Neuro Exam 3

Point-to-Point Synaptic Connection

Point-to-Point Synaptic Connection

Restricts synaptic communication (restricts flow of info/communication). Uncontrolled/non p2p would be a seizure

Secretory Hypothalamus Synaptic Connection

Stimulates and releases neurohormones. Give you widespread and extended influence over space and time

ANS Synaptic Connection

Provides divergence, presynaptic neuron that causes widespread postsynaptic neurons

Diffuse Modulatory Systems Synaptic Connection

Dopaminergic system that regulates movement, raphe nuclei, keeping us awake, mood elevated depending on what NT is involved

Hypothalamus Defect

Fatal disruption to body function. Failure to develop or disrupted during development. Cannot live without a hypothalamus.

Dorsal Thalamus Defect

Blind spot, lack of feeling. Upper quadrantanopia and feeling. Not as serious as hypothalamus defect.

The Secretory Hypothalamus and Homeostasis

Regulates body temperature and blood composition

Hypothalamus commands in cold weather

Shiver, goosebumps, turn blue. Shunts bloods to organs

Hypothalamus commands in hot weather

Turn red, sweat. Cool the body down by sweating (move liquid inside of body to outside and evaporate off in order to cool you down)

Oxytocin

"love hormone". lactation and decrease hypothalamic function. Expressed during sexual behavior, social recognition, ironically during ethnocentric behavior (committing racist acts)

Vasopressin

"ADH". Regulate blood volume and salt concentration. Leads to water retention by decreasing increased salt concentrations in the blood

Secretory Hypothalamus communication between Kidneys and Brain

Hypothalamus kicks off posterior pituitary gland production of ADH --> kidney produces renin --> releases angiotensin from liver --> go to the blood vessels and kidneys --> relay back up to the subfornical organ. The communication from the kidney will increase thirst. (increase ADH makes you thirst and continues the cycle/loop until you no longer feel thirsty)

Hypothalamic Control of Anterior Pituitary

Parvocellular pathway. Secrete hyperplasia tropic hormone --> portal circulation to either secrete or stop secreting hormone based on stimulation of the particular area.

Secretory Hypothalamus and Stress Response

Periventricular hypothalamus secrete CRH --> ACTH released into circulation --> ACTH stimulates cortisol (stress hormone) release from adrenal cortex

ANS

Sympathetic = fight Parasympathetic = flight

Somatic Motor System

Directly ends on skeletal muscle

Sympathetic Nervous System

Has an automatic or sympathetic ganglia

Parasympathetic Nervous System

Closer to actual muscle or gland that it's activating on and is closer to individual area that it's going to exert its control

Sympathetic division primarily uses what as a primary transmitter

Epinephrine

Parasympathetic division primarily uses what as a primary transmitter

Acetylcholine (releases much closer to actual organ)

Enteric division location

Lining of esophagus, stomach, intestines, pancreas, and gallbladder

Enteric division composition

Myenteric (Auerbach's) plexus and submucous (Meissner's) plexus

Myenteric (Auerbach's) plexus

network of nerves between the two muscular layers (operates muscles)

Submucous (Meissner's) plexus

Controls activity of mucosal glands and muscle

Preganglionic NTs on ANS: ACh

Causing typical ACH to evoke a fast EPSP

Preganglionic NTs on ANS: Ganglionic ACh

Release of ganglion level activates slow EPSPs and IPSPs

Preganglionic NTs on ANS: Preganglionic terminals

Small EPSPs

Postsynaptic NTs: Parasympathetic

Release ACh = local effect

Postsynaptic NTs: Sympathetic

Release norepinephrine = far reaching effects

Postsynaptic NTs: Parasympathomimetic

Mimics or promotes ACh or inhibits norepinephrine

Postsynaptic NTs: Sympathomimetic

Mimics or promotes norepinephrine actions or inhibits ACh

What are the 4 diffuse modulatory systems of the brain

Noradrenergic Locus Ceruleus, Serotonergic Raphe Nuclei, Dopaminergic Sunstantia Nigra and Ventral Tegmental Area (VTA), and Cholinergic Basal Forebrain and Brain Stem Complexes

