Flashcards
Endocrine System
Cards in this deck (37)
- 1Endocrine vs. Nervous systemThe endocrine and nervous system work together to coordinate functions of the body
The endocrine system is slower but broader than the nervous system since it acts on all cells of the body while the nervous system targets specific muscles and glands - 2HormonesMediator molecules that are released in one area of the body but act on the cells of another area
- 3Primary endocrine glandsGlands that secrete hormones only
(PPPAT)
Pituitary gland
Pineal
Parathyroid
Adrenal
Thyroid - 4Secondary endocrine glandsGlands that secrete hormones as a secondary function
(PLOSSSPHHATTK)
Pancreas
Liver
Ovaries
Stomach
Small intestine
Skin
Placenta
Heart
Hypothalamus
Adipose tissue
Testis
Thymus
Kidneys - 5Pituitary glandOne of the master glands since it releases a number of hormones
- 6PinealSecretes melatonin (which helps you feel sleepy)
- 7ParathyroidLocated behind the thyroid gland and it helps regulate calcium levels
- 8Adrenal GlandsHas a cortex and medulla region
Cortex: releases aldosterone
Medulla: Adrenalin (epinephrine and norepinephrine) - 9ThyroidLocated around the trachea and it helps regulate metabolism in the body
- 10Endocrine vs. exocrine glandsEndocrine: secrete products directly into interstitial fluid which then enters the bloodstream - the endocrine gland are highly vascular since they rely on the cardiovascular system to circulate the hormones throughout the body
Exocrine: secretes products into ducts or other surfaces of the body - 11Hormone receptorsProteins located on or in cells that hormones will bind to in order for an effect to occur
Two types:
Water soluble receptors : Receptors located on the outside,cell membrane
Lipid soluble receptors: Receptors located on the inside of the cell - 12Down regulationWhen there is excess hormones present the number of receptors will decrease and so the sensitivity of that organ or tissue (target cell) for that particular hormone decreases
- 13Up regulationdeficient amount of hormones present which increases the number of receptors and increases target tissue sensitivity to the hormone
- 14Circulating hormonesMost hormones are circulating hormones
Pass from the secretory cells where they were made and enter interstitial fluid and then the blood
They target distant tissues or cells and travel in the blood - 15Local hormonesThey target the same secretory cell that made them or they will target neighboring cells without entering the bloodstream first
Ex. Paracrines: act on neighboring cells
Autocrines: act on the same cell - 16Responses of hormonesThe response of a hormone depends on both the hormone itself and the target cells
Ex. insulin on liver increases synthesis of glycogen while on adipose tissue it increases synthesis of triglycerides
Responses include:
1. Synthesis of new molecules
2. changing cell permeability
3. Transporting substances in and out of cells
4. Altering the rate of metabolic actions
5. Causing contractions of smooth and cardiac muscle - 17Controlling secretion of hormonesHormones are secreted in short bursts when needed (they can be continuously secreted or only when needed)
Secretion is regulated by:
1. Signals from the nervous system
2.Chemical changes in the blood
3. Other hormones
Most hormone regulation is done by negative feedback loops but can be positive as well (ex.labor- oxytocin) - 18Hypothalamus and Pituitary GlandHypothalamus: Master of the pituitary, main connection between the nervous and endocrine systems, secretes 9 hormones (2 of which are just stored in the pituitary)
Pituitary: secretes 7 hormones, has two lobes: posterior and anterior lobe, attached to the hypothalamus by the infundibulum - 19Anatomy of the pituitary GlandPosterior lobe (neurohypopysis) : secretes 2 hormones that were made by the hypothalamus, made up of neural tissue
Anterior lobe (adenohypophysis): makes of 75% of the weight of entire gland,secretes 7 hormones - 20Hypophyseal Portal SystemThe hypothalamus produces inhibiting and releasing hormones that control the anterior pituitary- hormones get to the pituitary by this system
Blood flow: Superior hypophyseal arteries -> primary plexus -> portal veins-> secondary plexus-> anterior hypophyseal veins
In the hypothalamus above the optic chiasm we have neurosecretory cells that synthesize these releasing and inhibiting hormones and package them into vesicle. The vesicles reach the axon terminals through axonal transport and then the nerve impulses stimulate these vesicles to undergo exocytosis. The hormones diffuse into the primary plexus of the hypophyseal portal system .
