chapter 14 - hormonal comunication Flashcards
what is the endocrine system
made up of endocrine glands to secrete chemicals called hormones
where are hormones secreted to
bloodstream
what does pituitary gland do
produces growth hormone, ADH
what does thyroid gland do
produces thyroxine which controls rate of metabolism
what does adrenal gland do
produces adrenaline
what does pancreas do
produces insulin which converts excess glucose to glycogen in liver and glucagon which converts glycogen back to liver
what are target cells
cells in target organs containing receptors for hormone
what are steroid hormones
lipid soluble
pass through lipid component of cell membrane and bind to steroid hormone receptors
hormone receptor complex acts as transcription factor which facilitates or inhibits transcription of a specific gene, e.g oestrogen
what are non steroid hormones
hydrophilic so cannot pass directly through cell membrane
bind to specific receptors on cell surface membrane of target cell
triggers cascade reaction e.g adrenaline
what is difference between hormonal and nervous system
hormonal system uses hormones whereas nervous system used nerve impulses
hormonal system transmits by blood system whereas nervous system is transmited by neurones
hormonal system is slow but long laster whereas nervous system is fast but short-lived
what is adrenal gland
2 glands located on top of kidney
adrenal cortex
adrenal medulla
what does adrenal cortex do
outer region of glands that produces hormones vital to life such as cortisol and aldosterone
what does adrenal medulla do
inner regions of glands that produce non-essential hormones such as adrenaline
what hormones do adrenal cortex produce
glucocorticoids
mineralocorticoids
androgens
what do glucocorticoids do
-regulate metabolism by controlling how body converts fats,proteins and carbohydrates to energy.
Regulate blood pressure
corticosterone which works with cortisol to regulate immune response
controlled by hypothalamus
what do mineralocorticoids do
e.g aldesterone
controls blood pressure by maintaining balance between salt and water concentrations in blood and body fluids
controlled by signals triggers by kidney
what do androgens do
release male and female sex hormones
what do adrenal medulla produce
adrenaline
noradrenaline
what does adrenaline do
increases heart rate sending blood quickly to muscles and brain
raises blood glucose concentration by converting glycogen to glucose in the liver
what does noradrenaline do
works with adrenaline in response to stress increasing heart rate, widening of pupils, widening of air passages in lungs, and narrowing of blood vessels
where is pancreas found
upper abdomen behind stomach
what is function of pancrease
exocrine gland - produce enzymes released via duct into duodenum
endocrine gland - produces hormones and release them into blood
what 3 enzymes are produced in exocrine gland in pancreas
amylase - breaks down starch into simple sugars e.g pancreatic amylase
proteases - breaks down proteins into amino acids e.g trypsin
lipases- breaks down lipids into fatty acids and glycerol e.g pancreatic lipase
what hormone is produced in endocrine gland in pancreas
insulin and glucagon to control blood glucose concentration
what is islets of langerhans
endocrine tissue within exocrine tissue producing insulin and glucagon secreted directly into bloodstream
what does islet of langerhans look under micrscope
large spherical clusters, lightly stained
what cells are in islet of langerhans
alpha cells - produce and secret glucagon
beta cells - produce and secrete insulin
what colour stain are alpha and beta cells
alpha cells are stained blue
beta cells are stained pink
what increases blood glucose concentration
diet-eating carbohydrate rich food
glycogenolysis - glycogen broken down to glucose
gluconeogenesis - glucose produced from non carbohydrate sources such as glycerol and amino acids
what decreases blood glucose concentration
respiration
glycogenesis - production of glycogen
how does insulin increase absorption of glucose from cells
binds to glycoprotein recpetors causing change in tertiary structure of glucose protein channels causing them to open and allow glucose into cells
how does insulin lower blood glucose concentration
increase rate of absorption of glucose by cells
increase respiratory rate of cells
increase rate of glycogenesis
increase rate of glucose to fat conversion
inhibit release of glucagon from alpha cells in islet of langerhans
which cells have glucagon receptors
liver cells
fat cells
how does glucagon increase blood concentration
increase rate of glycogenolysis
increase gluconeogenesis
reduce amount of glucose absorbed by liver cells
how is insulin secreted
1) at normal blood glucose concentrations, potassium ion channels in plasma membrane of b-cells are open so potassium diffuse out. Inside cell has -70MV
2) when blood glucose concentration rises, glucose enters cell by glucose transporter
3) glucose is metabolised inside mitochondria forming ATP
4) ATP binds to ATP sensitive potassium channels closing them so potassium ions no longer diffuse out causing depolarisation, -30Mv
5) depolaroisaton causes voltage gated calcium ion channels to open so calcium ions enter cell and cause secretory vesicles to release insulin by exocytosis
what is type 1 diabetes
unable to product insulin as b cells in islet of langerhans do not work
may be caused by autoimmune response
what is type 2 diabetes
cannot effectively use insulin because b cells dont produce enough insulin or body doenst respond to it becuase insulin glycoprotein dont work
caused by overweight, physical inactivity
how is type 1 diabetes controlled
insulin injections
how is type 2 diabetes controlled
regulate intake of carbohydrates , increase exercise
what is hypoglycaemia
very low blood glucose concentration
how is stem cells used in diabetes
replace faulty b-cells
advantages of stem cells
donor availability is not an issue as stem cells could produce unlimited sources
reduced likelihood of rejection
no longer need insulin rejection
how does adrenaline work
1) adrenaline is hydrophilic so cant pass cell membrane therefore binds to receptor activating enzyme adenylyl cyclase
2) Adenylyl cyclase converts ATP to cyclic AMP which acts as second messenger and activates other enzymes ( protein kinases) to convert glycogen to glucagon
how does adrenal medulla control heart rate
has 2 centres linked to SAN in heart by motor neurones
one centre increases heart rate by sending impulses through sympathetic nervous system transmitted by accelerator nerve
one centre decreases heart rate by sending impulses through parasympathetic nervous system transmitted by vagus nerve
what receptors affect heart rate
baroreceptors - detect changes in blood pressure. Found in aorta, vena cava and carotid artery
chemoreceptors - detect change in level of chemicals in blood such as co2. Located in aorta, carotid artery and medulla
