Midsem Flashcards
what is the function of astrocytes
including influencing neurite growth, regulating extracellular fluid content, removing neurotransmitters.
what is the function of oligodendrocytes
produce myelin sheaths that surround axons iwthin the CNS
what is the function of schwann cells
produce myelin sheaths that surround axons within the PNS
what is the outermost germ layer
ectoderm
what is the middle germ layer
mesodern
what is the innermost germ layer
endoderm
what are transcription facrtotds
proteins that regulate the expression of specific genes. They interact with DNA, binding to the enhancer or promoter regions of a specific gene to regulate its expression
what does presence or absence of a particular transcription factor determine
the fate of a cell by regulating which genes are turned on/off
what is a morphogen?
Morphogens are diffusible chemical substance that acts over long distances to instruct cells to adopt
suitable fates for tissue patterning by forming an activity gradient
what are visceral behaviours
- Automatic/reflex responses
- Innate, well developed at birth
- Visceral/homeostatic behaviours - maintaining metabolism - digestion, respiration, thermogenesis and blood flow + metabolite constitution
what are sensorimotor circuits
sensory neurons detect changes and motor neurons respond to these changes
list the 3 distinct senosry ganglia in the head (visceral afferent)
- visceral snesory ganglia geniculate
- petrosal (IX)
- nodose (X)
what are some unifying features of visceral afferents
- pseudo-unipolar sensory neurons that innervate different visceral organs and convey interoceptive sensory information from the body to the brainstem
- Terminate within the brainstem at the nucleus of the solitary tract (NTS)
what is visceral sensory ganglia geniculate responsible for?
taste - ant. 2/4 of tongue and travels via crnail n 7 (facial n )
what is petrosal (IX) responsible for?
special visceral taste info form the postioer 3rd of the mechanoreceptors located in the carotid bifurficsation and travels via hte 9th cranial n
what is the nodose (X) sensory ganglia
vagus n - general visceral sneosry innervaiton fo th eres to fht ebody
what is the baroreflex
the neural mechansims responsibel for regulting arterial blood pressure and HR - - To maintain oxygen supply
- Removal of co2
Minimising short term blood pressure fluctuations
how can mean arterial pressure be calculated
Mean arterial pressure = cardiac output x total peripheral resistance
how is cardiac output calculated
heart rate x stroke volume
what is inferred from low mean arterial pressure
inadequat eblood flow to the organs / shock
explain how piezo 1 and 2 work
- Elevated BP
- Elevates vascular wall
- PIEZO channels are activated causing inflow of Na+ an Ca2+ and membrane depolarisation
- Action potentials are generated and are transmitted to the medullary cardiovascular centre
how do baroreceptors respond to increased blood pressure
increased blood pressure = increased stertch, increased barorecpetor ffiring rate
what is the baroreflex in response to hypertenion
- In response to hypertension, the baroreflex inhibits sympathetic efferent and increase cardiovagal activity ( decrease HR, increase SNA)
what is the baroreflex to hypotension
- In response to hypotension, the baroreceptors are less active (or silent) and cause an increase in sympathetic efferent activity (increase HR increase SNA) and reduced cardiovagal activity (Increase HR)
