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bipolar neuron : neuron with two processes from the cell body, typically in opposite directions
https://openstax.org/books/biology/pages/36-key-terms
candela : (cd) unit of measurement of luminous intensity (brightness)
https://openstax.org/books/biology/pages/36-key-terms
circadian : describes a time cycle about one day in length
https://openstax.org/books/biology/pages/36-key-terms
cochlea : whorled structure that contains receptors for transduction of the mechanical wave into an electrical signal
https://openstax.org/books/biology/pages/36-key-terms
cone : weakly photosensitive, chromatic, cone-shaped neuron in the fovea of the retina that detects bright light and is used in daytime color vision
https://openstax.org/books/biology/pages/36-key-terms
cornea : transparent layer over the front of the eye that helps focus light waves
https://openstax.org/books/biology/pages/36-key-terms
fovea : region in the center of the retina with a high density of photoreceptors and which is responsible for acute vision
https://openstax.org/books/biology/pages/36-key-terms
free nerve ending : ending of an afferent neuron that lacks a specialized structure for detection of sensory stimuli; some respond to touch, pain, or temperature
https://openstax.org/books/biology/pages/36-key-terms
glabrous : describes the non-hairy skin found on palms and fingers, soles of feet, and lips of humans and other primates
https://openstax.org/books/biology/pages/36-key-terms
glomerulus : in the olfactory bulb, one of the two neural clusters that receives signals from one type of olfactory receptor
https://openstax.org/books/biology/pages/36-key-terms
Golgi tendon organ : muscular proprioceptive tension receptor that provides the sensory component of the Golgi tendon reflex
https://openstax.org/books/biology/pages/36-key-terms
gustation : sense of taste
https://openstax.org/books/biology/pages/36-key-terms
hyperopia : (also, farsightedness) visual defect in which the image focus falls behind the retina, thereby making images in the distance clear, but close-up images blurry
https://openstax.org/books/biology/pages/36-key-terms
incus : (also, anvil) second of the three bones of the middle ear
https://openstax.org/books/biology/pages/36-key-terms
inner ear : innermost part of the ear; consists of the cochlea and the vestibular system
https://openstax.org/books/biology/pages/36-key-terms
iris : pigmented, circular muscle at the front of the eye that regulates the amount of light entering the eye
https://openstax.org/books/biology/pages/36-key-terms
kinesthesia : sense of body movement
https://openstax.org/books/biology/pages/36-key-terms
labyrinth : bony, hollow structure that is the most internal part of the ear; contains the sites of transduction of auditory and vestibular information
https://openstax.org/books/biology/pages/36-key-terms
lens : transparent, convex structure behind the cornea that helps focus light waves on the retina
https://openstax.org/books/biology/pages/36-key-terms
malleus : (also, hammer) first of the three bones of the middle ear
https://openstax.org/books/biology/pages/36-key-terms
mechanoreceptor : sensory receptor modified to respond to mechanical disturbance such as being bent, touch, pressure, motion, and sound
https://openstax.org/books/biology/pages/36-key-terms
Meissner’s corpuscle : (also, tactile corpuscle) encapsulated, rapidly-adapting mechanoreceptor in the skin that responds to light touch
https://openstax.org/books/biology/pages/36-key-terms
Merkel's disc : unencapsulated, slowly-adapting mechanoreceptor in the skin that responds to touch
https://openstax.org/books/biology/pages/36-key-terms
middle ear : part of the hearing apparatus that functions to transfer energy from the tympanum to the oval window of the inner ear
https://openstax.org/books/biology/pages/36-key-terms
muscle spindle : proprioceptive stretch receptor that lies within a muscle and that shortens the muscle to an optimal length for efficient contraction
https://openstax.org/books/biology/pages/36-key-terms
myopia : (also, nearsightedness) visual defect in which the image focus falls in front of the retina, thereby making images in the distance blurry, but close-up images clear
https://openstax.org/books/biology/pages/36-key-terms
nociception : neural processing of noxious (such as damaging) stimuli
https://openstax.org/books/biology/pages/36-key-terms
odorant : airborne molecule that stimulates an olfactory receptor
https://openstax.org/books/biology/pages/36-key-terms
