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 mucus that coats the olfactory epithelium, aiding in the detection of odorants.

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

• Taste buds are sensory organs located on the tongue that detect dissolved chemicals, allowing for the perception of taste.

• Equilibrium is maintained by the vestibular apparatus in the inner ear, which detects changes in head position and movement.

Vision

Vision is the process by which light is detected and interpreted by the eyes. The retina contains rods and cones, which are photoreceptors responsible for detecting light intensity and color.

• Optic disc is a blind spot on the retina where the optic nerve exits the eye; it lacks photoreceptors.

• Fovea centralis is the region of the retina with the highest concentration of cones, responsible for sharp central vision.

• Lacrimal gland produces tears that lubricate and protect the eye.

• Lens focuses light onto the retina; its shape is adjusted by ciliary muscles.

Hearing and Equilibrium

The ear is responsible for detecting sound and maintaining balance. Sound waves are transmitted through the outer, middle, and inner ear, where they are converted into neural signals.

• Cochlea is the spiral-shaped organ in the inner ear that contains hair cells for hearing.

• Semicircular canals detect rotational movements and contribute to equilibrium.

• Auditory ossicles (malleus, incus, stapes) transmit sound vibrations from the eardrum to the inner ear.

• Middle ear communicates with the nasopharynx via the auditory (Eustachian) tube.

Taste and Smell

Taste and smell are chemical senses that detect dissolved molecules. Taste buds are found on the tongue, while olfactory receptors are located in the nasal cavity.

• Taste buds detect sweet, sour, salty, bitter, and umami flavors.

• Olfactory neurons transmit signals to the olfactory bulb and then to the brain for odor perception.

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.

• Endocrine glands include the pituitary, thyroid, adrenal, pancreas, and gonads.

• Hormones are chemical messengers that affect target cells throughout the body.

Major Endocrine Glands and Hormones

• Thyroid gland produces thyroid hormones (T3 and T4) that regulate metabolism.

• Parathyroid hormone regulates calcium levels in the blood.

• Adrenal cortex secretes corticosteroids, including aldosterone (regulates sodium) and cortisol (regulates metabolism and stress response).

• Pancreas produces insulin and glucagon to regulate blood glucose levels.

• Hypothalamus and pituitary gland coordinate the release of many hormones, including growth hormone, ADH, and oxytocin.

Hormonal Regulation and Feedback

• Negative feedback is the primary mechanism for hormone regulation, maintaining homeostasis.

• Antagonists are hormones that have opposing effects (e.g., insulin and glucagon).

Key Terms

• Gonadotropins: Hormones that stimulate the gonads (FSH and LH).

• Receptors: Proteins on target cells that bind specific hormones.

Chapter 19 – The Blood

Functions and Components of Blood

Blood is a connective tissue that transports nutrients, gases, hormones, and waste products throughout the body. It also plays a role in immunity and homeostasis.

• Red blood cells (erythrocytes) transport oxygen and carbon dioxide.

• White blood cells (leukocytes) are involved in immune defense.

• Platelets are cell fragments that aid in blood clotting.

• Plasma is the liquid component of blood, containing water, proteins, and dissolved substances.

Blood Cell Formation and Function

• Hemopoiesis is the process of blood cell formation, occurring in the bone marrow.

• Phagocytosis is the process by which certain white blood cells engulf and destroy pathogens.

• Basophils release histamine during allergic reactions.

• Fibrinogen is a plasma protein involved in blood clotting.

Blood Types and Immunity

• Blood types are determined by the presence of specific antigens (A, B, AB, O) on red blood cells.

• Antibodies in plasma react with incompatible blood types, leading to agglutination.

• Anti-B is an antibody that reacts with B antigens.

Key Terms

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

• Cribriform plate: Part of the ethmoid bone, important in the olfactory system.

Chapter 20 – The Heart

Structure and Function of the Heart

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.

• Apex is the pointed end of the heart, located inferiorly.

• Base is the broad superior portion of the heart.

• Pericardial refers to the sac surrounding the heart.

Blood Flow Through the Heart

• Blood enters the right atrium from the systemic circulation and is pumped to the lungs via the right ventricle.

• Oxygenated blood returns to the left atrium and is pumped to the body via the left ventricle.

• Valves (tricuspid, bicuspid/mitral, pulmonary, aortic) ensure unidirectional blood flow.

• SA node is the heart's pacemaker, initiating electrical impulses.

Electrical Conduction System

• EKG (electrocardiogram) records the electrical activity of the heart.

• P wave represents atrial depolarization.

• QRS complex indicates ventricular depolarization.

Key Terms

• Antagonists: Substances that oppose the action of another.

• Receptors: Structures that detect specific stimuli.

Additional info: Key Terms Table