The Hypothalamus and Autonomic Control Flashcards
Is the hypothalamus in the telencephalon or the diencephalon?
Diencephalon
Which ventricle does the hypothalamus surround?
Third ventricle
How many major nuclei are in the hypothalamus?
11
What is the major function of the hypothalamus?
Regulate homeostasis
What are the 2 sections of the pituitary gland?
- Anterior/adenohypophysis
- Posterior/neurohypophysis
What is the adenohypophysis?
Anterior pituitary
What is the neurohypophysis?
Posterior pituitary
What are parvocellular neurons?
Small diameter neurons in the hypothalamus which project into the pituitary stalk, communicate with the anterior pituitary/adenohypophysis
What are troph cells?
Hormone releasing cells in the anterior pituitary/adenohypophysis
How are hormones released from the adenohypophysis?
- Parvocellular neurons in the hypothalamus release releasing hormones into the circulation which enter the anterior pituitary capillaries through a portal vein
- Neurohormones activate receptors on troph cells
- Troph cells release their own hormones into the general circulation
What are magnocellular neurons?
Large diameter neurons in the paraventricular and supraoptic nuclei of the hypothalamus whose axons project into the posterior pituitary/neurohypophysis
Which nuclei in the hypothalamus contain magnocellular neurons? (2)
- Paraventricular nucleus
- Supraoptic nucleus
How are hormones released from the neurohypophysis?
Magnocellular neuron axons project into the neurohypophysis and release hormones directly into the systemic circulation
Which hormones are released from the adenohypophysis?
Tropic hormones (e.g. growth hormone, gonadotropic hormones)
Which hormones are released from the neurohypophysis? (2)
- ADH/vasopressin
- Oxytocin
Which effectors does the ANS innervate? (3)
- Smooth muscle
- Cardiac muscle
- Glands
What are the 2 sections of the ANS?
- Sympathetic
- Parasympathetic
What are visceral nerves?
- Nerves innervating internal organs
- Includes cranial nerves
How is sensory information passed to the brain?
Via visceral afferents
What are the 2 types of neurons in the ANS?
- Preganglionic
- Postganglionic
Where are preganglionic neurons found?
In the CNS
Where are postganglionic neurons found?
In ganglia in the periphery
What kind of neuron are preganglionic neurons?
All cholinergic
Which receptors do preganglionic neurons target on the postganglionic neurons?
Nicotinic ACh receptors
Which region of the spinal cord contains the preganglionic neurons of the sympathetic nervous system?
Between T1 and L3
Where is the white matter in the spinal cord?
Around the outside
Where is the grey matter in the spinal cord?
In the middle
What is the intermediolateral cell column?
Region in the lateral horn of the spinal chord containing the preganglionic sympathetic neurons, running from T1 to L3
Where in the spinal cord are the preganglionic sympathetic neurons found?
Intermediolateral cell column
What is the sympathetic chain ganglion?
Chain of ganglia joined together containing sympathetic preganglionic axons and postganglionic neurons which runs alongside the spinal cord
What is the prevertebral ganglion?
Ganglia separate from the sympathetic chain ganglia where preganglionic sympathetic fibres synapse onto postganglionic fibres
What kind of neurons are the postganglionic sympathetic neurons which come from the prevertebral ganglia?
Noradrenergic
What controls sympathetic preganglionic neurons?
Ventrolateral medulla
Which 2 areas of the body do preganglionic parasympathetic neurons come from?
Cranial and sacral
How do preganglionic sympathetic neurons differ from preganglionic parasympathetic neurons?
Preganglionic sympathetic neurons are short but preganglionic parasympathetic neurons are long and reach closer to their effectors
What kind of neuron are postganglionic parasympathetic neurons?
Cholinergic
Which receptors do postganglionic parasympathetic neurons target on their effector organs?
Muscarinic ACh receptors
What does the oculomotor nerve control?
Pupil constriction/dilation
What is cranial nerve III?
Oculomotor nerve
How much parasympathetic outflow is carried by the vagus nerve?
80%
What is cranial nerve X?
Vagus nerve