Diffused modulatory systems of the brain: common principles of the 4 systems

Small set of neurons at core, arise from brain stem, one neuron influences many others (tons of divergence), and synapses release transmitter molecules into extracellular fluid

Noradrenergic Locus Coeruleus

Projects to almost every part of brain. This nucleus is involved in regulation of attention, arousal, sleep-wake cycle, learning and memory, mood and brain metabolism. "blue spot" refers to blue color it has in fresh brain tissue that results from presence of cells with higher concentrations of melanin

What is moderated by Locus Coeruleus

Noradrenaline (aka norepinephrine). Stress and panic responses and how it moderates alertness level

Serotonergic Raphe Nuclei

Path: innervate many of the same areas as noradrenergic system Function: together with noradrenergic system, comprise the ascending reticular activating system

• Particularly involved in sleep-wake cycles, and mood Activation: new, unexpected, nonpainful sensory stimuli

Dopaminergic Substantia Nigra and Ventral Tegmental Area (VTA)

Dopamine reward pathway. Projects to the striatum and facilitates the initiation of voluntary movements. VTA innervates circumscribed region of telencephalon

Cholinergic Systems: Basal Forebrain Complex and Pontomesencephalotegmental Complex

Head down to basal ganglia. Has to do a lot with learning and memory. Releases ACh as its primary transmitter. Regulates excitability of thalamic relay nuclei

Drugs and the Diffuse Modulatory Systems

Psychoactive drugs act on CNS Many drugs of abuse used because they mimic the structures of either serotonin or dopamine

Stimulants (cocaine & amphetamine)

Block reuptake Cocaine: increases amount of dopamine released and targets its reuptake Amphetamine: block norepinephrine and dopamine stimulants and stimulates dopamine release

Role of hypothalamus

Regulates homeostasis

Three components of neuronal response

Humoral response, visceromotor response, somatic motor response

Humoral response of hypothalamus

Blood

Visceromotor response of hypothalamus

Motor response in plexi in gut and down gut tube

Somatic motor response of hypothalamus

Things that make us seek out food, water, heat, cold

Motivated behavior examples of responses when body is cold

Body shivers, blood shunted away from body surface, urine production inhibited, body fat reserves - mobilizes

Motivated behavior of lateral hypothalamus

Initiates motivation to actively seek or generate warmth - homeostasis

Prandial state: anabolism

Take energy and store it as glycogen and triglycerides (nutrients)

Postabsorptive state: catabolism

Break down complex macromolecules

What state should be pushed when wanting to gain weight?

Prandial state

What state should be pushed when wanting to lose weight?

Postabsorptive state

Role of leptin hormone in regulation of body fat and feeding

Normalizes weight over time, regulates body mass even through forced starvation or feeding. Driven by hypothalamus

What part of the hypothalamus is involved with anorexia?

Lateral hypothalamic syndrome due to more leptin signaling

What part of the brain is involved with obesity?

Ventromedial hypothalamic syndrome due to less leptin signaling

What happens when leptin levels increase?

Arcuate neurons release alpha melanocyte stimulating hormone and cocaine and amphetamine related transcripts (anorexic peptides that diminish appetite), increases energy expenditure

Affects on periventricular nucleus of hypothalamus

Cause blood to diminish appetite

Affects on visceral motor of the intermediate grey of the spinal cord

Signal parts of the body to increase activity due to elevated leptin levels

Response to elevated leptin levels

Alpha melanocyte hormones send positive impulse to periventricular nucleus--> stimulates release of ACTH and thyrotropin from anterior pituitary. Alpha melanocyte hormone send negative response to lateral hypothalamic area

Response to decreased leptin levels

Neuropeptide Y and agouti related send negative signal to periventricular nucleus --> inhibit ACTH and TSH and activate parasympathetic division and stimulate feeding behavior --> stimulating lateral hypothalamic area

Lateral hypothalamic neurons stimulating feeding behavior contain:

Melanin-concentrating hormone (MCH) and orexin

What is orexin released by?

