Comprehensive Study Notes for ANP College Course: Homeostasis, Endocrine, Digestive, Metabolism, Respiratory, Blood, Cardiovascular, Lymphatic/Immune, and Urinary Systems

Homeostasis and Feedback Mechanisms

Definition and Importance of Homeostasis

Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. This balance is essential for normal physiological function and survival.

• Homeostatic imbalance: Occurs when the body cannot maintain internal stability, often leading to disease.

Feedback Mechanisms

Feedback mechanisms regulate homeostasis by responding to changes in the internal environment.

• Negative feedback: The most common mechanism; it reverses a change to restore balance. Example: Regulation of blood glucose levels.

• Positive feedback: Amplifies a change, moving the system further from equilibrium. Example: Blood clotting, childbirth.

Systems Involved in Feedback

• Nervous system: Provides rapid, brief, and targeted responses; effectors are usually muscle fibers or glands.

• Endocrine system: Produces slower, longer-lasting responses; targets cells throughout the body.

Endocrine System

Endocrine vs. Exocrine Glands

• Endocrine glands: Secrete hormones directly into the bloodstream; no ducts.

• Exocrine glands: Secrete substances (e.g., enzymes, sweat) through ducts to specific locations.

Hormones and Receptors

• Hormone: A chemical messenger produced by endocrine glands, transported by blood to target organs.

• Hormonal receptors: Two main types:

  • Membrane-bound receptors: Bind amino acid-based hormones (e.g., insulin).

  • Intracellular receptors: Bind steroid hormones (e.g., cortisol).

Insulin and Glucagon

• Secreted by: Pancreatic islets (Islets of Langerhans).

• Insulin: Released in response to high blood glucose; lowers glucose by promoting uptake into cells.

• Glucagon: Released in response to low blood glucose; raises glucose by stimulating glycogen breakdown.

Types of Diabetes

• Type 1 Diabetes: Autoimmune destruction of insulin-producing cells; requires insulin therapy.

• Type 2 Diabetes: Insulin resistance; often associated with obesity and lifestyle factors.

Digestive System

General Functions and Divisions

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

• Alimentary canal: Mouth, pharynx, esophagus, stomach, intestines.

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

Six Essential Activities of Digestion

• Ingestion

• Propulsion

• Mechanical digestion

• Chemical digestion

• Absorption

• Defecation

Peritoneum and Related Terms

• Peritoneum: A serous membrane lining the abdominal cavity and covering abdominal organs.

• Visceral peritoneum: Covers organs.

• Parietal peritoneum: Lines the cavity wall.

Layers of the GI Tract

• Mucosa: Innermost layer; secretion and absorption.

• Submucosa: Connective tissue; contains blood vessels and nerves.

• Muscularis externa: Smooth muscle; responsible for peristalsis and segmentation.

• Serosa: Outermost layer; protective.

Key Terms

• Peristalsis: Wave-like muscle contractions moving food through the GI tract.

• Mastication: Chewing.

• Deglutition: Swallowing.

• Most nutrient absorption: Occurs in the small intestine.

Metabolism

Anabolism and Catabolism

• Anabolism: Building up molecules from smaller units; requires energy.

• Catabolism: Breaking down molecules into smaller units; releases energy.

Enzymes

• Enzyme: Biological catalyst that speeds up chemical reactions without being consumed.

• Importance: Essential for metabolic processes; lower activation energy.

Adenosine Triphosphate (ATP)

• ATP: The primary energy carrier in cells.

• ATP from Glycolysis: 2 ATP per glucose molecule.

• ATP from Glycolysis, Krebs Cycle, and Electron Transport: 36-38 ATP per glucose molecule.

• Oxygen: Required for cellular respiration; CO2 is produced as a waste product during metabolism.

Nutrient Absorption States

• Absorptive state: Nutrients are being absorbed; energy is stored.

• Post-absorptive state: No absorption; energy is mobilized from stores.

