Endocrine system Flashcards
How does hormone release process work?
Endocrine gland
Bloodstream
Target organs
What is a hormone and what is their function?
Body’s chemical messengers
Communicate with specific organs
Instigate a process within
What else can stimulate hormone release (other than hormones)?
Stimulation by signals from nervous system (e.g. induced ovulation)
3 chemical structures of hormones?
Amines - from amino acids
Protein (peptides) - from chains of amino acids
Steroid - from cholesterol
Name of hormone glands (6)
Pituitary gland
Thyroid gland (2)
Adrenal gland (2)
Pancreas
Ovary (2)
Testes (2)
Location of pituitary gland
Forebrain
Ventral to hypothalamus
Location of 2 thyroid glands
Midline and ventrally over the first rings of trachea
Location of 2 adrenal glands
On the cranial pole of each kidney
Location of pancreas
Loop of duodenum
Structure of pancreas?
Pink lobular gland
Location of 2 ovaries
Dorsally and bilaterally within the abdomen
Location of 2 testes
Lie within the scrotum
Function of pituitary gland
Controls actions of many other glands
What is connected to pituitary gland?
Hypothalamus by infundibulum
Function of hypothalamus
Direct link between 2 control systems: nervous and endocrine
What hormones are secreted in the posterior pituitary gland?
Oxytocin
Anti-Diuretic Hormone (ADH)
What hormones are secreted in the anterior pituitary gland? (6)
Growth hormone (GH)
Thyroid Stimulating Hormone (TSH)
Adrenocorticotropic Hormone (ACTH)
Follicle stimulating Hormone (FSH)
Luteinising Hormone/ Interstitial Cell Stimulating Hormone (LH/ICSH)
Prolactin
Thyroid Stimulating Hormone (TSH): Target
Thyroid gland
Thyroid Stimulating Hormone (TSH): Function
Stimulates the thyroid gland to release thyroxine
Growth Hormone (GH): Target
Tissues/ mainly bones
Growth Hormone (GH): Functions (2)
- Growth of bones
- Synthesis of new protein
Adrenocorticotropic Hormone (ACTH): Target
Cortex of adrenal gland
Adrenocorticotropic Hormone (ACTH): Function
Help the adrenal cortex release corticosteroids
Prolactin: Target
Mammary glands
Prolactin: Functions (2)
- Stimulates development of mammary glands
- Production of milk
Follicle Stimulating Hormone (FSH): Target
Germ cells of the ovaries/ Seminiferous tubules of the testes
Follicle Stimulating Hormone (FSH): Function
Stimulates development of the follicle in ovary/ sperm in the seminiferous tubules of testes
Luteinising hormone/ Interstitial cell stimulating: Target
Follicle of the ovaries (F)/ Interstitial cells of testes (M)
Luteinising hormone/ Interstitial cell stimulating: Function
Ovulation & development of corpus luteum in ovary (F)
Stimulates production of testosterone by interstitial cells of testes (M)
Anti-Diuretic Hormone ADH: Target
Distal convoluted tubules & collecting ducts of kidneys
Anti-Diuretic Hormone ADH: Function
Makes DCT and CD of kidneys more permeable to water
So water can move back into circulation
Oxytocin: Target
Smooth muscle of uterine wall
Mammary glands
Oxytocin: Function (2)
Smooth muscle wall of uterus to contract at parturition
Stimulates let-down of milk from mammary glands
Hormones secreted by Thyroid gland
Thyroxine & Calcitonin
Thyroxine T4: Target
All systems of body
Thyroxine T4: Functions (4)
- Increases oxygen use by cells
- Increases carb breakdown
- Increases metabolic rate
- Promotion of growth
Calcitonin: Target
Blood and bones
Calcitonin: Function
Lowers amount of calcium in blood by decreasing rate of resorption of calcium by kidneys
Location of parathyroid gland
Either side of thyroid glands, in pairs
What is secretion of parathormone dependent on?
Levels of calcium detected in blood
Parathormone: Gland
Parathyroid gland
Parathormone: Targets (2)
Digestive system and bones
Parathormone: Function (2)
Reabsorption of calcium from bones and increases calcium uptake from digestion
Name of endocrine cells in pancreas?
Islets of langerhans
Hormones released by pancreas
Insulin
Glucagon
Somatostatin
Regions of pancreas
Left lobe
Right lobe
Body
3 main cells that make up the islets of Langerhans?
Alpha cells (glucagon)
Beta cells (insulin)
Delta cells (somatostatin)
Insulin: Target
Most cells except RBC
Insulin: Function
Increases uptake of glucose by cells
Causes glucose to be converted in2 glycogen and stored in liver & muscle cells
Glucagon: Targets (2)
Liver and muscles
Glucagon: Function
Converts glycogen back into glucose
Somatostatin: Target
Alpha & Beta cells
Somatostatin: Function (2)
Regulates insulin & glucagon secretion to avoid spikes in glucose
Decreases gut motility
2 areas of adrenal glands
Outer cortex and inner medulla
Produced by adrenal medulla glands?
Adrenaline and noradrenaline
Produced by adrenal cortex glands?
Glucocorticoids e.g. cortisol
Mineralocorticoids e.g. aldesterone
Adrenaline and noradrenaline: Targets (4)
Heart
Blood vessels
Airways
Gut
Adrenaline and noradrenaline: Function
Involved in fight, flight and fright response
Glucocorticoids e.g. cortisol: Target
Many tissues
Glucocorticoids e.g. cortisol: Function
Reduce glucose uptake by cells
Raising BGL
Mineralocorticoids e.g. aldosterone: Target
DCT of kidney
Mineralocorticoids e.g. aldosterone: Function
Increases sodium & water reabsorption
Thus raising blood pressure
Hormones secreted by ovaries?
Oestrogen and progesterone
Oestrogen: Target (4)
Reproductive tract
Pituitary gland
Mammary tissues
Behavioural centres
Oestrogen: Function (4)
Prepares the reprod. tract for mating
Inhibits release of FSH by pituitary gland
Encourages development of mammary tissues
Causes behavioural changes linked with oestrus
Progesterone: Target
Reproductive tract & hypothalamus
Progesterone: Function
Inhibits further development of follicles
Prepares and maintains the reproductive tract and pregnancy
Testosterone: Target
Diff tissues and behavioural centres
Testosterone: Function
Stimulates sperm production
Male behavioural characteristics and libido
Development of male sexual characteristics
Homeostatis
Constant internal environment within the body: from int/ext environment
What maintains homeostatis?
Control systems: endocrine and nervous system
Example of endocrine mechanism of homeostatis?
Control of blood sugar levels
A rise in blood sugar levels is caused by…
Release of insulin from pancreas
Which in turn causes
Uptake of glucose from blood by cells
A fall in blood sugar levels is caused by …
Release of glucagon from pancreas
which in turn causes
Conversion of glycogen in the liver into glucose for release into the blood stream
Example of nervous mechanism of homestatis
Thermoregulation
What happens when body temp drops?
Vasoconstriction: reduces heat loss
from evaporation & radiation
What happens when body temp rises?
Vasodilation: increases heat loss from evaporation and radiation
What is negative feedback?
Away from set point
Return to set point
Corrective measures are switched off
Example of negative feedback mechanism?
Control of blood glucose levels
Example of positive feedback mechanism?
Hormone oxytocin
Uterine contractions
Amplifying mechanism
