Hormonal Communication - Module 5 Flashcards
What is an endocrine gland?
A gland that secretes hormones directly into the bloodstream
What is an exocrine gland?
A gland that secretes chemicals through ducts and into organs e.g digestive system
Why is it important that the pituitary gland and the hypothalamus are close together?
So hormonal and neuronal communication are coordinated
What are the two types of hormone?
- Steroid hormones
- Non steroid hormones
How do steroid hormones function?
Are they are LIPID soluble they enter the cell membrane and form hormone receptor complexes acting as transcription factors for genes
How do non steroid hormones function?
As they are HYDROPHILIC they cannot get through the cell membrane so they bind to cell surface receptors and cause a cascade of reactions
Describe the structure of the adrenal gland
Adrenal cortex is the outer layer of the
Adrenal medulla is the inner layer
What is the role of the adrenal medulla?
To secrete adrenaline and noradrenaline
What is the role of noradrenaline?
To aid adrenaline, dilating pupils and relaxing airways/blood vessels
What is the role of adrenaline?
To raise heart rate and blood glucose concentrations
What is the role of the adrenal cortex?
To secrete hormones such as glucocorticoids, minerlocorticoids, androgens
What is aldosterone?
Mineralocorticoid which maintains salt water blood balance
What are androgens?
Release of small amounts of sex hormones
What does cortisol control?
Metabolism
How does the hormonal response differ to the neuronal response?
It is slower and less specific however the effects tend to last longer
When is the medulla of the adrenal gland activated?
When the sympathetic nervous system is stimulated
What is the fight or flight response?
When danger is detected the body automatically triggers a series of physical responses
List 5 physiological responses of the fight or flight response
- Increased HR to allow more oxygen to muscles
- Pupils dilate for better vision
- Non essential systems shut down
- Blood glucose levels rise for respiration
- Smooth muscles airways relax to allow more oxygen in
What detects a threat?
Autonomic neuronal system
Once a threat is detected, the hypothalamus is informed.
What is the sympathetic nervous system response?
Sympathetic nervous system;
1. Sends impulses to glands and smooth muscles
2. Sends signals to adrenal medulla to secrete adrenaline and noradrenaline
Once a threat is detected, the hypothalamus is informed.
What is the response from the adrenal cortical system?
- The pituitary gland releases ACTH
- And the adrenal cortex releases a further 30 hormones to be secreted into the blood stream
What type of hormone is adrenaline?
Non steroid hormone - so it binds to cell surface receptors and triggers a cascade of reactions inside the cell
Describe the cascade of reactions caused by adrenaline
- Adrenaline binds to surface activating ADENYLYL CYCLASE
- Adenylyl cyclase triggers conversion of ATP to cAMP on the inside of surface membrane
- Increase in cAMP activation specific protein kinases enzymes and activate more enzymes (cascade) including the enzyme converting glycogen to glucose
What does Adrenalin trigger liver cells to do?
Glycogenolysis - glycogen to glucose
What part of the brain is responsible for changes in HR?
Medulla oblongata
How is heart rate increased in a centre in the brain?
Impulses are sent to SAN through sympathetic nervous system through the accelerator nerve
How is heart rate decreased in a centre in the brain?
Impulses are send through the parasympathetic nervous system through the vagus nerve
What are the 2 receptors that provide information affecting heart rate?
- Baroreceptors
- Chemoreceptors
What do baroreceptors do?
They detect changes in blood pressure and are present in the aorta, vena cava and carotid artery
What is a caratoid artery?
Main artery in neck providing blood for the brain
What does a chemoreceptor do? Provide a specific example
Chemoreceptors detect chemical changes in the blood
E.g sensitivity to pH means that if pH decreases it will stimulate an increase in heart rate as it will be caused by increase levels of CO2 meaning the faster the blood flows the faster CO2 is exhaled
What is hyperglycaemia?
Very high blood glucose
What is hypoglycaemia?
Very low blood glucose
How is type 1 diabetes treated?
Using insulin injections, insulin pump, islet cell transplant and pancreas transplant
What increases the risk of type 2 diabetes?
Obesity, sedentary lifestyle, high sugar diet
How is type 2 diabetes treated?
Life style changes
Weight loss, regular expertise, change in diet
