PSL - CNS and senses up until Lec 4 Flashcards
what make up the CNS vs the PNS
the CNS is made up of brain and spinal cord while the PNS is made of everything outside the CNS as it includes all neurons and parts of neurons outside CNS
how is the PNS further divided into
PNS is divided into the somatic nervous system which controls volunatry action using skeletal muscle and then the autonomic nervous sytem which maintain the viseral functions like heart rate and breathing
what is the enteric nervous system
it is part of autonomic nervous system which is controlled by digestion and movement of gut as it gets input from spinal cord but cna also work independentaly
What are the ventricles in the brain and what are they filled with
thereare 4 ventricles: 2 lateral vnetricals-one in each hemisphere-, third ventricle, fourth ventricle which are connected to spinal cord through central canal
all are filled with CSF
order the following from one with most number of neurons to least: CNS, enteric nervous system, and PNS
CNS has the most as the brain by itself contain around 86 billion and then the spinal cord has another 1 billion
PNS which has around less than 1 billion
ENS which has around 100-600 millions
What are glia cells
found in both CNS and PNS to protect and support neurons
how are the white and grey matters of teh CNS different
grey matter- have nerve cell bodies, unmyelinated axons, nd dendritis, the cell bodies are arranged in layers or in clusters called nuclei
white matter- consist of myelinated axons running in bundles called tracts
What are clusterrs of neurons called in PNS and what are bundles of axons called in PNS
cluster of neurons= ganglia
bundle of axons= nerves
how many segments does the CNS have and what do these segments consist of
there are 31 segments and each has pair of spinal nerves which consist of dorsal root and ventral root
How much energy does the brain utilizes
the brain make up around 2% of body’s mass but gets 15% of blood pumped by heart and consumes half of body’s glucose
even though that sounds like brain is using too much, thta is nothing compared to amount of energy other computers need that try to mimic teh brain
How does the CNS save energy
by limiting the communication of neurons since neurons communicate by sending AP down their axons, these AP takes lot of energy and energy supply to CNS support low rate of firing as it permits only 4% of neruons to fir in the cortex which is one spike every 6 sec
so communication is expensive and CNS has to use it sparingly
what is the difference between the dorsal root and ventral roots of the segment in spinal cord
dorsal root- carries afferent signal which is an incoming sensory signal and the dorsal root ganglion has cell bodies of neurons carrying these signals
ventral root- caries the efferent signal which is an outgoing one from CNS to body which also includes motor signals
dorsal= toward the back, ventral= toward the belly
where can the grey matter be found and where are the dorsal and ventral horns
the grey matter is in teh middle of spinal cord and has butterfly shape where it has ventrical and dorsal horn on each side
wht are the two nuclei in the grey matter
sensory nuclei- in dorsal horn because the signal arrive on dorsal root as somatic sensory nuclei get signal from skin and visceral sensory nuclei get signal from viscera , there is one somatic on eth right dorsal horn and one viseral one the left dorsal horn
efferent nuclei- are ventral, the autonomic efferent nuclei on the right ventral horn sends command to gland and smooth muscle and the somatic motor nuclei in leftventral horn send command to skeletal muscle
what are the 3 types of tracts that the white matter consist of
ascending tracts- carry sensory signal to brain, are mainly dorsal since sensory signal arrive at dorsal horn
descending tracts- are ones carrying signal from brain as they are mainly ventral, where the outgoing signal leave CNS
propriospinal tracts- stay in the spinal cord
How does the knee crack reflex happen when the physician hit the knee with rubber hammer
the hammer stretch’s a ligament below the kneecap and the snesory fibers carry this stretch news to dorsal horn and the sensory fibres send a branch up to teh brain but aslo excites neurons in ventral horn so those send signal out to the leg muscles to contract and counter the stretch so teh spinal cord ends up responding to stimuli without consulting the brain
\What are teh major six divisions of the brain
the cerebrum, cerebellum, pons, medulla, diencephalon, midbrain
What does teh cerebral grey matter include
an outer layer called cortex, limbic sysrtem, and basal ganglia to help control movement
What make up the brain stem and what are some of the main functions of the brain stem
brain stem consist of the medulla, pons, and midbrain and it is the main central center for any autonomic functions and reflexes like breathing, swallowing, vomitting, and regulating blood pressure
what cranial nerves arise from brain stem
cranial nerves III-X, XII,
What connects the 2 hemispheres
the corpus callosum whoch is large bundle of myelinated sheath
what are cranial nerves
the ones that enter and leave teh brain rather than the spinal cord, the information arrive or leave brain to go otr come from peripheray
What are the functions of the parts that make up teh diencephalon
thalamus- process information going to and from cerebral cortex
hypothalamus- regultes behavioural and endocrine and autonomic homeostasis ]
pituitary and pineal glands secrete hormones
what consist teh diencephalon
the thalamus, hypothalamus, pituitary, and pineal