olfaction : sense of smell
https://openstax.org/books/biology/pages/36-key-terms
olfactory bulb : neural structure in the vertebrate brain that receives signals from olfactory receptors
https://openstax.org/books/biology/pages/36-key-terms
olfactory epithelium : specialized tissue in the nasal cavity where olfactory receptors are located
https://openstax.org/books/biology/pages/36-key-terms
olfactory receptor : dendrite of a specialized neuron
https://openstax.org/books/biology/pages/36-key-terms
organ of Corti : in the basilar membrane, the site of the transduction of sound, a mechanical wave, to a neural signal
https://openstax.org/books/biology/pages/36-key-terms
ossicle : one of the three bones of the middle ear
https://openstax.org/books/biology/pages/36-key-terms
outer ear : part of the ear that consists of the pinna, ear canal, and tympanum and which conducts sound waves into the middle ear
https://openstax.org/books/biology/pages/36-key-terms
oval window : thin diaphragm between the middle and inner ears that receives sound waves from contact with the stapes bone of the middle ear
https://openstax.org/books/biology/pages/36-key-terms
Pacinian corpuscle : encapsulated mechanoreceptor in the skin that responds to deep pressure and vibration
https://openstax.org/books/biology/pages/36-key-terms
papilla : one of the small bump-like projections from the tongue
https://openstax.org/books/biology/pages/36-key-terms
perception : individual interpretation of a sensation; a brain function
https://openstax.org/books/biology/pages/36-key-terms
pheromone : substance released by an animal that can affect the physiology or behavior of other animals
https://openstax.org/books/biology/pages/36-key-terms
pinna : cartilaginous outer ear
https://openstax.org/books/biology/pages/36-key-terms
presbyopia : visual defect in which the image focus falls behind the retina, thereby making images in the distance clear, but close-up images blurry; caused by age-based changes in the lens
https://openstax.org/books/biology/pages/36-key-terms
proprioception : sense of limb position; used to track kinesthesia
https://openstax.org/books/biology/pages/36-key-terms
pupil : small opening though which light enters
https://openstax.org/books/biology/pages/36-key-terms
reception : receipt of a signal (such as light or sound) by sensory receptors
https://openstax.org/books/biology/pages/36-key-terms
receptive field : region in space in which a stimulus can activate a given sensory receptor
https://openstax.org/books/biology/pages/36-key-terms
receptor potential : membrane potential in a sensory receptor in response to detection of a stimulus
https://openstax.org/books/biology/pages/36-key-terms
retina : layer of photoreceptive and supporting cells on the inner surface of the back of the eye
https://openstax.org/books/biology/pages/36-key-terms
rhodopsin : main photopigment in vertebrates
https://openstax.org/books/biology/pages/36-key-terms
rod : strongly photosensitive, achromatic, cylindrical neuron in the outer edges of the retina that detects dim light and is used in peripheral and nighttime vision
https://openstax.org/books/biology/pages/36-key-terms
Ruffini ending : (also, bulbous corpuscle) slowly-adapting mechanoreceptor in the skin that responds to skin stretch and joint position
https://openstax.org/books/biology/pages/36-key-terms
semicircular canal : one of three half-circular, fluid-filled tubes in the vestibular labyrinth that monitors angular acceleration and deceleration
https://openstax.org/books/biology/pages/36-key-terms
sensory receptor : specialized neuron or other cells associated with a neuron that is modified to receive specific sensory input
https://openstax.org/books/biology/pages/36-key-terms
sensory transduction : conversion of a sensory stimulus into electrical energy in the nervous system by a change in the membrane potential
https://openstax.org/books/biology/pages/36-key-terms
stapes : (also, stirrup) third of the three bones of the middle ear
https://openstax.org/books/biology/pages/36-key-terms
stereocilia : in the auditory system, hair-like projections from hair cells that help detect sound waves
https://openstax.org/books/biology/pages/36-key-terms
superior colliculus : paired structure in the top of the midbrain, which manages eye movements and auditory integration
https://openstax.org/books/biology/pages/36-key-terms
suprachiasmatic nucleus : cluster of cells in the hypothalamus that plays a role in the circadian cycle
