Nerve tissue Flashcards
Nissl Bodies
ribosomes scattered in the cytoplasm of the neuron. Stain dark purple
initial segment
is where the action potential is generated
epineirum
basal membrane
type 4 collagen and integrin
The blood brain barrier
Cell body
it’s the central part of the neuron which has neuron, organelles, projections called dendrites, and a long projection called axon
axon
conducting region which generates electrical signals
Neuron classifications by structure:
unipolar:
bipolar: rare; associated with receptos for special senses, found in olfactory epithelium in the ganglia os vestibulochoclear
multipolar: ubiquitous (todos lados) are generally motorneurons, spinal cord and in the cerebral and cerebellar cortices.
Neurons classifications by function
-
sensory/afferent neurons- senses to CNS
- somatic afferent -convey sensations of pain, temp, touch, preassure of the body surface
- visceral afferent- transmit pain impulses and other sensations from internal organs mucous membrans, glands and blood vessels
-
motor/efferent neurons- CNS to muscles
- somatic efferent: voluntary impulses to skeletal muscle
- visceral efferent: involuntary impulses to smooth muscle, cardial conducting cells and glands
- interneurons: located in CNS, establish networks of neuronal circuits between sensory and motoneurons and other interneurons
Identify parts of the nervous system and the classification
The sensory (afferent) component ___________ information and _________ to the CNS for processing
The sensory (afferent) component that receives information and transmits it to the CNS for processing
most unipolar
The motor (efferent) component ___________ to ________ such as muscles and cells
The motor (efferent) component transmits to effectors such as muscles and cells
mostly multipolar
The motor component divides in:
- Somatic – motor output controlled consciously or voluntarily (eg, by skeletal muscle effectors)
- Autonomic – motor output not controlled consciously (eg, by heart or gland effectors)
Fight and flight responses
- icreases heart rate
- raises clood pressure
- diverts blood flow to working muscles
- releases sugars/fats into bloodstream
- inhibits digestion
- reduces appetite
- dilates pupils
sympathetic control
“Rest and digest”. Control the body’s response while at rest .
- slows down heart rate
- decreases blood preassure
- dilates blood vessels
- promotes energy storage
- stimulates digestion
- increases appetite
- constricts pupils
parasympathetic nervous system
The cells of the nervous system are derived from:
ectoderm
What are the cells of the nervous system?
neurons: responsible for the receptive, integrative, and motor functions of the nervous system
supporting cells (nueroglial cells): responsible for supporting, protecting, and assisting neurons in neural transmission
Types of support cells: Neuroglia
- astrocytes
- oligodendrocytes
- microglial cells
- ependymal cells
- schwan cells
What are neuroglia cells and their functions?
Known also as glial cells, do not participate in synaptic interactions and electical signaling. The most numerous type of cell in the brain. Lack axon and dendrites.
- Physical support and protection for neurons
- Insulation for nerve cell bodies and processes that facilitates rapid transmission
- repair neuronal injury
- regulation of the internal fluid environment
- clearance of neurotransmitters
- metabolic exchange between the vascular system and the neurons of the nervous system
What are the parts of the neurons?
The neuron structure :
- the nucleus is central y ovoid
- rER is a prominent feature
- numerous mithochondria
- neurofilaments
Perikaryon
the cell body of a neuron
Inclusions
brown or black melanin granules in some neurons in certain regions of CNS in the sympathetic ganglia. They can be composed of lipofuscin, lipid droplets, secreting granules (signaling molecules).
_________________ and ______________ are precursos of some pigments in inclusions, are also precursos of neurotransmitter dopamine and noradrenaline
Dihydrophenylalanine and methydopa are precursos of some pigments in inclusions, are also precursos of neurotransmitter dopamine and noradrenaline
Neural cytoskeletal components
they have neurofibrils from the cytoplasm into processes. Neurofibrils are composed of:
microtubules
neurofilaments
microfilaments
microfilamento MAP-3 is present only in axon
microfilamento MAP-2 is present in cell body and dendrite
nerve impulses will be received by _______ and they are transmitted ________ the _______.
nerve impulses will be received by dendrites and they are transmitted towards the body.
What organelle is abundant in dendrites?
mitochrondia
what is a axon and function?
