Hypothalamus/pituitary axis 1 Flashcards
Neuroendocrine system
A cross-talk between CNS and endocrine system
Hypothalamus
Point of integration
CNS
Rapid responses
Uses neurones which use action potential response
Anterior pituitary
Downstream signals??
Hypothalamus has direct influence over anterior pituitary
What does the neural communication give that endocrine doesn’t?
Motor function
Sympathetic/parasympathetic
Autonomic nervous system uses both neurotransmitters and chemical transmitter -> blend
Neural is usually faster
Integration
[figure on slide 2 (??)]
Advantages of having multiple steps in communication pathways
Regulation
Negative feedback
Exercise a finer level of control
Disadvantages of having multiple steps in communication pathways
Potentially slower
Potentially multiple points of failure <- but on the other hand, a fault is potentially easier to overcome with therapeutics by still stimulating the rest of the pathway
Hypothalamus
Collection of specialised nuclei and nerve tracts/pathways
Important in regulation of autonomic activity and part of the limbic system
Hypothalamus is involved in the following physiological processes (by influencing the systems that control the parameters)
Body temperature
Heart rate
Blood pressure
Blood osmolality
Water and food intake
Circadian cycles
What acts as the air interface between endocrine and neural systems?
Hypothalamus
What is the limbic system involved in?
Emotions; pain regulation or perception; learning and memory; associated with survival instincts; motivation; linked back to the hypothalamus to form responses to inputs
Note on reading around the subject -> look at how the links hypothalamus wth the cingulate gyros
*
Lesions in the limbic system can result in:
Voracious appetite
Increased sexual activity
Loss of fear and anger responses
Loss of memory due to hypothalamus being a par of the temporal lobe
Adenohypophysis versus neurohypophysis
?
4 types of hypothalamic reflexes
Milk ejection + uterine contraction -> regulated by neural input and humoral output
Urine flow + feedback loops -> regulated by a humoral input and a humoral output
Topic hormones
NOT released into the rest of the circulation -> can’t be from neuronal link
Table on slide 17
Important to pull things together
Water balance and its control
Key balance between water intake and loss
More than half of water loss is through urine: only regulated way
Remaining loss: ‘insensible loss’
Kidney nephron and reabsorption
Water reabsorbed in most of nephron is unregulated and couple to solute reabsorption
Urine produced can be either v concentrated or v dilute
How to kidneys vary their urine concentrating ability
B regulating water reabsorption in the collecting duct
Counter current multiplier system
** write yourself a proper reminder
Wtf is vasopressin
*** [SOMETHING] leads to
Elevated urine osmolality (increased reabsorption)
Decreased urine fow
Aquaporin channels
Key to water movement in cells
Steps 1-8 -> slides 27 and 28
** remember on the diagramme you’re looked down it and the centre is the side of the tube
Other routes to AVP effect
**
Secondary actions of AVP
Decreased body temp
Increased memory consolidation