Lateral neurons that make you hungry

What are the three phases of the model for short-term regulation of feeding

Cephalic, gastric, and substrate phases

Cephalic phase

Satiety signals low and orexigenic signals high, presented with food will increase interest in going after it. Releases ghrelin --> kick off neuropeptide Y and agouti related neurons in arcuate nucleus

Gastric phase

Stomach is full and distended, feeling of satiety. CCK released in intestines --> stimulates vagus nerve. Pancreas start releasing B cell products (insulin)

Substrate phase

Digestion phase, breaking stuff down

What phase is inulin levels at their highest?

Substrate phase

Changes in blood insulin levels before, during and after a meal

Insulin maximal when food is digested as glucose enters the bloodstream.

Why do we eat? Liking:

Hedonic reward to eating

Why do we eat? Wanting:

Drive reduction

Why do we eat? Electrical self-stimulation:

Experiments to identify sites of reinforcement

Effective sites for self-stimulation:

Trajectory of dopaminergic axons in the ventral tegmental area projecting to the forebrain

Why do we eat? Drugs that block dopamine receptors:

Reduce self-stimulation

Mesocorticolimbic dopamine system

Dopamine reward system in VTA that gets stimulated when eating things we like

Role of dopamine in motivation

Dopamine depleted animals "like" food but "don't want" food. Lack motivation to seek food but enjoyed when available

Stimulation of the dopamine axons

Produces craving for food without increasing the hedonic impact (won't make it taste better)

Changes in hypothalamic serotonin levels (low)

Postabsorptive period

Changes in hypothalamic serotonin levels (rise)

In anticipation of food

Changes in hypothalamic serotonin levels (spike)

During meals

Changes in hypothalamic serotonin level during mood elevation

Rise in blood tryptophan and brain serotonin

Anorexia nervosa and bulimia nervosa

Both accompanied by depression and try to supplement and stimulate serotonin release. Approached more as a psychiatric disorder not a hormonal eating disorder

Motivated behavior of drinking: pathways triggering volumetric thirst

Hypovolemia: decrease in blood volume. Inside mechanoreceptors in major blood vessels sensing that there's not enough fluid in the system --> stimulate vagus nerve --> nucleus of solitary tract and hypothalamus --> slow blood flow to kidneys and slow release of urine to trigger thirst

Motivated behavior of drinking: pathways triggering osmotic thirst

Hypertonicity: increase concentration of dissolved substances in blood (salt). Release of vasopressin (aka ADH), act with VLT --> affect vasopressin secreting magnocellular neurosecretory cells and communicate with posterior pituitary --> release blood to inhibit urine production

What happens if we do not have vasopressin?

Diabetes insipidus (large amounts of pale, watery urine)

What is a loss of insulin called?

Diabetes mellitus

Temperature regulation

Humeral visceromotor and somatic motor responses - hypothalamus will help drive

Humeral visceromotor response and temperature regulation

Neurons in medial preoptic area of hypothalamus

Somatic motor (behavioral) responses and temperature regulation

Neurons in lateral hypothalamic area

Process during a fall in temperature

Thyroid stimulating hormone released by anterior pituitary --> thyroxine gets released from thyroid gland --> increases metabolism

What is a genotype

What people argue "you are what you are when you're born"

Genotype for male

XY

Genotype for female

XX

Are X or Y chromosomes larger?

X

X and Y contain how many genes

1500 and 50 respectively

Where do x-linked diseases occur more and why?

More often in men than women. Women have more copies of all the genes, so have less chance of getting a genetic related disease because they have a better chance of having a good copy of the transcripts on the second gene.

SRY gene

Sex determining region of the Y chromosome, encodes for TDF (testes determining factor)

When do gonads develop?

Within the first 6 weeks, and promote many of the sex related hormones that drive genetic triggers and expression in genes for the person whether they be male or female

Where are major sex hormones (steroids) synthesized?

Cholesterol

Where are steroids (sex hormones) released?

Endocrine glands

Where do endocrine glands get regulated?

Pituitary gland

What is male hormone equivalent of aromatase into estradiol hormone for females?

Testosterone