nervous tissue Flashcards
what is the nervous system
enables the body to respond to continuous changes in its external and internal environments
what is the central nervous system
spinal cord and brain
what is the peripheral nervous system
cranial, spinal peripheral nerves and ganglia
what is the main component of the nervous system
nervous tissue
what is the function of neurones
conducing cells
- structural and functional unit of nervous system
what is the function of neuroglial cells
supportive and protection cells
- not involved impulse transfer
when does the neural tube develop
3rd week from the ectoderm
what induces neurulation in embryos
- axial structure notochord
what is neurulation
formation of the embryonic neural plate and its transformation into the neural tube
what does the neural crest cells form
- pigment cells
- neurones of the dorsal root ganglia of spinal nerves
- autonomic ganglia
- Schwann cells
- adrenal medulla
- bone and cartilage of lower jaw
what does the neural tube form
- CNS
- neurons and most gilal cells
what does the cranial part of the neural tube form
brain
what does the trunk of the neural tube form
spinal cord
what are the shapes of neurons
- rounded
- oval
- star shaped
- pyramidal shape
how many neurones dose a human have
more than 10 billion
what is the size of neurons
5 micrometers to 130 micrometers
what are the main parts of a neuron
- cell body/ soma/ perikaryon
- processes - axon and dendrites
what is the structure of the neurons cell body
- 4-100 micrometers
- energetic and synthetic centre of neurone
- contains majority of organelles
what is the neurolemma
cytoplasmic membrane of the neurone
what is the structure of the nucleus in the neuron
- single and large
- moves to periphery if cell is injured
- fine chromatin
what is found in the cytoplasm of the cell body of the neuron
- golgi complex, mitochondria and lysosomes
- melanin or lipofuscin
- nissl body
- neurofibrils
what are nissl bodies
highly developed rER organised into aggregates of parallel cisterns and polyribosomes
where are nissl bodies present
cell body and dendrites
what is the function of nissl bodies
high level of protein synthesis for maintenance and repair and production of neurotransmitters and enzymes