A&PII Lab 1: The Endocrine System Flashcards
Hormones
the endocrine system achieves its function by the secretion of these
Primary endocrine glands
located in the cranial cavity; includes the pituitary gland & the pineal gland (posterior to thalamus)
Endocrine glands of the neck
thyroid & parathyroid glands
Endocrine gland in the thoracic cavity
thymus (also part of the lymphatic system)
Endocrine glands of the abdominal cavity
pancreas, adrenal glands (cortex/medulla); retroperitoneal
Endocrine glands of the pelvic cavity
gonads (female ovaries in the pelvic cavity; male testes in the scrotum)
Hypophysis
the entire pituitary gland is also called this; “a growth”; named due to its location beneath the brain; once called the master gland (actually under the control of the hypothalamus)
Infundibulum
narrow stalk that attaches the pituitary to the hypothalamus
Adenohypophysis
anterior pituitary; composed of glandular epithelium; its cells secrete hormones under the direction of the hypothalamus
Tropic hormones
GH, TSH, ACTH, FSH/LH
Growth hormone (GH)
regulates metabolism and body growth
Adrenocorticotropic hormone (ACTH)
activates the adrenal gland
Thyroid-stimulating hormone (TSH)
stimulates the thyroid gland
Prolactin (PRL)
stimulates milk secretion by the mammary glands
Follicle-stimulating hormones (FSH)
stimulates development of ova in females and sperm in males
Luteinizing hormone (LH)
stimulates secretion of sex hormones by the gonads
Neurohypophysis
posterior pituitary; composed of nervous tissue; the 2 distinct neuronal cell bodies produce the hormones in the hypothalamus; the axons extend through the infundibulum (also considered part of the this)
Antidiuretic hormone (ADH)
stimulates water reabsorption in the kidneys to reduce urine volume; aka vasopressin due to its actions of vasoconstriction in order to maintain blood pressure
Vasopressin
pharmaceutical agent used to replenish ADH is termed this; sometimes Arginine vasopressin (AVP)
Oxytocin (OT)
stimulates contractions of the uterus and milk secretion by the mammary glands
Pineal gland/body
located within the cranial cavity; located near the center of the brain at the epithalamus; contains secretory cells called pinealocytes, which synthesize 1 hormone from the neurotransmitter melatonin; calcifies as we age (contributes to sleep problems in the elderly)
Melatonin (MT)
regulates biological rhythms, including sleep cycles; may also inhibit reproductive functions
Thyroid gland
soft, butterfly-shaped organ in the anterior side of the neck that wraps around the larynx just beneath the skin
Lobes
2 parts of the thyroid (right and left), connected by a narrow bridge
Isthmus
narrow bridge connecting the 2 lobes of the thyroid gland
Follicles
internally, the thyroid is composed of these microscopic parts that contain large insoluble protein molecules (colloid)
Colloid
large insoluble protein molecules inside the follicles of the thyroid
Follicle cells
the walls of the follicles of the thyroid are simple cuboidal or simple columnar epithelium, consisting of these secretory cells
Thyroglobulin
follicle cells secrete this large component of the colloid, which is a precursor to 2 thyroid hormones (T4 & T3)
Parafollicular cells (C cells)
located between follicles; secrete a 3rd hormone (calcitonin)
Thyroxine (T4)
secreted by follicle cells, it regulates the breakdown of glucose and the synthesis of most cells of the body
Triodothyronine (T3)
secreted by follicle cells; it works in conjunction with thyroxine to produce the same effects; together they are referred to as thyroid hormone (TH)
Calcitonin
secreted by the parafollicular cells; stimulates the production of new bone material; an important effect of producing new bones is the reduction of calcium levels in the blood; acts as an antagonist to PTH
Parathryoid glands
usually 4 pea-sized glands embedded within the posterior side of the larger thyroid gland; secrete 1 hormone
Parathyroid hormone (PTH)
provides an opposite effect of calcitonin by increasing calcium levels in the blood (antagonist of calcitonin); works with calcitonin to regulate calcium levels in the blood and the concentration of calcium in bone
Adrenal glands
paired glands located in the abdominopelvic cavity, each one immediately superior to a kidney and attached to it by a capsule of dense connective tissue; 2 parts to each - superficial ___ cortex & deep ___ medulla
Adrenal cortex
yellowish outer fringe of the adrenal gland; produces more than 2 dozen steroid hormones, collectively called corticosteroids
Corticosteroids
steroid hormones produced by the adrenal cortex
Zona glomerulosa
outer zone of the adrenal cortex; “small ball”; forms about 15% of the volume of the adrenal cortex; its cells secrete mineralocorticoids (MCs)
Mineralocorticoids (MCs)
steroid hormones that affect the electrolyte composition of body fluids; primary member of this group = aldosterone
Aldosterone
mineralocorticoid which causes the retention of sodium ions in cells
Zona fasciculata
middle region of the adrenal cortex; “little bundle”; occupies the largest portion of the adrenal cortex (78% of its volume); its cells are larger and contain more lipid than those of the zona glomerulosa, giving the cells a pale, foamy appearance; they secrete glucocorticoids (GCs)
Glucocorticoids (GCs)
steroid hormones that effect the rates of glucose metabolism; primary hormone of this group is cortisol (or hydrocortisone)
Cortisol
AKA hydrocortisone; a glucocorticoid that reduces inflammation after its conversion to cortisone by the liver
Zona reticularis
inner region of the adrenal cortex; “little network”; forms a narrow band bordering the adrenal medulla (7% of the total volume of the adrenal cortex); its cells form a branching, folded network, and secrete androgens
Androgens
precursor molecules to the sex hormones, testosterone in males and estrogen in females
Adrenal medulla
inner, reddish-brown region of each adrenal gland; its cells are quite large compared to those of the adrenal cortex, and the border between the 2 parts is irregular; the cells develop as an extension of the nervous system; its secretions/neurotransmitters participate in the sympathetic response of fight/flight; 2 populations of cells are present, each one responsible for the synthesis of either epinephrine or norepinephrine
Epineprine (EPI)
accelerates cellular energy utilization and the mobilization of energy reserves to increase ATP availability to critical organs; this hormone exerts its effect via adrenergic receptors
Norepinephrine (NEP)
dependent upon adrenergic receptor type; mimics the effects of epinephrine
Pancreas
“sweetbread”; soft, oblong organ located between the stomach and small intestine near the midline of the abdominopelvic cavity
3 parts of the pancreas
head, body, tail (medial to lateral)
Pancreatic islets (islets of Langerhans)
the endocrine cells of the pancreas are isolated into small clusters known as these; each one contains 2 primary secretory cell types - alpha & beta
Alpha & beta cells
synthesize and secrete pancreatic hormones into the bloodstream
Insulin
peptide hormone secreted by beta cells when glucose levels exceed normal levels; enhances glucose absorption into cells and its utilization by metabolism; stimulates glucagon formation in liver and skeletal muscle cells
Glucagon
peptide hormone secreted by alpha cells when glucose levels fall below normal levels; stimulates the breakdown of glycogen in liver and skeletal muscle cells, stimulates the breakdown of triglycerides in fat cells, & stimulates glucose production in the liver
