Lecture 26: Neuroendocrinology Flashcards
What is endocrinology?
the study of hormones, their receptors and their intracellular signalling pathways
Define hormones
chemical messengers produced in one location and transported to a second location (target cells) where they exert their effects.
Hormones often reach their target via what?
the bloodstream
Do hormones act in high or low concetrations?
low concentrations
What are the 4 principle functions of the endocrine system?
- maintain homeostasis
- regulation of growth and development
- control energy storage and use
- mediate the body’s response to environmental cues
What is the purpose of maintaining homeostasis?
to maintain a stable internal environment in the face of a changing external environment
What are the 4 types of hormone communication in the body?
- autocrine
- paracrine
- endocrine
- neurocrine
Describe autocrine communication of homrones
a cell releases a hormone to have an effect on itself to cause a response ie. the target cell is the cell that released the hormone
Describe paracrine communication of hormones
a cell releases a hormone to have an effect on a target cell which is in the same tissue as the cell releasing the hormone ie. the cell releasing the hormone acts locally
Describe endocrine communication of hormones
A cell releases a hormone which enters the bloodstream and has an effect on a target cell far away
Describe neurocrine communication communication of hormones
The cell releasing the hormone is a neuron and it releases the hormone which enters the bloodstream and has an effect on a cell far away from the cell releasing the hormone
How can we chemically classify hormones?
Where do these come from?
- peptide/protein hormones (dependent on length)
- amine hormones (derivatives of tyrosine)
- steroid hormones (synthesised from cholesterol)
- prostaglandins (synthesised from arachidonic acid)
What are the fates of secreted hormones?
- excreted in the urine of faeces
- inactivated by metabolism
- activated by metabolism
- bind to a receptor and produce a cellular response
How do we achieve spatial and temporal specificity?
hormones can be temporarily released and we can achieve spacial specificity by receptors being expressed on certain tissues and only those receptors can bind to hormones
Describe the synergic effect of hormones
the effect of two hormones working together is larger than the combined effect of each individual hormone
What does the circadian rhythm explain?
it shows that physiological functions are controlled by a clock
Where does our body clock reside?
in the suprachiasmatic nucleus
What is the body clock in the suprachiasmatic nucleus regulated by?
light
How long is the rhythm of our biological clock?
about 25 hours
Which gland releases melatonin?
the pineal gland
When is melatonin secreted?
in the dark
Describe the biological clock, the release of melatonin and mention the Zeitgeber
The body clock resides in the suprachiasmatic nucleus in the hypothalamus. This clock is regulated by light. The rhythm is longer in the dark and light adjusts it every day. The rhythm is generated by the clock and it is adjusted by light every 24hrs. The internal cue that regulates this clock is melatonin which is produced by the pineal gland and is secreted in the dark