July 29, 2021
In this IBDP Biology blog post, we will be discussing the further physiological processes within human bodies and how we control these processes.
Control of ADH by negative feedback
- Neurosecretory cells in the hypothalamus synthesise and transport ADH to the posterior pituitary gland where it is stored
- Osmoreceptors in the hypothalamus detect an increase in blood solute concentration when levels of water in the blood drop
- In response to this nervous activation, ADH is released from the posterior pituitary and travels in the blood to the kidneys
- ADH makes the epithelium of the collecting ducts more permeable to water
- This increases the amount of water reabsorption by the kidneys, causing blood solute concentration to drop
- With a drop in blood solute concentration, ADH secretion is inhibited (negative feedback)
- If blood solute concentration is low (due to excessive water intake), the collecting duct remains impermeable to water and urine is dilute
The structural features of an exocrine glands
- Exocrine glands have ducts through which they secrete their product
- The ducts / ductules arise from a cluster of cells called an acinus
- Acini are lined by a single layer of secretory cells which release the exocrine product into the lumen of the duct via secretory vesicles
- Secretory cells are held together by tight junctions, and possess a highly developed RER and golgi network for material secretion
That is all for this post!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fvasopressin.wordpress.com%2Frelease-and-feedback%2F&psig=AOvVaw0RmsL_UGt4fZmPotJgZbm_&ust=1627663439514000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCIjlgf_ciPICFQAAAAAdAAAAABAD
https://www.google.com/url?sa=i&url=http%3A%2F%2Fib.bioninja.com.au%2Foptions%2Foption-d-human-physiology%2Fd2-digestion%2Fexocrine-glands.html&psig=AOvVaw0cAFxZC4JXqA4ebDgyw0B2&ust=1627663498979000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCICFyZfdiPICFQAAAAAdAAAAABAD
Drafted by Venetia (Biology)