conduct air; bronchi have cartilage, bronchioles do not.

• Alveoli: Site of gas exchange; thin walls facilitate diffusion.

Mechanics of Breathing

• Inspiration: Diaphragm contracts, thoracic cavity expands, air flows in.

• Expiration: Diaphragm relaxes, thoracic cavity decreases, air flows out.

• Elastic recoil: Lungs return to resting state after inspiration.

Gas Exchange and Transport

• Internal respiration: Gas exchange between blood and tissues.

• External respiration: Gas exchange between alveoli and blood.

• Oxygen transport: Mostly bound to hemoglobin.

• Carbon dioxide transport: Dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.

• Equation for bicarbonate formation:

$\mathrm{CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-}$

• Factors affecting gas movement: Membrane thickness, surface area, partial pressure gradients.

Respiratory Disorders

• Asthma: Airway inflammation and constriction; treated with bronchodilators and anti-inflammatory drugs.

• Cystic fibrosis: Genetic disorder causing thick mucus and impaired breathing.

Digestive System

Overview and Functions

The digestive system breaks down food, absorbs nutrients, and eliminates waste. It consists of the alimentary canal and accessory organs.

• Main functions: Ingestion, digestion, absorption, elimination.

• Layers of the canal: Mucosa, submucosa, muscularis, serosa.

Alimentary Canal Anatomy

• Organs: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

• Accessory organs: Salivary glands, liver, gallbladder, pancreas.

Digestive Processes

• Mechanical digestion: Chewing, mixing, churning.

• Chemical digestion: Enzymatic breakdown of macromolecules.

• Absorption: Nutrients pass into blood or lymph.

Stomach and Small Intestine

• Stomach: Acidic environment, protein digestion, protection by mucus.

• Small intestine: Duodenum, jejunum, ileum; main site of nutrient absorption.

• Villi and microvilli: Increase surface area for absorption.

Large Intestine and Accessory Organs

• Large intestine: Water absorption, formation of feces.

• Liver: Produces bile, metabolizes nutrients.

• Gallbladder: Stores and releases bile.

• Pancreas: Secretes digestive enzymes and bicarbonate.

Digestive Disorders

• Common disorders: Ulcers, inflammatory bowel disease, lactose intolerance.

Urinary System

Overview and Functions

The urinary system removes waste products from the blood, regulates fluid and electrolyte balance, and maintains acid-base homeostasis.

• Main organs: Kidneys, ureters, urinary bladder, urethra.

• Kidney functions: Filtration, reabsorption, secretion, excretion.

Kidney Anatomy and Physiology

• Nephron: Functional unit; consists of glomerulus, tubules.

• Glomerular filtration: Blood pressure forces water and solutes into Bowman's capsule.

• Tubular reabsorption: Selective movement of substances from filtrate back to blood.

• Tubular secretion: Additional wastes added to filtrate.

Fluid and Electrolyte Balance

• Hormones: ADH (antidiuretic hormone), aldosterone regulate water and sodium balance.

• Acid-base balance: Kidneys excrete H+ and reabsorb HCO3-.

Urinary Disorders

• Kidney failure: Loss of kidney function; treated with dialysis or transplant.

• UTIs: Infections of urinary tract; more common in females due to shorter urethra.

Reproductive System

Overview and Functions

The reproductive system enables production of offspring and secretion of sex hormones. It includes male and female organs with specialized functions.

• Male organs: Testes, epididymis, vas deferens, seminal vesicles, prostate, penis.

• Female organs: Ovaries, uterine tubes, uterus, vagina, external genitalia.

Male Reproductive Physiology

• Spermatogenesis: Production of sperm in seminiferous tubules; regulated by FSH and LH.

• Testosterone: Promotes development of male secondary sex characteristics.

Female Reproductive Physiology

• Oogenesis: Production of ova in ovaries; regulated by FSH and LH.

• Menstrual cycle: Cyclical changes in endometrium; includes follicular, ovulatory, and luteal phases.

• Hormones: Estrogen and progesterone regulate cycle and secondary sex characteristics.

Reproductive Disorders

• Common disorders: Infertility, polycystic ovary syndrome, prostate cancer.

Additional info: For lab material, refer to lab handouts as indicated in the study guide.