Lecture 8 - Nervous System #1 Flashcards
What are the two major divisions of the Nervous system?
- > Central nervous system (brain and spinal cord) - > peripheral nervous system (anything else, adjacent nerves etc.)
What are the main properties of the nervous system
Excitable - > respond to stimuli
Conductivity - > excited cells conduct and transport impulse
Secretion - > neurotransmitters are secreted in reaction to impulses
Longevity - > most neurons will last a lifetime
Amitotic - > (amitotic cells cannot replicate through mitosis) *LAST TWO ARE CONNECTED*
types of nervous tissue
Neurons - > larger, responsible for impulse propigation
Neuroglia - > smaller, support/ maintain neuron cells
Label the neuron
astrocytes
- > in CNS
- > form blood-brain barriers by covering caplaries with perivascualr feet
- > small molecules can go through the gaps and into the bloodstream (water or glucose)
oligodendrocytes
- > reponsible for making myelin (allows faster impulse propgation)
- > attached to myelin sheath of neuron
- > in CNS
Microglia
- > in CNS
- > small cells near blood vessels which clear away waste/ dead cells (phagocytic cells)
Ependymal cells
- > in CNS
- > form epithlial membrae that lines brain and spinal cavities
- > produce cerebrospinal fluid
Satelite cell
- > in PNS
- > small flat cells which surround the neronal soma (cell body of unipolar neurons)
pns ganglia
ganglia (pl. ganglion) are a group of neuron cell bodies located in the peripheral nervous system which house the cell bodies of afferent and efferent nerves
schwaan cells
- > in PNS
- > cells encicling PNS axons with myelin sheaths
- > gaps in between are called nodes of ranvier
- > increase propogation speed
Myelinated vs Unmyelated axons
Myelinated
- > fully covered
- > white tissue
Unmyelinated
- > embeded in the surface; not wrapped
- > grey matter
- > adding chocolate chips to cookies
What are synapses
- > where a neuron connects to either another neuron or muscle
- > use chemical neurotransmitters to induce an electrical charge
What are the parts of the synapses
- Presynaptic bulb
- > synaptic vescicles
- > Synaptic end bulb
- > presynaptic membrane - Postsynaptic neuron
- > Postsynaptic membrane
(neurotransmitter receptor site)
- Synaptic crest
Classification of Neurons
- > Multipolar neurons (most neurons)
- > Bipolar neurons (cell body intergrated in middle of axon)
- > unipolar neuron (attaches to middle of the axon)
Basic functions of nervous tissue
Sensory (input) - > senses changes with sensory receptors
Integration - > interpreting and remembering those changes
Motor (output) - > reacting to those changes with EFFECTORS
What are effectors?
a gland or a muscle that becomes active in response to stimuli
(muscular contractions or glandular secretion)
Classification of Nerves
Mixed nerves - > both sensory and motor fibres; send impulses to and from CNS
Sensory (afferent) nerves - > send impulses towards CNS
Motor (efferent) nerves - > send impulses away from CNS
Sensory Neurons
- > neurons of the sensory nervous system
- > conduct impulses from somatic and visceral receptors
- > most unipolar, cell bodies found in poserior root ganglia
Interneurons
- > receives, processes and stores information from stimuli from many different neurons
- > “decides” how body responds to stimuli
- > generally multipolar
Motor neurons
- > conduct motor output to somantic and viceral effectors
- > all multipolar
parts of a nerve cell
- > Endoneurium (wraps axon)
- > perineurim (wraps fasicles/multiple axons)
- > epineurium (wraps nerve)
What is the fasicle
A bundle of axons wrapped in perineurium
which two systems further divide the peripheral nervous system and what are their functions
Sensory (afferent) division
- > conduct impulses to the CNS
Motor (efferent) division
- > conduct impulses away from the CNS to effectors (muscles or glands)
which two divisions make up the motor division of the PNS; what are their functions
Somatic nervous system
- > conducts impulses from CNS to skeletal muscles
Autonomic nervous system
- > conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands (involuntary)
which two divisions make up the autonomic nervous system of the PNS; what are their functions
Sympathic division
- > mobilizes body systems during activity
Parasympathic division
- > promotes housekeeping activities during rest
- > conserves energy
What are the types of nerve function
- > sensory nerve axons function to bring sensation stimuli to the brain
- > motor never axons function to bring stimuli from the brain to the target organ (muscle, gland etc.) to elicit a response
Directional terms to descibe the brain
Rostral - > Towards the nose
Caudal - > Towards the tail
List all layers of cranial meninges
- > Dura Mater (strongest, 2 outter layers)
- > Arachnoid mater (where cerebrospinal fluid circulates, choroid plexus, arachnoid villi)
- > Pia mater (thin delicate; wet paper towel)
choroid plexus main functions
- > blood - cerebrospinal fluid barrier
- > cerebrospinal fluid production
list all cranial dural septa and what do they do
*septa/septum devide things*
Falx Cerebri - > protects into longitudinal fissure and separates brain into left and right cerebral hemispheres
Tentorium cerebelli - > separates the cerebrum from cerebellum; anterior surface has a gap (tentorial notch) to allow passage of brainstem
Falx cerebelli - > partition which separates left and right cerebellar hemispheres
Diaphragma selae - > small semptum between pituitary and hypothalamus
functions of cerebrospinal fluid
- > allows brain to “float” and reduce its weight
- > prevents ingury from physical trauma
- > forms liquid cushion around CNS structures
Name all brain ventricles
- > Lateral Ventricles (Left/Right)
- > Third Ventricle
- > Fourth Ventricle
Explain the blood-brain barrier and how it works
- > strictly regulates wht substances can enter the interstitial fluids of the brain
- > Perivascular feet (astrocytes) are the “gatekeeper” which block wastes, certain proteins etc. from entering
nissl bodies
also know as chromotophilic substances, large granular bodies found in neurons
neurofibrils
intermidiate filaments found in the cytoplasm of neurons
axon hillock
where where the axon terminal and cell body merge
synaptic boutons
aka. axon terminal, small swellings found at the terminal ends of axons, where synapses are located
neuroglial cells
support cells
