Endocrine System Flashcards
Hypothalamus
location and function
- brain region controlling the pituitary gland
- below thalamus in the deep subcortical (Under the cortex) area of the brain
Functions:
- temperature, circulation, sexual function, lactation and uterine contraction regulation
- produces neurohormones, Releasing hormones stimulate the production of hormones in the pituitary gland, whilst inhibiting hormones inhibit
neurohormones produced by the hypothalamus to manipulate hormone production by the pituitary gland include:
- Anti-diuretic hormone (ADH): This increases water absorption in the kidneys.
- Corticotropin-releasing hormone (CRH): This stimulates the release of corticosteroids by the adrenal glands, regulating metabolism and immune response.
- Gonadotropin-releasing hormone (GnRH): GnRH stimulates the production of follicle stimulating hormone (FSH) and luteinizing hormone (LH)
- Growth hormone-releasing hormone (GHRH) or growth hormone-inhibiting hormone (GHIH): GHRH prompts the release of growth hormone (GH)
- Oxytocin: This is involved in the release of breast milk, orgasm, and smooth muscle contraction. It also regulates body temperature by helping to redistribute heat, increasing levels of oxytocin help induce sleep.
- Prolactin-releasing hormone (PRH) or prolactin-inhibiting hormone (PIH): PRH stimulates the production of breast milk
- Thyrotropin releasing hormone (TRH): TRH triggers the release of thyroid stimulating hormone (TSH), causing the release of thyroid hormones which regulate metabolism, energy, growth, and development
pituitary gland
location, structure and function
- pea-sized, ovoid shaped structure attached via the infundibulum to the hypothalamus
- pituitary gland has two main parts: neurohypophysis and adenohypophysis
- stores some of the hormones that the hypothalamus produces, before releasing them into the blood
- anterior lobe is larger, making up 75% of the gland and has a larger role in the release of hormones
anterior lobe secretes a total of 7 different hormones into the bloodstream, which are as follows:
- human-growth hotmone (hGH)
- Thyroid-stimulating (TSH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL): stimulates milk production
- Adrenocorticotropic hormone (ACTH): body’s stress response, causes production of cortisol in the adrenal cortex
- Melanocyte-stimulating hormone (MSH): MSH can cause darkening of the skin
posterior lobe of the pituitary gland is only involved in the release of two hormones
oxytocin and antidiuretic hormone (ADH).
- Oxytocin is involved in childbirth, milk production, and orgasm.
- ADH is important in reducing water loss by decreasing urination and sweating, therefore increasing blood pressure
Pineal gland
location and structure and function
- located posterior to the thalamus
- pineal gland has a base that is directed anteriorly and is divided into a superior and inferior laminae by the pineal stalk
function: involved in the secretion of the hormone Melatonin also regulates the sleep-wake cycle by reacting to the amount of light hitting the retina.
thyroid gland
location, structure and function
- at the base of the neck, it’s the largest gland
- located in the anterior portion of the neck at the level of the C5-T1 vertebrae, deep to the sternothyroid and sternohyoid muscles
- consists of two lobes, right and left, which ascend upwards to the thyroid cartilage, joined together by an isthmus
- function: important in regulating metabolism. It produces 2 important metabolic hormones, thyroxine (T4) and triiodothyronine (T3)
parathyroid glands
location, structure and function
- parathyroid glands (usually 4 in total) are small, flattened, and oval structures located on the posterior surface of each lobe of the thyroid gland
- they lie between the fibrous capsule of the thyroid gland and its external fascial sheath
- The glands are separated into two superior and two inferior ones
- The parathyroid glands maintain calcium levels in the blood by producing parathyroid hormone
Describe enteric endocrine system
- gastrointestinal tract can produce hormones and it’s known as the enteric endocrine system
- hormone secreting cells are located throughout lining of stomach and small intestine
- the cells produce hormones in response to environment inside stomach and intestine, reacting to amount of food moving through
Pancreas (an accessory digestive gland)
function, location, shape, parts
- it releases the hormones insulin and glucagon, which regulate blood sugar levels
- an oblong-shaped organ positioned at the level of the transpyloric plane (L1)
- With the exception of the tail of the pancreas, it is a retroperitoneal organ, located deep within the upper abdomen in the epigastrium and left hypochondrium regions
- four parts: a head, neck, body, and tail
function of pancreas glands: 6 gastrointestinal hormones
Gastrin: stimulated by presence of peptides and amino acids
Secretin: produced in response to acidic pH levels, and causes production of water and bicarbonate
Ghrelin: stimulates appetite and feeding
Motilin: involved in movement and contractions of GI tract
Cholecystokinin: This stimulates the secretion of pancreatic enzymes and emptying of the gallbladder in response to an increase in fatty acids and amino acids in the small intestine
Gastric inhibitory polypeptide: This prevents gastric movement and secretions, and causes the release of insulin in response to an increase in glucose and fat
Adrenal glands (suprarenal)
location, structure and function
- two triangular shaped glands found on top of the kidneys
- yellowish appearance and are located between the superomedial aspects of the kidneys and the diaphragm
- glands are divided into two parts; the adrenal cortex and the adrenal medulla:
Adrenal cortex is the outer part of an adrenal gland, and produces glucocorticoids hormones: - Hydrocortisone (cortisol): regulates energy production, blood pressure, and heart function.
- Corticosterone: plays role in immune responses and reduction in inflammation.
- Aldosterone: controls blood pressure
- adrenal medulla is the inner portion of the gland
- helps the body deal with stress by producing two hormones:
- epinephrine (adrenaline): body’s fight or flight response, increasing heart rate and blood glucose levels, and causing an increase in blood flow to the brain and muscles
- norepinephrine: works with adrenaline, by constricting blood vessels and increasing blood pressure during the stress response
Adrenal glands zones and the hormones they produce
Zona glomerulosa (outermost) : produces mineralocorticoids which regulates salt balance and blood volume
Zona fasciculata (middle) : produces glucocorticoids which regulates glucose metabolism
Zona reticularis (inner layer of cortex) : produced androgens which stimulates masculinization
Medulla: produces stress hormones which stimulates sympathetic NS
