The Hypothalamus

Question 1

principle function of the hypothalamus

Answer 1

physiological homeostasis

drive behaviors eg rage, sleep, feeding

Question 2

Coronal Zones

Answer 2

Lateral, Medial and Periventricular Zones

Question 3

Sagittal regions

Answer 3

Anterior, Tuberal, Posterior

Question 4

Suprachiasmatic Nuclei function

Answer 4

circadian rhythm

Question 5

Suprachiasmatic Nuclei pathway

Answer 5

retina –> optic chiasm –> suprachiasmatic nuclei –> lateral horn of spinal cord –> pineal gland

Question 6

Pituitary anatomy

Answer 6

Adenohypophysis (anterior) - innervated by arcuate nuc.

Neurohypophysis (posterior) - supraoptic and paraventricular nuc.

Question 7

Arcuate Nuclei function

Answer 7

parvocellular neurons secrete releasing / inhibiting factors

combine signals related to feeding behaviors

Question 8

Parvocellular Neurons

Answer 8

neurons in the Arcuate Nuclei that secrete releasing/inhibiting factors
activates autonomic pattern generators to regulate feeding

Question 9

Pituitary hormones

Answer 9

prolactic - mammary glands
ACTH - adrenal cortex
TSH - thyroid gland
Gonadotrophins (eg FSH) - ovaries, testes

Question 10

Hypophyseal portal system

Answer 10

fenestrated structure of capillaries that facilitates rapid exchange between hypothalamus and pituitary

Question 11

Arcuate Nuclei pathway

Answer 11

releasing/inhibiting factors secreted to hypophyseal portal system –> enters anterior pituitary –> stimulates secretion of hormones

Question 12

Paraventricular & Supraoptic Nuclei function

Answer 12

Magnocellular neurons release vasopressin and oxytocin

acts as antidiuretic and also stimulates lactation

Question 13

Magnocellular neurons

Answer 13

neurons in Paraventricular and Supraoptic nuclei that release vasopressin and oxytocin

Question 14

Hypopituitarism

Answer 14

damage to hypothalamus/pineal gland cuases decrease of hormones –> decreased growth/responses

Question 15

Hyperpituitarism

Answer 15

increased hormones –> increased growth

Question 16

Antidiuretic process

Answer 16

water loss triggers releasing of more vasopressin (paraventricular and supraoptic nuc) –> increases water reabsorption in kidneys

Question 17

Lactation process

Answer 17

mechanoreceptors in nipples cause release of oxytocin –> increases contraction of myoepithelial cells in mammary glands for lactation

Question 18

Circumventricular organs

Answer 18

sites where blood-brain barrier is highly permeable --> allows passage of chemosensory stimuli
area postrema
subfornical organ
pineal gland
OVLT

Question 19

Area Postrema

Answer 19

(circumventricular organ) vomiting

Question 20

Subfornical organ

Answer 20

(circumventricular organ) osmoregulation, cardiovascular regulation, energy homeostasis

Question 21

OVLT

Answer 21

(circumventricular organ) has osmoreceptos that are sensitive to osmotic pressure in blood
fever induction

Question 22

Mammillothalamic Tract pathway

Answer 22

mammillary bodies –> mammillothalamic tract –> anterior nucleus of thalamus and midbrain reticular formation

Question 23

Medial Forebrain Bundle pathway

Answer 23

autonomic/somatic info

septal nucleus –> medial forebrain bundle –> lateral nucleus

Question 24

Fornix pathway

Answer 24

autonomic/somatic info

Hippocampus –> fornix –> mammillary bodies

Question 25

Stria Terminalis pathway

Answer 25

autonomic/somatic info | amygdala --> stria terminalis --> preoptic & tuberal nuclei

Question 26

Hypothalamic Tract pathway

Answer 26

retina --> hypothalamic tract --> suprachiasmatic nuc

Question 27

Brainstem and Spinal cord inputs

Answer 27

visceral and somatic info from: reticular formation, periaqueductal gray, solitary and parabrachial nuc. through: Dorsal Longitudinal Funiculus and Medial Forebrain Bundle

Question 28

Autonomic circuits (4 nuclei)

Answer 28

``` 4 brainstem areas that network tgt w/ hypothalamus to regulate Solitary Nucleus Parabrachial Nuclei Reticular Formation Periaqueductal Gray ```

Question 29

Solitary Nucelus (function)

Answer 29

principle visceral sensory nuclei w/ info regarding tase (IX) and internal organ status

Question 30

Parabrachial Nuclei (function and pathway)

Answer 30

carries generalised visceral sensory info | solitary --> parabrachial --> Hypothalamus, thalamus, amygdala

Question 31

Reticular Formation (function)

Answer 31

Central pattern generator centers | cardio/respiratory functions, urination

Question 32

Periaqueductal Gray (function)

Answer 32

origin of descending pain control pathway | central pattern generator for responses to threats

Question 33

Detrusor Muscles

Answer 33

bladder muscles taht contract to expel urine/ relax to collect

Question 34

Vesicovesical reflex

Answer 34

stretching of bladder wall causes detrusor muscles to contract (only active in children)

Question 35

Urine collection process

Answer 35

sympathetic input from T11-L2 inhibit detrusor muscles from contracting --> onuf's nucleus in S2 innervates external urethral sphincter, keeps it contracted

Question 36

Urine elimination process

Answer 36

tension receptors in bladder wall convey info to periaqueductal gray, preoptic hypothalamus and thalamus - -> visceral sensory cortex in insula for conscious awareness - -> periaqueductal gray assesses social appropriateness - -> approval signal sent to pontine micturition center - -> inhibits sympathetic and lower motor neurons, allow detrusor muscles to contract

Question 37

Medial Preoptic nucleus (function)

Answer 37

regulates body temperature - receives signal when temp too HIGH (20% of neurons are warm sensitive and fire faster as temp increases) --> stimulates blood vessel dilation, panting/sweating

Question 38

Posterior Nucleus (function)

Answer 38

regulates body temperature - receives signal when temp too LOW stimulates blood vessel constriction, shivering

Question 39

Dorsomedial Nuclei (function)

Answer 39

lesions affecting the dorsomedial nuclei produce rage

Question 40

Lateral Nucleus (function)

Answer 40

regulate food intake | lesions of lateral hypothalamus --> starvation

Question 41

Ventromedial Nucleus (function)

Answer 41

regulate food intake | lesions of ventromedial hypothalamus --> obesity

Question 42

Gherlin

Answer 42

chemical that encourages eating secreted by the stomach

Question 43

Leptin

Answer 43

chemical that stops feeding, released by fat cells | binds to receptors in arcuate nucleus