Nervous System Part 1 - Overview and Nervous Cells Flashcards
what are the functions of the nervous system?
- sensory: detect changes in environment (internal or external)
- integration: processing and decision making (takes sensory information, decides what to do, and tell the motor to do it)
- motor: telling the body what to do in response
what are the two structural organizations of the nervous system?
- central nervous system
- peripheral nervous system
what is the CNS composed of?
the brain and the spinal cord
what does the spinal cord run through?
the vertebral canal of the vertebral bones
what does the PNS include?
all aspect of the nervous system that are not the brain and spinal cord
where is our integration centre?
the CNS
- (our brain and spinal cord)
- decision making system
what works together to bring sensory information in, make decisions and then send motor signals to the body
the CNS and the PNS
what is the biggest component of the PNS?
the nerves
what are the two types of nerves we have in our PNS?
- cranial nerves which originate in the brain
- spinal nerves which originate on the spinal cord
- both have many many branches that go all throughout the body
which types of nerves does the cranial and spinal nerves include through the body?
cranial and spinal nerves will include sensory and motor nerves all throughout the body
what is another word for afferent?
sensory
what is another word for efferent?
motor
- remember by: motor signals are Exiting the brain and spinal cord
what are the components of the PNS?
- cranial nerves
- spinal nerves
- ganglia - little ball looking things
- enteric plexuses in small intestine
- sensory receptors in skin
what is a ganglia?
a place where a nerve in the PNS is going to meet up with another nerve and pass the signal between the two of them
where do we have sensory receptors?
all over the body!
- skin
- organs
- muscles
where are all of the internal and external environmental changes be originally detected?
in the sensory receptors
- which are then connected to a sensory nerve which will bring the information to the CNS
what is often called the brain of the gut?
the enteric nervous system
- the enteric plexuses in small intestine
- this is because it has its own tiny nervous system separated from the others
what does somatic mean?
of the body
which side of the nervous system is our voluntary/conscious aspect?
the somatic nervous system (SNS)
which side of the nervous system will sense and control aspects of body functioning that are involuntary and subconscious?
the autonomic nervous system (ANS)
what is an effectors?
the place in the body where we will cause a change
what are our somatic sensory?
sensory receptors and nerves that detect things like touch, pain and pressure
(conscious)
what is the somatic motor aspect of the SNS
the somatic sensory sends the message to the CNS, and then we get the motor response
- the voluntary control of skeletal muscle
ESSENTIALLY:
- motor signals that are voluntary and that you would notice on a conscious level
what is the visceral sensory aspect of the ANS?
where we detect changing in things that are on a subconscious level
- ex. change in blood glucose level or blood pressure
what is on the response side of the visceral sensory receptors?
an autonomic motor response
- all involuntary
what can we subdivide the autonomic motor system into?
- sympathetic
- parasympathetic
do the sympathetic and parasympathetic aspect of the ANS work mostly with each other or opposite to each other?
opposite
what are the effectors of the motor side of the autonomic nervous system?
- smooth muscle
- cardiac muscle
- glands
what is the enteric nervous system (ENS) involved in?
sensory signaling in the gastrointestinal tract
what are the effectors of the ENS?
smooth muscle, glands and endocrine cells of the GI tract
- things involves in digestion
what do endocrine cells produce?
hormones
what is the sensory aspect of the GI tract going to do?
sense changes in the GI tract such as pressure, chemical level and nutrient levels
can the ENS function on its own?
yes, it can make decisions without sending information all the way back to the CNS
what can override the decisions that the enteric nervous system is making?
the motor aspect of the autonomic nervous system
ex. if you eat a lot of food, the enteric releases a lot of chemicals to digest the food, the enteric signals tell the enteric motor signals to digest, the motor signals tell the effectors but then you run from a tiger, all the blood instead is going to the muscles to run away first, then goes to digest the food
- why you shouldn’t swim after eating
what is the main function cell of the nervous system?
the neuron
what does a neuron do?
sends nervous signals (electrical signals) to other neurons, effectors and/or back to the brain or spinal cord
- they are our signal transmitting cells and they are the core the the nervous system
what are the three components of a neuron?
