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.