M5 C14: hormonal communication Flashcards
what is the endocrine system?
where hormones are secreted by glands that are used to send information to bring about a response.
what are steroid hormones?
lipid soluble so can pass through membrane and bind to receptors in the nucleus
what are non steroid hormomes?
hydrophilic so cant pass through bilayer and bind to receptors on outside of cell
where are steroid hormones made?
Cortex of adrenal gland
what is the medulla part of the adrenal gland?
neuronal function
where is the adrenal gland in the body?
Above the kidney
what neurotransmitters does the medulla secrete?
adrenaline, noradrenaline
both increase heart rate, blood pressure, slows metabolic rate, validation near muscles
what steroid hormones are made in the cortex?
mineralcorticoids
glucocorticoids
androgens
what are mineralcorticoids?
aldosterone- blood pressure, osmotic balance
what are glucocorticoids?
cortisol which regulates metabolic rate
what are androgens?
sex hormones eg estrogen
where is the pancreas?
upper abdomen directly behind the stomach.
what is the 2 main functions of the pancreas?
an exocrine gland and an endocrine glad.
what is the pancreas next to?
duodendum
what does the duodendum do?
enzymes are released into here by the pancreas eg ligase, amylase, these travel along the pancreatic duct
what is the endocrine role of the pancreas?
insulin, glucagon are made in the pancreas
what are the Islets of Langerhans?
Small regions of endocrine tissue that are responsible for producing insulin and glucagon.
What color are the beta cells stained using a differential staining technique?
Blue
What color are the alpha cells stained using a differential staining technique?
Pink
Fill in the blank: Using a differential staining technique, the beta cells are stained _______.
blue
Fill in the blank: Using a differential staining technique, the alpha cells are stained _______.
pink
What is the primary function of insulin?
Decreases blood glucose levels.
What is the primary function of glucagon?
Increases blood glucose levels.
Which cells in the pancreas secrete insulin?
β cells (in islets of Langerhans).
Which cells in the pancreas secrete glucagon?
α cells (in islets of Langerhans).
What effect does insulin have on glucose uptake?
Regulates the placement of channel proteins in the surface membrane of target cells so more glucose is absorbed from the blood. involved in glycogenesis converting glucose to glycogen
What processes are activated by glucagon to increase blood glucose levels?
Glycogenolysis- breakdown of glycogen to glucose
gluconeogenesis- production of glucose from non-carbohydrate sources.
What is glycogenesis?
Production of glycogen from glucose.
This process is stimulated by insulin, promoting glucose storage.
What is gluconeogenesis?
Production of glucose from non-carbohydrate sources.
This process is stimulated by glucagon, especially during fasting.
What is glycogenolysis?
Breaking down of stored glycogen into glucose.
This process is stimulated by glucagon when blood glucose levels are low.
True or False: Insulin is a globular protein composed of 51 amino acids.
True.
Insulin’s structure allows it to be soluble in water and function effectively in the bloodstream.
what is glucagons strucutre?
coiled ribbon secondary strucutre
What is the normal blood glucose level?
90 mg/100 cm³ blood.
Maintaining this level is crucial for metabolic functions.
When blood glucose levels rise, which cells detect this change?
Beta cells of the pancreas.
They respond by secreting insulin to lower blood glucose levels.
Fill in the blank: Glucagon activates enzymes involved in the conversion of amino acids and fats to _______.
glucose.
This process helps to increase blood glucose levels during fasting.
what are beta cells like at normal blood glucose concentration levels?
the potassium channels in the plasma membrane of ß cells are open and potassium ions diffuse out of the cell. The inside of the cell is at a potential of -70mV with respect to the outside of the cell.
what happens when blood glucose rises initially in a beta cell?
When blood glucose concentration rises, glucose enters the cell by a glucose transporter.
The glucose is metabolised inside the mitochondria, resulting in the production of ATP.
What happens to potassium channels in beta cells when blood glucose rises?
the atp made in the mitochondria leads to the potassium channels closing, leading to depolarization of the membrane to -30mv
This triggers the opening of voltage-gated calcium channels, resulting in insulin secretion.
what does depolarisation of the beta cell membrane do?
This triggers the opening of voltage-gated calcium channels,Calcium ions enter the cell and cause secretory vesicles to release the insulin they contain by exocytosis.
List the three processes related to carbohydrate metabolism stimulated by glucagon.
- Glycogenolysis
- Gluconeogenesis
- Increased glucose release from the intestines
These processes help raise blood glucose when levels are low.
What is the role of ATP in insulin secretion?
ATP binds to potassium channels causing them to close.
This results in depolarization of the cell and subsequent calcium influx, leading to insulin release.
What is the effect of insulin on fatty acids?
More fatty acids are used in respiration.
Insulin promotes the conversion of glucose to fats for storage.
How do insulin and glucagon work together?
They regulate blood glucose concentration through opposing actions.
Insulin lowers blood glucose, while glucagon raises it, maintaining homeostasis.
what is Glycogenolysis?
Breaking down of stored glycogen into glucose
what is Gluconeogenesis?
Production of glucose from non carbohydrate sources
what is Glycogenesis?
