L14 The Hypothalamus + Autonomic Control Flashcards
How many major nucleis does the Hypothalamus have?
11
What is the role of the hypothalamus?
It’s primary role is to maintain homeostasis, which is the body’s ability to keep its internal environment stable
Briefly describe how homeostasis works (5)
1) Disruption to a vital parameter
2) Sensory inputs (varied)
3) Integration by hypothalamus
4) Activates autonomic NS/ Neuroendocrine/ Behavioural
5) Restoration of vital parameter within physiolgical range
What are the major nucleis of the hypothalamus (that we need to know)?
- Paraventricular nucleus
- Supraoptic nucleus
- Anterior Pituitary (Adenohypophysis)
- Posterior Pituitary (Neurohypophysis)
How are troph cells stimulated in the adenohypophysis?
Troph cells stimulated by releasing hormones from parvocellular neurons of the hypothalamus
Where are Magnocellular neurons primarily located?
These neurons have their cell bodies located in the hypothalamus, primarily within the supraoptic nucleus (SON) and the paraventricular nucleus (PVN)
How does the neurohypophysis regulate essential body functions related to social behaviour and reproduction?
It releases hormones from the magnocellular neurons directly into systemic cirulcation
Magnocellular neurons release oxtocin and vasopressin
What are the major pituitary hormones?
- Tropic hormones
(Neurohypophysis)
- ADH/ vasopressin: Fluid balance
- Oxytocin: Parturition and lactation
Is the autonomic nervous system (ANS) voluntary?
No, its involuntary
What are the two efferent pathways of the ANS?
Sympathetic and parasympathetic
What are the innervate effectors (muscles/glands that sends signals through nerves) for ANS?
Smooth muscle
Cardiac muscle
Glands
Why can’t the ANS function without the hypothalamus?
The hypothalamus acts as a central control center, integrating information from various parts of the brain and body and so without it the ANS would lack central coordination necessary to maintain a stable interval environment
Which of the following requires greater input from the hypothalamus?
A) Pupillary constriction/dilation
B) Salivation
C) Regulation of body temperature
C) Regulation of body temperature requires the greatest input from the hypothalamus.
What are the anatomical organisations of ANS?
The ANS uses a two neuron chain to connect the central nervous system (CNS) to target organs
- Preganglionic neuron: CNS (brain or spinal cord)
and then - Postganglionic neuron: (Sympathetic and parasympathetic ganglia)
Why is the IML Cell column T1-L3 important?
IML= Intermediolateral
It’s crucial because it is the origin of the preganglionic neurons of the sympathetic nervous system. These neurons are responsible for initiating the ‘fight or flight’ response
What is a sympathetic chain?
They consists of two chains of interconnected ganglia (clusters of nerve cell bodies)
What controls the sympathetic preganglionic neurons?
Ventrolateral medulla
Where within the spinal cord is the parasympathetic organisation found?
Sacral region (lower half)
Would you expect a sympathetic chain in the parasympathetic organisation?
No, ganglions are alone and not chained
What are the two cranial outflow segments within the PNS?
- Oculomotor nerve (CN III) - originates from midbrain
- Vagus nerve (CN X) - originates from medulla
Why is the vagus nerve important?
The vagus nerve (cranial nerve X) carries 80% of total parasympathetic outflow
Which CNS are the muscarinic receptors found?
They are general found in the parasympathetic nervous system.
General found at the synapse between the postganglionic parasympathetic neuron and the target organ.
Which CNS are the adrenergic receptors found?
Found in sympathetic nervous system
Most postganglionic neurons of the SNS release norepinephrine as their neurotransmitter.
