Comprehensive Study Notes: Anatomy & Physiology Core Systems and Processes

Musculoskeletal System

Osseous Tissue

Osseous tissue, or bone tissue, is a specialized connective tissue that forms the rigid part of bones. It provides structural support, protection, and enables movement.

• Compact vs Spongy Bone: Compact bone is dense and forms the outer layer of bones, providing strength. Spongy bone is lighter, found at the ends of long bones, and contains red bone marrow.

• Bone Fractures: A fracture is a break in bone continuity. Types include simple, compound, and comminuted fractures.

• Skeletal Muscle Contraction: Skeletal muscles contract via the sliding filament mechanism, involving actin and myosin filaments.

Example: The femur contains both compact and spongy bone, allowing it to withstand forces and produce blood cells.

Anatomy & Physiology of the Heart

Cardiac Activity Control

The heart's activity is regulated by intrinsic and extrinsic mechanisms to maintain effective circulation.

• Autonomic Control: The autonomic nervous system modulates heart rate and contractility via sympathetic and parasympathetic inputs.

• Cardiac Cycle: The cardiac cycle consists of systole (contraction) and diastole (relaxation), ensuring blood flow through the heart chambers.

• Cardiac Output: Cardiac output is the volume of blood pumped by the heart per minute. $\text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate}$

Example: During exercise, sympathetic stimulation increases heart rate and cardiac output.

Circulatory System

Blood Pressure Regulation

Blood pressure is regulated by neural and hormonal mechanisms to ensure tissue perfusion.

• Baroreceptor Reflex: Baroreceptors in the carotid sinus and aortic arch detect changes in blood pressure and adjust heart rate and vessel diameter.

• RAAS System: The renin-angiotensin-aldosterone system regulates blood volume and pressure.

Example: A drop in blood pressure triggers the baroreceptor reflex, increasing heart rate.

Respiratory System

Ventilation and Gas Exchange

The respiratory system enables gas exchange and regulates blood pH.

• Factors Affecting Ventilation: Airway resistance, lung compliance, and neural control influence ventilation.

• Pulmonary Disorders: Obstructive and restrictive disorders affect airflow and gas exchange.

• CO2 and pH Relationship: Increased CO2 lowers blood pH (acidosis); decreased CO2 raises pH (alkalosis).

Example: Asthma increases airway resistance, reducing ventilation.

Digestive & Metabolism

Digestive Processes and Metabolism

The digestive system breaks down food and absorbs nutrients, while metabolism refers to all chemical reactions in the body.

• Digestive Enzymes: Enzymes like amylase, protease, and lipase aid in digestion.

• Metabolic Pathways: Catabolism breaks down molecules for energy; anabolism builds complex molecules.

Example: Glucose is metabolized via glycolysis to produce ATP.

Urinary System

Renal System Structure & Function

The urinary system maintains fluid and electrolyte balance, removes waste, and regulates blood pressure.

• Kidney Structure: Includes renal cortex, renal medulla, and renal pelvis.

• Nephron Structure: Composed of corpuscle (glomerulus and Bowman's capsule), tubules (proximal, loop of Henle, distal, collecting duct).

• Renal Physiology: Kidneys filter blood, regulate fluid/electrolyte balance, secrete waste, and produce erythropoietin.

Glomerular Filtration Rate (GFR)

GFR is the total volume of filtrate formed each minute, indicating kidney function.

• Factors Influencing GFR: Pressure, surface area, membrane permeability.

• Intrinsic Regulation: Myogenic and tubuloglomerular feedback mechanisms.

• Extrinsic Regulation: Neural and hormonal control.

Example: Dehydration reduces GFR due to decreased blood volume.

Processes of Urine Formation

Urine formation involves filtration, reabsorption, secretion, and excretion.

• Filtration: Blood is filtered in the glomerulus; filtrate enters tubules.

• Reabsorption: Useful substances are reabsorbed into blood.

• Secretion: Additional wastes are secreted into tubules.

• Excretion: Urine is expelled via the ureters, bladder, and urethra.

Example: Glucose is reabsorbed in the proximal tubule; excess is excreted in diabetes.

RAAS System

The renin-angiotensin-aldosterone system regulates blood pressure and fluid balance.

• Short-term: Baroreceptor reflex adjusts blood volume.

• Long-term: RAAS increases sodium and water reabsorption, raising blood pressure.

Example: Low blood pressure stimulates renin release, activating RAAS.

Fluid and Electrolyte Balance

Hormonal Influence

Hormones like ADH and aldosterone regulate fluid and electrolyte balance.

• ADH: Increases water reabsorption in kidneys.

• Aldosterone: Promotes sodium reabsorption and potassium excretion.

Disorders of Water Balance

Imbalances include dehydration, hypotonic hydration, and oedema.

• Dehydration: Water output exceeds intake, increasing plasma osmolarity.

• Hypotonic Hydration: Water intake exceeds output, diluting plasma sodium.

• Oedema: Excess fluid accumulates in interstitial spaces.

Acid-Base Balance

The kidneys regulate acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate.

• Acidosis: Excess acid lowers blood pH.

• Alkalosis: Excess base raises blood pH.

Lymphatic and Immune Systems

Innate Defences

Innate immunity provides immediate, non-specific protection against pathogens.

• Physical Barriers: Skin, mucous membranes, hair, cilia.

• Chemical Barriers: Sweat, saliva, tears, stomach acid.

• Cellular Defences: Phagocytes, natural killer cells.

Adaptive Defences

Adaptive immunity is specific and involves lymphocytes (T and B cells).

• Helper T Cells: Activate other immune cells by recognizing antigens.

• Cytotoxic T Cells: Destroy infected cells.

• B Cells: Produce antibodies to neutralize pathogens.

Cell Type	Function
Helper T Cell	Activates immune response
Cytotoxic T Cell	Kills infected cells
B Cell	Produces antibodies

Secondary Immune Response & Vaccines

Memory cells enable a faster, stronger response upon re-exposure to antigens. Vaccines stimulate this response.

Immune Disorders

• Immunodeficiency: Inability to mount an effective immune response (e.g., AIDS).

• Autoimmune Diseases: Immune system attacks self-tissues.

• Hypersensitivity: Allergic reactions mediated by IgE antibodies.

Microbes & Infection

Types of Microbes

Microbes include bacteria, fungi, protozoa, algae, and viruses.

• Bacteria: Classified by shape (bacilli, cocci, spirilla).

• Viruses: Obligate parasites requiring host cells for replication.

• Fungi: Eukaryotic cells with cell walls.

Relationships Between Microbes and Humans

Microbes can be symbiotic, commensal, or pathogenic.

• Symbiosis: Two organisms living together.

• Pathogenicity: Ability to cause disease.

Factors Affecting Infection

Infection depends on host susceptibility, pathogen virulence, and transmission.

• Host Susceptibility: Poor health, immunodeficiency, lack of vaccination.

• Pathogen Transmission: Direct contact, airborne, vector-borne.

Events in Infection Disease

Infection involves entry, multiplication, spread, damage, and exit of pathogens.

• Portals of Entry: Skin, mucous membranes, respiratory and digestive tracts.

• Incubation Period: Time between exposure and symptom onset.

• Acute vs Chronic Infection: Acute is rapid and short-lived; chronic is prolonged.

Additional info:

• Some pharmacology content is present (routes of drug administration, pharmacokinetics/dynamics), but the majority of the material is directly relevant to Anatomy & Physiology core topics.