hypothalamus Flashcards
Nervous system development and function in after-development life is the result of
a NS with physiological system interaction
all systems are important to each other
what does the limbic system and the hypothalamus do
Limbic system “flavors (drives) our acts”; hypothalamus “somatosizes [physiologicalizes] our acts
Hypo – can take you thoughts and feeling and make them into change in physiology
what is the hypo a master of
The neuroendocrine system - releasing hormones into the blood system
ANS – lead to direct physiological effects in the body
The hypo can go back to influence the limbic system - example
Your back or stomach hurting can influence your mood
what is the Central autonomic network
network of visceral afferents
This info is integrated at different levels of the NS
Central autonomic network: input to
brainstem and forebrain structures
what does CAN coordinate
ANS and behavioral needs
Direct connections of CAN - medulla > BS nuclei
To (medulla) nucleus of the solitary tractto > Brainstem nuclei (e.g. vagal motor nucleus)
control of HR and stomach contractions
Direct connections CAN - Ventrolateral medullary reticular formation
To (medulla) nucleus of the solitary tractto > entrolateral medullary reticular formation
modulate BP by altering blood flow in vascular beds
ANS input that are associated with behavior come in at what level of the brain
the midbrain
CAN integrative responses - To(midbrain) periaqueductal grey
Behavioral patterns related to autonomic responses
Example ‘fight or flight behavior’ related to the autonomic response of shunting blood to muscles and brain; involves connections from PAQ to medullary RF
CAN integrative responses - To (midbrain) parabrachial nucleus
Behavioral responses to taste
Relay of visceral sensory information to forebrain nuclei
CAN integrative responses - To (subcortical limbic nuclei) amygdala
autonomic responses of patterned behavioral responses (usually emotion based):
Example:fear or rage; physiologic reactions to chemotherapy occur upon entering treatment room
CAN integrative responses - To (thalamus, cortex) visceral sensory thalamus and visceral sensory cortex
anterior insula and on to anterior cingulate
conscious awareness visceral sensations:
Hunger pains, full stomach, breath holding feeling; conscious awareness and reaction to feeling
what happens whne emotional stress drives the limbic system
it is an increase of sympathetic activity, this is outside of the feedback loop and therefore is not regulated
This cannot be regulated
regulated and non regulated heart rate
normal - Feedback regulated cardiac function
limbic - Influence of mental stress on the heart; not feedback regulated
organs ANS innervation
Two-neuron chains; dual innervation of organs
Sympathetic location
thoraco-lumbar
Sympathetic controls what
Control of pupil dilation
Smooth muscle of the eyelid
sympathetic NT
NOR
parasympathetic is in control of what
Control of micturation- pass urine
lesion in para leads to
disruption of bladder function.
lesion in sym leads to
Horner’s syndrome
The pupil is still constricted
Horner’s syndrome presenations
pupil constriction
partial ptosis of eyelid
decreased sweating; increased vasodilation; ‘dry & red skin’)
cause of Horner’s syndrome
lesion ipsilateral sympathetic outflow to head & neck
para NT
Ach
empty - innervation
Parasympathetic innervation:
S2-4 spinal segment
+ detrussor muscle
cholinergic system
empty reflex
Vesicoparasympathetic reflex: elimination; contracts bladder (detrussor); relaxes urethra
fill - innervation
Sympathetic innervation:
L1-3 segments
- detrussor muscle (b-adrenergic receptor)
+ internal sphinctor (a-adrenergic receptor)
fill - reflex
Vesicosympathetic reflex:
filling; relaxes bladder (detrussor)
tightens the urethra (internal sphinctor)
help - innervation
Somatic motor innervation
S2-4 spinal segments; Onuf’s nucleus
+ external sphinctor muscle
help - reflex
Vesicopudendal reflex:
voluntary control;
inhibited during voiding;
contracted during restraint (‘hold-it’)
where do bladder afferents go to and what do they carry
to lumbar & sacral spinal levels carry pressure, pain
cholinergic system
uses Ach
+ detrussor muscle action
contracts the bladder wall
internal sphinctor action
keeps the fluid in the bladder
what is interesting about B-adrenergic receptor/a-adrenergic receptor
The same transmitter has a different response because of the different receptors
what is the External sphincter innervated by - what kind of fiber
alpha motor neuron
neuron in the sacral cord and travel over pudendal
what kind of control is the external sphincter
Voluntary control
Para bladder innervation orginates where
originate in the intermediate grey of the sacral segment
para bladder post ganglionic fiber innervate what
Post ganglionic fiber innervates the bladder wall and causes the contraction of the bladder –Ach
Sympathetic bladder fibers originate where
originates in the lumbar cord
sym bladder post ganglion fibers go where
Post gang goes to contract the sphincter and relax the detrussor muscle
what does the Coordinating center - bladder
coordinate bladder contraction and inhibitor of the external sphincter – allows the bladder to empty
Make sure that these systems are coordinated
Coordinating center bladder - inputs
Input from spinal afferents
what activates the coordinating center
the cortex near the frontal eye fields
what can override holding of the bladder
the cortex
what happens when we have the urge to go - hold it
Cortex activates pontine somatic center- to hold it
(+) External sphincter
(–) Detrussor muscle
what happens when we want to go - empty
Cortex activates pontine parasympathetic center - to go
(+) Detrussor
(–) External sphincter
Pontine centers for micturition are activated by what
ascending info
spinopontinespinal reflexes
where is the coordinating center for bladder
the pons