Production of glycogen from glucose
what is type 1 diabetes?
a autoimmune disease where not enough insulin is produced to lower the blood glucose concentration
what causes type 1 diabetes?
immune system attacks the beta cells so they become damaged and don’t release insulin
could be hereditary/ genetic
what are the treatments for type 1 diabetes?
insulin injections
insulin pump
pancreas transplants
stem cell therapy
what is type 2 diabetes?
where target cells don’t respond to insulin or the body doesn’t produce enough insulin to lower blood glucose concentration
what can cause type 2 diabetes?
poor diet
lack of exercise
old age
overweight
high carb diet
glycoprotein insulin receptor not responding/ malfunctioning
treatments of type 2 diabetes?
insulin injections
improved diet
more exercise
medication
what are some symptoms of diabetes/
high blood glucose concentration
excessive thirst/ need to urinate
glucose in urine
constant hunger
weightloss
blurred vision
tiredness
why is medically produced insulin good?
large quantities can be made
no religious/ ethical concerns
less chance of allergies as it is a pure form
cheaper
less risk of infection
where does the fight or flight response start
hypothalamus
what happens after signals are sent to the hypothalamus in the fight or flight response?
the sympathetic nervous system is activated
what happens once the sympathetic nervous system is activated in the fight or flight response?
impulses activate glands and smooth muscle
and
activates adrenal medulla
what happens once the adrenal medulla is activated?
releases noradrenaline and
adrernaline
what happens to adrenaline and noradrenaline once released?
they go into the bloodstream
what else is activated by the hypopthalamus in the fight ir flight response?
the adrenal-cortical system that releases CRF
what happens once CRF is released in the fight or flight response ?
pituitary gland secretes hormone ACTH
what does ACTH do once released?
ACTH arrives at adrenal cortex and releases approximately 30 hormones
how does adrenaline have a cascade affect?
adrenaline activates cAMP which activates protein kinases which phosphorylate (activate) other enzymes which convert glycogen to glucose.
What triggers the fight or flight response?
Activation of the sympathetic nervous system.
Which part of the brain controls heart rate?
Medulla oblongata.
What is the average resting heart rate of a human heart?
Approximately 70 times a minute.
Which nervous system increases heart rate?
Impulses sent through the sympathetic nervous system by the accelerator nerve
Which nerve is responsible for decreasing heart rate?
Impulses sent through the parasympathetic nervous system by the vagus nerve
What do baroreceptors detect?
Changes in blood pressure.
Where are baroreceptors located?
Aorta, vena cava, and carotid arteries.
What do chemoreceptors detect?
Changes in levels of particular chemicals.
Where are chemoreceptors found?
Aorta, carotid artery, and medulla.
how do chemoreceptors control heart rate?
Increased metabolic activity means more carbon dioxide is produced by tissues from increased respiration lowering Blood pH
the Centre in medulla oblongata that speeds heart rate, increases frequency of impulses to SAN via the sympathetic nervous system.
SAN increases heart rate.
Increased blood flow removes carbon dioxide faster.
Carbon dioxide level returns to normal.
how do baroreceptors decrease heart rate?
If blood pressure is too high, impulses are sent to the medulla oblongata centre which decreases heart rate. Impulses are then sent along the parasympathetic neurones to the SAN which decreases heart rate.
how do baroreceptors increase heart rate?
impulses are sent to the medulla oblongata centre which increases heart rate. Impulses are sent along the sympathetic neurones to the SAN which increases heart rate
Fill in the blank: Adrenaline and noradrenaline increase the ________ of impulses produced by the SAN.
frequency.
What hormone activates the adrenal-cortical system?
CRF (Corticotropin-Releasing Factor).
What does ACTH stand for?
Adrenocorticotropic hormone.
What is the role of the sinoatrial node (SAN)?
It initiates the heartbeat and regulates heart rate.
True or False: Increased muscular activity leads to a decrease in heart rate.
False.
What happens when blood pressure is too high?
Impulses are sent to the medulla oblongata to decrease heart rate.
What is the effect of low blood CO2 concentration on heart rate?
It decreases heart rate.
What does the adrenal cortex release in response to ACTH?
Approximately 30 hormones.
What is the role of the medulla oblongata in heart rate control?
It has centers that increase or decrease heart rate.
Fill in the blank: The ________ nerve sends impulses to the SAN to increase heart rate.
sympathetic.
What does increased blood flow during exercise help with?
Removes carbon dioxide faster.
What is the role of the accelerator nerve?
It sends impulses to increase heart rate.
What happens to carbon dioxide levels during increased respiration?
More carbon dioxide is produced by tissues.
What is the role of the atrioventricular node (AVN)?
It relays impulses from SAN to the ventricles.
What is the effect of high blood CO2 concentration on heart rate?
It increases heart rate.
Fill in the blank: The ________ system is responsible for controlling heart rate.
autonomic.
How can heart rate be determined?
By taking a pulse
A common method for measuring heart rate
how does adrenaline trigger glycogenolysis in liver cells?
adrenaline binds to the membrane
this activates adenyl cyclase which converts ATP to CAMP
CAMP phosphorylates into protein kinases which then activates multiple enzymes then breaks down glycogen to glucose
