L1 - Introduction to the endocrine system Flashcards
1
Q
What is a hormone
A
- The endocrine system is a system of ductless glands which secrete chemical messengers (Hormones) into the blood
- The hormones are then carried in the blood and are able to act on cells possessing the appropriate hormone receptors (target tissues)
2
Q
What is the pituitary gland also sometimes called
A
- The master gland
3
Q
Role and location of thyroid and parathyroid glands
A
- Situated in the neck
- Important in the control of metabolic rate and calcium homeostasis
4
Q
Role of the pancreas
A
- Secretes digestive enzymes directly into the GI tract (exocrine function)
- It also secretes the hormone insulin into the blood
- Insulin regulates blood glucose concentrations and glucose utilisation
5
Q
Location of the adrenal glands
A
- Lie on top of the kidneys
6
Q
What are the adrenal glands divided into
A
- Outer cortex
- Inner medulla
7
Q
What is the inner medulla of the adrenal glands concerned with
A
- Stress response, cortex with stress, sodium and glucose homeostasis
8
Q
Role of the gonads
A
- Secrete the female and male reproductive hormones respectively
- These are responsible for the development of secondary sexual characteristics and reproduction
9
Q
How do hormones produce their effects
A
- By interaction with receptors which may be intracellular or membrane-bound
10
Q
What are the major types of receptors involved in hormone action
A
- Steroid Hormone Receptors
- G-Protein Coupled Receptors
- Tyrosine Kinase Receptors
11
Q
How do steroid hormone receptors function
A
- The hormone crosses the cell membrane and binds to a receptor which may be cytoplasmic or nuclear.
- The hormone receptor complex then binds to the hormone-response element of the DNA to influence gene transcription.
- The receptor may be constitutively active
12
Q
How do g-protein coupled receptors work
A
- The hormone binds to the 7TM receptor to cause synthesis of a second messenger, eg inositol trisphosphate or cyclic AMP.
- Second messengers phosphorylate intracellular, regulatory protein to influence cellular activity (eg smooth muscle contraction).
13
Q
How do tyrosine kinase receptors function
A
- Membrane-bound enzyme which is a single strand of protein.
- Often two receptors must be present for hormone action (dimerized receptor).
- One hormone molecule binds to each receptor, the receptor then acts as an enzyme to phosphorylate ‘tyrosine’ components of intracellular, regulatory proteins.
14
Q
What are the two broad classes of hormones
A
- Peptide hormones
- Steroid hormones (+ thyroid hormone)
15
Q
What are peptide hormones
A
- Chains of amino acids, highly water soluble, susceptible to protease attack.
- Unable to cross the cell membrane without a carrier protein, act on membrane-bound receptors.
