CS

Study Guide_Exam 2 (1)

Ch 20: Blood Vessels

Blood Vessel Structure & Function

  • Types of Blood Vessels: Include arteries, veins, and capillaries.

  • Tunics of the Vessels: Vessels generally consist of three layers:

    • Tunica Intima: The innermost layer, composed of endothelial cells.

    • Tunica Media: The middle layer, made of smooth muscle and elastic fibers.

    • Tunica Externa (Adventitia): The outer layer, consisting of connective tissue.

Comparison of Arteries and Veins

  • Characteristics of Arteries:

    • Generally thicker walls due to higher pressure.

    • More elastic

    • Thick muscle

    • smaller lumen

  • Characteristics of Veins:

    • Thinner walls, larger lumen, and possess valves to prevent backflow.

Types of Arteries

  • Elastic Arteries: Large and close to the heart. More elastic, less smooth muscle. Function: pressure reservoir (systole/distole)

  • Muscular Arteries: More smooth muscle less elastic fibers Function: regulate blood flow rate (constrict/dilate)

  • Arterioles: Smallest arteries; regulate blood flow into capillaries.

Types of Veins

  • Venules: Smallest veins, collecting blood from capillaries.

  • Medium-sized Veins: Have valves to prevent backflow.

  • Large Veins: Close to the heart; carry blood back with help from nearby muscles.

Types of Capillaries

  • Continuous Capillaries: Endothelial cells provide uninterrupted lining. Allow small substances to pass; found most capillaries of muscles, skin, thymus, lungs, brain and spinal cord.

  • Fenestrated Capillaries: Have pores for filtration; found in kidneys and small intestine.

  • Sinusoidal Capillaries: Large and leaky; found in liver, spleen , and red bone marrow.

Blood Flow through Capillaries

  • Metarteriole

  • Precapillary sphincters regulate blood flow into the capillary beds, allowing for control of nutrient exchange and blood distribution based on tissue needs.

  • Throughfare channels provide a direct route for blood to flow from arterioles to venules.

Pathways of Blood Vessels

Simple: 1 artery-1 vein

Anastomoses:Arterial, Venous, Arteriovenous

Portal system: two capillary beds

Capillary Exchange

  • Diffusion: Movement of substances from higher concentration to lower.

  • Transcytosis/Vesicular Transport: Movement of large, polar substances across endothelium.

  • Bulk Flow: Governed by:

    • Hydrostatic Pressure: push water out (filtration)

    • Colloid Osmotic Pressure: Pulls water in (absorbtion)

Blood Flow in the Systemic Circulation

  • Elastic Arteries

  • Muscular Arteries

  • Arterioles

  • Metarterioles

  • True Capillaries

  • Venules

  • Medium Venules

  • Large Venules

Local Blood Flow

Depends on:

  1. Degree of Vascularization

    -Angiogenesis (formation of new vessels)

    -Regression (return of original vessels)

  2. Local Regulatory factors (vasodilators vs vasoconstrictors)

  3. Total blood flow (CO)

Factors Affecting Blood Pressure

  • Cardiac Output: Volume of blood pumped by heart.

  • Heart Rate: Number of beats per minute.

  • Stroke Volume: Amount of blood ejected with each heartbeat.

  • Mean Arterial Pressure: Average pressure in arteries during one cardiac cycle.

  • Vascular Resistance: Resistance blood faces as it flows through vessels.

Measurement of Blood Pressure

  • Systemic Blood Pressure: Measured in the arteries.

  • Diastolic Blood Pressure: Pressure during heart relaxation.

  • Pulse Pressure: Difference between systolic and diastolic pressures.

Venous Return

  • Assisted by valves, respiratory pump, and skeletal muscle pump.

Regulation of Blood Pressure & Blood Flow

  • Hormonal Regulation: Hormones like adrenalin can affect heart rate and vessel tone.

Pulse

  • Bradycardia: Slow heart rate.

  • Tachycardia: Fast heart rate.

Circulatory Routes

  • Systemic Circulation: Not included in lecture exam.

  • Pulmonary Circulation: Carries blood to the lungs for oxygenation.

  • Hepatic Portal Circulation: Blood from digestive organs to liver.

  • Fetal Circulation: Unique features in developing fetus.

Ch 21: Lymphatic Systems

Components of the Lymphatic System

  • Lymph: Fluid containing white blood cells.

  • Lymph Vessels: Includes capillaries, vessels, trunks, ducts.

  • Primary Lymphatic Organs:

    • Bone Marrow: Site of blood cell production.

    • Thymus: Site for T-cell maturation.

  • Secondary Lymphatic Organs:

    • Spleen: Filters blood and houses lymphocytes.

    • Lymph Nodes: Filter lymph and contain immune cells.

    • Lymphatic Nodules: e.g., MALT, involved in immune responses.

Functions of the Lymphatic System

  • Drain excess interstitial fluid, transport dietary lipids, and facilitate immune responses.

Formation & Flow of Lymph

  • Formed from interstitial fluid; flows through lymphatic vessels towards heart.

Routes of Drainage

  • Lymph is eventually filtered through lymph nodes before returning to blood circulation.

Ch 22: Immune Systems

Innate Immunity

  • 1st Line of Defense:

    • Skin & Mucous Membranes: Physical barriers to pathogens.

  • 2nd Line of Defense:

    • Cells: Phagocytes, NK cells that target pathogens.

    • Antimicrobial Proteins: e.g., Complement system, Interferons to combat infections.

    • Physiological Responses: Inflammatory response and fever to eliminate pathogens.

Adaptive Immunity

  • 3rd Line of Defense: Tailored response to specific pathogens.

Cell-Mediated Immunity

  • Clonal Selection: Process for T-cells.

  • Antigens: Substance recognized by immune system.

  • Lymphocyte Structure:

    • B-cells and T-cells play specific roles in immune response.

  • Antigen Processing and Presentation:

    • Antigen Presenting Cells (APCs) prepare antigens for T-cells.

  • Major Histocompatibility Complex (MHC):

    • MHC I: Present on all nucleated cells; signals cytotoxic T-cells.

    • MHC II: Present on APCs; signals helper T-cells.

  • Thymic Selection: Positive and negative selection processes for T-cells.

  • Types of Mature T Cells: Identify various effector and memory cells.

  • Activation of T-Cells: Triggers effector responses to eliminate invaders.

Antibody-Mediated Immunity

  • Activation of B-Cells:

    • Converts to plasma cells and memory cells.

  • Antibodies (Immunoglobulins):

    • Involved in neutralizing antigens; five classes of antibodies with distinct functions.

  • Immunological Memory:

    • Distinguishes primary and secondary immune responses.

  • Types of Acquired Immunity:

    • Active Immunity: Naturally or artificially acquired.

    • Passive Immunity: Naturally (e.g. maternal antibodies) or artificially acquired (e.g. serum).

Hypersensitivities

  • Types I-IV: Various allergic and immune reactions.