Nervous excitable tissue L3 Flashcards
What is the nervous system split into?
The central nervous system (CNS) and the peripheral nervous system (PNS)
What is the CNS?
Brain and spinal cord
What is the PNS?
Cranial nerves, spinal nerves, somatic nervous system (SNS) and autonomic nervous system (ANS)
What colour is grey matter in living tissue and why?
It is pink due to blood in the many capillaries coursing through this tissue
What 2 major areas is the brain sectioned into?
Gray matter and white matter
What is gray matter made up of?
It is made up of neuron perikarya (cell bodies), glial cells, axons, dendrites, synapses
What is white matter made up of?
axons and myelin sheaths and glial cells. There are no neuron perikarya (cell bodies) and no synapses
What are the functional divisions of PNS? HINT SAME
Sensory (Afferent) and Motor (Efferent) divisions
What are the sensory (afferent) divisions?
They carry signals to the CNS - receptors to CNS. The somatic division such as touch and pressure and the visceral sensory division such as taste and hunger
What are the motor (efferent) divisions?
From the CNS to effectors. The somatic motor division with effectors such as skeletal muscles and visceral motor division (also called ANS) with effectors in the glands and cardiac/smooth muscles
What can the autonomic nervous system be split into to?
The sympathetic and parasympathetic divisions
What is the somatic nervous system?
Motor innervation of all skeletal muscles
What is the autonomic nervous system?
Motor innervation of smooth muscle, cardiac muscle and glands
Brain cell types?
Neurons, astrocytes, microglia, oligodendrocytes (CNS) and schwann cells (PNS)
What do astrocytes do?
They release growth factors, create scar tissue and control the blood-brain-barrier (BBB).
What do capillaries do in the brain?
They form the blood-brain-barrier (BBB)
What do the oligodendrocytes do?
They provide myelin sheaths that insulate axons
What are the microglia and what do they do?
They are the macrophages of the brain and they provide an immune system, against infections but they release molecules that kill neurons
What is the soma?
The cell body
What do dendrites do?
They receive information
What do axons do?
They conduct information away
What is the synapse?
It is where 2 neurons “meet”
What is the myelin sheath?
It is a protective neuronal “covering”
What is the trigger zone?
The axon hillock
What is the conducting zone?
The axon - may be from 1mm to more than 1m long
What is the output zone?
axon terminals
What is the input zone?
Dendrites and cell body
Neurons can be classified depending on the number of branches directly from cell body. What are these?
Unipolar which is 1 branch, biopolar which is 2 branches and multipolar which can be many branches
For studying neurons what does the H&E method do?
H&E stains the nucleus but no detail on the cytoplasm can be seen
For studying neurons what does the Nissl method do?
Stains RNA but note absence from axon
For studying neurons what does the heavy metal impregnation method do?
Shows detail of cytoplasm, negative image of nucleus.
For studying neurons what does the gold method do?
Shows detail of neuronal shape and presence of cytoskleton in dendrites and axons
What are sensory neurons?
They are nerves that make you feel. They deliver information from sensory receptors in PNS to CNS
What are motor neurons?
They are nerves that make you move.They deliver commands from CNS to PNS, muscle glands.
Explain the 6 steps of neurotransmission:
- Action potentials reach the presynaptic terminal
- This stimulates Ca2+ entry
- Neurotransmitters are then released from synaptic
vesicles - The neurotransmitter crosses the synaptic junction at synapse.
- On the postsynaptic terminal, the transmitter binds to the receptor
- The receptor is activated to transmit a signal in postsynaptic neuron
What is the diameter fo synaptic vesicles?
40-60nm
Where are synaptic vesicles concentrated?
In clusters at nerve terminals
What does neurotransmitter release involve for presynaptic transmitter release?
The targeting of synaptic vesicles (SVs) to release sites, the docking of SVs to plasma membrane and priming to fuse SVs during impulse and then fusion/exocytosis & transmitter release and finally the retrieval of SV by endocytosis.