Cells and tissues of the nervous system Flashcards
PNS consists of nerves of (2)
- Cranial nerves
- Spinal nerves
What fibres do spinal nerves carry (4)
- Afferent -Sensory
- Efferent - motor
Efferent- motor consist of :
- Somatic motor
- Autonomic motor
Autonomic consist of :
- sympathetic
- parasympathetic
2 cell types making up the nervous system
Neurons Glia/ glial cells
Are glial cells excitable
No, supporting cells that support neurons.
Typical neuron consists of (4)
MULTIPLE DENDRITES, 1 CELL BODY, 1 AXON & SYNAPTIC TERMINALS
What is the cytoplasm of the cell body of a neuron known a, and What is the cytoplasm of the axon of a neuron known as?
and what is the rough endoplasmic reticulum(rER) called?
cell body cyto-Perikaryon
Axon cyto- Axoplasm
rER- Nissl bodies
Do neurons proliferate by mitosis
No, they proliferate by amitosis (unusual form of cell division in which the nucleus and cytoplasm divide by constriction without the formation of chromosomes)
Are neurons or glia bigger
Neurons
Axons may or may not be covered in a
Myelin sheath
Purpose of a myelin sheath
Increase conduction speed by “saltatory conduction” where the action potential jumps fron on mylein sheath to other, without going striaght into each myelin sheath.
Myelin sheath is formed by what type of glial cell -in the PNS -in the CNS
PNS - Schwann cells CNS - oligodendrocytes
3 types of neurons
Multipolar - e.g. motor neurons
Bipolar olfactory mucosa, retinal nerve fibres
Pseudounipolar - e.g. sensory neurons
What type of neurons are motor neurons
Multipolar
What type of neurons are sensory neurons
Pseudounipolar
Name 6 types of glial cells + which of these are in the CNS (4) and the PNS (2)
CNS: 1.Astrocytes 2. Oligodendrocytes 3. Microglial cells 4. Ependymal cells PNS: 1. Schwann cells 2. Satellite cells
Most abundant glial cell in the CNS
Astrocytes
2 functions of astrocytes
- Provide structural and biochemical support to neurons
- Forms part of BBB (due to its end feet projections)
Function of microglia, and why do you need specific cells for this function?
Phagocytosis and scar tissue formation, because of the BBB
What is the function of oligodendrocytes and Schwann cells?
Myelination
Function of ependymal cells (a type of glial cell)
Linning the cavaties of the brain called: ventricles and they also line the central canal of the spinal cord.
What is the function of satellite cells?
Unknow, but they surround neural cell bodies
What is grey matter composed of
Cell bodies of neurons
Focused collections of neuronal cell bodies are called in the CNS
nuclei
- Focused collections of neuronal cell bodies outside the CNS are called
- what is the name given to bundle of axons connecting nuclei?
1- ganglia, e.g. DRG
- Fibre tracts or nerve tracts
Function of the BBB (brain blood barrier
SEMIPERMEABLE membrane allowing passage of water, some gases, and hydrophobic (O2, CO2) molecules by passive diffusion, as well as the selective transport (transport protein required) of molecules such as glucose and amino acids
Circumventricular organs are those that lack a
BBB They have a highly permeable microvasculature
Where are circumventricular organs found
Midline structures around the third and fourth ventricles
Drugs entering brain have to be … … or use suitable … or else it can’t cross the BBB
lipid soluble vectors
What special feature do astrocytes have
Long end feet projections that surround synapses & capillaries
BBB consists of (3)
- Tight junctions between endothelial cells
- Thick basal lamina
- Endfeet of astrocytes that surround endothelial cells
name the 4 ventricles and indicate which part of the brain they lie?
- (1st and 2nd )lateral ventricles - (2, L & R), c-shaped located in the cerebral hemispheres
- 3rd ventricle- The interventricular foramen (formen of munro) connects the lateral ventricles and the 3rd. the 3rd ventricle lies in the diencephalon.
- 4th ventricle lies behind the pons and medulla and in front of cerebellum ( lies in the hindbrain). The cerebral aqueduct lies in the midbrain and connects the 4th ventricle with the 3rd ventricle
CSF is found where (3) and where is formed or produced and where it is absorbed?
- brain cavaties (VENTRICLES)
- CENTRAL CANAL OF SPINAL CORD
- SUBARACHNOID SPACE
CSF is formed by the choroid plexus in each ventricle
CSF is absorbed by ararachnoid villi into saggital sinus ( venous channel in the brain).
CSF protects the brain by providing…
buoyancy which prevents the weight of the brain from compressing the cranial nerve roots and blood vessels against the internal surface of the cranium
3 layers of meninges
Dura Arachnoid Pia
Which layer of the meninges is vascularised
Pia
What direction does the impulse travel in the multipolar and the in the pseudounipolar neurons?
Multipolar neuron: from the denderite —- to cell body—– to Axon
Pseudounipolar neuron: denderite—- bypass the cell body striaght to axon
Where does the cell body of the multipolar neuron lie?
- Multipolar neurons: the cell bodies are stuitated in the CNS ( brain or spinal cord)
- Pseudounipolar neurons: the cell bodies are situated at the doorsal root ganglia
Collection of neural cell bodies in the spinal cord is called?
grey matter
