Chapter 16,17 Check your understanding

Blood Composition and Plasma

Plasma Components

Blood plasma is the liquid component of blood, serving as a transport medium for cells and dissolved substances.

• Water: Makes up about 90-92% of plasma; acts as a solvent and helps regulate temperature.

• Proteins: Includes albumin, globulins, and fibrinogen; essential for osmotic balance, immunity, and clotting.

• Electrolytes: Sodium, potassium, calcium, chloride, bicarbonate; maintain pH and osmotic balance.

• Nutrients: Glucose, amino acids, lipids, vitamins.

• Waste Products: Urea, creatinine, bilirubin.

• Hormones and Gases: Oxygen, carbon dioxide, hormones.

Example: Albumin is the most abundant plasma protein and is crucial for maintaining blood osmotic pressure.

Plasma Proteins

Plasma proteins perform various functions in the body.

• Albumin: Maintains osmotic pressure and transports substances.

• Globulins: Involved in immune responses (antibodies).

• Fibrinogen: Essential for blood clotting.

Most Important: Albumin is considered the most important for osmotic balance.

Blood Cell Formation and Leukemia

Mechanism of Red Blood Cell Formation (Erythropoiesis)

Erythropoiesis is the process of producing red blood cells (RBCs) in the bone marrow.

• Stimulated by erythropoietin, a hormone released by the kidneys in response to low oxygen levels.

• Requires iron, vitamin B12, and folic acid.

• Occurs in several stages: proerythroblast → erythroblast → reticulocyte → mature erythrocyte.

Example: Chronic blood loss increases erythropoietin production, stimulating RBC formation.

Leukemia

Leukemia is a cancer of blood-forming tissues, leading to excessive production of abnormal white blood cells.

• Impairs normal blood cell function.

• Symptoms include anemia, infections, and bleeding.

Hormones and Blood Cell Regulation

Erythropoietin and Thrombopoietin

Erythropoietin (EPO): Hormone that stimulates RBC production.

• Released by kidneys in response to hypoxia (low oxygen).

• Acts on bone marrow.

Thrombopoietin: Hormone that stimulates platelet production.

• Produced mainly by the liver.

Hematopoiesis: The process of blood cell formation from stem cells in the bone marrow.

Stimulus for Erythropoietin Release

• Main stimulus: Hypoxia (low oxygen levels in tissues).

Average Life Span of RBC

• Approximately 120 days.

Functions of RBCs, WBCs, and Platelets

• RBCs: Transport oxygen and carbon dioxide.

• WBCs: Defend against infection and foreign substances.

• Platelets: Involved in blood clotting.

Platelet Plug Formation

Platelets adhere to damaged blood vessel walls, aggregate, and release chemicals to form a temporary plug.

• Essential for stopping bleeding (hemostasis).

Blood Clotting Cascade

The clotting cascade is a series of enzymatic reactions leading to the formation of a fibrin clot.

• Involves intrinsic and extrinsic pathways.

• Final step: conversion of fibrinogen to fibrin.

Blood Properties and Transport

RBCs in Different Solutions

• Hypertonic Solution: RBCs shrink (crenation).

• Hypotonic Solution: RBCs swell and may burst (hemolysis).

• Isotonic Solution: RBCs maintain normal shape.

Transferrin

Transferrin is a plasma protein that binds and transports iron in the blood.

Ferritin and Hemophilia

• Ferritin: Protein that stores iron in cells.

• Hemophilia: Genetic disorder causing impaired blood clotting due to deficiency of clotting factors.

Respiratory System Structure and Function

Primary Function of the Respiratory System

The main function is gas exchange: supplying oxygen to the blood and removing carbon dioxide.

Site of Gas Exchange

• Alveoli: Tiny air sacs in the lungs where gas exchange occurs.

• Oxygen diffuses into blood; carbon dioxide diffuses out.

Ventilation

Ventilation refers to the movement of air in and out of the lungs.

• Actual site of gas exchange: Alveolar-capillary membrane.

Sequence of Air Flow in the Respiratory Tract

• Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

Type I and Type II Alveolar Cells

• Type I cells: Form the structure of the alveolar wall; site of gas exchange.

• Type II cells: Secrete surfactant, which reduces surface tension and prevents alveolar collapse.

Surfactant

Surfactant is a substance that decreases surface tension in the alveoli, aiding in lung expansion.

Diaphragm and Intercostal Muscles

• Diaphragm: Main muscle of respiration; contracts to increase thoracic volume during inspiration.

• External intercostal muscles: Assist in elevating the rib cage during inspiration.

Movement of Air into the Lungs

• Occurs due to pressure differences: air moves from higher to lower pressure.

• Inspiration: thoracic cavity expands, pressure drops, air enters.

Intrapleural Pressure

Intrapleural pressure is the pressure within the pleural cavity; it is always slightly negative compared to atmospheric pressure, keeping the lungs inflated.

Respiratory Volumes and Capacities

Different volumes and capacities are measured to assess lung function.

Term	Definition	Typical Value (Adult)
Tidal Volume (TV)	Volume of air inhaled or exhaled in a normal breath	~500 mL
Vital Capacity (VC)	Maximum amount of air exhaled after maximum inhalation	~4800 mL
Inspiratory Reserve Volume (IRV)	Additional air inhaled after a normal inspiration	~3100 mL
Expiratory Reserve Volume (ERV)	Additional air exhaled after a normal expiration	~1200 mL
Residual Volume (RV)	Air remaining in lungs after maximal exhalation	~1200 mL

Equations:

• Vital Capacity: $VC = TV + IRV + ERV$

• Total Lung Capacity: $TLC = VC + RV$

Inspiration vs. Expiration

• Inspiration: Active process; diaphragm contracts, thoracic volume increases.

• Expiration: Usually passive; diaphragm relaxes, thoracic volume decreases.

Example: During exercise, both inspiration and expiration become active processes.

Additional info: Some questions in the file refer to regulatory mechanisms and clinical conditions (e.g., hemophilia, leukemia) that are important for understanding pathology and physiology in clinical practice.