Respiratory System

Major Function

The respiratory system supplies oxygen to the blood and removes carbon dioxide.

Four Processes of Respiration

• Pulmonary ventilation: Movement of air into and out of the lungs.

• External respiration: Gas exchange between lungs and blood.

• Transport of gases: Movement of O2 and CO2 in the blood.

• Internal respiration: Gas exchange between blood and tissues.

Oxygen Transport

• Transported: Mostly bound to hemoglobin in red blood cells; some dissolved in plasma.

• Partial pressure of oxygen: High in alveoli and arteries; low in tissues and veins.

Carbon Dioxide Transport

• Transported: Dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.

• Partial pressure of CO2: High in tissues and veins; low in alveoli and arteries.

Blood

General Functions

• Transport of gases, nutrients, hormones, and waste.

• Regulation of pH, temperature, and fluid balance.

• Protection against infection and blood loss.

Components of Blood

• Plasma: Liquid portion (~55%); contains water, proteins, nutrients, hormones.

• Formed elements: Cells and cell fragments:

  • Erythrocytes: Red blood cells; transport oxygen.

  • Leukocytes: White blood cells; defense against infection.

  • Platelets: Cell fragments; involved in clotting.

Blood Grouping

• Agglutinogens: Antigens on red blood cell surfaces.

• Agglutinins: Antibodies in plasma.

• Blood types: A, B, AB, O; determined by presence/absence of agglutinogens.

Blood Type	Agglutinogens	Agglutinins
A	A	Anti-B
B	B	Anti-A
AB	A, B	None
O	None	Anti-A, Anti-B

Heart and Blood Vessels

Pulmonary and Systemic Circuits

• Pulmonary circuit: Carries blood from the heart to the lungs and back.

• Systemic circuit: Carries blood from the heart to the rest of the body and back.

General Structure of the Heart

• Coverings: Pericardium (protective sac).

• Chambers: Two atria (upper), two ventricles (lower).

• Valves: Ensure one-way flow; atrioventricular and semilunar valves.

Pathway of Blood Through the Heart

• Right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → body

Phases of the Cardiac Cycle

• Systole: Contraction phase; blood is pumped out.

• Diastole: Relaxation phase; chambers fill with blood.

Arteries vs. Veins

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

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

Pulse and Blood Pressure

• Pulse: Rhythmic expansion of arteries due to heartbeat.

• Blood pressure: Force of blood against vessel walls; measured as systolic/diastolic (e.g., 120/80 mmHg).

Lymphatic and Immune System

General Functions

• Returns excess tissue fluid to the bloodstream.

• Defends against pathogens.

Main Parts of the Lymphatic System

• Lymphatics: Network of vessels.

• Lymph: Fluid transported by lymphatics.

• Lymph nodes: Filter lymph and house immune cells.

Innate Defenses

• First line: Skin and mucous membranes.

• Second line: Phagocytes, natural killer cells, inflammatory response, antimicrobial proteins, fever.

Adaptive Defenses

• Characteristics: Specific, memory-based.

• Humoral branch: B-cells produce antibodies targeting extracellular pathogens.

• Cellular branch: T-cells target infected cells directly or indirectly; crucial for immune response.

Antigen

• Antigen: Substance that triggers an immune response.

Urinary System

General Components

• Kidneys, ureters, bladder, urethra.

Functions of Kidneys

• Filter blood, remove waste, regulate fluid and electrolyte balance.

Structure of Nephrons

• Nephron: Functional unit of the kidney.

• Renal corpuscle: Includes glomerulus (capillary network) and glomerular capsule (Bowman's capsule).

• Renal tubule: Proximal convoluted tubule, nephron loop (loop of Henle), distal convoluted tubule.

Filtrate vs. Urine

• Filtrate: Fluid filtered from blood in the glomerulus; contains water, ions, small molecules.

• Urine: Final waste product after reabsorption and secretion; excreted from the body.

Three Steps of Urine Formation

• Glomerular filtration

• Tubular reabsorption

• Tubular secretion