Chapter 16: The Endocrine System

Overview of the Endocrine System

The endocrine system is one of the two primary extrinsic regulatory systems in the human body, working alongside the nervous system to maintain homeostasis through the secretion of hormones.

• Hormones are chemical messengers secreted by endocrine glands that regulate physiological processes.

• Endocrine glands are ductless and release hormones directly into the bloodstream.

• Major endocrine glands include the pituitary, thyroid, parathyroid, adrenal, pineal, and pancreas.

Classes of Chemical Messengers

• Autocrine: Act on the same cell that secretes them.

• Paracrine: Affect nearby cells.

• Endocrine: Travel through the bloodstream to distant targets.

• Neurotransmitters: Released by neurons at synapses.

Hormone Mechanisms and Control

• Lipid-soluble hormones (e.g., steroids) pass through cell membranes and bind to intracellular receptors, affecting gene expression.

• Water-soluble hormones (e.g., peptides) bind to cell surface receptors and use second messengers (like cAMP) to exert effects.

• Hormone secretion is controlled by negative feedback, neural stimuli, and hormonal stimuli.

Key Terms and Disorders

• Prostaglandins: Local hormones with diverse functions, including inflammation and smooth muscle contraction.

• Diabetes Mellitus: A disorder of insulin production or response, with Type 1 (autoimmune) and Type 2 (insulin resistance) forms.

• Diabetes Insipidus: Caused by ADH deficiency, leading to excessive urination.

Table: Major Endocrine Glands and Hormones

Chapter 17: The Cardiovascular System I – The Heart

Functions and Anatomy of the Heart

The heart is a muscular organ responsible for pumping blood throughout the body, supplying oxygen and nutrients, and removing wastes.

• Located in the mediastinum, about the size of a fist.

• Enclosed by the pericardium (fibrous and serous layers).

• Heart wall layers: epicardium (outer), myocardium (muscle), endocardium (inner).

Chambers, Valves, and Circuits

• Four chambers: right/left atria, right/left ventricles.

• Valves: Atrioventricular (AV) (tricuspid, bicuspid/mitral) and semilunar (pulmonary, aortic).

• Pulmonary circuit: right heart to lungs; systemic circuit: left heart to body.

Cardiac Muscle and Conduction

• Cardiac muscle cells are striated, branched, and connected by intercalated discs.

• Intrinsic conduction system: SA node → AV node → Bundle of His → bundle branches → Purkinje fibers.

Cardiac Cycle and Output

• Cardiac cycle: sequence of events in one heartbeat (systole and diastole).

• Cardiac output ():

• Heart sounds: "lub" (AV valves close), "dup" (semilunar valves close).

Key Terms

• Preload: degree of stretch of heart muscle before contraction.

• Afterload: resistance the heart must overcome to eject blood.

• Stroke volume (SV): amount of blood pumped per beat.

• Venous return: blood returning to the heart.

Clinical Terms

• Myocardial infarction: heart attack.

• Angina pectoris: chest pain due to reduced blood flow.

• Arrhythmias: abnormal heart rhythms (e.g., tachycardia, bradycardia, fibrillation).

Chapter 18: The Cardiovascular System II – Blood Vessels

Blood Vessel Structure and Function

• Arteries: carry blood away from the heart; thick, elastic walls.

• Veins: return blood to the heart; thinner walls, valves prevent backflow.

• Capillaries: sites of exchange; thin, single-cell layer.

Blood Pressure and Circulation

• Blood pressure (BP): force of blood against vessel walls; measured in mmHg.

• Systolic (contraction) and diastolic (relaxation) pressures.

• Measured with a sphygmomanometer; Korotkoff sounds indicate flow.

• BP equation: (total peripheral resistance)

Special Circulations and Disorders

• Hepatic portal circulation: directs blood from GI tract to liver.

• Varicose veins: dilated, twisted veins.

• Aneurysm: vessel wall bulge; risk of rupture.

• Hypertension: high blood pressure.

Chapter 19: Blood

Functions and Composition of Blood

• Transports gases, nutrients, wastes, hormones.

• Regulates pH, temperature, and fluid volume.

• Protects against infection and blood loss.

• Components: plasma (liquid), formed elements (RBCs, WBCs, platelets).

Blood Cells and Hematopoiesis

• RBCs (erythrocytes): carry oxygen via hemoglobin.

• WBCs (leukocytes): immune defense; granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

• Platelets: cell fragments for clotting.

• Hematopoiesis: blood cell formation in bone marrow.

Blood Typing and Disorders

• Blood types: A, B, AB, O; determined by antigens on RBCs.

• Rh factor: positive or negative.

• Hemolytic Disease of the Newborn (HDN): Rh incompatibility.

• Disorders: anemia, leukemia, hemophilia, polycythemia.

Chapter 20: The Lymphatic System and Immunity

Lymphatic System Structure and Function

• Returns interstitial fluid to blood, absorbs fats, and provides immune defense.

