BION 204 Exam 3 Study Guide: Endocrine, Blood, and Cardiovascular Systems

Chapter 9 – The Endocrine System

Overview of the Endocrine System

The endocrine system is a network of glands that secrete hormones to regulate various bodily functions. Hormones are chemical messengers that travel through the bloodstream to target organs.

• Hormone: A chemical substance produced by glands, transported in the blood, and affecting target cells/organs.

• Functions of Hormones: Regulation of metabolism, growth, development, tissue function, and mood.

• Endocrine vs. Exocrine Glands: Endocrine glands secrete hormones directly into the bloodstream; exocrine glands release substances through ducts.

Hormone Classification and Mechanisms

• Chemical Classifications: Hormones can be classified as amino acid-based (proteins, peptides, amines) or steroids (derived from cholesterol).

• Direct Gene Activation vs. Second Messenger System:

  • Direct Gene Activation: Steroid hormones pass through the cell membrane and bind to intracellular receptors, directly influencing gene expression.

  • Second Messenger System: Non-steroid hormones bind to cell surface receptors, triggering a cascade via second messengers (e.g., cAMP) inside the cell.

• Endocrine vs. Nervous System: The endocrine system uses hormones for slower, longer-lasting effects; the nervous system uses electrical impulses for rapid, short-term responses.

Major Endocrine Glands and Hormones

• Major Glands: Pituitary, thyroid, parathyroid, adrenal, pancreas, gonads (ovaries/testes), pineal, thymus.

• Hormone Regulation: Hormone levels are regulated by feedback mechanisms, often negative feedback loops.

• Hormone Graphs: Understanding hormone secretion patterns over time can help identify normal vs. abnormal function.

Chapter 10 – Blood

Composition and Function of Blood

Blood is a connective tissue composed of plasma and formed elements (red blood cells, white blood cells, platelets).

• Plasma: The liquid component, making up about 55% of blood volume; contains water, proteins, nutrients, hormones, and waste products.

• Formed Elements: Red blood cells (RBCs), white blood cells (WBCs), and platelets.

Red Blood Cells (Erythrocytes)

• Function: Transport oxygen and carbon dioxide.

• Normal Count: Approximately 4-6 million per microliter of blood.

• Hemoglobin: The oxygen-carrying protein in RBCs.

• Anemia: A condition where the blood has a reduced oxygen-carrying capacity, often due to low RBC count or hemoglobin.

White Blood Cells (Leukocytes)

• Function: Defend the body against infection and disease.

• Types: Neutrophils, lymphocytes, monocytes, eosinophils, basophils.

• Leukemia: A cancer of white blood cells, leading to abnormal proliferation.

Platelets (Thrombocytes) and Hemostasis

• Function: Essential for blood clotting (hemostasis).

• Hemostasis: The process of stopping bleeding, involving vascular spasm, platelet plug formation, and coagulation.

• Phases of Hemostasis:

  1. Vascular spasm

  2. Platelet plug formation

  3. Coagulation (clotting)

• Clotting Factors: Proteins in plasma that help form blood clots.

• Hemolytic Disease of the Newborn: Occurs when maternal antibodies attack fetal RBCs due to blood type incompatibility (often Rh factor).

Blood Typing and Transfusion

• Blood Types: Determined by the presence of antigens (A, B, AB, O) and Rh factor (+ or -) on RBCs.

• Transfusion Reactions: Occur if incompatible blood is transfused, leading to agglutination and hemolysis.

Chapter 11 – The Cardiovascular System

Structure and Function of the Heart

The heart is a muscular organ that pumps blood throughout the body via the circulatory system.

• Location: In the thoracic cavity, between the lungs, slightly left of midline.

• Layers of the Heart: Epicardium (outer), myocardium (muscular middle), endocardium (inner lining).

• Chambers: Two atria (upper), two ventricles (lower).

• Valves: Atrioventricular (tricuspid, bicuspid/mitral) and semilunar (pulmonary, aortic) valves prevent backflow.

Blood Flow Through the Heart

• Pathway: Blood enters right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → body.

• Oxygenation: Right side pumps deoxygenated blood to lungs; left side pumps oxygenated blood to body.

Cardiac Conduction System

• Components: Sinoatrial (SA) node, atrioventricular (AV) node, bundle of His, bundle branches, Purkinje fibers.

• Function: Coordinates the heartbeat via electrical impulses.

• Electrocardiogram (ECG/EKG): Measures electrical activity of the heart.

Cardiac Cycle and Heart Sounds

• Systole: Contraction phase; blood is pumped out of chambers.

• Diastole: Relaxation phase; chambers fill with blood.

• Heart Sounds: "Lub-dub" sounds correspond to valve closures.

Blood Vessels and Circulation

• Types of Vessels: Arteries (carry blood away from heart), veins (carry blood to heart), capillaries (exchange sites).

• Blood Pressure: The force of blood against vessel walls; measured in mmHg.

• Pulse: The rhythmic expansion of arteries with each heartbeat.

Formulas and Measurements

• Cardiac Output (CO): The amount of blood pumped by the heart per minute. Formula: $CO = HR \times SV$ Where HR = heart rate (beats per minute), SV = stroke volume (mL per beat)

• Blood Pressure: Systolic/diastolic pressure (e.g., 120/80 mmHg).

Factors Affecting Heart Rate and Blood Pressure

• Influences: Exercise, stress, hormones, autonomic nervous system, blood volume, and vessel elasticity.

• Common Sites for Pulse: Radial artery (wrist), carotid artery (neck), etc.

Table: Comparison of Blood Vessels

Vessel Type	Function	Wall Thickness	Pressure
Artery	Carry blood away from heart	Thick	High
Vein	Carry blood to heart	Thin	Low
Capillary	Exchange of gases/nutrients	Very thin (one cell layer)	Very low

Additional info: Some explanations and examples were expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.