Endocrine system Flashcards
What controls the endocrine system?
the hypothalamus
do endocrine glands have a duct?
no
what is a hormone?
chemicals that travel through the blood stream to a target organ and cause and effect
what does autocrine mean?
a hormone that has an effect on the original cell that produced it (insulin)
what does endocrine mean?
a hormone transported in the blood to a target organ
what does exocrine mean?
a substance, that is not a hormone, released by a duct (pancreas and digestive enzymes)
what does paracrine mean?
a hormone that has an effect on local cells (testosterone/oestrogen)
what are the seven main endocrine glands?
-pineal
-pituitary
-adrenal
-ovaries
-testes
-thyroid
-pancreas
-parathyroid
what are three hormone organs that secrete hormones but this is not their main purpose?
stomach - gastrin
kidneys - erythropoeitin
small intestine - secretin
what is the pineal gland?
- in the brain
- produces melatonin (wake/sleep patterns and photoperiodic functions)
what is the hypothalamus?
- control centre of endocrine system
what is the pituitary gland?
- control over many endocrine gland
- ventral to forebrain
- two lobes (anterior and posterior)
- anterior lobe - adeno-hypophysis
- posterior lobe - neuro-hypophysis
what hormones does the anterior pituitary gland secrete?
- somatotrophic/growth hormone
- thyroid stimulating hormone
- adrenocorticotrophic hormone
- follicle stimulating hormone
- luteinising hormone
- luteotropic/prolactin hormone
- interstitial cell stimulating hormone
what is the somatotrophic hormone?
- influences growth of bones and soft tissues by increasing the uptake of amino acids and protein production and increasing fat deposits
what is the overgrowth of soft tissue when an animal has finished growing in terms of somatotrophic hormones called?
acromegaly
what is the thyroid stimulating hormone?
- stimulates the growth of the thyroid gland
- hormones T3 and T4
- stimulates the release of thyroxine which controls the metabolic rate
- controlled by negative feedback
what is the adrenocorticotrophic hormone?
- stimulates hormonal production from the adrenal cortex
- stimulates the release of corticosteroids and mineralcorticoids
- hypothalamus releases corticotropin-releasing hormone stimulating ACTH release
what is the follicle stimulating hormone stimulate in females?
- stimulates development of follicles on the ovary in females
what is the luteinising hormone responsible for?
- responsible for release of ova from the mature ovarian follicle and inital formation of corpus luteum in the female and targets the Leydig cells stimulating testosterone production in the male
what is the luteotrophic hormone?
- prolactin
- stimulates corpus luteum to produce progesterine
- stimulate milk let down
what is the interstitial cell stimulating hormone?
- stimulates secretion of testosterone from the interstitial cells in the testis
what hormones are in the posterior pituitary gland?
- oxytocin
- anti-diurectic hormone
what is oxytocin?
- causes uterine contractions and milk let down by acting on the smooth muscle of the uterus and mammary glands
what does an anti-diuretic hormone do?
- vasopressin
- regulates absorption of water from the distal convoluted tubule in the kidneys, so increases the reabsorption of water and decreases the volume of urine produced
what happens if ADH is deficient?
the kidney is unable to concentrate the urine and huge volumes of very dilute urine are produced
- diabetes insipidus
what does the hypothalamus produce?
- produces releasing and inhibiting hormones which control the pituitary gland and tells it what hormones need to be produced or when to stop producing these
what systems does the hypothalamus connect?
connects endocrine and nervous system
what is the thyroid gland?
- two lobes, either side of the trachea
- parathyroid glands lie adjacent to the thyroids
- made up of follicles which produce the hormones thyroxin and tri-iodothyronine and the cells in between the follicles which produce the hormone thyrocalcitonin
where is the thyroid gland found?
midline, caudal to, or at the level of the larynx with two lobes found either side of the trachea
what are the two thyroid hormones?
- thyroxine and triodothyronine
- release stimulated by the TSH from the anterior pituitary gland
- iodine needed for their manufacture
what is calcitonin?
-thyroid hormone
- controls blood calcium level
- hormone causes fall in blood calcium by decreasing gut absorption and increasing the amount of calcium stored in the bones
what are the parathyroid glands?
- produce parathyroid hormone
- part of calcium control system
- raises/controls blood calcium levels
- antagonistic effect to calcitonin
what is calcitonin produced by?
produced by parafollicular cells or C cells
what do the two thyroid hormones do?
regulate metabolic rate of the body, increasing it along with HR, BP, and nervous system activity
what can the somatotrophic hormone be stimulated by?
- can be stimulated by puberty, exercise, stress, hyperglycaemia, some amino acids, and sleep
what does the follicle stimualting hormone target in males?
- targets the sertoli cells = sperm production in the male
how is the luteinising released in the bitch and the queen?
- released spontaneously in the bitch but only released in response to mating in the queen
what are the adrenal glands?
- cortex produces 40+ steroid hormones to facilitate homeostasis
- produces androgens and oestrogens
what are the two steroid hormones?
- glucocorticoids
- mineralcorticoids
what are glucocorticoids?
- steroid hormones
- promotes gluconeogenesis
- anti-inflammatory
- anti-pruitic
- immunosuppressive
- increase the bodies tolerance to stress
- examples - cortisone and cortisol
what are mineralocorticoids?
- steroid hormones
- involved with tissue repair and inflammation
- main function is the metabolism of electrolytes and water in the kidneys
- examples - aldosterone
what is the adrenal medulla?
- adrenaline and nor-adrenaline
- increase HR and BP
- fight or flight response
what is the pancreas?
- mixed gland (exocrine and endocrine)
- islets of langerhans (endocrine)
what are the three cells of the islets of langerhans?
- alpha cells - glucagon
- beta cells - insulin
- delta cells - somatostatin
what are alpha cells?
glucagon
- increase blood glucose
- glycogen into glucose
- stimulate gluconeogenesis
what are beta cells?
insulin
- lower blood glucose by allowing glucose into cells
what are delta cells?
somatostatin
- balances fluctuations in blood glucose by inhibiting release of glucagon and insulin
what is diabetes mellitus?
- hyperglycaemia
- glucose cannot enter cells
- renal threshold reached so glucose is excreted by urine - glucouria
what is gluconeogenesis?
metabolic process that occurs in liver and kidneys to produce glucose
what are the ovaries?
- progesterone - corpus luteum, metoestrus maintains pregnancy
- oestrogen - produced by developing follicles during oestrus and responsible for physical and behavioural signs
what are testes?
- pituitary gland releases FSH and LH at puberty
- induce growth of seminiferous tubules (sperm production)
- induce growth of leydig cells (interstitial cells) in response to interstitial cell stimulating hormone
what is testosterone?
responsible for:
- development of male charaacteristics
- male behaviours
- development of spermatozoa
What are other organs in the endocrine system?
- placenta
- kidneys
- stomach
- duodenum
- corpus luteum
- pineal gland
what are the three layers of the adrenal gland cortex?
- zona glomerulosa (outermost)
- zona fasciculata
- zona reticularis
