Anatomy & Physiology: Muscular, Cardiovascular, Lymphatic, and Respiratory Systems Study Guide

Muscle Tissue

Types and Characteristics of Muscle

Muscle tissue is specialized for contraction and is essential for movement, posture, and various bodily functions. There are three main types of muscle tissue, each with unique structural and functional characteristics.

• Skeletal Muscle: Voluntary, striated muscle attached to bones for movement.

• Cardiac Muscle: Involuntary, striated muscle found only in the heart.

• Smooth Muscle: Involuntary, non-striated muscle found in walls of hollow organs.

Functional characteristics: excitability, contractility, extensibility, elasticity.

Skeletal Muscle Structure

• Gross Anatomy: Includes connective tissue wrappings (epimysium, perimysium, endomysium), attachments (direct/indirect).

• Microscopic Anatomy:

  • Sarcolemma: Muscle cell membrane.

  • Sarcoplasm: Cytoplasm of muscle fiber.

  • Sarcoplasmic Reticulum: Stores calcium ions.

  • Myofibrils: Composed of repeating units called sarcomeres.

  • Sarcomere: Functional unit; contains thick (myosin) and thin (actin) filaments.

  • Striations: Due to arrangement of actin and myosin; includes A bands, I bands, Z lines, H zone, M line.

Sliding Filament Theory: Explains muscle contraction via interaction of actin and myosin filaments.

Muscle Contraction

• Excitation-Contraction Coupling: Sequence from action potential (electrical) to contraction (mechanical).

• All-or-None Principle: Muscle fibers contract fully or not at all.

• Motor Unit: A motor neuron and all the muscle fibers it innervates.

• Muscle Twitch: Single contraction-relaxation cycle.

• Summation: Increased force by increasing frequency of stimulation.

• Tetanus: Sustained contraction from rapid stimulation.

Muscle Metabolism

• ATP Sources: Creatine phosphate, anaerobic respiration, aerobic respiration.

• Muscle Fiber Types: Slow, fast, intermediate twitch fibers.

Smooth Muscle

• Characteristics: Sheets or bundles, single-unit (sheets) or multi-unit (individual fibers).

Blood and Hematopoiesis

Blood Components and Functions

• Plasma: Liquid matrix for transport, regulation, and protection.

• Formed Elements: Erythrocytes (RBCs), leukocytes (WBCs), platelets.

Erythrocytes (Red Blood Cells)

• Function: Transport oxygen via hemoglobin.

• Hemoglobin: Protein that binds oxygen.

• Erythropoiesis: Formation of RBCs, regulated by erythropoietin (EPO).

Leukocytes (White Blood Cells)

• Granulocytes: Neutrophils (phagocytosis), eosinophils (allergies, parasites), basophils (histamine, inflammation).

• Agranulocytes: Lymphocytes (T and B cells, immunity), monocytes (phagocytosis).

Hemostasis

• Vascular Spasm: Vasoconstriction to reduce blood loss.

• Platelet Plug Formation: Platelets adhere and aggregate.

• Coagulation: Cascade of reactions leading to fibrin clot formation.

Blood Types: A, B, AB, O, Rh+/- (antigens and antibodies determine compatibility).

Cardiovascular System: Heart

Heart Structure and Function

• Layers: Pericardium, myocardium, endocardium.

• Chambers: Right/left atria (receive blood), right/left ventricles (pump blood).

• Valves: Ensure unidirectional blood flow (tricuspid, bicuspid/mitral, pulmonary, aortic).

Name	Location
Tricuspid Valve	Between right atrium and right ventricle
Pulmonary Valve	Between right ventricle and pulmonary artery
Bicuspid (Mitral) Valve	Between left atrium and left ventricle
Aortic Valve	Between left ventricle and aorta

Cardiac Physiology

• Conduction System: SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers.

• ECG Waves: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

• Cardiac Cycle: Sequence of events in one heartbeat (systole and diastole).

• Cardiac Output: $CO = HR \times SV$ (heart rate × stroke volume)

• Frank-Starling Law: Increased preload increases stroke volume.

Blood Vessels and Circulation

Blood Vessel Anatomy

• Layers: Tunica intima (inner), tunica media (middle, smooth muscle), tunica externa (outer, connective tissue).

• Types: Arteries, arterioles, capillaries, venules, veins.

Venous Return: Aided by valves, skeletal muscle pump, and respiratory pump.

Blood Pressure and Regulation

• Blood Pressure (BP): Force of blood against vessel walls.

• Peripheral Resistance (PR): Affected by blood viscosity, vessel length, vessel diameter.

• Vasomotor Center: Sympathetic control of vessel tone.

Cardiovascular Centers and Hormonal Control

• Chemical Controls: Catecholamines (norepinephrine, epinephrine), ADH, angiotensin II, aldosterone, ANP.

• Endothelial Factors: Endothelin (vasoconstrictor), nitric oxide (vasodilator).

Lymphatic System

Functions and Components

• Functions: Returns interstitial fluid to blood, immune defense, absorption of dietary fats.

• Lymph: Fluid transported by lymphatic vessels.

• Lymphoid Organs: Lymph nodes, spleen, thymus, tonsils, MALT (mucosa-associated lymphatic tissue).

• Cells: Lymphocytes (T and B cells), macrophages, dendritic cells.

Respiratory System

Functions and Anatomy

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

• Zones: Conducting zone (airways), respiratory zone (gas exchange in alveoli).

• Alveoli: Type I cells (gas exchange), Type II cells (surfactant production).

Mechanics of Breathing

• Inspiration: Diaphragm and external intercostals contract, thoracic volume increases, pressure decreases.

• Expiration: Usually passive; forced expiration uses abdominal and internal intercostal muscles.

• Gas Exchange: Occurs by diffusion across respiratory membrane.

Gas Transport

• Oxygen: Mostly bound to hemoglobin; small amount dissolved in plasma.

• Carbon Dioxide: Transported as bicarbonate (HCO3-), dissolved in plasma, or bound to hemoglobin.

• Bohr Effect: Increased CO2 and H+ lower hemoglobin's affinity for O2.

Respiratory Control

• Centers: Medullary respiratory center, pontine respiratory center.

• Regulation: Chemoreceptors respond to CO2, O2, and pH changes.

Key Abbreviations and Terms

• ATP: Adenosine triphosphate

• BP: Blood pressure

• CO: Cardiac output

• ECG/EKG: Electrocardiogram

• EDV: End diastolic volume

• ESV: End systolic volume

• HR: Heart rate

• ICF/ECF: Intracellular/Extracellular fluid

• PR: Peripheral resistance

• SV: Stroke volume

• WBC/RBC: White/Red blood cell

Additional info: Some content was expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.