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A&P Lab Practical 3
Endocrine Glands
39
Anatomy
Undergraduate 1
02/21/2012

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Term
Thyroid hormone
Definition
Produced by the thyroid gland - the single most important hormone influencing the rate of cellular metabolism and body heat production
Term
Endocrine system
Definition
Acts with the nervous system to coordinate and integrate the activity of the body's cells
Employs hormones
Term
Hormones
Definition
Chemical messengers which are produced by epithelial cells and released into the blood to be transported throughout the body
Term
Target organs
Definition
Organs that respond to a particular hormone
Term
Pituitary gland
Definition
consists of 2 lobes - the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis)
Attached to the hypothalamus by the infundibulum
Term
Anterior pituitary lobe
Definition
"Master endocrine gland," controlled by releasing or inhibiting hormones from the ventral hypothalamus
Secretes 4 tropic hormones
-Gonadotropins (follicle-stimulating hormone and luteinizing hormone)
-adrenocorticotropic hormone (ACTH)
-thryoid-stimulating hormone (TSH or thyrotropin)

Other important hormones (not directly involved the regulation of other endocrine glands)
-growth hormone (GH)
-prolactin
Term
Hypophyseal portal system
Definition
Consists of the primary capillary plexus, hypophyseal portal veins, and secondary capillary plexus, leading releasing or inhibiting hormones from the ventral hypothalamus to the anterior pituitary lobe
Term
Follicle-stimulating hormone and Luteinizing hormone
Definition
Gonadotropins secreted by the anterior pituitary lobe
Regulate gamete production and hormonal activity of the ovaries and testes
Term
Adrenocorticotropic hormone
Definition
Secreted by the anterior pituitary lobe
Regulates the endocrine activity of the adrenal cortex
Term
Thyroid-stimulating hormone
Definition
Secreted by the anterior pituitary lobe
Influences the growth and activity of the thyroid gland
Term
Growth hormone
Definition
Secreted by the anterior pituitary lobe
A general metabolic hormone that helps determine body size - growth of muscle and long bones
Hyposecretion --> pituitary dwarfism
Hypersecretion --> gigantism and acromegaly
Term
Prolactin
Definition
Secreted by the anterior pituitary lobe
Stimulates breast development and promotes and maintains lactation by the mammary glands after childbirth
Term
Posterior pituitary lobe
Definition
Does not synthesize the hormones it releases, but acts as a storage area for oxytocin and antidiuretic hormone, which are transported to it via neural axons
Term
Oxytocin
Definition
Produced in the hypothalamus and stored in the posterior pituitary lobe
Stimulates powerful uterine contractions during birth and milk ejection in the lactating mother
Term
Antidiuretic hormone
Definition
Produced by the hypothalamus and stored by the posterior pituitary lobe
Causes distal and collecting tubules of the kidneys to reabsorb more water from the urinary filtrate, reducing urine output and conserving water
Hyposecretion --> diabetes insipidus
Hypersecretion --> edema, headache, disorientation
Term
Pineal gland
Definition
Located in the roof of the third ventricle of the brain
Produces melatonin
Plays a role in the biological rhythms of the body
Term
Melatonin
Definition
Secreted by the pineal gland
Exhibits a diurnal cycle - peaks at night, making us drowsy, and is lowest around noon
Appears to exert some inhibitory effect on the reproductive system that prevents precocious sexual maturation
Term
Thyroid gland
Definition
composed of two lobes joined by a central mass, located in the throat, just below the larynx
Secretes thyroid hormone and calcitonin
Term
Thyroid hormone
Definition
Secreted by the thyroid gland
Composed of thyroxine and triodothyronine
Control the rate of body metabolism and cellular oxidation
Hyposecretion --> myxedema (mental and physical sluggishness)
Hypersecretion --> elevated metabolic rate, nervousness, etc
Term
Calcitonin
Definition
Secreted by the thyroid gland
Decreases blood calcium levels by stimulating calcium salt deposit in the bones (acts antagonistically to parathyroid hormone)
Term
Parathyroid glands
Definition
Found embedded in the posterior surface of the thyroid gland
Secretes parathyroid hormone
Term
Parathyroid hormone
Definition
Secreted by the parathyroid gland
The most important regulator of calcium balance of the blood
When blood calcium levels decrease, PTH causes release of calcium from bone matrix and causes the kidney to reabsorb more calcium from the filtrate, and stimulates kidneys to convert vitamin D to calcitriol
Hyposecretion --> tetany
Hypersecretion --> bone fractures
Term
Thymus
Definition
Bilobed gland in the superior thorax, between the sternum and the heart
Secretes thymlin, thymosins, thymopoeitins
Term
Parathyroid hormone
Definition
Secreted by the parathyroid gland
The most important regulator of calcium balance of the blood
When blood calcium levels decrease, PTH causes release of calcium from bone matrix and causes the kidney to reabsorb more calcium from the filtrate, and stimulates kidneys to convert vitamin D to calcitriol
Hyposecretion --> tetany
Hypersecretion --> bone fractures
Term
Adrenal glands
Definition
Adrenal medulla and cortex
Located atop the kidneys
Term
Adrenal medulla
Definition
Directly controlled by the sympathetic nervous system
Secrete epinephrine and norepinephrine
Term
Adrenal cortex
Definition
Secretes the corticosteroids (mineralocorticoids like aldosterone, glucocoricoids like cortisol, and gonadocorticoids like androgens and estrogens)
Term
Mineralcorticoids
Definition
Secreted by the adrenal cortex
Aldosterone regulates water and electrolyte balance in the extracellular fluids
Term
Glucocorticoids
Definition
Secreted by the adrenal cortex
Cortisol, cortisone, and corticosterone enable the body to resist long-term stressors by increasing blood glucose levels
Term
Gonadocorticoids
Definition
Produced by the adrenal cortex
Androgens and estrogens produced throughout life in insignificant amounts
Hypersecretion --> abnormal hairiness (hirsutism) and musculinization
Term
Pancreas
Definition
Located partially behind the stomach in the abdomen
Functions as an endocrine and exocrine gland
Produces digestive enzymes and blood sugar regulation hormones (insulin and glucagon)
Term
Insulin
Definition
Secreted by the pancreas
Decreases blood sugar levels
Hyposecretion --> diabetes mellitus
Hypersecretion --> hypoglycemia
Term
Glucagon
Definition
Secreted by the pancreas
Acts antagonistically to insulin
Stimulates the liver to break down glycogen stores to glucose and release it into the blood
Term
Gonads
Definition
Female gonads = ovaries, produce estrogens and progesterone
Male gonads = testes, produce testosterone
Term
Estrogens
Definition
Secreted by the ovaries
Responsible for the development of the secondary sex characteristics of the female at puberty
Term
Testosterone
Definition
Secreted by the testes
Promotes the maturation of the reproductive system accessory structures, brings about the development of the male secondary sex characteristics, and is responsible for sex drive
Term
Endocrine glands
Definition
Pituitary, thyroid, parathyroid, adrenal, pineal, thymus, (pancreas and gonads produce hormones and exocrine products)
Term
Primary sex organs (gonads)
Definition
Testes in males, ovaries in females
Produce sex cells called gametes, secrete sex hormones
Term
Accessory reproductive organs
Definition
Ducts, glands, external genitalia
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