Hormones and behaviour Flashcards
What are hormones?
- Chemical messengers that are released into bloodstream and affect the function of target cells at a distance from their source.
How many classes of hormones are there?
3
What are protein hormones?
- Most vertebrate hormones are proteins **composed of amino acids. **
- Can be stored in endocrine cells and include examples such as insulin and ghrelin.
- Bind to receptors on the SURFACE of target cells.
What are monoamine hormones?
- Derived from a** single amino acid**.
- Include hormones like epinephrine and dopamine.
- Some act as both hormones and neurotransmitters.
What are steroid hormones?
- **Produced mainly by the adrenal glands, gonads, and brain. **
- Derive from cholesterol and include cortisol and testosterone.
- Bind to receptors INSIDE target cells, and are not stored but released immediately.
What are the 2 different glands?
Exocrine and endocrine.
What are exocrine glands?
- Secrete products through ducts to an epithelial surface (skin or digestive tract).
- Produce substances like enzymes, mucus, sweat, and saliva.
- Include salivary glands, sweat glands, sebaceous glands, and pancreas.
- Functions in digestion, lubrication, protection, and temperature regulation.
What are endocrine glands?
- Release hormones directly into the bloodstream.
- Regulate body processes such as growth, metabolism, and reproduction.
- Include glands like the pituitary, thyroid, adrenal, and pancreas.
- Hormones travel to target organs and tissues to exert effects.
What are glands? How do they link to hormone production?
- A group of cells formed by ingrowth from an epithelial surface.
**- Not all glands produce hormones **
How do hormones influence behaviour?
- May influence sensory, central processing, and output systems.
- Hormones do not directly cause behaviour, but change the probability of certain responses.
What is the effect of hormones on target cells?
- Hormones interact with receptors, leading to activation of enzymatic pathways/changes in gene expression.
- Hormones may change cell morphology/size.
- Responsiveness depends on hormone concentration, number of target recepors, and the influence of other hormones.
What are the 2 feedback mechanisms?
Positve and negative
What is positive feedback?
- A process where a hormone’s release stimulates further release, amplifying its effect.
- Often seen in reproductive systems, e.g., oxytocin during childbirth.
- Leads to rapid changes or intensification of a particular behavior or physiological response.
What is negative feedback?
- A regulatory process that maintains homeostasis by reducing hormone production when levels rise.
- Involves a hormone inhibiting its own release or the release of another hormone.
- Helps stabilize physiological processes and behaviors, such as temperature, metabolism, and stress response.
What is hormone clearance?
- Hormones are broken down by enzymes, the liver, and bloodstream disintegration.
- Hormones are excreted via bile or urine.
How do you determine hormone bheaviour effects?
- A hormonally dependent behaviour should disappear when hormone action is blocked or removed.
- Restoration of missing hormonal sources should reinstate absent behaviour.
- Hormone concentrations and the behaviour should be covariant.
What is neural transmission vs hormonal communication?
Neurons:
- Travel along existing nerve tracks.
- Messages have rapid onset and offset, taking place in milliseconds (ms).
- Subject to voluntary control.
Hormones:
- Travel throughout the body via the circulatory/system,
- Effects may take minutes or hours to manifest and last longer.
- No voluntary control over relase.
Hormone Receptors
Steroid hormones?
- Not water-soluble and require carrier proteins to travel in the bloodstream.
- Blind to receptors inside target cells.
Hormone Receptors
Protein hormones?
- Cannot pass through plasma membranes.
- Bind to receptors on the target cell surface.
Regulation of Receptors
Up-Regulation?
- Increased production of receptors.
e.g., when hormone concentrations are low, it increases sensitivity.
Regulation of Receptors
Down-regulation?
- Decreased prodcution of receptors lowers sensitivty.
- Hormones may regulate receptors for other hormones.
