Exam 3 Study Guide: Endocrine, Blood, Cardiovascular, and Lymphatic Systems

Chapter 9: The Endocrine System

Overview of the Endocrine System

The endocrine system is a major regulatory system of the body, working alongside the nervous system to maintain homeostasis. While the nervous system provides rapid, short-term control, the endocrine system exerts slower, longer-lasting effects through the release of hormones.

• Endocrine glands are ductless and release hormones directly into the bloodstream.

• Exocrine glands secrete substances via ducts to the body's surface or into body cavities (e.g., sweat glands).

• Only cells with specific hormone receptors can respond to a given hormone.

Roles of the Endocrine System

• Regulation of metabolism

• Control of growth and development

• Maintenance of electrolyte, water, and nutrient balance

• Mobilization of body defenses

• Reproduction

Hormone Mechanisms and Classes

• Lipophilic (steroid) hormones can cross the plasma membrane and bind to intracellular receptors.

• Hydrophilic (amino acid-based) hormones require surface receptors and often use a second messenger (e.g., cAMP) to relay the signal inside the cell.

• Chemical classes of hormones:

  • Amino acid-based hormones (most common)

  • Steroids (derived from cholesterol)

  • Prostaglandins (local hormones derived from fatty acids)

Second messenger: An intracellular molecule (such as cAMP) that mediates the effects of a hormone that cannot cross the plasma membrane.

Major Endocrine Glands and Hormones

Refer to Table 9.1 for a summary of the major endocrine glands and their hormones. Most hormones are amino acid-based; exceptions include steroid hormones from the adrenal cortex and gonads.

Table 9.2 lists hormones produced by organs not primarily considered endocrine organs (e.g., kidneys, heart).

Stimuli for Hormone Release

• Hormonal stimuli: Hormones stimulate other endocrine glands to release hormones.

• Humoral stimuli: Changes in blood levels of ions or nutrients trigger hormone release.

• Neural stimuli: Nerve fibers stimulate hormone release.

• Most hormone release is regulated by negative feedback mechanisms.

Pituitary Gland and Hypothalamus

• The pituitary gland is the "master gland" and has two lobes:

  • Anterior pituitary: Produces and releases hormones (e.g., GH, TSH, ACTH, FSH, LH, PRL).

  • Posterior pituitary: Stores and releases hormones made by the hypothalamus (e.g., ADH, oxytocin).

• The hypothalamus controls the pituitary via releasing and inhibiting hormones and direct neural connections.

Hormonal Regulation of Homeostasis

• PTH (parathyroid hormone) increases blood calcium by stimulating osteoclasts, increasing intestinal absorption, and reducing renal excretion.

• Calcitonin lowers blood calcium by inhibiting osteoclasts and increasing calcium deposition in bones.

• Aldosterone (from adrenal cortex) regulates sodium and potassium balance; its release is stimulated by the renin-angiotensin system, high potassium, or ACTH.

• Insulin (from pancreas) lowers blood glucose by promoting cellular uptake; glucagon raises blood glucose by stimulating glycogen breakdown.

Stress Responses

• Short-term stress: Mediated by adrenal medulla (epinephrine/norepinephrine); increases heart rate, blood pressure, and energy availability.

• Long-term stress: Mediated by adrenal cortex (cortisol, aldosterone); increases glucose availability, suppresses immune response, retains sodium/water.

Hormone Abbreviations

• GH: Growth Hormone

• TSH: Thyroid-Stimulating Hormone

• ACTH: Adrenocorticotropic Hormone

• FSH: Follicle-Stimulating Hormone

• LH: Luteinizing Hormone

• PRL: Prolactin

• ADH: Antidiuretic Hormone

Example: Insulin and glucagon work together to maintain blood glucose homeostasis; after a meal, insulin lowers glucose, while between meals, glucagon raises it.

Chapter 10: Blood

Composition and Functions of Blood

Blood is a connective tissue with a liquid matrix (plasma) and formed elements (cells and cell fragments). It transports substances, regulates temperature, and protects against disease.

• Plasma: The liquid matrix; contains water, proteins (e.g., albumin), nutrients, hormones, and waste products.

• Formed elements: Erythrocytes (RBCs), leukocytes (WBCs), and platelets (thrombocytes).

Physical Characteristics of Blood

• pH: 7.35–7.45

• Volume: ~5–6 L in adult males, ~4–5 L in adult females

• Viscous, slightly alkaline

Plasma Proteins

• Albumin: Most abundant plasma protein; produced by the liver; maintains osmotic pressure and transports substances.

Formed Elements

• Erythrocytes (RBCs): Biconcave, anucleate; transport oxygen and carbon dioxide; most abundant.

• Leukocytes (WBCs): Nucleated; defend against pathogens; classified as granulocytes or agranulocytes.

• Platelets: Cell fragments; essential for blood clotting (hemostasis).

All formed elements derive from hematopoietic stem cells in the red bone marrow.

Leukocyte Classification

• Granulocytes: Neutrophils, eosinophils, basophils (contain granules in cytoplasm).

• Agranulocytes: Lymphocytes, monocytes (lack visible granules).

Hemostasis (Blood Clotting)

1. Vascular spasm

2. Platelet plug formation

3. Coagulation (fibrin clot formation)

Blood Groups and Transfusions

• ABO blood groups: Determined by presence/absence of A and B antigens on RBCs.

• Agglutination: Clumping of RBCs due to antibody-antigen reaction.

• Hemolysis: Destruction of RBCs, which can occur in incompatible transfusions.