control over the external sphincter - voluntary control comes from
the cortex
coordinate bladder contraction and inhibitor of the external sphincter
Lesions rostral to sacral spinal cord disrupt
control andcoordination
Lesions at the sacral spinal cord disrupt
control andcoordination
Uninhibited reflex bladder lesion
lesion between cortex and pons
Uninhibited reflex bladder - is the pontine center intact
pontine center intact
Uninhibited reflex bladder- consequences
Incontinent; emptying complete
Automatic reflex bladder - lesions
lesion between pons and sacral spinal cord
Automatic reflex bladderis the pontine center intact
pontine center disconnected
Automatic reflex bladder - consequences
Incontinent; incomplete emptying
Non-reflex: LMN bladder - lesion
injury bilateral sacral cord or spinal roots lesion
Non-reflex: LMN bladder - consequences
Incontinence; severe retention
(overflow incontinence)
Neural to humoral
NT released in the blood system and then travel to another place in the body
EX: the heart is responsive to neuron-to-neuron transmitter and circulating NT
Neuron to humoral to endocrine to humoral
Neuron makes neural hormone and release it into a portal system – this is picked up by a gland (normally) – this then make a neural hormone and releases it into the blood system
where is insulin a transmitter
the brain
this has complications with diabetes
Anterior hypo is between what two structures
Between the anterior commissure and the optic chiasm
Supraoptic nucleus (SON) and Paraventricular nucleus (PVN) have cconnectcions with what two structure
hypo to the posterior pit
Supraoptic nucleus (SON) and Paraventricular nucleus (PVN) NT and hormone relase
direct release – vasopressin and oxytocin
Magnocellular neurons
what is the function of vasopressin
reuptake of the fluid through the kidney tubercles- fluid regulation and pressure
most things in the anterior hypo have to do with what
fluid balance
Suprachiasmatic nucleus (SCN) get what kind of input
gets direct retinal ganglion input, called the biological clock
This is why light entrains the circadian rhythms
Regulate our physiology by physical patterns
Anterior hypothalamus is responsible for
fluid electrolyte balance; temperature regulation; aging; circadian rhythms
Medial basal hypothalamus role
endocrine regulation
Has control over all the steroid hormones
steroid hormones and cells
can influence the DNA of a cell – as well influencing the receptor on the cell surface
indirect release of medial basal hypothalamus neurons
The neuron in the hypo make a neuronal hormone (releasing factor) that is release in the medial eminence
Releasing factor (RF) is transported in the blood to the ant pituitary
RF is picked up by the neurons in ant pit
these release an activity neurohormone into the blood
Negative Feedback control - medial basal hypo
have enough of product this loop with come back and shut down production
short loop - medial basal hypo
pituitary hormone inhibits at the hypothalamus (e.g. pituitary hormones)
Stop the release of the corticotropic releasing factor
long loop - medial basal hypo
target organ/gland hormone inhibits at the hypothalamus (e.g. steroid hormones)
Higher centers
target organ/gland hormone inhibits at the hippocampus (cortex) then to hypothalamus (e.g. gluccocorticoids)
cortisol > activates the hippocampus > inhibition of the hypo > stop CRF from being released
stress and loops
Stress: if we keep on releasing cortisol, this leads to our hippocampal neurons being activated all the time
Constant activation of our hippo neurons causes them to metabolically burn out
Hippo – memory and learning
Gluccocorticoids
Mobilize energy
Increase cardiovascular activity and readiness
Suppress long term building projects: growth, reproduction, immunity…
When you do not inhibit the hypo there is BLANK release of cortisol
more
When gluc-cort kept on being release - what does the hippo do
tries to protect itself
protection: neurons take there receptors off of the surface of the cells > now things cannot come in > eventually leads to the greater release of cort because the hippocampus is not activating
In the end the hippo neurons will die from being overactivated – loss
Posterior hypothalamus role
mediates physiological response to emotion and drives
major output of the hypothalamus
Posterior hypothalamus connection
limbic system
link between the hypo and the ANS, forebrain (cortex), and limbic
Posterior hypothalamus location
From the mamillary body to the midbrain
Lateral hypothalamus connection
Connects to forebrain limbic nuclei; brainstem nuclei of ANS
Lateral hypothalamus role
emergency and survival responses (mediated with/via posterior hypothalamus);
center for rage response
Hypothalamic hypophyseal tract
carries the direct neuro release from the ant hypo to the pos pit
Median eminence portal system
Medial basal release their releasing hormones
Releasing factor path
Mammillothalamic tract
Meaning full memory and learning
Emotions and drive
Medial forebrain bundle
From the post hypo there is direct connections
Major pathway foe the output of the post hypo
Hypothalamus general functions
Detects information
Compares“to a setpoint”
Output – effects a response
Detects information - External environment
visual, cortical, hippocampal
Detects information - internal environment
visceral afferents, specialized neurons sensitive to physiological stimuli (e.g. osmoreceptors; gluccoreceptors)
Compares“to a setpoint
Integrative nuclei; determine need for a response
The hypo has an idea where the body should be – and compare it to what you are at the moment
role of the hypo
smart control coordinating center.
Its main function is to keep your body in a stable state called homeostasis.
It does its job by directly influencing your autonomic nervous system or by managing hormones
Output – effects a response
ANS via brainstem
Endocrine via pituitary
Behavioral means via limbic system/cerebral cortex