- the cell body which contains all the typical organelles
- dendrites (extensions of the cytoplasm from the cell body)
- the axon
what are dendrites responsible for?
helping to direct electrical nervous signals in towards the cell body
what are axons responsible for?
carrying signals away from the cell body to the axon terminals to go to another neuron or an effector
are axons cytoplasmic extensions of the cell body?
yes
do all axons have myelin sheath?
no
what is a myelin sheath?
a fatty tissue that is wrapped around the axon
- speeds up how fast an electrical signal can move - allows the signal to hop
what helps the neurons function at their absolute best?
the non-nervous cells of the nervous system
- helper cells
what is another name for non-nervous cells?
the glial cells
what is an astrocyte?
- its a type of glial cell in the CNS
- a fairly large glial cell
- most are positioned between a blood capillary and a neuron
what is the function of an astrocyte?
to regulate which substances can come into contact with the neuron
- makes sure that nothing bad from the blood capillary can get into the neuron and that all the waste products get out into the blood
- also acts as a glue to hold things together
what is an oligodendrocyte?
a type of glial cell in the CNS
- kind of bulbous (smooth ball structure)
- have cytoplasmic extensions that shoot out
what is the function of an oligodendrocyte?
to create myelin sheath
what colour is myelin sheath?
very light, appear white (the white matter in the brain)
what is a microglial cell?
a type of glial cell in the CNS
- a smaller cell that is not as numerous as some of the other cells in the CNS
what is the function of the microglial cells?
to destroy viruses and bacteria that are in the CNS
what are the ependymal cells?
a type of glial cell in the CNS
- cuboidal epithelial cells
- line specific cavities in the brain and spinal cord (where there are open cavities)
- have cilia on them; on the luminal surface (facing into the open space)
ex. found in ventricles
what is the function of the ependymal cells?
to line specific cavities in the brain and spinal cord (where there are open cavities)
how come we have fewer glial cells in the PNS?
because the PNS is out in the body. it does not have the same internal protective system that the CNS has
why doesn’t the PNS needs microglial cells?
because the PNS has all of the other immune system cells to protect from viruses and bacteria
what are the two types of glial cells that we find in the PNS?
- satellite cells
- schwann cells
what are satellite cells?
a type of glial cell in the PNS
- kind of flat, squash down cells
- surrounding a cell body of a PNS cell within a ganglion
what is a ganglion?
where one neuron is passing a signal to another neuron
what will be within a ganglion?
satellite cells covering the cell bodies
what is the function of a satellite cells?
to regulate nutrient and waste movement between the neuron and the external environment
- similar to astrocyte of the CNS
what is a schwann cell?
- a type of glial cell in the PNS
- similar to the oligodendrocyte of the CNS
- flat cells that wrap around the axons of the PNS to form the myelin sheath
what is the function of a schwann cell?
wrap around the axons of the PNS to form the myelin sheath
- similar to the oligodendrocyte cells
what is multiple sclerosis?
an autoimmune disease where the immune cells of your body attack the myelin sheaths surrounding nervous system cells (surrounding axons)
- a progressive loss of body function starting with muscle weakness all the way to potentially complete breakdown of CNS function (signals cannot travel fast enough without function myelin sheaths)
what does the name multiple sclerosis come from?
multiple - happens in multiple areas around the body and on multiple neurons
sclerosis - the myelin sheaths deteriorate to form a sclerosis (a hardened plaque, instead of the squashy fatty material that it is supposed to be)
when does multiple sclerosis first appear?
between the ages of 20 and 40 years
- females are affected twice as often as males
are there drugs that can cure multiple sclerosis?
no, only several drug treatments that can slow the progression of multiple sclerosis
