Chapters 17-20 Study Guide: Special Senses, Endocrine System, Blood, and Heart

Chapter 17 – The Special Senses

Overview of Special Senses

The special senses include vision, hearing, taste, smell, and equilibrium. These senses rely on specialized sensory organs and receptors to detect environmental stimuli and transmit information to the brain for interpretation.

• Olfactory glands produce substances that coat the olfactory glands, aiding in the detection of odors.

• Photoreceptors are specialized cells in the retina that respond to light and enable vision.

• Equilibrium is maintained by the semicircular canals and vestibular apparatus in the inner ear.

• Taste buds are sensory organs located on the tongue that detect different taste modalities.

Key Terms and Concepts

• Optic disc: The point on the retina where the optic nerve exits; known as the "blind spot" because it lacks photoreceptors.

• Photoreceptors: Cells (rods and cones) that detect light in the retina.

• Cochlea: Spiral-shaped organ in the inner ear responsible for hearing.

• Semicircular canals: Structures in the inner ear involved in balance and equilibrium.

• Taste buds: Clusters of gustatory cells that detect taste stimuli.

• Cribriform plate: Part of the ethmoid bone through which olfactory nerves pass.

Examples and Applications

• Example: When a person eats food, taste buds on the tongue detect sweet, salty, sour, bitter, and umami flavors, sending signals to the brain for interpretation.

• Example: The semicircular canals detect rotational movements of the head, helping maintain balance.

Chapter 18 – The Endocrine System

Overview of the Endocrine System

The endocrine system consists of glands that secrete hormones directly into the bloodstream. These hormones regulate various physiological processes, including growth, metabolism, and reproduction.

• Hypothalamus: Controls the pituitary gland and regulates many endocrine functions.

• Thyroid gland: Produces hormones that regulate metabolism.

• Adrenal cortex: Secretes corticosteroids involved in stress response and metabolism.

• Pancreas: Produces insulin and glucagon to regulate blood glucose levels.

• Gonadotropins: Hormones that stimulate the gonads (ovaries and testes).

Key Hormones and Functions

• ADH (Antidiuretic Hormone): Regulates water balance by increasing water reabsorption in the kidneys.

• Growth Hormone: Stimulates growth and cell reproduction.

• Oxytocin: Affects uterine contractions and milk ejection during childbirth and lactation.

• Thyroid hormones: Affect metabolic rate and development.

Examples and Applications

• Example: When blood sodium levels are low, aldosterone from the adrenal cortex increases sodium reabsorption in the kidneys.

• Example: Insulin lowers blood glucose by promoting uptake of glucose into cells.

Chapter 19 – The Blood

Overview of Blood and Its Functions

Blood is a connective tissue composed of plasma and formed elements (red blood cells, white blood cells, and platelets). It transports nutrients, gases, hormones, and waste products throughout the body.

• Red blood cells (RBCs): Carry oxygen from the lungs to tissues and remove carbon dioxide.

• White blood cells (WBCs): Defend the body against infection and disease.

• Platelets: Involved in blood clotting.

• Plasma: The liquid component of blood containing water, proteins, and dissolved substances.

Key Processes and Properties

• Hemopoiesis: The process of blood cell formation, primarily occurring in the bone marrow.

• Phagocytosis: The process by which certain WBCs engulf and digest pathogens.

• Blood typing: Classification of blood based on the presence of antigens (e.g., Anti-A, Anti-B).

• Fibrinogen: Plasma protein essential for blood clotting.

Examples and Applications

• Example: During an injury, platelets aggregate at the site and fibrinogen is converted to fibrin, forming a clot.

• Example: Basophils release histamine during allergic reactions.

Blood Components Table

Component	Main Function
Red Blood Cells (Erythrocytes)	Transport oxygen and carbon dioxide
White Blood Cells (Leukocytes)	Immune defense
Platelets (Thrombocytes)	Blood clotting
Plasma	Transport nutrients, hormones, and waste

Chapter 20 – The Heart

Overview of Heart Structure and Function

The heart is a muscular organ that pumps blood throughout the body via the circulatory system. It consists of four chambers: two atria and two ventricles, and is equipped with valves to ensure unidirectional blood flow.

• Atria: Upper chambers that receive blood returning to the heart.

• Ventricles: Lower chambers that pump blood out of the heart.

• Valves: Prevent backflow of blood (e.g., tricuspid, bicuspid/mitral, semilunar valves).

• SA node (Sinoatrial node): The heart's natural pacemaker, initiates electrical impulses.

• EKG (Electrocardiogram): Records the electrical activity of the heart.

Key Processes and Pathways

• Blood flow through the heart:

  1. Blood enters the right atrium from the body (systemic circulation).

  2. Passes to the right ventricle, then to the lungs via the pulmonary artery.

  3. Returns to the left atrium from the lungs (pulmonary circulation).

  4. Passes to the left ventricle, then pumped out to the body via the aorta.

• EKG Waves:

  • P wave: Atrial depolarization

  • QRS complex: Ventricular depolarization

  • T wave: Ventricular repolarization

Examples and Applications

• Example: The SA node controls the heart rate by generating regular electrical impulses.

• Example: The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.

Heart Chambers and Valves Table

Chamber	Receives Blood From	Pumps Blood To	Associated Valve
Right Atrium	Body (systemic veins)	Right Ventricle	Tricuspid Valve
Right Ventricle	Right Atrium	Lungs (pulmonary artery)	Pulmonary Semilunar Valve
Left Atrium	Lungs (pulmonary veins)	Left Ventricle	Bicuspid (Mitral) Valve
Left Ventricle	Left Atrium	Body (aorta)	Aortic Semilunar Valve

Key Terms Glossary

• Antagonists: Muscles or hormones that oppose the action of another.

• Anti-B: Antibody that reacts with B antigen on red blood cells.

• Apex: The pointed end of the heart.

• Base: The broad, superior portion of the heart.

• Cribriform plate (Ethmoid bone): Structure through which olfactory nerves pass.

• Fibrinogen: Plasma protein involved in blood clotting.

• Formed elements: Cellular components of blood (RBCs, WBCs, platelets).

• Gonadotropins: Hormones that stimulate the gonads.

• Pericardial: Refers to the membrane surrounding the heart.

• Receptors: Specialized cells or proteins that detect stimuli.

• Taste buds: Sensory organs for taste.

Formulas and Equations

• Cardiac Output: The amount of blood pumped by the heart per minute. $\text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate}$

• Blood Pressure: The force exerted by blood on vessel walls. $\text{Blood Pressure} = \text{Cardiac Output} \times \text{Peripheral Resistance}$

Additional info: Some explanations and examples have been expanded for academic completeness and clarity.