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What are the functions of IGF's?
- A. Increase growth rate
- cause cells to grow and multiply by increasing uptake of amino acids into cell's and accelerating protein synthesis. Decrease breakdown of proteins and the use of amino acids for ATP production. Help maintain muscle and bone mass and promote healing of injuries and tissue repair.
- B. Increasing Lipolysis-
- IGF's enhance lipolysis in adipose tissue, which results in increased use of the released fatty acids for ATP production by body cells
- C. Elevsting blood glucose-
- IGF's and HGH influence carbohydrate metabolism by decreasing glucose uptake by most body cells, which decreases their use of glucose for ATP production. Spares glucose so that it is available to neurons for ATP production in times of glucose scarcity. IGF and HGH may also stimulate the liver to release glucose into the blood, thereby raising blood glucose levels.
What are thyroid follicles?
Microscopic spherical sacs, make-up most of thyroid gland
Describe the Thyroid stimulating hormone (TSH) 3/7
- stimulate thyroid gland to synthesize and secrete the two thyroid hormones, triiodothyronine(Tz) and thyroxine(t4)
Thyrotropin-releasing hormone (trh)-from hypothalamus controls TSH secretion release of TRH, in turn dependson blood levels of T3 and T4:high levels of T3 and T4 inhibit secretion of TRH via negative feedback
Describe the follicle-stimulating hormone (fsh) 4/7
Initiates the development of sevral ovarian follicles, saclike arrangements of secretory cells that surround a developing oocyte(future ovum). Also stimulates ovarian follicles to secrete estrogens; suppressed by estrogens
(GhRH) Gonadotropin-releasing hormone stimulate sperm production in testes from hypothalamus; suppressed by testerone.
Describe Lutenizing hormone(LH) 5/7
triggers ovulation in females; release of oocyte from an ovary. After ovulation, LH stimulates secretion of progesterone (female sex hormone) by the ovary. Together FSH and LH stimulate the ovary to secrete estrogens. Estrogen and progesterone prepare the uterus for implantation of a fertilized ovum and help prepare the mammary glands for milk secretion. Males, LH stimulates the testes to secrete testerone, secretion of Lh, like that of FSH is stimulated by gonadotropin-releasing hormone (GnrH)
Describe Prolactin hormone 6/7
helps initiate and maintain milk production by the mammary glands. Once the mammary glands have been primed by other hormones(estrogen, progesterone, glucocorticoids, human growth hormone, thyroxine, amd insulin) exerting permissive effects, prolactin brings about milk production. Ejection of milk from the mammary gland depends on the hormone oxytocin, released from posterior pituitary these two hormones act synergistically. Together, milk secretion and ejection constitute lactation.
What is PIH?
Prolactin Inhibiting Hormone-inhibits the release of prolactin from the anterior pituitary most of the time. Each month before menstruation begins, the PIH diminishes and the blood level of prolactin rises but not enough to stimulate milk production; also results in tender breasts.
During pregnancy, the prolactin level rises, stimulated by PRH(prolactin releasing hormone) from the hypothalamus. When an infant sucks it causes reduction in hypothalamic secretion of PIH and an increase in prolactin secretion.
Explain MSH(Melanocyte-stimulating hormone) 7/7
Increases skin pigmentation in amphibians by stimulating the dispersion of melanin granules in melanocytes. May influence brain activity in humans. Excessive levels of CRH can stimulate MSH release, and prolactin-inhibiting hormone(PIH) inhibits MSH release.
Name target issues and principal actions(PA) of hormone HGH (1/7)
1. HGH-target: liver; PA-stimulates liver, muscle, cartlage, bone and other tissues to synthesize and secrete insulin-like growth factors(IGF's) IGF's promote groth of body cells, protein synthesis, tissue repair, lipolysis and elevation of blood glucose concentration.
Name target issues and principal actions(PA) of hormone TSH (2/7)
2. TSH-target:Thyroid gland; PA-stimulates synthesis and secretion of thyroid hormones by thyroid gland
Name target issues and principal actions(PA) of hormone FSH (3/7)
3. FSH-target: Ovaries and Testes; PA-In females initiate development of oocytes and induces ovarian secretion of estrogens. In males, stimulates testes to produce sperm.
Name target issues and principal actions(PA) of hormone LH (4/7)
4. LH-target: ovaries and testes; PA-stimulates secretion of estrogens and progesterone, ovulation and formation of corpus luteum; in males stimulates testes to produce testerone.
Name target issues and principal actions(PA) of hormone PRL (5/7)
5. PRL-target: mammary glands; PA-Together with other hormones, promotes milk production by mammary glands
Name target issues and principal actions(PA) of hormone ACTH (6/7)
6. ACTH-target: Adrenal cortex; PA-stimulates secretion of glucocorticoids by adrenal cortex
Name target issues and principal actions(PA) of hormone MSH (7/7)
7. MSH-target: Brain; PA-may influence brain activity when present in excess, can cause darkening of skin
What is the function of the posterior pituitary, what is it also known as and what hormones does it release?
Synthesizes hormones, Neurohypophysis
OT(oxytocin) & ADH (antidiuretic hormone)
What are the inferior hypophyseal arteries?
Supplies blood to posterior pituitary, branches from internal carotoid arteries.
What is a capillary plexus?
