Lecture 27 Flashcards
Where are the adrenal glands?
Superior to each kidney, they are lateral to the spinal cord and blood vessels.
What are the two seperate glands?
Adrenal cortex and adrenal medulla
What do the 3 layers of adrenal cortex release?
Outermost layer secretes mineral corticoids like aldosterone, middle layer secretes cortisol, the inner layer produces androgens
What does the adrenal medulla produce and where is it?
It is in the middle of the adrenal gland and produces adrenaline
When is cortisol produced?
It is produced when required
How does it get around the body?
Carried in the blood bound to a carrier protein
What are the steps of cortisol binding, and response in the cell?
- It travels to the target cell and passes through the cell membrane
- Then binds to a specific receptor
- Moves into the nucleus
- Activates specific genes
- mRNA to form protein
- Protein has effect on the cell
- It takes a long time to effect
What can cortisol release?
Stress or non-stress/ neural inputs
What does the hypothalamus secrete when under stress or non stress neural inputs
Corticotropin releasing hormone (CRH)
CRH causes the anterior pituitary gland to secrete what?
adrenocorticotropic hormone (ACTH)
What does the adrenal cortex secrete after being signaled by ACTH?
Cortisol
What response does cortisol have on muscles?
An increase in protein breakdown and a decrease in glucose uptake
What response does cortisol have on fats?
Increases fat breakdown and decreases glucose uptake
What response does cortisol have on liver?
Glucose synthesis
What are some other effects that occur from cortisol?
Helps one to cope with stress but in the long-term is suppresses immune system, it is also essential for maintaining normal blood pressure
Cortisol secretion is controlled by what feedback?
Negative feedback (EXCEPT during the stress response)
When do you get a peak in cortisol?
In the mornings/ upon wakening
What happens when there is a disturbance in normal sleep patterns?
It affects the cortisol pathway can lead to issues in the immune-system
What is the function of cortisol?
Increases blood glucose levels, increasing fat, protein and carbohydrate metabolism to maintain blood glucose, up regulating immune responses, promoting anti-inflammatory actions, increasing blood pressure, increasing heart and blood vessel tone and contraction and activation of the central nervous system.
What is Addison’s disease?
Lowered secretion of both cortisol and aldosterone
What happens when there is low cortisol concentration?
It leads to ACTH secretion, its similar to hormone involved in stimulation of melatonin production which binds to the receptors of melatonin receptors.
What are other symptoms of Addison’s disease?
Low blood pressure and weakness from lack of fuel, brain is weak, issues with blood potassium and much more
What happens when you have Cushing’s syndrome?
Too much cortisol, which causes depositions of fats in certain areas. You get fats on the back of your neck, on face and stomach.
What are other symptoms of Cushing’s syndrome
High blood pressure and weakness causing muscles to waste away.
How is the adrenal medulla activated?
By the sympathetic pre-ganglionic fibre
Why is noradrenaline secreted?
It is secreted as a part of the sympathetic nervous systems response to stress
How does noradrenaline travel through the body?
Action potentials travel down the pre sympathetic fibres which then cause a release in acetyl choline causing another action potential to be sent down the post ganglionic chain then the release of the noradrenaline at the target tissue
How does adrenaline travel through the body?
Action potential released down the pre ganglionic neuron from the hypothalamus, then it causes a response within the adrenal medulla, that action potential releases hormone into the blood and acts on the same cells that the sympathetic nervous system acts on, by doing that it can extend and prolong the actions of the CNS. This is called flight, fight or fright response.
What does an increase in adrenaline cause?
It makes the actions from the sympathetic nervous system last longer particularly in times of stress
Why is the adrenaline feed straight into the blood?
Because it needs to be a fast response
What type of hormone is adrenaline?
Catecholamines still water soluble
Is adrenaline an amplified response?
Yes as the second messenger doubles
Stress causes the hypothalamus to do what?
Send action potentials down to the pre ganglionic fibres to act on the adrenal medulla which causes a release in adrenaline.
What affects does adrenaline have?
Forces us to use our stored glucose in the skeletal muscles and liver. In fats it increases breakdown of fat to fatty acids
What are some other affects on the SNS from adrenaline?
Some systems are activated for physical activity and systems not crucial for short-term survival are shut down.
What is stress?
Its a stimuli that activates the hypothalamus
What does the hypothalamus activate when under stress?
The hypothalamus activates the adrenal glands, sympathetic nervous system and posterior lobe of the pituitary gland
How does your body responds to the stress signal?
Same response no matter what the stimulus was or is
What affect does stress have on the hypothalamus which in turn has an affect on sympathetic nervous system? and so on
It stimulates the SNS to send action potentials down the sympathetic pre ganglionic fibres, then stimulates the adrenal medulla to secrete adrenaline which then increases blood glucose, heart rate and blood pressure.
What affect does stress have on the hypothalamus which in turn has an effect on the anterior pituitary gland? and so on
Causes the hypothalamus to secrete CRH, which then causes the anterior pituitary gland to secrete ACTH, which then causes the adrenal cortex to secrete and SYNTHESIS cortisol and therefore increases the blood glucose and blood pressure.
What affect does stress have on the hypothalamus which in turn has an effect on the posterior pituitary? and so on
The hypothalamus to send action potentials down to the posterior pituitary to release the ADH and therefore causes an effect in the kidneys and causes a decrease in water excretion and an increase in blood volume and blood pressure.
