Anatomy & Physiology Exam Study Guide: Blood, Heart, and Major Vessels

Blood: Structure, Composition, and Function

Special Connective Tissue

Blood is classified as a special connective tissue that develops from mesenchyme, an embryonic connective tissue. This classification is based on its cellular components suspended in a liquid extracellular matrix (plasma).

• Mesenchyme: The embryonic tissue from which all connective tissues, including blood, originate.

• Plasma: The liquid matrix of blood, making up about 55% of its volume.

Major Components of Whole Blood

Whole blood consists of plasma and formed elements (cells and cell fragments).

• Plasma: Contains water, proteins (albumin, globulins, fibrinogen), electrolytes, nutrients, hormones, and waste products.

• Formed Elements:

  • Red blood cells (erythrocytes): Transport oxygen and carbon dioxide.

  • White blood cells (leukocytes): Defend against pathogens.

  • Platelets (thrombocytes): Involved in blood clotting.

Table: Major Components of Plasma

Component	Function
Water (about 90%)	Solvent for carrying other substances
Proteins (albumin, globulins, fibrinogen)	Osmotic balance, immune response, clotting
Electrolytes (Na+, K+, Ca2+, etc.)	Osmotic balance, pH buffering, regulation of membrane permeability
Nutrients, hormones, wastes	Transported to/from cells

Most abundant plasma protein: Albumin

Blood pH

• Normal blood pH is tightly regulated between 7.35 and 7.45.

• Maintaining pH is critical for enzyme function and overall homeostasis.

Hemoglobin Structure and Function

• Hemoglobin (Hb): A protein in red blood cells responsible for oxygen transport.

• Structure: Four polypeptide chains, each with a heme group that binds oxygen.

• Forms: Oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), carbaminohemoglobin (HbCO2).

Hormonal Control of Erythropoiesis

• Erythropoietin (EPO): Hormone produced by the kidneys that stimulates red blood cell production in response to hypoxia (low oxygen levels).

Red Blood Cell Destruction and Hemoglobin Metabolism

• Old RBCs are broken down in the spleen and liver.

• Hemoglobin is split into heme and globin; heme is further broken down into iron (recycled) and bilirubin (excreted in bile).

• Pigments from hemoglobin breakdown: Bilirubin (yellow), biliverdin (green).

Blood Typing and ABO System

• Blood types are determined by the presence of antigens (A, B) on RBC surfaces.

• Antibodies in plasma react with foreign antigens, leading to agglutination if mismatched.

• Example: Type A blood has A antigens and anti-B antibodies.

Anemia: Types and Causes

• Anemia: A condition characterized by a deficiency of red blood cells or hemoglobin, leading to reduced oxygen transport.

• Causes: Blood loss, decreased RBC production, increased RBC destruction.

Hemostasis and Blood Clotting

• Hemostasis: The process of stopping bleeding, involving vascular spasm, platelet plug formation, and coagulation.

• Coagulation: A cascade of reactions leading to the conversion of fibrinogen to fibrin, forming a stable clot.

• Clotting factors: Proteins in plasma essential for coagulation (see Table 17.3 in textbook).

Thromboembolic and Bleeding Disorders

• Thromboembolic disorders: Conditions where clots form inappropriately (e.g., deep vein thrombosis, pulmonary embolism).

• Bleeding disorders: Conditions where clotting is impaired (e.g., hemophilia, thrombocytopenia).

Heart: Anatomy, Physiology, and Pathology

Gross Anatomy and Orientation

• The heart is located in the thoracic cavity, within the mediastinum, and oriented with the apex pointing left and inferiorly.

• Major anatomical features: atria, ventricles, septa, valves.

Microscopic Anatomy of Cardiac Muscle

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

• Intercalated discs contain desmosomes (mechanical connection) and gap junctions (electrical connection).

Intrinsic Cardiac Conduction System

• Specialized cardiac cells generate and conduct electrical impulses, coordinating heartbeats.

• Main components: SA node, AV node, bundle of His, bundle branches, Purkinje fibers.

Action Potential of Contractile Cardiac Muscle Cells

• Cardiac action potentials have a prolonged plateau phase due to Ca2+ influx, allowing sustained contraction.

• Phases: rapid depolarization, plateau, repolarization.

The Cardiac Cycle

• The cardiac cycle consists of all events associated with one heartbeat: atrial systole, ventricular systole, and diastole.

• Key events: ventricular filling, isovolumetric contraction, ventricular ejection, isovolumetric relaxation.

Blood Flow Through the Heart

• Deoxygenated blood enters the right atrium, passes to the right ventricle, and is pumped to the lungs.

• Oxygenated blood returns to the left atrium, passes to the left ventricle, and is pumped to the systemic circulation.

Heart Wall and Coverings

• Three layers: epicardium (outer), myocardium (muscular middle), endocardium (inner).

• Pericardium: double-walled sac enclosing the heart, providing protection and reducing friction.

Heart Pathology

• Pathologies may involve the pericardium (pericarditis), valves (stenosis, regurgitation), or myocardium (myocardial infarction/heart attack).

Autonomic Regulation of Heart

• Cardiac function is regulated by the autonomic nervous system via the medulla oblongata.

• Cardioacceleratory center (sympathetic) increases heart rate; cardioinhibitory center (parasympathetic) decreases heart rate.

• Regulatory centers are located in the medulla oblongata.

Stroke Volume Calculation

• Stroke volume (SV) is the amount of blood ejected by a ventricle per beat.

• Formula: $SV = EDV - ESV$ where EDV = end-diastolic volume, ESV = end-systolic volume.

Major Arteries and Veins: Structure and Function

Major Vessels and Their Connections

• Major arteries and veins are responsible for transporting blood to and from all body regions.

• Examples:

  • Jugular vein: Drains blood from the head and neck.

  • Renal artery: Branches from the aorta to supply the kidneys.

Areas Served or Drained by Vessels

• Each major vessel serves or drains specific anatomical regions.

• Understanding these connections is essential for clinical practice and diagnosis.

Summary Table: Examples of Major Arteries and Veins

Vessel	Type	Region Served/Drained
Jugular vein	Vein	Drains head and neck
Renal artery	Artery	Supplies kidneys
Brachial artery	Artery	Supplies upper arm
Femoral vein	Vein	Drains lower limb
Superior vena cava	Vein	Drains upper body to right atrium
Aorta	Artery	Main systemic artery

Additional info: Some details, such as the specific content of textbook figures and tables, were inferred based on standard Anatomy & Physiology curricula.