https://openstax.org/books/biology/pages/36-key-terms
tastant : food molecule that stimulates gustatory receptors
https://openstax.org/books/biology/pages/36-key-terms
taste bud : clusters of taste cells
https://openstax.org/books/biology/pages/36-key-terms
tectorial membrane : cochlear structure that lies above the hair cells and participates in the transduction of sound at the hair cells
https://openstax.org/books/biology/pages/36-key-terms
tonic activity : in a neuron, slight continuous activity while at rest
https://openstax.org/books/biology/pages/36-key-terms
tympanum : (also, tympanic membrane or ear drum) thin diaphragm between the outer and middle ears
https://openstax.org/books/biology/pages/36-key-terms
ultrasound : sound frequencies above the human detectable ceiling of approximately 20,000 Hz
https://openstax.org/books/biology/pages/36-key-terms
umami : one of the five basic tastes, which is described as “savory” and which may be largely the taste of L-glutamate
https://openstax.org/books/biology/pages/36-key-terms
vestibular sense : sense of spatial orientation and balance
https://openstax.org/books/biology/pages/36-key-terms
vision : sense of sight
https://openstax.org/books/biology/pages/36-key-terms
There are three basic types of hormones: lipid-derived, amino acid-derived, and peptide. Lipid-derived hormones are structurally similar to cholesterol and include steroid hormones such as estradiol and testosterone. Amino acid-derived hormones are relatively small molecules and include the adrenal hormones epinephrine...
https://openstax.org/books/biology/pages/37-chapter-summary
Hormones cause cellular changes by binding to receptors on target cells. The number of receptors on a target cell can increase or decrease in response to hormone activity. Hormones can affect cells directly through intracellular hormone receptors or indirectly through plasma membrane hormone receptors.
https://openstax.org/books/biology/pages/37-chapter-summary
Lipid-derived (soluble) hormones can enter the cell by diffusing across the plasma membrane and binding to DNA to regulate gene transcription and to change the cell’s activities by inducing production of proteins that affect, in general, the long-term structure and function of the cell. Lipid insoluble hormones bind ...
https://openstax.org/books/biology/pages/37-chapter-summary
Water levels in the body are controlled by antidiuretic hormone (ADH), which is produced in the hypothalamus and triggers the reabsorption of water by the kidneys. Underproduction of ADH can cause diabetes insipidus. Aldosterone, a hormone produced by the adrenal cortex of the kidneys, enhances Na+reabsorption from the...
https://openstax.org/books/biology/pages/37-chapter-summary
The reproductive system is controlled by the gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are produced by the pituitary gland. Gonadotropin release is controlled by the hypothalamic hormone gonadotropin-releasing hormone (GnRH). FSH stimulates the maturation of sperm cells in mal...
https://openstax.org/books/biology/pages/37-chapter-summary
Insulin is produced by the pancreas in response to rising blood glucose levels and allows cells to utilize blood glucose and store excess glucose for later use. Diabetes mellitus is caused by reduced insulin activity and causes high blood glucose levels, or hyperglycemia. Glucagon is released by the pancreas in respons...
https://openstax.org/books/biology/pages/37-chapter-summary
Parathyroid hormone (PTH) is produced by the parathyroid glands in response to low blood Ca2+levels. The parafollicular cells of the thyroid produce calcitonin, which reduces blood Ca2+levels. Growth hormone (GH) is produced by the anterior pituitary and controls the growth rate of muscle and bone. GH action is indirec...
https://openstax.org/books/biology/pages/37-chapter-summary
Hormone levels are primarily controlled through negative feedback, in which rising levels of a hormone inhibit its further release. The three mechanisms of hormonal release are humoral stimuli, hormonal stimuli, and neural stimuli. Humoral stimuli refers to the control of hormonal release in response to changes in extr...
https://openstax.org/books/biology/pages/37-chapter-summary
The pituitary gland is located at the base of the brain and is attached to the hypothalamus by the infundibulum. The anterior pituitary receives products from the hypothalamus by the hypophyseal portal system and produces six hormones. The posterior pituitary is an extension of the brain and releases hormones (antidiur...