Capillary network that receives oxytocin and antidiuretic hormone secretd from the axon terminals of the neurosecretory cells. The inferior hypophyseal arteries drain into capillary plexus.
What are posterior hypophyseal veins?
hormones pass from plexus to PHV for distribution to target cells
What is Oxytocin(OT)/principal actions, what are the target tissues, where does it originate from and where is it stored?
Released/stimulated during the stretching of the cervix, responsible for sexual pleasure. Stimulates contraction of myoepithelial cells in mammary glands to cause milk injection.
target tissues are uterus and breasts(mamillary glands) during and after delivery of baby.
originate from hypothalamus and stored in posterior pituitary(neurohypophysis)
What is antidiuretic hormone(ADH)/principal actions, what are the target tissues, where does it originate from and where is it stored?
It decreases urine production, causes kidneys to return more water to the blood. Also decreases water through sweating.
- Target tissues: Kidneys, sweat glands(sudoriferous, and arterioles)
- Originate from hypothalamus and stored in posyerior pituitary.
Explain regulation of ADH secretion and actions of ADH; include what osmoreceptors are.
- 1. High blood osmotic pressure stimulates hypothalamic osmoreceptors due to
(decline in blood volume)-diarrhea, -hemorrhage, -excessive sweating
Osmoreceptors-neurons in the hypothalamus that monitor blood osmotic pressure.
2. Osmoreceptors activate hypothalamic Neurosecretory cells that synthesize and release ADH
3. ADH into bloodstream from posterior pituitary, neurosecretory cells receive excitatory input from osmoreceptors. Excytosis cause ADH containing vesicles. Liberated ADH diffuses into capillaries of PP then carried to bloodstream to target tissues.
4.Kidneys stimulated; water loss; decrease output of urine, blood pressure increased
5. Low blood osmotic pressure inhibits the osmporeceptors
6. Reduce or stop ADH secretion. Kidneys retain less water forming a larger volume of urine, sweat glands increase and arterioles dilate. Blood volume and osmotic pressure of body fluids return to normal. (decreased urination can be caused by drugs, morphine, alchohol and nicotene)
What is the thyroid gland and where is it located? Define trachea, AND thyroid follicles.
it is located in inferior to the larynx(voicebox)composed of right and left lobes on either side of trachea.
Trachea-is connected by an isthmus(narrow passage) that lies anterior to trachea
Thyroid follicles-microscopic spherical sacs, makeup most of thyroid gland
explain follicular cells and the thyroid hormones it contains
Follicular cells-consisted on the wall of each follicle of thyroid; produces two hormones
- T3-triiodothyronine-contains 3 atoms of iodine
- T4-Thyroxine-contains four atoms of iodine
What are parafollicular cells and calcitonin?
parafollicular cells-lie between follicle cells, produce calcitonin
- Calcitonin-helps regulate calcium homeostasis when blood level is high, decreases the level of calcium in the blood by inhibiting the action of osteoclasts(breakdown extracellular matrix)
- -secretion of calcitnonin controlled by negative feedback
Formation, storage and release of thyroid hormones process
- 1. Iodine trapping
- 2. Synthesis of thyroglobulin
- 3. Oxidation of iodide
- 4. Iodination of tyrosine
- 5. coupling of t1 and t2
- 6. Pinocytosis and difestion of colloid
- 7. Secretion of thyroid hormones
- 8. transport in blood
Explain formation of thyroid hormones
Iodide trapping, and synthesis of thyroglobulin(TGB).
Iodide trapping-thyroid follicular cells trap iodide ions (I-) by actively transporting them from blood into cytosol. Iodide normally contains most of iodide in the body.
Synthesis of thyroglobulin(TGB)-while follicular cells are trapping, they are also synthesizing thyroglobulin-TGB(glycoproteins produced in RER, packaged in golgi complex into secretory vesicles and then secretd into lumen of follicle
Explain storage of thyroid hormones
Oxidation of iodide, Iodination of tyrosine and coupling of T1 and T2.
Oxidation of iodide-negatively charged iodide ions undergo oxidation(removal of electrons) transforming them into iodine molecules. Pass out of follicular cells into follicle.
Iodination of tyrosine- Iodine molecules bind with tyrosines, amino acid components of TGB. The binding yields monoidotyrosine(T1) and attachment of two iodine molecules produces diiodotyrosine(T2). The combined TGB and attaced iodine molecules forms a sticky material termed: colloid that accumulates the lumen of follicle.
Coupling of T1 and T2-last step of synthesis of thyroid hormone: one t1 and t2 join to form T3 or two T2 molecules join to form T4.
Explain the release of thyroid hormones
Pinocytosis and digestion of colloid; secretion of TH, and Transport in blood.
Pinocytosis and digestion of colloid-droplets of colloid re-enter follicular cells by pinocytosis and merge with lysosomes
Secretion of thyroid hormones-Because T3 and T4 are lipid soluable, they diffuse through plasma membrane into interstitial fluid and enter blood; most T4 converted to T3; removal of iodine.
Transport in blood-Most T3 and T4 travel through blood bound to transport protein TGB
What are the actions of thyroid hormones?
- -Increase BMR
- -Stimulate cells to use ATP
- -stimulate protein synthesis
- -Increase breakdown of triglycerides
- -Enhance some actions of norepinephrine and epinephrine
- -Stimulate body growth