Special Senses, Nervous System, and Endocrine System Review

Flashcards covering general and special senses, the anatomy and physiology of the eye and ear, gustation, olfaction, the Autonomic Nervous System (ANS), and the Endocrine System based on lecture notes.

General senses

Sensations found throughout the body, including touch, pressure, pain, and temperature.

Special senses

Sensations located in specialized organs, including vision, hearing, smell, taste, and equilibrium.

Ascending pathway (afferent)

Sensory pathways that carry information up the spinal cord to the brain.

Descending pathway (efferent)

Motor pathways that carry information from the brain down the spinal cord.

Fibrous Tunic

The outer layer of the eye wall, composed of the cornea and sclera.

Cornea

The transparent, curved structure of the fibrous tunic that refracts light.

Sclera

The white of the eye that provides protection and shape.

Vascular Tunic (Uvea)

The middle layer of the eye containing the choroid, iris, and ciliary body.

Choroid

The part of the vascular tunic containing blood vessels that provide nutrients to the retina.

Ciliary body

The structure in the vascular tunic containing ciliary muscles that control the shape of the lens.

Iris

The colored part of the eye that controls the size of the pupil and regulates the amount of light entering the eye.

Retina (Nervous Tunic)

The inner layer of the eye that contains rods and cones and converts light energy into nerve impulse signals.

Aqueous humor

The fluid filling the anterior cavity that maintains intraocular pressure and nourishes the cornea and lens.

Vitreous humor

The fluid filling the posterior cavity that helps maintain the shape of the eye and keeps the retina pressed against the choroid.

Accommodation

The process of changing the shape of the lens to focus on near or distant objects via the ciliary muscles.

Conjunctiva

A thin, transparent membrane that covers the sclera and lines the inside of the eyelids, helping to lubricate and protect the eye.

Lacrimal Apparatus

The system that produces and drains tears, which contain lysozyme to destroy bacteria.

Optic chiasma

The location where optic nerves cross, conveying action potentials to the opposite side of the brain for perception.

Rods

Photoreceptors that detect black and white vision, are numerous in the peripheral retina, and provide low-blurry visual acuity in low light.

Cones

Photoreceptors that detect color vision, are concentrated in the fovea centralis, and provide high sharp visual acuity in bright light.

Blind spot (optic disc)

The area where the optic nerve exits the eye, containing no photoreceptors.

Fovea centralis

An area located in the back of the retina that contains only cones and provides the sharpest vision.

Tympanic membrane

A structure in the ear that vibrates in response to sound waves collected by the pinna.

Auditory ossicles

A chain of three bones (malleus, incus, and stapes) that transmit and amplify vibrations to the inner ear.

Auditory tube

A tube connecting the middle ear to the pharynx that helps equalize pressure on both sides of the eardrum.

Cochlea

The part of the inner ear involved in hearing.

Vestibule and Semicircular canals

Parts of the inner ear involved in equilibrium and balance.

Gustation

The sense of taste, considered a chemosense because it detects chemicals dissolved in saliva.

Olfaction

The sense of smell, considered a chemosense because it detects airborne chemicals (odorants) dissolved in mucus.

Filiform papillae

Papillae located at the front of the tongue with no taste buds, used primarily to sense texture.

Umami

One of the five major tastants, described as savory.

Autonomic Nervous System (ANS)

The system that controls involuntary body functions like heart rate, respiration, and digestion.

Sympathetic division

The fight-or-flight system that prepares the body for stressful situations by increasing heart rate and dilating pupils.

Parasympathetic division

The rest-and-digest system that conserves energy and supports routine maintenance like digestion and urination.

Hormone

A chemical messenger secreted into the blood that affects the activity of a target tissue or organ.

Paracrine

A type of signaling where a hormone acts on nearby cells.

Autocrine

A type of signaling where a hormone acts on the same cell that secreted it.

Exocrine gland

A gland that secretes substances through ducts onto a surface or into a cavity.

Lipid-Soluble Hormones

Hormones including steroids (testosterone, cortisol) and thyroid hormones ($T_3$ and $T_4$) that travel bound to carrier proteins.

Water-Soluble Hormones

Hormones including peptides and amines that travel freely in the blood and bind to receptors on the exterior surface of target cells.

Hypothalamohypophysial tract

Nerve fibers connecting the hypothalamus and posterior pituitary to carry action potentials for hormone release.

Antidiuretic Hormone (ADH)

A hormone released in response to low blood pressure or dehydration that causes the kidneys to conserve water.

Oxytocin

A hormone that stimulates uterine contractions during labor and milk ejection through a positive feedback loop.

Calcitonin

A thyroid hormone that lowers blood $Ca^{2+}$ by inhibiting osteoclasts and stimulating osteoblasts.

Parathyroid hormone (PTH)

A hormone that raises blood $Ca^{2+}$ by stimulating osteoclasts and promoting Vitamin D formation.

Aldosterone

An adrenal cortex hormone that regulates $Na^+$ and water balance by promoting $Na^+$ reabsorption in the kidneys.

Cortisol

A stress response hormone from the adrenal cortex that raises blood glucose.

Insulin

A pancreatic hormone that lowers blood glucose levels.

Glucagon

A pancreatic hormone that targets the liver to raise blood glucose levels.

Thymosin

A hormone produced by the thymus that helps develop T-cells for immune development, active mostly in childhood.

all of the preganglionic neurons of the ANS are insulated

With myeline sheath