5.1.4 Hormonal Communication Flashcards
What is the endocrine system made up of?
Endocrine glands
What is an endocrine gland?
A group of cells that are specialised to secrete chemicals, known as hormones. They get secreted directly into bloodstream. E.g. pancreas and adrenal glands
What are hormones?
They are chemical messengers as they carry info from one part of the body to another. They can be steroid, protein, glycoproteins, polypeptide, amines or tyrosine derivatives.
Where and when are hormones secreted?
Directly into the bloodstream when a gland is stimulated. This stimulation occurs when there is a change in concentration of a certain substance, such as blood glucose conc. hormones can also be triggered by other hormones or nerve impulses
How are hormones transported
They are transported via the blood plasma all over the body once secreted. They diffuse out the blood and bind to specific receptors for that hormone, either found on the membrane or in the cytoplasm of thr cells of target organs, known as target cells
What happens once hormone binds to target cells
A physiological response will be produced.
What are steroid hormones
They are lipid soluble and can pass through the cell membrane and bind to steroid hormone receptors to from a hormone receptor complex. These receptors are present in cytoplasm or nucleus. The HRC acts as a transcription factor which either facilitates or inhibits the transcription of a specific gene
What are non steroid hormones
They are hydrophilic and can’t laws directly through the cell membrane. Instead they bind to specific receptors on cell surface membrane of target cell, triggering a cascade of reactions mediated by second messengers. Adrenaline is example
How does hormonal communication differ to neuronal communication
- Slower and less specific
- Longer lasting and more widespread effect
- Travel by bloodstream
- Effect permanent and irreversible
What are the three types of hormones released by the adrenal cortex
Controlled by pituitary gland in brain and releases:
- glucocorticoids
- mineralocorticoids
- androgens
What do glucocorticoids do?
These hormones include cortisol which help regulate metabolism by controlling how the body converts fats, protein, and carbohydrates to energy. Also helps regulate blood pressure and cardiovascular function in response to stress. Another hormone is corticosterone, which works with cortisol to regulate immune response and suppress inflammatory reactions
What do mineralocorticoids do
A hormone include aldosterone, which helps control blood pressure by maintaining the balance between salt and water concentration in the blood and body fluids. It’s released by signals triggered by the kidney.
Androgens
Small amounts of male and female sex hormones are released - their impact is relatively small compared with the larger amounts of hormones like oestrogen and testosterone, but they are still important.
When are the hormones of the adrenal medulla released
When the sympathetic nervous system is activated. And this happens when the body is stressed.
What does adrenaline do?
Increases heart rate, sends blood quickly to muscles and brain. Rapidly increases blood glucose levels by converting glycogen to glucose in liver.
