12 - Intro to Endocrine System Flashcards
What are the general characteristics of a control system?
What are two important control centres in the brain?
- Hypothalamus: endocrine system
- Medulla oblongata: ventilation and CVS
Describe the HPA axis as an example of negative feedback.
- Response to stress
What are biological rhythms?
- Set point of control centre varies, following circadian rhythm
- Biological clock in brain in small group of neurones called suprachiasmatic nucleus
- Zeitgebers keep body on cycle, e.g light, temperature
- Melatonin release from pineal gland sets clock
What causes jet lag?
- Mismatch between environmental cues, Zeitgebers, and body clock.
- As you move across time zones
Explain how osmolality is regulated.
Reference: 275 - 295 mOsm/kg, useful to investigate hyponatraemia
Explain how plasma glucose is regulated.
What is neurocrine control?
What are the similarities and differences between the endocrine and the nervous system for control?
What are the different classes of hormones?
- Catecholamines stored in vesicles in cell
- Steroid hormones not stored but precursor cholesterol is
How are hormones transported around the blood?
What factors determine hormone levels?
- Rate of production
- Rate of delivery e.g high blood flow more hormone
- Rate of degradation
What cells do hormones act on?
What is a tropic and trophic hormone?
- Tropic: other endocrine glands as their target, mainly released from anterior pituitary gland
- Trophic: stimulate growth in target tissue
How are hormones inactivated?
- In liver and kidney
- Steroid inactivated by small change in chemical structure increasing their water solubility so they can be excreted
- Protein degraded to amino acids and reused for protein synthesis
Where does the control of appetite originate from?
- Sateity centre of the hypothalamus called arcuate nucleus
- Contains primary neurones that sense metabolite levels and sends inputs to secondary neurones to coordinate response via vagus nerve
What are the two types of primary neurone in the arcuate nucleus, and what do they release?
- Orexigenic: NPY and AgRP to stimulate appetite
- Anorexigenic: Pro-opiomelanocortin which can be cleaved to b-endorphin, ACTH, a-MSH, to supress appetite
- a-MSH acts on melanocortin 4 receptors to supress and the b-endorphin from POMC makes you happy
What hormone outside of the hypothalamus stimulates appetite?
What hormones suppress appetite?
PYY: short peptide hormone from ileum and colon in response to feeding. Inhibits excitatory neurones and stimulates inhibitory ones
What can be used to treat early type 2 diabetes?
Pramlintide, analogue of amylin
What is the overall control of appetite system?
What happens if you have a loss of funcyion leptin gene mutation and how can it be treated?
- Obesity, cannot stop eating so inject them with leptin
- Cannot inject leptin into normal obese people, appear to be resistant
