Neuro Test 3

"orexi"

"to eat"

cingluate cortex

(an emotion-processing cortical region) sends information regarding emotional state.

what are the major hypothalamic nuclei involved in appetite/feeding

-Lateral hypothalamus (LH) -Ventromedial hypothalamus (VMH) -Arcuate nucleus -Paraventricular nucleus (PVN)

celiac ganglion

-Liver - stimulates glucose production & release -Stomach, pancreas, small intestine - inhibits digestion -Adrenal gland (stimulates secretion of epinephrine, norepinephrine from adrenal medulla)

What does the ANS regulate?

-Secretion of saliva, sweat, tears, mucus -Heart & blood vessels to control blood pressure and blood flow -Oxygen delivery (lung bronchi) -Digestion and metabolism (liver, GI tract, pancreas) -Kidney, urinary bladder, large intestine -Sex & reproduction -Interacts with body's immune system

What are the subdivisions of the ANS

-The sympathetic ANS -The parasympathetic ANS the divisions operate in parallel with generally opposing functions

what are the major regions of the CNS that regulate the autonomic nervous system function?

-hypothalamus -amygdala -Brainstem

what does cortisol elicit in the brain and body?

-mobilizing energy stores -increasing arousal/vigilance -focusing attention -suppressing immune function

Projections of the parasympathetic nervous system

-ocularmotor nerve -facial nerve -glossopharyngeal nerve -vagus nerve -splanchic nerve

hormones involved in hunger

-orexin (hypothalamus) -ghrelin (stomach) -insulin (pancreas) -leptin (fat cells) -PYY increase (digestive tract)

What are the principal inputs to the hypothalamus?

-prefrontal cortex -cingluate cortex -hippocamous and amygdala -reticular formation and nucleus of the solitary tract -thalamus -hypothalamus -retina input

where do postganglionic cells of the sympathetic ANS innervate the vasculature and/or viscera

-superior cervical ganglion -thoracic ganglion -celiac ganglion -collateral ganglia

Hypothalamus functions: emotional & motivated behaviors

1. Fight-or-flight behavioral response to threatening stimuli or situations. 2. Motivated behaviors including feeding, sexual and other behaviors integral to promoting survival and reproduction. 3. Aggression, rage

What is the common pattern for most hormones of the hypothalamus-anterior pituitary complex

1. Parvocellular hypothalamic neurons project to the median eminence -> their hormones enter the hypophyseal portal blood supply. 2.These hypothalamus-secreted factors stimulate (or inhibit) anterior pituitary cells to release their hormones. 3.Hormones released into bloodstream.. 4.Target endocrine gland in the body is activated by the hormone. 5.Peripheral hormones in bloodstream feedback to hypothalamus to regulate its release (to make sure the system doesn't become overstimulated.)

hypothalamus functions: Basic physiological needs

1. Stress response (influencing blood flow to specific tissues, and by stimulating the secretion of adrenal stress hormones) 2. Ingestive behavior (feeding, drinking) 3. Blood pressure 4. Sleep-wake cycle, circadian function 5. Body temperature 6. Energy metabolism (via influence on feeding, digestion, and metabolic rate) 7. Reproduction (via hormonal control of mating, pregnancy and lactation)

the bodies stress response

1.Hypothalamic Pituitary Adrenal (HPA) stress axis (CRH -> ACTH -> cortisol) 2. Autonomic Nervous System ('fight or flight' physiological responses)

can you answer these?

1.What are major subdivision of the hypothalamus? 2.What the major inputs/outputs of the hypothalamus? 3.A major aspect of hypothalamic function is its interaction with the pituitary; what are the different parts of the pituitary & what different functions do they each serve? 4.Be able to explain the HPA stress axis (CRH -> ACTH -> cortisol and its downstream effects on brain and body) 5.What are the effects of chronic stress on the body and behavior? On the brain?

What are the two main neurotransmitters used in the autonomic nervous system?

Acetylcholine (ACh) Norepinephine (NE)

satiety signals

As food fills the stomach. stretch receptors provide signals to hypothalamus. Other hormone from the gut and fat slow feeding. These signals are sent to the hypothalamus to indicate a feeling of fullness and satisfaction.

What are the two categories of hypothalamus functions?

