BIOL10002 Lecture Notes - Lecture 12: Adrenal Medulla, Adrenal Gland, Extracellular Fluid
Lecture 12
The Endocrine System and Hormones, part 1
Hormones
- signalling molecules, secreted into interstitial fluid, passed into blood
and then travel to target cell, i.e. hormone action (also called endocrine
action)
- released by specific cell types
3 chemical groups;
1. Peptides (proteins) – Major group
- easily transported in blood (water soluble)
- released by exocytosis, packed in vesicles
2. Steroids (lipids)
- act at nuclear level increases transcription
- lipid soluble, therefore not stored in vesicles – secretion is regulated by
regulating synthesis
- synthesised from cholesterol
3. Amines
- mostly synthesised from tyrosine (amino acid)
- can be water-soluble or lipid soluble, so mode of action differs
Glands
Endocrine – collection of cells that secrete hormones (pancreas secretes insulin, glucagon directly into blood)
Exocrine – have ducts that carry molecules to specific location (pancreas secretes enzymes and bicarbonate via duct
to duodenum)
Fight or flight response
- comes from adrenal gland (has an outer cortex and inner medulla), which is on top of the kidneys
- Brain detects danger - Signals sent to adrenal gland to release E and NE.
- The release is very rapid as adrenal medulla is regulated by nervous system
- the release of Epinephrine (E) and Norepinephrine (NE) is stimulated and are released in response
Actions
1. Heart beats faster, blood pressure increases
2. Divert blood flow to skeletal and cardiac muscles
3. Liver cells break down glycogen and secrete glucose – energy
4. Fat cells release Fatty acids - energy
Target cells
- Circulatory system
- Muscles
- Liver and Fat cell
Hypothalamus and Pituitary
Note: anterior is a gland – CELLS
posterior is neural – NO CELLS
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Document Summary
Signalling molecules, secreted into interstitial fluid, passed into blood and then travel to target cell, i. e. hormone action (also called endocrine action) 3 chemical groups: peptides (proteins) major group. Released by exocytosis, packed in vesicles: steroids (lipids) Act at nuclear level increases transcription. Lipid soluble, therefore not stored in vesicles secretion is regulated by regulating synthesis. Can be water-soluble or lipid soluble, so mode of action differs. Endocrine collection of cells that secrete hormones (pancreas secretes insulin, glucagon directly into blood) Exocrine have ducts that carry molecules to specific location (pancreas secretes enzymes and bicarbonate via duct to duodenum) Comes from adrenal gland (has an outer cortex and inner medulla), which is on top of the kidneys. Brain detects danger - signals sent to adrenal gland to release e and ne. The release is very rapid as adrenal medulla is regulated by nervous system. The release of epinephrine (e) and norepinephrine (ne) is stimulated and are released in response.