Transmit the stimuli to other neurons effector cells, convey info away from cell body to another neuron or efector (muscle)
Axon Hillock
site from where axon originates (el cuello). Usually lacks cytoplasmic organelles such as Nissl Bodies and golgi cisternae.
What is the initial segment?
It’s the region between the axon hillock and the myelin sheath and its where the action potential is generated
plasmalemma
the cell membrane of neurons
Nerve impulses are conducted _________along ____________ than along _______________
Nerve impulses are conducted much faster along myelinated axons than along unmyelinated axons.
White matter
area where we have myelinated axons
gray matter
area where we have unmyelinated axons
anterograde transport
transport is from the cell body to axon terminal. Its used in translocation of organelles and vesicles as well of macromolecules, such as actin, myosin, clathrin.
retrograde transport
transport is from the axon terminal to the cell body. Small molecules and proteins destined for degradation are transported to endolysosomes of th soma.
Some viruses use it to spread fro one neuron to the next and its how toxins are transported into the CNS
Which specilized juction facilitate transmission of impulses between presynaptic and postsynaptic neuron?
synapses
What are we seeing? What its happening?
Diagram showing a synapse releasing neurotransmitters by exocytosis from the terminal bouton. Presynaptic terminals always contain a large number of synaptic vesicles containing neurotransmitters, numerous mitochondria, and smooth ER as a source of new membrane. Some neurotransmitters are synthesized in the cell body and then transported in vesicles to the presynaptic terminal. Upon arrival of a nerve impulse, voltage-regulated Ca2+ channels permit Ca2+ entry, which triggers neurotransmitter release into the synaptic cleft. Excess membrane accumulating at the presynaptic region as a result of exocytosis is recycled by clathrinmediated endocytosis, which is not depicted here.
Classification of synapses
axodendritic: axon conecta con dendritas de otro axon
axosomatic: axon conecta con soma, cuerpo.
serial axoaxonic:
axoaxonic: Axon conecta con otro axon
Where can happen synapses?
terminal bouton and on passage bouton
synapses can be :
chemical or electrical
What are neuromusculat junction/motor end plate?
where neruon synapse with skeleytal muscle, the specialized synapse.
What are peripheral nerves?
Bundles of nerve fibers outside the CNS sorrunded by several investments of connective tissue
Peripheral nerve structure:
Smaller elements, fiber, will be covered by endoneurium, then the fascicles will be covered by perinerium, and the groups of fasciles will be covered by epinerium
epineurium
Epinerium is composed of dense irregular collagenous connective tissue containing some thick elastic fibers that completely surround the nerve
perineurium
Its inner surface is lined by several layers of epithelioid cells joined to one another by zonulae occludentes (tigh juctions) and sorround by basal laminae to have the blood brain barrier
covering fascicles
endonerium
cover the nerve fibers, loose connective tissue
Peripheral neuroglia
Central Nervous System neuroglia
ALME
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
There not easy to identify in H&E
astrocytes
Two types: protoplasmic, in grey matter, and fibrous in white matter.
stellete shaped cells. they have many short branching processes, the foot of astrocytes form part of the blood brain barrier. Remove ions, neurotransmitter, and remnant if neuronal metabolism.
They have intermediate filaments called glial fibrillar acidic protein, GFAP, this is unique to astrocytes.
oligodendrocytes
Two types: interfasicullar o satellite
manufacturing and maintaining myelin of CNS , a single cell can provide for 50 axons.
microglial
originate in bone marrow and its part of phagocytic cell population. They clear the debris and damaged structures in CNS
ependymal cells
low columnar to cuboidal epithelial cells lining ventricles of brain and central canal of spinal cord. some have cilia to move cerebrospinal fluid
Schwann Cells
Envelop one axon per cell to provide myelin covering
function: support myelinated and unmyelinared nerve.
Peripheral Nervous system neuroglia
Nodes of ranvier
rich in votage Na ion channels
blood brain barrier
group of capillaries in brain in order to protect from the entrance of molecules could damage this tissue. Epithelial cell with tight junctions resting in basal lamina, perocytes (substitue for smooth muscle for contraction) then the foot processes of the astrocytes
internuerons
most abundant. Impulses between sensory and efferent neruons.