https://openstax.org/books/biology/pages/37-chapter-summary
The thyroid gland is located in the neck and is composed of two lobes connected by the isthmus. The thyroid is made up of follicle cells that produce the hormones thyroxine and triiodothyronine. Parafollicular cells of the thyroid produce calcitonin. The parathyroid glands lie on the posterior surface of the thyroid gl...
https://openstax.org/books/biology/pages/37-chapter-summary
The adrenal glands are located on top of the kidneys and consist of the renal cortex and renal medulla. The adrenal cortex is the outer part of the adrenal gland and produces the corticosteroids, glucocorticoids, and mineralocorticoids. The adrenal medulla is the inner part of the adrenal gland and produces the catecho...
https://openstax.org/books/biology/pages/37-chapter-summary
The pancreas lies in the abdomen between the stomach and the small intestine. Clusters of endocrine cells in the pancreas form the islets of Langerhans, which are composed of alpha cells that release glucagon and beta cells that release insulin.
https://openstax.org/books/biology/pages/37-chapter-summary
Some organs possess endocrine activity as a secondary function but have another primary function. The heart produces the hormone atrial natriuretic peptide, which functions to reduce blood volume, pressure, and Na+concentration. The gastrointestinal tract produces various hormones that aid in digestion. The kidneys pro...
https://openstax.org/books/biology/pages/37-chapter-summary
acromegaly : condition caused by overproduction of GH in adults
https://openstax.org/books/biology/pages/37-key-terms
Addison’s disease : disorder caused by the hyposecretion of corticosteroids
https://openstax.org/books/biology/pages/37-key-terms
adenylate cyclase : an enzyme that catalyzes the conversion of ATP to cyclic AMP
https://openstax.org/books/biology/pages/37-key-terms
adrenal cortex : outer portion of adrenal glands that produces corticosteroids
https://openstax.org/books/biology/pages/37-key-terms
adrenal gland : endocrine glands associated with the kidneys
https://openstax.org/books/biology/pages/37-key-terms
adrenal medulla : inner portion of adrenal glands that produces epinephrine and norepinephrine
https://openstax.org/books/biology/pages/37-key-terms
adrenocorticotropic hormone (ACTH) : hormone released by the anterior pituitary, which stimulates the adrenal cortex to release corticosteroids during the long-term stress response
https://openstax.org/books/biology/pages/37-key-terms
aldosterone : steroid hormone produced by the adrenal cortex that stimulates the reabsorption of Na+from extracellular fluids and secretion of K+.
https://openstax.org/books/biology/pages/37-key-terms
alpha cell : endocrine cell of the pancreatic islets that produces the hormone glucagon
https://openstax.org/books/biology/pages/37-key-terms
amino acid-derived hormone : hormone derived from amino acids
https://openstax.org/books/biology/pages/37-key-terms
androgen : male sex hormone such as testosterone
https://openstax.org/books/biology/pages/37-key-terms
anterior pituitary : portion of the pituitary gland that produces six hormones; also called adenohypophysis
https://openstax.org/books/biology/pages/37-key-terms
antidiuretic hormone (ADH) : hormone produced by the hypothalamus and released by the posterior pituitary that increases water reabsorption by the kidneys
https://openstax.org/books/biology/pages/37-key-terms
atrial natriuretic peptide (ANP) : hormone produced by the heart to reduce blood volume, pressure, and Na+concentration
https://openstax.org/books/biology/pages/37-key-terms
beta cell : endocrine cell of the pancreatic islets that produces the hormone insulin
https://openstax.org/books/biology/pages/37-key-terms
calcitonin : hormone produced by the parafollicular cells of the thyroid gland that functions to lower blood Ca2+levels and promote bone growth
https://openstax.org/books/biology/pages/37-key-terms
colloid : fluid inside the thyroid gland that contains the glycoprotein thyroglobulin
https://openstax.org/books/biology/pages/37-key-terms
corticosteroid : hormone released by the adrenal cortex in response to long-term stress
https://openstax.org/books/biology/pages/37-key-terms
cortisol : glucocorticoid produced in response to stress
https://openstax.org/books/biology/pages/37-key-terms
Cushing’s disease : disorder caused by the hypersecretion of glucocorticoids
https://openstax.org/books/biology/pages/37-key-terms