Basic physiological needs and emotional and motivated behaviors

orexigenic signals

Blood glucose levels are monitored by receptors in the stomach, liver, and intestines. Hormones released from the gut act on the brain. These signals are sent to the hypothalamus to indicate hunger. Food seeking increases.

what is the first step in the hypothalmic-pituitary-adrenal (HPA) axis?

Corticotropin releasing hormone (CRH)

Are both the anterior and posterior pituitary glands?

The anterior pituitary gland is an actual gland (as opposed to the posterior pituitary, which is essentially extension of the brain).

Principle efferent (output) from hypothalamus

The hypothalamus has many reciprocal projections. Such projections include hypothalamic outputs to: •Prefrontal cortex, septum, cingulate cortex •Hippocampus •Amygdala •Periaqueductal gray •Brain Stem •Spinal Cord

What is the hypothalamus?

The hypothalamus is part of a brain region called the diencephalon. It is situated below the thalamus & is connected to the pituitary gland, which works together with the hypothalamus to control hormone release in the body.

what is something the ANS and SMS do not have in common?

Unlike somatic motor system, ANS 'lower motor neurons' lie outside the CNS, within autonomic ganglia

what is the thalamus?

a 'relay station' that connects somatosensory system and motor system to the cortex.

what is the autonomic nervous system (ANS)?

a division of the peripheral nervous system that controls numerous involuntary physiological process of the body's internal organs, smooth and cardiac muscles

stress

a state of mental or emotional strain or tension resulting from demanding circumstances

what transmitter does the parasympathetic postganglionic neuron use?

acetylcholine (ACh)

retina input

also comes to the hypothalamus to contribute to circadian regulation.

posterior pituitary (neurhypophysis)

back portion; secretes the hormones oxytocin and vasopressin.

what are some body functions that fall under ANS control?

blood pressure heart rate digestion respiratory rate papillary response

what is something the ANS and SMS have in common?

both have 'upper motor neurons' that send commands to 'lower motor neurons'

do postganglionic neurons in the sympathetic and parasympathetic divisions use different neurotransmitters

both use Ach and only sympathetic uses NE

how does chronic stress effect the brain?

chronic stress and cortisol treatment significantly reduces dendrite length in hippocampus, but recovery is possible (from a study)

thoracic ganglion

contains cells that will constrict blood vessels, relax airways, and accelerate heart rates

what does the autonomic nervous system do (ANS)?

controls all PNS-innervated tissues and body organs other than skeletal muscle

vagus nerve

cranial nerve 10, innervates: -Lung to constrict airways -Heart to slow heartbeat -Stomach to stimulate digestion -Pancreas to stimulate release of insulin and digestive enzymes -Small intestine to dilate blood vessels in gut

oculomotor neve

cranial nerve 3, leads to pupil constriction

facial nerve

cranial nerve 7, stimulated salivation

glossopharyngeal nerve

cranial nerve 9, stimulates salivation

Parasympathetic ANS

dedicated to long term bodily maintenance ('rest & digest').

what happens in the LH or VMH if lesioned or damaged

destroying th LH leads to and animal having no interest in eating destroying the VMH leads an animal to eat excessively (thereby developing extreme obesity)

Yerkes-Dodson law

dictates that performance increases with physiological or mental arousal, but only up to a point. When levels of arousal become too high, performance decreases.

superior cervical ganglion

dilates pupils, inhibits salivation

taste adversion

eat something, have a bad experience, then don't try to eat it again

role of leptin

fat cells produce it and secrete it into the bloodstream, it works to suppress hunger by acting on receptors in the hypothalamus (e.g., arcuate nucleus)

leptin

fat cells release it and it decreases hunger

satiety

feeling of fulfillment or satisfaction

splanchinc nerve

from sacral spinal cord, innervates large intestine, bladdar, and reproductive organs

anterior pituitary (adenohypophysis)

front portion; secretes hormones that influence growth, sexual development, skin pigmentation, thyroid function and adrenocortical function (stress hormones).

What does the ANS innervate?

glands smooth muscle cardiac muscle

hypothalamus

has intrinsic sensory neurons (i.e. cells within hypothalamic regions that project to other hypothalamic nuclei) that respond to physiological stimuli, such as temperature, blood osmolality, or glucose.