Hormones released by the anterior pituitary enter the secondary plexus - 21Tropic HormonesReleased by the anterior pituitary that act on other endocrine glands
- 22Hypophyseal Portal System- Posterior pituitarySingle capillary bed
Inferior hypophyseal artery-> capillary plexus of the infundibular process -> posterior hypophyseal veins - 23Controlling the secretions of the anterior pituitaryDone by the neurosecretory cells and the negative feedback loops
1. Neurosecretory cells
-5 releasing hormones
-2 inhibiting hormones
7 hormones total that can inhibit or stimulate secretions of the anterior pituitary
2. Negative feedback loops
-when specific hormones are high in blood concentrations then AP secretions decrease
Ex. GnRH stimulates the secretions of LG which targets the ovaries to release progesterone, progesterone levels cause a decrease in the release of LH and GnRH - 24Cells of the anterior pituitarySomatotrophs: secretes human growth hormone (hGH)
Thyrotrophs: thyroid stimulating hormone (TSH)
Gonadotrophs: FSH and LH
Lactotrophs: Prolactin (PRL) which stimulates milk production in mammary glands
Corticotrophs: adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH) - 25hGHSecreted by somatotrophs in short bursts. Somatotrophs are the most numerous cells in the anterior pituitary which makes hGH the most plentiful hormone
Main function is to secrete and synthesize insulin like growth factors which can either enter the blood stream directly or act locally like autocrines and paracrines - 26Insulin like growth factor (IGF)Functions:
1.Increase growth and repair of cells
2. Promote lipolysis
3. Slow glucose uptake of cells
Main targets:
Liver, skeletal muscle, cartilage, and bone - 27Regulation of hGHRegulated by two hypothalamic hormones: GHRH and GHIH - these two are regulated by the blood glucose levels
Somatotrophs especially release hGH during sleep, increases functioning of SNS, low blood fatty acids, and high amino acids - 28Gigantism and acromegalyBoth due to too much release of hGH
BUT Gigantism is when there is excess hGH in children whereas acromegaly is excess hGH in adults - 29TSHReleased by thyrotroph cells and TSH function is to synthesize and secrete two thyroid hormones; T3 and T4
The release of TSH by thyrotrophs is regulated by the hypothalamic hormone called thyrotropin releasing hormone (TRH)
The release of TRH depends on the blood concentration of T3 and T4
when concentrations are high then TRH is inhibited via a negative feedback loop
Note: T3 and T4 increase basal metabolic rate - 30FSHReleased by gonadotroph cells
Functions of FSH are that they contribute to follicle formation in ovaries, stimulates estrogen secretion by follicles, and stimulates sperm production in testis
The hypothalamic hormone that regulates FSH secretion is GnRH
GnRH depends on the levels of estrogen (females) and testosterone (males)
High levels suppress GnRH - 31LHSecreted by gonadotrophs
Function for females includes stimulation of ovulation of the 2nd oocyte from an ovary, formation of the corpus luteum, secretions of estrogen and progesterone
In males, LH stimulates interstitial (leydig) to release testosterone
The hypothalmic hormone that regulates this is GnRH (suppressed in high levels of estrogen and testosterone) - 32ProlactinReleased by lacototroph cells
The function of prolactin by itself is not huge but with other hormones and under the right conditions prolactin stimulates milk production in mammary glands
The hypothalamic hormones that regulate prolactin released by lactotrophs include PRH and PIH (releasing and inhibiting)
Most of the time we have PIH released but during pregnancy PRH is released while suckling inhibits PIH
Note: right before menstruation, PRH increases slightly (not enough for milk production) which may cause tenderness in breasts - 33Adrenocorticotropic hormone (ACTH)Released by corticotroph cells
The function is to release other cortisols and glucocorticoids by the cortex region of the adrenal glands
The hypothalamic hormone that controls secretions of the corticotrophs is the corticotropin releasing hormone (CRH)
Glucocorticoids inhibits the release of CRH and ACTH - 34Posterior PituitaryDoes NOT synthesize hormones but it does store 2 hypothalamic hormones; oxytocin and antidiuretic hormone (ADH)
- 35OxytocinTargets the uterus and the breasts
During delivery: the stretching of the cervix of the uterus stimulates the release of oxytocin which in turn stimulates smooth muscle contractions of the uterus
After deliver: oxytocin stimulates milk ejection in response to suckling or even by just hearing a babies cry
Unknown function in males and women not pregnant - 36ADHAKA vasopressin
In the kidneys is decreases urine production, in sweat glands it decreases sweating and in blood vessels, they constrict increasing BP
Alcohol and coffee are diuretics so they decrease the secretion of ADH
Dehydrated (high blood osmotic pressure) - ADH is released
Over-hydrated (low blood osmotic pressure) - ADH is repressed - 37—
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- Year 1 Semester 2 Flashcards on Endocrine System, created by Raeesa Zulfiqar on 17/04/2017.
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- Raeesa Zulfiqar
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