Summary Cell biology-Histology lecture 4 Nervous tissue and Digestive system
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Course
Cell Biology-Histology (AB1138)
Institution
Vrije Universiteit Amsterdam (VU)
This document is a summary about the most important topics mentioned in the lecture. The specific nervous tissues and nervous cells are explained, as well as the gut and the different cells lining the gut.
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
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