neural control of sexual behaviour and eating regulation

Question 1

what is the thalamus?

Answer 1

The largest portion of the diencephalon, located above the hypothalamus, contains nuclei of the cerebral cortex and receives info from it.

Question 2

What is the lateral geniculate nucleus?

Answer 2

A group of cell bodies within the lateral genicular body of the thalamus that receives fires from the retina and projects fibres to the primary visual cortex.

Question 3

What is the medial gesticulate nucleus?

Answer 3

A group of cell bodies within the medial genicular body of the thalamus, receives fibres from the auditory system and projects fibres to the primary auditory cortex.

Question 4

what is the ventrolateral nucleus?

Answer 4

A nucleus of the thalamus that receives input from the cerebellum and sends axons of the primary motor cortex.

Question 5

what is the hypothalamus?

Answer 5

The group of nuclei of the diencephalon situated beneath the thalamus, involved in regulation of the autonomic nervous system, control of the anterior and posterior primary glands, and integration of species-typical behaviour.

Question 6

What is the optic chiasm?

Answer 6

An x-shaped connection between the optic nerves, located below the base of the brain, just anterior to the posterior gland.

Question 7

What is the anterior pituitary gland?

Answer 7

The anterior part of the pituitary glans, an endocrine gland whose secretions are controlled by the hypothalamic hormone.

Question 8

what is the neurosectory cell?

Answer 8

A neuron that secretes a hormone or hormonelike substance.

Question 9

What is the posterior pituitary gland?

Answer 9

The posterior part of the pituitary gland; an endocrine gland that contains hormone-secreting terminal buttons of axons whose cell bodies lie within the hypothalamus.

Question 10

What is the midbrain?

Answer 10

The mesencephalon; the central of the three major divisions of the brain.

Question 11

what is the mesencephalon?

Answer 11

The midbrain; a region of the brain that surrounds the cerebral aqueduct; includes the tectum and the tegmentum.

Question 12

what is the tectum?

Answer 12

The dorsal part of the midbrain; includes the superior and inferior colliculi.

Question 13

What is the superior colliculi?

Answer 13

Protrusions on top of the midbrain; part of the visual system.

Question 14

What is the inferior colliculi?

Answer 14

Protrusions on top of the midbrain; part of the auditory system.

Question 15

what is the brain stem?

Answer 15

The “stem” of the brain, from the medulla to the midbrain, excluding the cerebellum.

Question 16

what is trhe tegmentum?

Answer 16

The ventral part of the midbrain; includes the periaqueductal gray matter, reticular formation, red nucleus, and substantia nigra.

Question 17

Identify the roles of spinal and brain mechanisms in male sexual behaviour:

Answer 17

• Spinal cord= Sexual reflexes such as sexual posturing, erection, ejaculation. vibratory stimulation of the penis can be elicit ejaculation in men with complete transection of the spinal cord, as long as the damage is located above the tenth thoracic segment.
  ○ LSt cells: group of neurons in the lumbar region of the rat spinal cord plat a critical role in triggering ejaculation.
  
  • Brain mechanisms= excitatory and inhibitory control of the circuits responsible for the erection and ejaculation.
    ○ Stimulating the MPA produces copulatory behaviour, destroying it permanently abolished the behaviour.
    ○ Destruction of the SDN (part of the MPA) in lab animals impairs mating behaviour.
    ○ Ejaculation in men is accompanied by an increase in behaviour in the brain’s reinforcement mechanisms, several thalamic nuclei, the lateral putamen, and the cerebellum.

Question 18

what is the MPA?

Answer 18

• An area of cell bodies just rostral to the hypothalamus; plays an essential role in male sexual behaviour.

Question 19

what is the SDM?

Answer 19

A nucleus in the preoptic area that is much larger in males than in females; first observed in rats; plays a role in male sexual behaviour.

Question 20

What is the periaqueductal grey matter?

Answer 20

the region of the midbrain that surrounds the cerebral aqueduct; plays an essential role in various species-typical behaviours, including female sexual behaviour.

Question 21

What is the nucleus paragigantocellularis?

Answer 21

A nucleus of the medulla that receives input from the medial preoptic area and contains neurons whose axons form synapses with motor neurons in the spinal cord that participate in sexual reflexes in males.

Question 22

What is the ventromedial nucleus of the hypothalamus (VMH)?

Answer 22

A large nucleus of the hypothalamus located near the walls of the third ventricle; plays an essential role in female sexual behaviour.

Question 23

Identify the roles of brain mechanisms in female sexual behaviour:

Answer 23

• The most important forebrain region for female sexual behaviour is the ventromedial nucleus of the hypothalamus (VMH). Its destruction abolished copulatory behaviour, and its stimulation facilitates this behaviour,
  
  • Both oestradiol and progesterone exert their facilitating effects on female sexual behaviour in this region, and studies have confirmed the existence of progesterone and oestrogen receptors in the VMH.
  • The priming effect of oestradiol is caused by an increase in progesterone receptors in the VMH.
  • The steroid sensitive neuron of the VMH sends axons to the periaqueductal grey matter (PAG) of the midbrain, these neurons, through their connections with medullary reticular formation, control the particular responses that constitute female sexual behaviour.
  • Orgasm in women is accompanied by an increased activity in regions similar to those activated during ejaculation in men and, in addition, in the periaqueductal grey matter.

