Nervous Tissue
Nervous tissue is derived from the ectoderm
Central nervous system: spinal cord and brain
Peripheral nervous system: the body in rest, like the guts
afferent system (input → sensory)
efferent system (output → motoration)
Cells which make the neural tissue are the neurons and neuroglia
Neurons
- cell body
- dendrites ← here is where the information comes in
- axons → the information flows through the axon to the end making contact with
dendrites of new neurons, if there is an axon potential
- nucleolus
- nucleus of neuron
Different types of neurons
a) Cortical pyramidal cell → longer dendrite than axon
b) retinal bipolar cell → small dendrite
c) retinal ganglion cell →
d) retinal amacrine cell
e) neurons in mesencephalic nucleus of cranial nerve V
f) Cerebellar Purkinje cells
the complexer the neuron, the more information that needs to be integrated.
Neurons communicate with chemical messengers via synapses and via gap junction
→ chemical messengers (neurotransmitters):
- acetylcholine
- amino acids (glutamine, GABA)
- biogenic amines (serotonin, dopamine, adrenaline)
→ in the axons (presynaptic) in vesicles and released after an electric stimulus via
exocytose
- results in activation of neurotransmitter receptor on the postsynaptic
membrane
Exon branches into smaller processors → telodendrion which ends with a synapse
Synaptic cleft: separation between pre and postsynaptic membrane
→ Neurotransmitters in synaptic vesicles are released at the presynaptic
membrane, while the postsynaptic membrane has receptors for the
neurotransmitters.
, Neuroglia (supporting cells)
- maintain physical structure of tissue
- repair tissue framework after injury
- perform phagocytose
- provide nutrients to neurons
- regulate the composition of the interstitial fluid surrounding neurons
→ found in peripheral nervous system
→ found in central nervous system
● Peripheral nervous system
- satellite cells which support cell bodies of neurons
- schwann cells which make myelin sheaths around peripheral nerves, the
also secrete neurotrophic factors
● Central nervous system
- Oligodendrocytes which make myelin sheaths around central nerves
- astrocytes:
- give support for central nervous system
- help form a barrier between the brain and blood
- secrete neurotrophic factors
- they take up kalium and neurotransmitters
- microglia which act as scavengers, like modified immune cells
- ependymal cells which form barriers between compartments
Schwann cells
● they ensheath axons in the peripheral nervous system, often they also make a myelin
sheath around it which enhances conduction rate of action potentials in axons via
saltatory conduction
● Nodes of Ranvier are for saltatory conduction
Nervous tissue is derived from the ectoderm
Central nervous system: spinal cord and brain
Peripheral nervous system: the body in rest, like the guts
afferent system (input → sensory)
efferent system (output → motoration)
Cells which make the neural tissue are the neurons and neuroglia
Neurons
- cell body
- dendrites ← here is where the information comes in
- axons → the information flows through the axon to the end making contact with
dendrites of new neurons, if there is an axon potential
- nucleolus
- nucleus of neuron
Different types of neurons
a) Cortical pyramidal cell → longer dendrite than axon
b) retinal bipolar cell → small dendrite
c) retinal ganglion cell →
d) retinal amacrine cell
e) neurons in mesencephalic nucleus of cranial nerve V
f) Cerebellar Purkinje cells
the complexer the neuron, the more information that needs to be integrated.
Neurons communicate with chemical messengers via synapses and via gap junction
→ chemical messengers (neurotransmitters):
- acetylcholine
- amino acids (glutamine, GABA)
- biogenic amines (serotonin, dopamine, adrenaline)
→ in the axons (presynaptic) in vesicles and released after an electric stimulus via
exocytose
- results in activation of neurotransmitter receptor on the postsynaptic
membrane
Exon branches into smaller processors → telodendrion which ends with a synapse
Synaptic cleft: separation between pre and postsynaptic membrane
→ Neurotransmitters in synaptic vesicles are released at the presynaptic
membrane, while the postsynaptic membrane has receptors for the
neurotransmitters.
, Neuroglia (supporting cells)
- maintain physical structure of tissue
- repair tissue framework after injury
- perform phagocytose
- provide nutrients to neurons
- regulate the composition of the interstitial fluid surrounding neurons
→ found in peripheral nervous system
→ found in central nervous system
● Peripheral nervous system
- satellite cells which support cell bodies of neurons
- schwann cells which make myelin sheaths around peripheral nerves, the
also secrete neurotrophic factors
● Central nervous system
- Oligodendrocytes which make myelin sheaths around central nerves
- astrocytes:
- give support for central nervous system
- help form a barrier between the brain and blood
- secrete neurotrophic factors
- they take up kalium and neurotransmitters
- microglia which act as scavengers, like modified immune cells
- ependymal cells which form barriers between compartments
Schwann cells
● they ensheath axons in the peripheral nervous system, often they also make a myelin
sheath around it which enhances conduction rate of action potentials in axons via
saltatory conduction
● Nodes of Ranvier are for saltatory conduction