What is the primary function of the hypothalamus

homeostasis. It uses hormones to coordinate autonomic, endocrine, and motor responses to fulfill the body's needs.

arcuate nucleus

hypothalamus nuclei, contains and appetite controller governed by hormones, like insulin. relies on two sets of neurons with opposing effects: NPY/AgRP neurons and POMC/CART neurons, two main functions of these neurons: 1)Some projections stay in the arcuate and influence each other's activity. 2)Other projections leave the arcuate and make connections in other nuclei of the hypothalamus to modulate food intake, particularly: -Paraventricular nucleus (PVN) -Lateral hypothalamus (LH)

Where does ACTH circulate and what does it act on?

in the blood, acts on the adrenal grands to produce cortisol, epinephrine, and norepinephrine

where are preganglionic cells of the parasympathetic ANS located?

in the cranio-sacral regions (cransial nerve nuclei in the brain stem and sacral cord)

where are the preganglionic cells of the sympathetic ANS located?

in the thoracic-lumbar spinal cord

collateral ganglia

innervates large intestine, bladder, reproductive organs

hunger

internal state of an animal seeking food

PPY

intestines release it and it decreases hunger

stress triggers the hypothalamus to secrete CRH where and what happens next?

into the anterior pituitary, these corticotropes then release adrenocorticotropic hormone (ACTH) into the blood stream

What does the somatic motor system do (SMS)?

it innervates and controls skeletal muscle, voluntary movement

Is the hypothalamus comprised of sub-nuclei?

it is comprised of several sub-nuclei that each have distinct functions. These nuclei are can be grouped in three hypothalamic regions: 1. The Supraoptic region (anterior region that sits just above the optic chiasm) 2. The Tuberal region (middle region that sits above the infundibulum) 3. The Mammillary region (posterior region that sits above the mammillary body)

Parvocellular secretory cells

located in hypothalamus secrete hormones that travel to the anterior pituitary. These hormones trigger anterior pituitary cells to secrete hormones that are released into bloodstream to act on glands throughout the body.

reciprocal projections

many brain regions that supply input hypothalamus get hypothalamic projections in return.

how is the stress response 'turned-off'?

negative feedback loop; cortisol can activate receptors in the hypothalamus to shut off this response •Cortisol circulates around the body and binds to corticoid receptors in the brain, including in the hypothalamus •This turns off secretion of CRH, and levels of overall cortisol in the body decrease

what brain region has control of appetite?

no single brain region has control of appetite but, the hypothalamus is important to regulation of metabolic rate, food intake, and body weight

What transmitter does the sympathetic postganglionic neuron use?

norepinephrine (NE), which often spreads far, even into the blood where it can circulate widley

What cells secrete corticotropin-releasing hormone and where are they located?

parvocellular cells of the paraventricular nucleus (PVN) of the hypothalamus in response to stress

Pituitary Gland

pea-sized structure attached to base of the brain that is the body's main endocrine gland.

What stressors activate the hypothalmic-pituitary-adrenal (HPA) axis?

physical and psychological stressors

what are corticotropes?

pituitary cells

what are the neurons in the autonomic ganglia called?

postganglionic neurons

what are postganglionic neurons stimulated by?

preganglionic neurons in the spinal cord or brain stem

What cells release ACh

preganglionic neurons in the sympathetic and parasympathetic divisions of the ANS

NPY/AgRP neurons

produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain.

POMC/CART

produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss.

Orexin

produced in lateral hypothalamus (LH) and it increases appetite and food intake by suppressing inhibitory post-ingestive feedback

reticular formation and nucleus of the solitary tract (brainstem region)

provide information re. arousal and visceral information

Thalamus

sends some information to hypothalamus.

ghrelin

stomach releases it and it increases hunger by stimulating NPY/AgRP neurons

Prefrontal cortex

supplies processed sensory information inform hypothalamic function.

hippocampus and amygdala

supply emotionally-relevant info to integrate autonomic responses with emotional state.

