A&P Sensory and Endocrine Systems Study Guide Flashcards

Comprehensive vocabulary flashcards covering the sensory receptors, ocular and auditory structures, and the major glands and hormones of the endocrine system.

Sensory receptor

A special cell or nerve ending that detects a specific type of stimulus, acting like a specialized antenna for environmental signals.

Olfactory Receptors

Chemoreceptors located in the nasal lining that detect dissolved chemical molecules in the air to facilitate the sense of smell.

Mechanoreceptors

Receptors found in the cochlea and vestibular apparatus of the ear for hearing and balance, and in the skin for detecting touch, pressure, and vibration.

Photoreceptors

Specialized receptors located in the retina of the eyes that detect light; includes rods and cones.

Thermoreceptors

Skin receptors specifically designed to detect changes in temperature, such as heat and cold.

Nociceptors

Skin receptors that detect tissue damage and are responsible for the sensation of pain.

Rods

Photoreceptors (about $120$ million per eye) concentrated at the periphery of the retina that detect dim light, black, white, and shades of grey.

Cones

Photoreceptors (about $6$ million per eye) concentrated in the fovea centralis that detect color and fine detail in bright light.

Fovea centralis

The center of the retina that serves as the sharpest vision zone due to its high concentration of cones.

Tympanic membrane

The eardrum; a thin membrane that vibrates when sound waves hit it and transmits those vibrations to the middle ear ossicles.

Ossicles

Three tiny bones in the middle ear—the Malleus, Incus, and Stapes—that amplify sound vibrations and pass them to the inner ear.

Organ of Corti

The true hearing organ located inside the cochlea containing thousands of hair cells that convert fluid waves into electrical signals.

Bony labyrinth

The protective, maze-like bony cavity of the inner ear that houses the cochlea, vestibule, and semicircular canals.

Vestibule

The central part of the bony labyrinth that connects the cochlea and semicircular canals, housing structures for hearing and equilibrium.

Semicircular canals

Structures in the inner ear oriented in three different planes to detect rotational movement for balance.

Sensory adaptation

The process where receptors stop responding as strongly to a constant stimulus over time, allowing the brain to focus on new stimuli.

Conduction deafness

Deafness caused by mechanical interference in the outer or middle ear, such as earwax buildup, a ruptured eardrum, or ossicle fusion.

Sensorineural deafness

Hearing loss caused by a problem in the inner ear or the auditory nerve, such as hair cell or nerve damage.

Hormones

Chemical messengers secreted by endocrine glands into the extracellular fluid and bloodstream to regulate metabolism, growth, and reproduction.

Secondary sex characteristics

Physical features developed at puberty (e.g., breast development or facial hair) that distinguish males from females but are not reproductive organs.

Estrogen

The primary female sex hormone produced by the ovaries responsible for secondary sex characteristics and the menstrual cycle.

Testosterone

The male sex hormone produced by the testes, which is directed by luteinizing hormone (LH) from the anterior pituitary.

Hypothalamus

The master controller of the endocrine system that makes ADH and Oxytocin and controls the anterior pituitary via the hypophyseal portal system.

Posterior Pituitary

Also called the neurohypophysis, it stores and releases ADH and oxytocin that were produced in the hypothalamus.

Oxytocin

A hormone made by the hypothalamus that causes uterine contractions during childbirth, milk ejection during breastfeeding, and promotes bonding.

ADH (Antidiuretic Hormone)

A hormone that acts on the kidney collecting ducts to increase water reabsorption into the blood, thereby reducing urine production.

Steroid Hormones

Lipid-soluble hormones made from cholesterol (e.g., Cortisol, Estrogen) that cross cell membranes to bind with receptors inside the cell.

Non-Steroid Hormones

Hormones made from amino acids or proteins (e.g., Insulin, ADH) that cannot cross cell membranes and must bind to surface receptors.

Glucocorticoids

A group of steroid hormones produced by the adrenal cortex, primarily Cortisol, that are released during stress to raise blood sugar.

Adrenal cortex

The outer layer of the adrenal glands that produces glucocorticoids like cortisol.

Pineal gland

A neuroendocrine organ deep in the brain that produces melatonin to regulate the circadian rhythm.

Melatonin

A hormone whose production is triggered by darkness and suppressed by light, regulating the sleep-wake cycle.

Thymosin

A hormone produced by the thymus gland that promotes the development and maturation of T-cells for the immune system.