Blood Composition and Function Quiz

Blood Composition and Function

• Blood is a connective tissue, consisting of cellular components (formed elements) and an extracellular matrix (plasma).
• Centrifugation separates blood based on density, creating distinct layers: plasma, buffy coat (platelets and leukocytes), and erythrocytes (red blood cells).
• Plasma comprises water, electrolytes, hormones, gases, nutrients, wastes, and proteins (albumen, globulins, transport proteins, fibrinogen).
• Serum is plasma minus the clotting proteins (fibrinogen).
• Blood's functions include distributing gases, nutrients, wastes, ions, chemical messengers, and heat across the body.
• Blood movement is driven by pressure differences, essential for all transport functions.

Formed Elements

• Erythrocytes (Red Blood Cells): Disc-shaped cells containing hemoglobin, responsible for oxygen transport.
• Hemoglobin (Hb): A protein with four peptide chains, capable of binding and releasing oxygen, carbon dioxide. Different forms include oxyhemoglobin, deoxyhemoglobin, and carbaminohemoglobin.
• Hematopoiesis: Blood cell formation occurring primarily in red bone marrow, utilizing hematopoietic stem cells. Yellow bone marrow primarily contains adipose tissue.
• Leukocytes (White Blood Cells): Include granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). They participate in immune responses.
• Platelets: Essential for blood clotting. Their precursor cell is the megakaryocyte.
• Neutrophils engulf bacteria.
• Eosinophils are involved in parasitic infections and allergies.
• Lymphocytes produce antibodies.
• Basophils release toxic substances.

Blood Analysis and Clinical Terms

• Hematocrit: The percentage of red blood cells in blood volume.
• Serum: The liquid portion of blood after clotting.
• Centrifugation: The method used to separate blood components based on density.
• Plasma proteins: Albumin, globulin, and fibrinogen, are not all components of plasma; collagen is not.
• Fibrinogen converts to fibrin during blood clotting(insoluble).

Erythrocyte Lifespan and Breakdown

• Erythrocytes have a lifespan of approximately 120 days.
• The liver and spleen detect and destroy aged or damaged red blood cells.
• Bilirubin is a byproduct of hemoglobin breakdown, excreted from the body.

Erythropoietin (EPO)

• Erythropoietin is a hormone that stimulates red blood cell production.

Heart Function (Overview)

• Pericardium: The membranes surrounding the heart (fibrous, parietal, visceral).
• Heart innervation: Autonomic nerves (sympathetic and parasympathetic) release neurotransmitters (norepinephrine, acetylcholine) affecting pacemaker cells, influencing heart rate.
• Pacemaker cells: Specialized cells generating electrical impulses that initiate heartbeat; have a unique channel, 'funny channels', crucial for maintaining their inherent rhythmic activity. They also use calcium channels instead of sodium channels to generate depolarization.
• Contractile cardiac cells: Depolarization from adjacent cells initiates an action potential via gap junctions in the intercalated discs. The action potential leads to contraction by a process involving calcium release.
• Calcium-induced calcium release (CICR): Calcium entering the cell triggers more calcium release from the sarcoplasmic reticulum (SR), a crucial step of contraction.
• Plateau phase: A delay in repolarization due to simultaneous calcium and potassium flow.