Endocrine System Flashcards
how do hormones travel from the hypothalamus to the anterior pituitary gland?
through the portal vessels
how does the hypothalamus stimulate the posterior pituitary gland to release hormones?
through nerve impulses
what hormones are released from the hypothalamus?
corticotrophin releasing hormone, gonadotrophin releasing hormone, thyrotrophin releasing hormone, growth hormone releasing hormone, somatostatin, prolactin releasing hormone, dopamine
What hormones are released from the anterior pituitary gland?
adrenocorticotrophin hormone, growth hormone, FSH, LH, prolactin
What hormones are released from the posterior pituitary gland?
Oxytocin, ADH
What is goitre?
an iodine deficiency resulting in over stimulation of thyroid gland, get a swelling at neck
What is the role of the thyroid hormone?
To form the basal metabolic rate, increase the metabolic rate and up-regulate adrenoreceptors
What is the role of insulin?
to lower blood glucose levels, by increasing the uptake of glucose in muscle and adipocytes. Also increases glycogen and lipid formation and protein synthesis
What stimulates insulin release and what inhibits it?
stimulates - high blood glucose levels, vagus nerve
inhibits - somatostatin, sympathetic NS and adrenaline
What is the role of glucagon?
To increase blood glucose level, by causing glycogenolysis and gluconeogenesis
What stimulates glucagon release and what inhibits it?
stimulates - low blood glucose levels, autonomic NS
inhibits - insulin, somatostatin
What is diabetes mellitus?
Insulin deficient, cells unable to uptake glucose to lower blood glucose levels
What does the medulla of the adrenal glands produce?
adrenaline
what layers of the cortex of the adrenal glands produce what?
glomerulosa - mineralocorticoid, aldosterone
fasiculata - glucocorticoid, cortisol
reticularis - androgens
Describe mechanical filtration in lymph nodes
high flow in vessels, gets into subscapular space and slows down, allows any particles in the fluid to settle on the cortex or the medullary cords
Describe biological filtration in lymph nodes
the cortex contains t cells which can phagocytose the particles and remove infection. the medulla contains b cells for an antibody response
what are the components involved in the immediate response to haemorrhage
vascular response, platelet response, coagulation, acts to prevents blood loss
explain the vascular response in stopping blood loss
adrenaline released upon blood loss or trauma, causes vasoconstriction to increase blood pressure and stop blood flow through the artery to reduce loss.
describe platelet response in stopping blood loss
platelets come into contact with collagen in blood vessel wall due to trauma, causes platelet aggregation. under positive feedback, release of thromboxane causes further aggregation, forms platelet plug to stop blood loss
describe the common pathway in coagulation cascade
factor X activated in presence of Ca, phosphate and factor V. Factor Xa then converts prothrombin to thrombin, this activates fibrinogen to soluble to fibrin, also activates factor XIII. factor XIIIa then converts soluble fibrin to insoluble fibrin
what is the difference between the extrinsic and the intrinsic pathway for coagulation
extrinsic - by tissue damage, initiates coagulation
intrinsic - by vascular damage, maintains the coagulation
describe fibrinolysis
plasminogen converted to plasmin which converts fibrin to soluble fibrin fragments, when coagulation no longer required
what is the aim of the short term physiological response to haemorrhage and how does the body achieve this?
restore blood pressure, by stimulating sympathetic NS, increases vasoconstriction, HR and stroke volume. also increases release of aldosterone and ADH for more fluid resoprtion
what is the aim of the medium term physiological response to haemorrhage and how is this achieved?
restore blood fluid, increasing vasoconstriction causes the hydrostatic pressure to decrease, meaning less fluid is pushed out through the capillaries, and more fluid is reabsorbed. also aldosterone and ADH increased with more renin release
what is the aim of the long term physiological response to haemorrhage and how is this achieved?
to restore blood constituents, erythropoietin released by kidney to stimulate RBC production, takes a few months
what are the stages in response to stress?
alarm - fight or flight, resistance - adaptation, exhaustion
describe the alarm stage in response to stress
sympathetic nervous system, increasing heart rate and stroke volume and vasoconstriction, stimulates glucagon for glucose release and adrenal medulla for adrenaline. adrenaline hormone increases the duration of this response and stimulates glucocorticoid production in adrenal cortex, cortisol. this is when stress is ongoing, increases gluconeogenesis and protein break down, immunosuppressant and anti-inflammatory
why is it important to know if patients are on steroid therapy
this medication suppresses the immune system, therefore they might not be respond as well to treatment
how can stress be used an analgesic
it releases endorphins which suppress nociception and pain pathway
describe the resistance stage in stress response
patient’s alarm response is sufficient to over come the stressor, either adapt to the stressor and become resistant or stressor removed.
describe the exhaustion stage in stress response
unable to remove stressor, stress response is maintained, cortisol levels are high for a long period of time, ill due to immunosupressant and adrenal failure
why is it important to control the levels of Ca in the body
for membrane potential, cardiac action potential and second messenger system - muscle contraction
how does the parathyroid hormone control plasma Ca
it is released when plasma Ca levels are low, causes activation of vitamin K for Ca absorption in the gut, increased Ca reabsorption in the kidney and stimulates enzyme colleginerase for osteoclast activity - more bone resorption to release Ca into the plasma
how does calcitonin control plasma Ca
released for prafollicular cells in response to high Ca levels, stimulates bone formation by osteoblasts, and more secretion of Ca in kidneys
how does vitamin D control plasma Ca
kidney converts it to calcitroil which increases absorption of calcium in diet
what diseases are caused by deficiency of vitamin D
weak bones and deformed formation in children - rickets or in adults just weak - osteomalacia
why can fixed appliances not be given before the age of 12
because the skull is still growing until the age of 12 so fixed appliances may alter the shape or structure of the forming skull and facial bones
what hormones are essential for normal growth
thyroid hormone, growth hormone and sex hormones
describe how thyroid hormone effects growth
growth in foetus and infant, required for protein synthesis in brain and neurone development, indirect growth, stimulated by growth hormone
what is the result of lack of thyroid hormone
severe mental impairments in infancy
describe the actions of growth hormone
anti-insulin, increases blood glucose levels and prevents glucose uptake in cells, stimulates IGF for proliferation of cartilage at epiphyseal plates, glucose release from liver,
what is the result of excess growth hormone in adults
acromegaly, cannot get longitudinal growth so increase in bulk, thicker bone in mandible and skull
what is the role of sex hormones in growth
cause the pubertal growth spurt, increases proliferation of cartilage but also causes closure of growth plates, stimulated by growth hormone and IGF 1
what hormone stunts growth
cortisol
