Nervous tissues
NERVOUS TISSUES
Nervous tissue is made up of cells known as neurons, which are adapted for the transmission of electrical impulses, together with associated neuroglia cells.
i. Commonly, all neurons have three things in structure
· a cell body, containing a nucleus. Surrounded by a plasma membrane, has a lot of mitochondria, golgi apparatus, endoplasmic reticulum, ribosomes but no centriole
· a dendron, Nerve fibres take/transmit impulses towards the cell body. The terminal branches of dendron are called dendrites
· an axon, a single fibre takes impulses away from the cell body
Neuroglia cells, are ten times more numerous than neurons, are found through out the Central Nervous System. Neuroglia mechanically support the neurons, supply the nourishment to neurone fibres, removed wastes from neurons, guiding axon migration and provide immune functions. Some are involved in the memory process by storing information in the form of RNA.
ii. Three types of neurons
· Afferent/Sensory /Receptor neurons, transmits impulses from receptor organ to the Central Nervous System
· Efferent/Motor neurons, transmits impulse from the Central Nervous System to effector i.e muscles or glands
· Interneurone (associative/relay/intermediate neurons), receives impulses from sensory neurons and transmits it to the motor neurons. It is found in the brain or spinal cord. Some can generate impulse and other transmits impulse from one to the other. It has varies shapes, bipolar and multipolar with one or more dendrons or axons.
Nervous tissue is made up of cells known as neurons, which are adapted for the transmission of electrical impulses, together with associated neuroglia cells.
i. Commonly, all neurons have three things in structure
· a cell body, containing a nucleus. Surrounded by a plasma membrane, has a lot of mitochondria, golgi apparatus, endoplasmic reticulum, ribosomes but no centriole
· a dendron, Nerve fibres take/transmit impulses towards the cell body. The terminal branches of dendron are called dendrites
· an axon, a single fibre takes impulses away from the cell body
Neuroglia cells, are ten times more numerous than neurons, are found through out the Central Nervous System. Neuroglia mechanically support the neurons, supply the nourishment to neurone fibres, removed wastes from neurons, guiding axon migration and provide immune functions. Some are involved in the memory process by storing information in the form of RNA.
ii. Three types of neurons
· Afferent/Sensory /Receptor neurons, transmits impulses from receptor organ to the Central Nervous System
· Efferent/Motor neurons, transmits impulse from the Central Nervous System to effector i.e muscles or glands
· Interneurone (associative/relay/intermediate neurons), receives impulses from sensory neurons and transmits it to the motor neurons. It is found in the brain or spinal cord. Some can generate impulse and other transmits impulse from one to the other. It has varies shapes, bipolar and multipolar with one or more dendrons or axons.
