Y12 Endocrine System Flashcards
What are the two kinds of glands in the body?
Exocrine and endocrine
What are endocrine glands?
Glands that secrete hormones isn’t extracellular fluid that surrounds the cells that make up the gland. The secretion usually passes into the capillaries to be transported by the blood. Endocrine glands are ductless.
What are exocrine glands?
Glands that secrete hormones into a duct that carries the secretion to the body surface of to one of the body cavities.
3 examples of exocrine glands?
Sweat glands
Salivary glands
Glands of the alimentary canal
What are the 9 major endocrine glands?
Pineal Hypothalamus Pituitary Thyroid Parathyroid Thymus Adrenal Pancreas Gonads
What are the endocrine hormones of the pituitary gland?
Follicle stimulating hormone Luteinising hormone Growth hormone Thyroid stimulating hormone Adrenocorticotropic hormones? Prolactin Antidiuretic hormone Oxytocin
Which hormones are released by the posterior lobe of the pituitary gland?
Oxytocin and antidiuretic hormone
What hormone does the thyroid release?
Thyroxine which targets most body cells to increase metabolic rate and thence oxygen consumption and heat production
What hormone do the parathyroid release?
Parathyroid hormone which targets the bones and kidneys to increase rate of osteoclast activity, increasing levels of calcium in blood and control phosphate levels
What does FSH target?
The gonads where it stimulates growth of follicles and the production of spermatogonia
What does Lutenising hormone target?
- Ovaries in females where it is involved in ovulation and maintainance of corpus luteum.
- leydig cells in the testes of males where it stimulates secretion of testosterone
What does growth hormone target?
All cells, stimulating growth and protein synthesis
What does thyroid stimulating hormone target?
Thyroid stimulating production of hormones of thyroid gland
What does the adrenocorticotropic hormone target?
The adrenal cortex where it stimulates secretion of hormones from the adrenal cortex
What does prolactin hormone target?
The mammary glands where it stimulates production of milk
What does antidiuretic hormone target?
The kidneys ( specifically the distal proximal tubule and collecting duct of nephrons) where it causes reabsorption of water
What does oxytocin target?
The uterus where it allows contractions during childbirth and
The mammary glands which allow the release of milk
Where is thymosins released and what is its effect?
It is released by the thymus and targets t lymphocytes to stimulate development and maturation of T lymphocytes
Where is aldosterone released and what is its effect?
Released by the adrenal cortex to target the kidney where it increases reabsorbtion of sodium ions and excretion of potassium ions
What hormones are released by the adrenal cortex?
Aldosterone and cortisol
Where is cortisol released and what is its effect?
The adrenal cortex to target most cells where it promotes normal metabolism; helps the body deal with stress and promotes repair of damaged tissues
What hormones are produced by the adrenal medulla?
Adrenaline and noradrenaline
Where is adrenaline and noradrenaline preleased and what are their effects?
Produced by the adrenal medulla and targets most tissues where it prepares the body for fight or flight response ; reinforcing the effects of the sympathetic nervous system
Where is insulin released and what is its effect?
The pancreas to target most cells where it stimulates uptake of glucose; lowers blood glucose level
Where is glucagon released and what does it target?
Released by the pancreas and targets the liver and fat storage tissues to stimulate breakdown of Glycogen and fat; increase blood glucose levels
Where is Androgens (testosterone) released and what does it target?
In the testes where it targets many tissues to stimulate sperm production, growth of skeleton and muscles; male sexual characteristics
Where is ostrogen released and what does it target?
Released by the ovaries, targeting many tissues to stimulate development of female characteristics and regulate menstrual cycle
Where is progesterone released and what does it target?
Released via the ovaries to target
..the uterus where it regulates menstrual cycle and pregnancy
..the mammary glands where it prepares the mammary glands for milk secretion
Where is the hormone calcitonin produced and target once released?
Produced by the thyroid to target bones kidneys and intestines where it is involved in calcium regulation
How do proteins and amine hormones send chemical messages?
