Endocrine System; The Glands Flashcards
Function of the hypothalamus
Maintain homeostasis and act as a control centre. Stimulates/inhibits body function. Links NS to endocrine
What Happens when Hypothalamus Receives Signal?
Will secrete neurohormones that control pituitary gland secretion
Corticotrophin Releasing Hormone (CRH)
Sends message to anterior pituitary gland stimulating adrenal gland to release corticosteroids which regulate metabolism/immune response
Gonadotrophin Releasing Hormone (GnRH)
stimulates anterior pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH) which work together to ensure function of ovaries/testes
Growth hormone-releasing hormone (GHRH) OR growth hormone-inhibiting hormone (GHIH)
also known as somatostatin. prompts anterior pituitary gland to release growth hormone. GH is essential to children’s healthy body composition. In adults, it aids healthy bone’s, muscle mass and fat distribution
Prolactin Releasing Hormone (PRH) OR Prolactin - Inhibiting Hormone (PIH)
prompts the anterior pituitary gland to stimulate breast milk production through the production of prolactin. PIH inhibits prolactin thus stopping breast milk production
Thyrotropin Releasing Hormone (TRH)
triggers the release of thyroid stimulating hormone that regulates metabolism, energy and growth/development
What does the Pineal Gland do?
Secretes Melatonin that controls circadian rhythm and inhibits some reproductive hormones. Also, its secretion is controlled by light levels
Circadian Rythm = when the body decides when it is time to go to sleep and be awake
Why is the Pituitary Gland Called the ‘Master Gland’?
Because its hormones control other parts of the endocrine system
How is it Connected to the Hypothalamus?
- It’s connected by the pituitary stalk (infundibulum)
How is the Pituitary Gland Connected to the Hypothalamus?
It’s connected by the pituitary stalk (infundibulum)
When and How does the Pituitary Gland Act?
It acts when the hypothalamus tells it to by sending hormones to other organs of the endocrine system instructing them to increase/decrease or inhibit hormone production
What are the Two Lobes of the Pineal Gland, and What do they do?
Anterior - produces and releases certain hormones when instructed via vessels from the hypothalamus
Posterior - releases different hormones when instructed via nerves from the hypothalamus
Adrenocorticotropic Hormone (ACTH)
stimulates the adrenal gland
Follicle Stimulating Hormone (FSH)
works with LH to ensure normal function of ovaries/testes
Growth Hormone (GH)
Essential in early years to maintain healthy body composition, muscle mass and fat distribution
Prolactin
stimulates breast milk production
Thyroid Stimulating Hormone (TSH)
stimulates the thyroid gland to produce hormones
The Posterior Lobe
It has many nerve endings coming from the hypothalamus so it can send hormones directly to the posterior lobe via these nerves and then the pituitary gland releases them
The Posterior Lobe Hormones
ADH - tells the kidneys to increase water absorption in the blood
Oxytocin - A variety of processing including contraction of the uterus during childbirth and stimulating breast milk production
What does the Thyroid Gland do?
Secretes metabolism hormones - all cells rely on the thyroid hormones for their metabolism regulation
What are the Two Main Hormones the Thyroid Makes?
It uses iodine to produce tri-iodothyronine (T3) and thyroxine (T4)
What Happens when Thyroid Hormone Levels are Low?
The hypothalamus releases thyroid releasing hormones (TRH) which signals to the pituitary gland to release thyroid stimulating hormone (TSH) causing the thyroid to produce more T3 and T4
What is a Normal Balance of T3 and T4?
20% T3 and 80% T4
What does the Parathyroid Gland Secrete and what Does that Hormone do?
It secretes parathyroid hormone which regulates Ca levels. Ca is needed in synapses, bones and causes muscles contraction
Parathyroid Hormone (PHT) regulates the amount of Ca absorbed from food and stored in the skeletal system. Also regulates the release of this stored Ca into the blood stream
What does the Thymus Gland do?
Only Active till puberty. Creates thymosin which produces T-Cells
What is the Outer Layer of the Adrenal Gland? And What Hormones do they Secrete?
