Week 6 - Endocrine System Flashcards
What are the 3 major components of the endocrine system? Briefly describe each
1) Glands - specialized cells that produce and secrete hormones
2) Hormones - substances that are secreted by glands into the circulatory system
3) Receptors - bind to specific hormones to result in physiological changes.
What hormones are secreted by the posterior pituitary gland and what is there function?
- Anti diuretic hormone (ADH) - Fluid regulation
* Oxytocin - child birth and breast feeding
What hormones are secreted by the anterior pituitary gland and what is there function?
- Growth hormone - growth
- Prolactin - Milk production
- FSH & LH - regulate the reproductive system
- TSH - stimulates the thyroid
- Adrenocorticotrophic hormone (ACTH) - adrenal glands
What hormones are secreted by the thyroid gland and what is there function?
• Thyroxine and triiodothonine - control basal metabolic rate
What hormones are secreted by the parathyroid gland and what is there function?
Parathyroid hormone - Regulates calcium, magnesium and phosphate ions in the blood stream.
What hormones are secreted by the adrenal gland and what is there function?
- Adrenaline & Noradrenaline - involved in the fight flight response
- Cortisol and aldosterone - Helps maintain hydration and electrolyte balance
What hormones are secreted by the pancreas and what is there function?
• Insulin & glucagon - regulate blood sugar levels
What hormones are secreted by the gonads and what is there function?
• Testosterone & Estrogen - Control growth and function of reproductive organs and are associated with the development of secondary sexual characteristics.
Define hormone
A hormones a chemical messenger that is released into the bloodstream by endocrine glands.
Identify the two classes that most hormones can be classified into
- Amino acid bases
* Steroids
What is the solubility of amino acid based hormones?
Water soluble
How do amino acid based hormones travel in the blood stream?
Travel in plasma
Where are the receptors for amino acid based hormones? Why?
Plasma membrane of the cell - they are polar and thus can diffuse directly across the cell membrane into a cell
List 3 examples of amino acid based hormones
- glucagon
- insulin
- adrenaline
- oxytocin
What are steroid based hormones derived from?
cholesterol
What is the solubility of steroid based hormones?
lipid soluble
How are steroid based hormones transported in the blood?
1) Specialized steroid hormone carriers
2) non-selectively by the protein albumin
Where are the receptors for steroid based hormones? why?
In the cytoplasm as they are able to diffuse directly across the plasma membrane.
List some examples of steroid bases hormones
- testosterone
- oestrogen
- progesterone
- cortisol
What are the three methods of controlling hormone release? Describe.
1) Humoral stimuli - hormones are secreted in response to direct changes in blood levels of ion & nutrients.
2) Neural stimuli - nerve fibres directly stimulate hormone release
3) Hormonal stimuli - hormones release is triggered by the hormones released by another endocrine organ.
Using the effect of parathyroid on calcium levels, explain the role of humoral stimuli on hormone secretion.
- When calcium levels are low it stimulates the parathyroid to secrete more PTH
- When calcium levels are high the secretion of PTH is inhibited.
Use the effect of sympathetic innervation of the adrenal glands as an example of neural stimuli on hormone release
• Sympathetic nerve fibres stimulate the adrenal glands to release adrenaline and noradrenaline
Describe the hypothalmic-pituitary axis and the different hormones released.
The hypothalamus releases hormones that stimulate the anterior pituitary gland to release hormones such as TSH, ADTH and GH that go on and effect the release of other hormones in various organs of the body.
Steroid hormones have a __________ mechanism on cell whereas amino acid based hormones use a _________?
- Direct effect - gene expression
* Indirect - second messenger
Why is hormone signalling rather slow compared to the nervous system?
- Hormone signalling required the binding of hormones to receptors located on distance cells, whereas neurotransmitters only have to diffuse directly across the synapse.
- Similarly, the NS involves electrical transmission of signals along the cell, whereas hormone signalling requires the binding of chemical to trigger intracellular responses.
What are tropic hormones?
Hormones that have other endocrine glands as their target.