Proteins and amines are water soluble so they can’t enter, instead Hormone attaches to protein specific receptor in the membrane of the target cell. The combo of hormone with the receptor causes a secondary messenger substance to diffuse through the cell and activate Particular enzyme.
How do steroid hormones send chemical messages?
Steroid hormones are lipid soluable so they enter the target cell and combine to a receptor protein inside the cell. The receptor may be mitochondria, on other organelles of in the nucleus. The hormone receptor complex activates the genes controlling formation of particular proteins
What type/s of hormones can enter the cell?
Lipid hormones
What type/s of hormones can enter the cell?
Amines and proteins
Why can steroid hormones enter the cell?
Cell membrane is made of a phospholipid bylayer. Steroid hormones are lipid soluable so they enter the target cell and combine to a receptor protein inside the cell.
Why cant amines and protein hormones enter the cell?
Proteins and amines are water soluble so they can’t enter, instead Hormone attaches to protein specific receptor in the membrane of the target cell.
What are the 2 lobes of the pituitary gland, how are they different?
Anterior lobe - releases and produces hormones. hormone secretions are controlled by regulating factors. Hormones are secreted into EF surrounding the cells of hypothalamus and carried by blood to Anterior lobe.
Posterior lobe- doesn’t produce hormones but releases them. Joined to hypothalamus by the nerve fibres that come from nerve cell bodies in hypothalamus and pass through the infundibulum to the posterior lobe.
Relationship between hypothalamus and pituitary gland? (Posterior lobe)
Posterior lobe-
+ not a true gland as doesn’t produce hormones. hormones are produced by neurosecretory neurons
+produced in the soma, travel down axon and are stored in the axon terminals in the posterior lobe.
+ nerve impulse triggers the release of hormones from axon terminals in posterior lobe and hormones are releases into bloodstream
(Antidiuretic hormone and oxytocin)
Relationship between hypothalamus and pituitary gland? (Anterior lobe)
+Hypothalamus produces releasing and inhibiting factors in neurosecretory neurons.
+factor is secreted into hypophyseal portal system and bloodstream carries factors directly into the anterior lobe
+ factors reach target endocrine cells (with corresponding receptors) and initiate a response:
Releasing factor would increase production/ release of hormone. Inhibiting factor would decrease production/ release of hormone.
(Eg, growth hormone inhibiting and releasing factor)
+ hormones released travel through extracellular fluid and into the bloodstream, travelling around it until it reaches its target cells.
What is the infundibulum?
Infundibulum is the sack like structure that joins the pituitary gland to the hypothalamus
Why is regulation of calcium essential?
Essential for nerve impulse contraction and bone strength. It is controlled by calcitonin, vitamin D and parathormone
What happens if blood calcium levels are low?
Stimulus: low blood calcium levels
Receptor: chemoreceptors in parathyroid gland
Modulator: parathyroid gland which releases parathormone
Effector:bones, kidneys, intestines
Response:
bones- osteoclast break down bone for calcium
kidneys- reabsorption of calcium
Intestines- absorption of calcium increase
Feedback: increased calcium in bloodstream (negative)
What happens if blood calcium levels are too high?
Stimulus: high blood calcium levels
Receptor: chemoreceptors in parathyroid gland
Modulator: thyroid which releases calcitonin
Effector:bones, kidneys, intestines
Response:
bones- osteoblasts build up bone for calcium
kidneys- decreased reabsorption of calcium
Intestines- decreased absorption of calcium increase
Feedback: decreased calcium in bloodstream ( negative)
What happens if thyroxine levels in blood are too high?
Stimulus: high levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces thyroid stimulating hormone inhibiting factor which stimulates the anterior lobe of PG to decrease TSH production and release.
Effector: thyroid gland
Response:thyroid produceses less thyroxine
Feedback, decreased levelsof thyroxine in bloodstream ( negative)
What happens if thyroxine levels in blood are too low
Stimulus: low levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces thyroid stimulating hormone inhibiting factor which stimulates the anterior lobe of PG to decrease TSH production and release.