Question 24

What is decerebration?

Answer 24

A surgical procedure that servers the brain stem, disconnecting the hindbrain from the forebrain

Question 25

Identify functions of the brain stem involved in eating regulation:

Answer 25

• The brainstem contains neural circuits that are able to control acceptance or rejection of sweet or bitter foods and can be modulated by satiation or physiological hinger signals, such as a decrease in glucose metabolism or the presence of food in the digestive system.
  
  • The area postrema and nucleus of the solitary tract (AP/NST) receive signals from the tongue, stomach, small intestine, and lover and send the information on to many regions of the forebrain. These signals interact and help control food intake.
    Lesions of the AP/NST disrupt both glucoprivic and lipoprivic eating

Question 26

What is melanin-concentrating hormone (MCH)?

Answer 26

One of two peptide neurotransmitters found in a system of lateral hypothalamic neurons that stimulate appetite and reduce metabolic rate.

Question 27

What is Orexin?

Answer 27

One of two peptide neurotransmitters found in a system of lateral hypothalamic neurons that stimulate appetite and reduce metabolic rate. Also called hypocretin.

Question 28

What is neuropeptide Y (NPY)?

Answer 28

A peptide neurotransmitter found in a system of neurons of the arcuate nucleus that stimulates feeding and insulin and glucocorticoid secretion; decreases the breakdown of triglycerides; and decreases body temperature.

Question 29

What is agouti-related protein (AgRP)?

Answer 29

A neuropeptide that acts as an antagonist at MC4Rs and increases eating.

Question 30

Identify functions of the hypothalamus involved in eating regulation:

Answer 30

• The lateral hypothalamus is involved in initiating eating and the ventromedial hypothalamus is involved in regulating satiety. The lateral hypothalamus contains two sets of neurons whose activity increases eating and decreases metabolic rate. These neurons secrete the peptides orexin and MCH (melanin-concentrating hormone). Food deprivation increases the level of these peptides. The axon of these neurons projects to regions of the brain involved in motivation, movements, and metabolism.
  
  • The release of neuropeptide Y in the lateral hypothalamus induces ravenous eating, an effect that is produced by excitatory connections of NPY-secreting neurons with the orexin and MCH neurons. NPY neurons in the arcuate nucleus of the in the hypothalamus receive input from glucose-sensitive neurons in the medulla. NPY neurons are the primary target of the ghrelin in the hypothalamus. Ghrelin also activates the mesolimbic reinforcement system by stimulating dopaminergic neurons in the ventral tegmental area, which increases the release of DA in the nucleus accumbens. When NPY is infused in the paraventricular nucleus, it decreases metabolic rate. Levels of NPY increase when an animal is deprived of food and fall again when the animal eats. Blocking NPY receptors supresses eating. NPY neurons also release a peptide called AgRP. This peptide is an antagonist at MC4 receptors and, like NPY, stimulates eating. Endocannabinoids also stimulate eating, by increasing the release of MCH and orexin.
  • Leptin desensitises the brain to hunger signals. It binds with receptors in the arcuate nucleus of the hypothalamus, when it inhibits NPY-secreting neurons, increasing metabolic rate and supressing eating. The arcuate nucleus also contains neurons that secrete CART, a peptide that supresses eating. These neurons, which are activated by leptin, have inhibitory connections with MCH and orexin neurons in the lateral hypothalamus. CART neurons also secrete a peptide called a-MSH, which serves as an agonist at MC4 receptors and inhibits eating. Ghrelin, which activated NPY/AgRP neurons and stimulates huger, also inhibits CART/a-MSH neurons and supresses the satiating effect of the peptides secreted by these neurons. The anorexigenic peptide, PYY, which is released by the gastrointestinal system, supresses the release of NPY and AgRP.

Question 31

What is the arcuate nucleus?

Answer 31

A nucleus in the base of the hypothalamus that controls secretions of the anterior pituitary gland; NPY-secreting neurons involved in feeding and control of metabolism.

Question 32

What is the paraventricular nucleus (PVN)?

Answer 32

A of the hypothalamus located adjacent to the dorsal third ventricle; contains neurons involved in the control of the autonomic nervous system and the posterior pituitary gland.

Question 33

what does CART stand for?

Answer 33

Cocaine and amphetamine which regulated transcript; a peptide neurotransmitter found in a system of neurons of the arcuate nucleus that inhibit feeding.

Question 34

what is the role of the A-melanocyte-stimulating hormone ( A -MSH)?

Answer 34

A neuropeptide that acts as an agonist at MC4Rs and inhibits eating