How does the brain decide whether to initiate eating?

the brain integrates insulin and blood glucose levels with other information to decide to eat

how does the anygdala help regulate the autonomic nervous system functions?

the central nucleus of the amygdala (CeA) contributes to parasympathetic outflow

how does the brainstem help regulate the autonomic nervous system functions?

the locis coerculus, rostral and caudal ventrolateral medulla and serotonergic cells of the pontine and medullare raphe contribute to sympathetic outflow

how does the hypothalamus help regulate the autonomic nervous system functions?

the paraventricular nucleus (PVN) is especially important, it projects to the brainstem to influence autonomic outflow

true or false: much of the autonomic nervous system function operates by visceral reflexes

true. Subconscious sensory signals from visceral organs enter spinal cord, brainstem or hypothalamus -> triggers subconscious reflex back to visceral organ to control activity. ex: baroreceptor reflex •Baroreceptors are located in the carotid sinus and aortic arch. •When they detect too much (or too little) stretch (due to elevated or decreased blood pressure, respectively), signals -> brainstem. •A descending signal travels back down -> sympathetic nervous system (via the vagus nerve) •This signal regulates blood pressure by controlling heart rate, strength of heart contractions, and diameter of blood vessels.

Sympathetic ANS

usually most active during crisis (real or perceived), mobilizing energy stores, preparing an organisms for 'fight-or-flight' reactions.

the neurobiology of the stress response

•Acute increases in cortisol is important to instigate actions, such as fight-or-flight. However, chronic stress/elevated cortisol can elicit adverse effects: -Hypertension, cardiovascular disease -Immunosuppression -Insulin resistance -Emotional disorders (anxiety, depression)

therapeutic use for ghrelin?

•Because of observations of altered ghrelin levels (and ghrelin function) in obese individuals, the idea of blocking ghrelin signaling with GHS-R antagonists is of interest as a means of preventing obesity. •It has been demonstrated that vaccinating rats against ghrelin can reduce weight gain. •It remains to be shown whether blocking ghrelin signaling is a viable long-term obesity therapy for humans. •Ghrelin agonists might be useful in the treatment of specific patient groups with anorexia. Interestingly, ghrelin levels can also be influenced by environmental factors... such as how much (or little) sleep an individual typically gets.

the arcuate nucleis and ghrelin

•NPY/AgRP neurons produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss. •Ghrelin stimulates NPY/AgRP neurons, which increases appetite

the arcuate nucleus and PYY

•NPY/AgRP neurons produce neuropeptide Y (NPY) and agouti-related peptide (AgRP) to stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons produce pro-opiomelanocortin (POMC) and cocaine- and amphetamine-related transcript (CART) to inhibit appetite and raise metabolism, promoting weight loss. •PYY, acts mainly by inhibiting NPY/AgRP neurons (reducing appetite, which is in opposition to effects of ghrelin).

the arcuate nucleus and leptin

•NPY/AgRP neurons stimulate appetite and lower metabolism, promoting weight gain. •POMC/CART neurons inhibit appetite and raise metabolism, promoting weight loss. •Leptin activates POMC/CART neurons and inhibits NPY/AgRP neurons, so leptin works to suppress hunger. •Leptin's effects on the arcuate are long-lasting.

role of PPY

•Peptide Tyrosine Tyrosine •Small peptide produced by the small intestine •from cells in the ileum and colon •Has low baseline levels that increase quickly when eating •Increased PYY levels -> decrease appetite •High doses of PYY have been reported to cause conditioned taste aversion in animals and nausea in humans. •Receptors located in the arcuate nucleus and vagus nerve input to the brainstem

ghrelin

•Peptide hormone released from cells in the stomach •Increases during fasting and decreases after a meal •Increased ghrelin levels -> produce increased appetite •Receptors located in multiple brain areas: arcuate nucleus, lateral hypothalamic area, nucleus accumbens, ventral tegmental area •Treating rats with ghrelin acutely stimulates food intake and growth hormone release; chronic ghrelin administration causes weight gain. •Intravenous infusion or subcutaneous injection of ghrelin to humans increases feelings of hunger as well as food intake. •Obese individuals •have low baseline levels •levels do not drop after a meal so no signal for "just ate a meal"

the lateral hypothalamus (LH)

•Stimulating the lateral hypothalamus (LH) brings on hunger. •Low blood glucose levels -> stimulates the LH to produce / release the hormone orexin, which triggers eating.

the ventromedial hypothalamus (VMH)

•Stimulating the ventromedial hypothalamus (VMH) depresses hunger.