Effector: thyroid gland
Response:thyroid produceses less thyroxine
Feedback, decreased levelsof thyroxine in bloodstream
What happens if there is high metabolism/ increased body temperature
Stimulus: increased metabolism/ body temperature
Receptor: thermoreceptors in the skin and hypothalamus as well as chemoreceptors in hypothalamus detect thyroxine levels
Modulator: hypothalamus releases thyroid stimulating hormone inhibiting factor which decreases TSH production in Anterior lobe of pituitary gland affecting the thyroid gland to produce less thyroxine
Effector: somatic cells
Response: decreased metabolism causes decreased protein synthesis and cell respiration
Feedback: reduced metabolism and reduced body temperature (negative)
What happens if there is low metabolism/ decreased body temperature
Stimulus: decreased metabolism/ body temperature
Receptor: thermoreceptors in the skin and hypothalamus as well as chemoreceptors in hypothalamus detect thyroxine levels
Modulator: hypothalamus releases thyroid stimulating hormone releasing factor which increases TSH production in Anterior lobe of pituitary gland affecting the thyroid gland to produce more thyroxine
Effector: somatic cells
Response: increased metabolism causes increased protein synthesis and cell respiration
Feedback: increased metabolism and increased body temperature (negative)
What is hyperthyroidism?
Overproduction of thyroxine
What is hypothyroidism?
Under production of thyroxine
Example of hyperthyroidism and hypothyroidism?
Hyper- Graves’ disease: most common type
Hypo- hashimotos: deficiency caused by attack on the thyroid gland by patients immune system
Causes and effects of hyperthyroidism?
Cause: caused by an immune system reaction and there seems to be genetic predisposition for the condition
Effect: enlargement of the thyroid, because cells are overstimulated: rapid heartbeat, weight loss, increased appetite, fatigue, sweating and anxiety. In Graves’ disease protruding eyeball
Treatment of hyperthyroidism?
- drugs that blocks thyroid glands use of iodine
- surgery to remove some of or all of gland
- drink containing radioactive iodine molecules which are taken up by thyroid cells which kills them
Cause and effect of hypothyroidism?
Cause: problems which thyroid gland or pituitary gland or hypothalamus, lack or iodine in diet, surgery removing gland
Effect: slow heart rate, unexplained weight gain, fatigue or feeling lack of energy, intolerance for cold, swelling of face and goitre
Treatment of hypothyroidism?
- inclusion of extra iodine in diet
- thyroxine tablets
- no cure and hormone tablets must be taken for rest of life
What happens if there is an autoimmune attack on the thyroid causing over production of thyroxine.
Stimulus: high levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces TSHIF cause my decreased production and release of TSH in pituitary gland
Effector: autoimmune response leads to increase in size of thyroid
Response: thyroid continues to produce thyroxine despite no TSH available
Feedback: thyroxine remains high in blood ( positive)
What happens if there is a lack of iodine in diet due to an autoimmune response destroys that thyroid cells or surgery?
Stimulus: low levels of thyroxine
Receptor: chemoreceptors in hypothalamus detect
Modulator: hypothalamus releases TSHRF to pituitary gland causing increase TSH
Effector: thyroid gland is for whatever reason not able to respond
Response: no thyroxine produced
Feedback: low levels of thyroxine (positive)
Define thermoregulation?
The regulation of body temperature, the balance of heat gain and heat loss in order to maintain a constant internal body temperature independent of environmental temperature
What may the body do if temperature is too high?
- Vasodilation: radiation and convection
- Sweating: evaporation allows increased heat loss
- long term they can be an decrease in metabolic rate= heat loss
- behavioural response
What may the body do if temperature is too low?
- vasoconstriction decreases blood flow to skin
- adrenal medulla stimulated to secret adrenaline and noradrenaline
- shivering increases friction and cell respiration
- increased thyroxine production/ metabolism
- behavioural response