The Adrenal Cortex - glands produce hormones vital for survival (cortisol-stress/fight/flight/freeze/metabolism/immune response/inflammation/circadian rhythm) and Aldosterone (BP)
What does the Adrenal Medulla do?
releases unessential hormones eg Adrenaline
What are the Two Types of Adrenal Cortex Hormones?
-
Gluococorticoids; (triggered by hypothalamus/pituitary gland) which induce:
- hydrocortisone (cortisol) which regulates production of energy
- Corticosterone working hydrocortisone to regulate immune response/suppress inflammatory response -
Mineralocorticoids (triggered by kidneys)
- Aldosterone balance of salt & water and BP control
What are the 2 Adrenal Medulla Hormones?
- Epinephrine (adrenaline) - stress response and glucose conversion (glycogen → glucose in liver)
- Norepinephrine (noradrenaline) - vasoconstriction
How is the Pancreas an Endo and Exo Gland?
Endo - hormone’s release into blood stream regularly for blood glucose regulation
Exo - Enzymes into digestive system to aid breakdown of food
What are the Pancreatic Hormones?
- Glucagon - glycogen → glucose
- Insulin - glucose → glycogen
- Somatostatin - If these hormones are too high, its secreted to maintain glucose conc or salt conc in blood
- Vasoactive Intestinal Peptide (VIP) - controls H2O secretion/absorption from intestines by stimulation of intestinal cells to release H2O/salts into intestines
What Hormones do the Ovaries Secrete?
- Oestrogen (oestradiol, Oestrone, Oestriol) - development of female characteristics
- Progesterone - regulation of menstrual cycle, preparation of uterus to recieve fertalised eg
What does the Hypothalamus do during Puberty to Stimulate the Release of Eggs?
- the hypothalamus begins to release gonadotrophin releasing hormone (GRH)
- which stimulates the pituitary gland to release follicle stimulating hormone (FSH) –
- which stimulates growth of ovarian follicles in order for an egg to be released at ovulation.
- Luteinising hormone (LH) is also released by the pituitary triggering the release of the egg from the ovary
What does Progesterone do?
prepares the uterus to receive a fertilised egg by thickening the lining of the uterus. If no fertilised egg is received the lining is shed through menstruation
What Hormones are Released when Pregnant?
-high levels of oestrogen/progesterone are released to prevent more eggs from maturing and being expelled.
-Prepares the body for pregnancy and lactation.
-Raised levels of oestrogen near the end of pregnancy cause the pituitary gland to release oxytocin
What does Oxytocin do?
chemical messenger that regulates emotional responses; lowers stress/anxiety; increases trust & romantic attachment; and enhances mother-infant bonding. Stimulates contractions during childbirth and lactation post birth.
What does Relaxin (Corpus luteum) do?
Released by ovaries just after ovulation in order to aid implantation of egg to uterus.
It increases during pregnancy and in preparation for birth as it relaxes ligaments in pelvis while softening and widening the cervix
Why is the Testes Location Good for its Function?
It’s located outside the body as the cooler temperature promotes sperm production
What do the Testes Secrete? And What does it Do?
Testosterone - develops male characteristics, maintain libido, sperm production, muscle mass and strength and bone density in adult life
How does the Hypothalamus Lead to Sperm Productions
- The hypothalamus releases gonadotrophin releasing hormone (GRH)
- GRH stimulates the pituitary gland to release FSH which helps to regulate sperm production
- LH stimulating the testes to make/secrete testosterone which is necessary for sperm production
What Hormones are Released by the Hypothalamus? (5)
- Corticotropin
- Gonadotropin
- Growth Hormones
- Oxytocin
- Thyrotropin
What Hormones are Secreted from the Pituitary Gland? (5)
- Adrenocorticotropin Hormone (ACTH)
- Follicle Stimulating Hormone (FSH)
- Growth Hormone (GH)
- Prolactin
- Thyroid Stimulating Hormone (TSH)
The Posterior Lobe Hormones
ADH and Oxytocin
What Hormones are Released by the Pancrease?
- Glucagon
- Insulin
- Somatostatin
- Vasoactive Intestinal Peptide (VIP)