• Major organs: lymph nodes, spleen, thymus, tonsils.

• Lymph nodes filter lymph and house immune cells.

Immunity

• Innate (nonspecific) immunity: barriers, phagocytes, inflammation.

• Adaptive (specific) immunity: B cells (antibody-mediated), T cells (cell-mediated).

• Antibodies: proteins that bind antigens; five classes (IgG, IgA, IgM, IgE, IgD).

• MHC molecules: present antigens to T cells.

Immune Disorders

• Autoimmune diseases: multiple sclerosis, lupus, rheumatoid arthritis.

• Allergies: hypersensitivity to harmless antigens.

• Immunodeficiency: HIV/AIDS.

Chapter 21: The Respiratory System

Structure and Function

• Organs: nose, pharynx, larynx, trachea, bronchi, lungs.

• Functions: gas exchange, pH regulation, voice production, olfaction.

• Alveoli: site of gas exchange; surfactant reduces surface tension.

Mechanics of Breathing

• Inspiration: diaphragm contracts, thoracic volume increases, pressure drops.

• Expiration: diaphragm relaxes, thoracic volume decreases, pressure rises.

• Gas exchange driven by partial pressure gradients (Dalton's Law).

Respiratory Volumes and Disorders

• Volumes: tidal volume, vital capacity, residual volume, etc.

• Disorders: asthma, COPD, emphysema, pneumonia, lung cancer.

Chapter 22: The Digestive System

Digestive Tract and Accessory Organs

• Alimentary canal: mouth → pharynx → esophagus → stomach → small intestine → large intestine → rectum → anus.

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

Digestion and Absorption

• Mechanical digestion: chewing, mixing, churning.

• Chemical digestion: enzymatic breakdown of food.

• Absorption: nutrients enter blood or lymph.

• Enzymes: amylase (carbs), protease (proteins), lipase (fats).

Disorders

• Peptic ulcers, hepatitis, cirrhosis, pancreatitis, GERD, appendicitis.

Chapter 23: Metabolism and Nutrition

Metabolic Pathways

• Glycolysis: cytoplasm, 2 ATP produced.

• Krebs cycle: mitochondria, 2 ATP produced.

• Electron transport chain: mitochondria, ~32 ATP produced.

• Total ATP from aerobic respiration: ~36 ATP per glucose.

Key Terms

• Catabolism: breakdown of molecules for energy.

• Anabolism: synthesis of complex molecules.

• Basal Metabolic Rate (BMR): energy expended at rest.

Nutrition

• Essential nutrients: vitamins, minerals, amino acids, fatty acids.

• Vitamins: A, B, C, D, E, K – each with specific functions.

Chapter 24: The Urinary System

Structure and Function

• Organs: kidneys, ureters, bladder, urethra.

• Functions: excretion, regulation of blood volume and composition, pH balance.

Nephron Anatomy and Urine Formation

• Nephron: functional unit; consists of glomerulus, Bowman's capsule, tubules, loop of Henle, collecting duct.

• Processes: filtration, reabsorption, secretion.

• Filtration pressure determined by hydrostatic and osmotic forces.

Hormonal Regulation

• ADH, aldosterone, ANP regulate urine volume and composition.

Disorders

• Renal calculi (kidney stones), glomerulonephritis, diabetes insipidus, incontinence.

Chapter 25: Fluid, Electrolyte, and Acid-Base Homeostasis

Fluid Compartments and Electrolytes

• Body water: intracellular, interstitial, plasma compartments.

• Electrolytes: ions like Na+, K+, Ca2+, Cl-.

Acid-Base Balance

• pH: measure of hydrogen ion concentration; normal blood pH ~7.4.

• Buffers, respiratory, and renal systems maintain pH.

• Disorders: acidosis, alkalosis (respiratory and metabolic types).

Chapter 26: The Reproductive System

Male Reproductive System

• Organs: testes, epididymis, vas deferens, seminal vesicles, prostate, penis.

• Spermatogenesis: production of sperm in seminiferous tubules.

• Hormonal control: FSH, LH, testosterone.

Female Reproductive System

• Organs: ovaries, fallopian tubes, uterus, vagina, vulva.

• Oogenesis: production of ova in ovaries.

• Menstrual cycle: regulated by FSH, LH, estrogen, progesterone.

Clinical Terms

• Vasectomy, tubal ligation, ovarian cysts, endometriosis, PCOS.

Chapter 27: Development and Heredity

Fertilization and Early Development

• Fertilization: sperm + egg → zygote.

• Stages: zygote → morula → blastocyst → implantation.

• Placenta: organ for nutrient/gas exchange; produces hormones.

Fetal Development and Birth

• Gestation: embryonic and fetal periods.

• Parturition: process of childbirth.

Key Terms

• Chorion, amnion, ectoderm, mesoderm, endoderm: embryonic membranes and germ layers.

• Cell differentiation: specialization of cells for specific functions.