Anatomy : nerves / Neuronal controll Flashcards
How does neuronal control occur ?
3
1- Neurones receive, integrate and communicate signals (afferent =sensory , interneurones =relay, Efferent =motor neurones )
2- The nervous system Is divided into :
-CNS - Brain and spinal cord (thinking, cognition, emotion and consciousness )
-PNS ( autonomic and somatic ) sensory , motor functions .
compare and contract the neuronal and endocrine system (6) -what is it made of ? -transmission ? -speed? -duration? -response proximity ?
nervous system : 1-made of neurones 2-uses electrical and chemical impulses 3-trasmission through neurotransmitters and neurones 4-speed of transmission is FAST 5-duration is SHORT TERM 6-response is LOCALIZED
Hormonal system : 1-secretory cells 2-uses chemicals called hormones 3-transmission occurs via blood plasma 4-speed of transmission is SLOW 5-Effect is LONG TERM 6-Response can be widespread even thought there are specific target organs
what is the basic function of the PNS and the CNS
CNS : controll system
Brain- main data handling computer
Cerebrum -regulates thought , emotions and memory
Cerebellum =coordination
Brain stem =Basic functions ( breathing , swallowing , heart rate - involuntary )
PNS:composed of all the sensory and motor nerves - take the data to and from CNS
- connects the CNS to organs
- split into Autonomic( which is involuntary control) and somatic ( which is Voluntary control = skeletal muscle )
describe the structure and effects of the parasympathetic nervous system
(6)
- nerves originate from the Brainstem = cranial nerves (sacral region of spinal cord )
- LONGER pre ganglionic neurone (releases ACh)
- SHORTER post ganglionic neurone (releases ACH)
- attaches to smooth muscle , glands
what does it do ? REST AND DIGEST -uses ACH to slow heart beat -stimulate digestion -stimulate bile release -constricts airways -stimulates tear production and salivation -constricts pupils
describe the effects of the sympathetic nervous system
6
Sympathetic nervous system = fight or flight response (nerves originates from T1-L2 of the spinal cord )
-SHORTER PRE ganglionic neurones (ACH)
-LONGER POST ganglionic neurones( NORADRENALINE)
Fight or flight :
-constricts blood vessels
-accleterates heart beat
-stimulates sweat production
-dialates pupils
-stimulates glucose production and release
-directs/ limits blood away from digestive system it organs which need it more
what is the difference between autonomic and somatic reflex arcs ?
they are the same for the AFFERENT PART
they are different at the EFFERENT part :
1-autonomic pathway has pre/post (2 step) GANGLIONIC neurones ( the post ganglionic is unmyelinated)
- the autonomic system all has the effectors as : cardiac tissue, glands or smooth muscle
-axon doesn’t necessarily end at synapse , they have post ganglionic varicosity’s ( modified axon ending enables Huge amount of neurotransmitter to be trasmitted and to diffuse further )
2- The efferent pathway in the Somatic NS is only one motor neurone with no ganglion ( it is myelinated )
-the neurone always ends at SKELETAL MUSCLE.
what are the structural classifications of neurones ?
(4)
ABPM
1-anaxonic neurones (short and you can’t tell the axons apart from the dendrites -found in brain and retina )
2-Bipolar- axons and single dendrite on opposite ends of the same soma ( sensory neurones ie : smell, sight, hearing)
3-Pseudounipolar neurone- axon splits into 2 - so one is peripheral and one is anterior .(the dendrites just emerge from the axon- they link up the CNS)
4- Mulitpolar neuron- most famous , 2 or more dendrites SEPERATE from the axon ( found everywhere)
what’s inside an axon soma ?(4)
1-Nissi bodies = RER and ribosomes = protein synthesis
2-Mitochondria
3-Neuropil surrounds cells = end bulbs, axons , background
4-the rest is the same as a normal cell
what are:
-neurotubules?
-neurofilaments ?
(3)
1- neurotubules =part of cytoskeleton, aid transportation of organelles, vesicles mRNA down axon and also into the soma.
2.Neurofilaments =part of cytoskeleton-regulate structure and axon diameter.
what's the connective tissue around : -neurone -nerve fascile -nerve (3)
- around a neurone = ENDONEURIUM
- around Nerve fasicle =PERINEURIUM
- around Nerves = EPINEURIUM
What are the neuroglia in the PNS ?
2
neuroglia = supporting cells
1) Schwann cells = produce myelin sheath around ONE axon.
2) Satellite cells =regulate the external chemical environment
What is the neuroglia in the CNS?
4
1) Oligiodendrocytes = form myelin sheath around MANY axons, not just one.
2) Astrocytes - maintain chemical /electrical gradients and environments by absorbing K+ ions and forms BLOOD BRAIN BARRIER
3) Ependymal cells- line the cerebral ventricles= spaces within the brain which contains CSF and the ependymal cells control what comes in and out!
4) Microglia = originate from monocytes and regulate immune defence in the brain (injury repair, Brain development )
how does myelination occur and why is it useful
4
1-schwaan cells wrap around the axon
2-consecutive layers of the membrane around the axon creates myeline 8 make of the phospholipid bilayer )
3-Cytoplasm and nucleus is pushed to the outside
advantages :
+saltatory conduction
+very quick conduction
+depolarisation at the nodes of ranvier
what are the meninges?
- structure
- layers
- function
covering of the Brain !
1-Dura mater (tough mother - dense irregular connective tissue, inelastic covering has 2 layers:
-meningeal layer
-periosteal layer (near skull outer layer )
normally joined together but they separate in dural- venous sinus ( cavities ) = collect blood
2-Arachnoid mater
- spider web like made of collagen and elastic fibres
- contains subdural / sub arachnoid space =CSF and blood vessels
3-Pia mater- thin layer surrounding brain!
what is the choroid plexus ?
2
- site of CSF production
- network of capillaries(with holes), ependymal cells
- ependymal cells filter the blood plasma