Example: Type A blood has A antigens and anti-B antibodies; transfusing type B blood would cause agglutination and hemolysis.

Chapter 11: The Cardiovascular System

Anatomy of the Heart

• The heart has four chambers: right/left atria and right/left ventricles.

• Valves ensure one-way flow: tricuspid, pulmonary, bicuspid (mitral), and aortic valves.

• Chordae tendineae anchor valve flaps to papillary muscles.

• Apex: Pointed end of the heart; base: broad superior region.

• PMI (Point of Maximal Impulse): Location where the heartbeat is most strongly felt.

Heart Wall and Coverings

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

• Pericardium: double-layered sac covering the heart.

Blood Flow Through the Heart and Circuits

• Blood flows through the heart in a specific sequence, passing through all chambers and valves.

• Pulmonary circuit: Right side pumps blood to lungs for oxygenation.

• Systemic circuit: Left side pumps oxygenated blood to the body.

Electrical Activity and Cardiac Cycle

• Electrical pathway: SA node → AV node → AV bundle (bundle of His) → bundle branches → Purkinje fibers.

• This sequence ensures coordinated contraction and efficient pumping.

• Cardiac cycle: Sequence of events in one heartbeat (systole and diastole).

• Heart sounds: "Lub" (AV valves close), "dup" (semilunar valves close).

Cardiac Output (CO) Formula:

$CO = HR \times SV$

Where HR = heart rate, SV = stroke volume.

Factors Affecting Cardiac Output

• Preload (venous return)

• Contractility (strength of contraction)

• Afterload (resistance in arteries)

• Heart rate (affected by autonomic nervous system, hormones, etc.)

Blood Vessels: Structure and Function

• Arteries: Thick-walled, carry blood away from heart.

• Veins: Thinner walls, valves, carry blood toward heart.

• Capillaries: Thin-walled, allow exchange of gases, nutrients, and wastes.

Capillaries are uniquely suited for exchange due to their thin walls and extensive branching.

Venous Return and Capillary Exchange

• Venous return aided by skeletal muscle pump, respiratory pump, and valves.

• Capillary exchange occurs via diffusion, filtration, and osmosis.

Blood Pressure

• Blood flows due to a pressure gradient from arteries to veins.

• Measured as systolic/diastolic pressure (e.g., 120/80 mmHg).

• Systolic: Pressure during ventricular contraction; diastolic: during relaxation.

Major Arteries and Veins

• Know the main vessels of the systemic circuit (see referenced figures).

• Portal circuits: Vascular pathways that pass through two capillary beds (e.g., hepatic portal system).

Pulse and Pressure Points

• Pulse: Rhythmic expansion of arteries with each heartbeat.

• Pressure points: Sites where arteries are close to the surface and can be compressed to stop bleeding.

Developmental Aspects

• Understand the changes in the circulatory system from fetal to adult life.

Chapter 12: The Lymphatic System and Body Defenses

Lymphatic System Overview

The lymphatic system returns interstitial fluid to the bloodstream, absorbs fats, and provides immune defense.

• Lymph: Fluid collected from tissues, returned to blood via lymphatic vessels.

• Lymphatic vessels are similar to veins (thin walls, valves).

• Lymph returns to circulation via thoracic duct and right lymphatic duct.

Lymphoid Organs and Tissues

• Lymph nodes: Filter lymph; more afferent than efferent vessels slow flow for filtration.

• Other organs: Spleen, thymus, tonsils, Peyer's patches, appendix.

Body Defenses: Innate vs. Adaptive Immunity

• Innate (nonspecific) defenses: Present at birth; include barriers (skin, mucous membranes), phagocytes, inflammation, fever, and antimicrobial proteins.

• Adaptive (specific) defenses: Develop after exposure; involve lymphocytes (B and T cells), antibodies, and memory cells.

Pathogen: Any disease-causing microorganism (e.g., bacteria, viruses, fungi, parasites).

Humoral vs. Cellular Immunity

• Humoral immunity: Mediated by B cells and antibodies in body fluids.

• Cellular immunity: Mediated by T cells that attack infected or abnormal cells.

Antigens, Haptens, and Antibodies

• Antigen: Substance that triggers an immune response.

• Hapten: Small molecule that is antigenic only when attached to a larger carrier.

• Antibody: Protein produced by B cells; binds specific antigens.

• Five classes of antibodies (MADGE):

  • IgM: First responder, agglutination

  • IgA: Found in secretions (mucus, saliva, milk)

  • IgD: B cell receptor

  • IgG: Most abundant, crosses placenta

  • IgE: Allergic responses, parasites

Active vs. Passive Immunity

Type	Active Immunity	Passive Immunity
Definition	Body produces its own antibodies	Antibodies are received from another source
Natural Example	Infection	Maternal antibodies via placenta or milk
Artificial Example	Vaccination	Injection of antibodies (antiserum)

Lymphocyte Development and Immunocompetence

• B cells mature in bone marrow; T cells mature in thymus.

• Immunocompetence: Ability of lymphocytes to recognize a specific antigen.

Tissue Transplant Rejection

• Occurs when recipient's immune system attacks transplanted tissue as foreign.

• Types: Autograft, isograft, allograft, xenograft.

• Minimized by tissue matching and immunosuppressive drugs.

Disorders of Immunity

• Autoimmune diseases (e.g., lupus, rheumatoid arthritis)

• Immunodeficiencies (e.g., AIDS)

• Hypersensitivities (allergies)

Additional info: For diagrams and figures referenced (e.g., heart anatomy, blood vessels), consult your textbook or lecture slides for visual identification practice.