Endocrine Intro & Appetite Flashcards
What group or neurones are responsible for controlling the “biological click”
Suprachiasmatic nucleus
What are zeitgebers?
Cues from environment to keep the body on 24 hour cycle. Temp, light, social interaction, exercise.
Melanin is also involved in setting the biological clock. Which gland is it secreted by?
Pineal gland
When are positive feedback loops used?
When rapid change needed - blood clotting, ovulation.
Which receptors measure osmotic pressure in the hypothalamus?
Osmoreceptors
What will happen to cells if blood osmolality increases?
Hypertonic solution. Cells will lose water to extracellular environment and shrink.
Where is ADH secreted from?
ADH
Where is ADH secreted?
Hypothalamus
How does the body respond to increased blood osmolality?
Osmoreceptors in hypothalamus detect change and trigger ADH release and thirst.
How does the body respond to a decrease in blood osmolality?
Osmoreceptors detect change and decrease ADH secretion from posterior pituitary, this leads to less water reabsorption in the kidney.
How do the endocrine and nervous system differ in terms of speed of control?
Endocrine = slow
Nervous system = fast
What hormones are peptide/polypeptide?
Insulin, glucagon, growth hormone
What hormones are amino acid derivatives (amines)?
NA and arenaline, dopamine, thyroid hormones, melatonin
What hormones are glycoproteins?
TSH, FSH, LH
What is the precursor for steroid hormone synthesis?
Cholesterol
Which hormones are steroid hormones?
Aldosterone, cortisol, testosterone, progesterone
What roles do hormone carrier proteins have?
- Increase solubility of hormone in plasma
- Increase half life
- Readily accessible reserve
What type of receptor does adrenaline bind to?
GPCR
What type of receptor does insulin bind to?
Tyrosine kinase
What receptors can lipid soluble hormones bind to?
- Cytoplasmic receptors, binds and enters nucleus
2. Pre-bound receptor on DNA
Give an example of a hormone that binds to a pre-bound receptor on DNA hormone response element.
Thyroid hormone.
What group of hypothalamic neurones are involved in controlling appetite?
Arcuate nucleus
What 2 types of primary neurones signal to the arcuate nucleus?
- Stimulatory neurones
2. Inhibitory neurones
What neurotransmitters are present in primary stimulatory neurones?
Neuropeptide Y (NPY) Agouti-related peptide (AgRP)
What do stimulatory neurones do?
Promote hunger
What neurotransmitters are present in primary inhibitory neurones?
POMC which yields alpha-MSH and beta-endorphin.
What do inhibitory neurones do?
Promote satiety
What hormone is released from the stomach wall when the stomach is empty, what effect does it have?
Ghrelin - stimulates excitatory primary neurones in arcuate nucleus
Which hormone is released by cells in the ileum and cool in response to feeding?
PYY (peptide-tyrosine-tyrosine)
What effect does PYY have?
Inhibits excitatory neurones of arcuate nucleus
Stimulates inhibitory neurones to suppress appetite.
Which hormone signals travel from the gut to the hypothalamus to influence hunger?
Ghrelin - stomach
PYY (ileum and colon)
Which hormones signal from the body to the hypothalamus in appetite regulation?
Leptin, insulin, amylin
What is leptin produced by?
Adipocytes
What 2 effects does leptin have on the arcuate nucleus?
Suppresses appetite:
- Stimulates inhibitory neurones
- Inhibits excitatory neurones
How does leptin influence heat generation?
Induces expression of uncoupling proteins in mitochondria to increase energy loss as heat.
How does insulin influence appetite?
Stimulates inhibitory neurones to suppress appetite.
Less important that leptin.
Where is amylin secreted from?
Beta cells in the pancreas
What effect does amylin have on appetite?
Suppresses appetite
Decreases glucagon secretion, slows gastric emptying.
Do the units mOsmol/L refer to the osmolality or osmolarity of the solution?
Osmolarity
A solution of normal saline has a concentration of 308 mOsmol/L (9.0g per litre). What concentration of Na+ ions would be in this solution?
154 mmol/L
In which region of the brain are the osmoreceptors located?
Hypothalamus
Which class of hormone does thyroid hormone fall under?
Amine hormone
Name the peptide precursor of the neurotransmitters αMSH, β-endorphin and ACTH.
POMC
