Neurons communicate quickly Flashcards
(22 cards)
What does the nervous system do?
Coordinates all our voluntary and involuntary functions
What are the dendrites?
Fairly short extensions of cytoplasm of the cell body. The are branches that carry messages, or nerve impulses to the cell body
What is the axon?
A single, long extension of the cytoplasm. Carries nerve impulses away from the cell body. Length may vary. They are much longer the closer to the spinal cord
What is the myelin sheath?
Fatty material, which most axons are covered by. These axons or nerve fibers that have a myelin sheath are call myelinated axons, those that don’t are called unmyelinated
What is the myelin sheath formed by?
Schwann cells.
What are the gaps between the myelin sheath called?
Nodes of Ranvier
What are the 3 main importance of a myelin sheath?
Insulator
Protects axon
Speeds up the transfer of nerve impulses
What are the synapses?
It occurs where the axon terminal of one neuron joins with a dendrite or cell body of another synapses. The neuron do not actually touch at the synapses, there is a small gap. Messages still have to be transferred.
How are messages transferred/ carried between the synapses?
Neurotransmitters
What are the three types of neurons?
Sensory, motor, and interneurons
What are sensory neurons?
Carry messages from the receptors in the ears, skin, eyes, and tongue, to the spinal cord and brain
What are motor neurons?
Carry messages from the central nervous system to the effector, which are the muscles and glands
What are interneurons?
Link between sensory and motor neurons
What are the four structural types of neurons?
Multipolar, bipolar, unipolar and pseudounipolar
Multipolar (Structure + function + where it is found)
1 axon, multiple dendrites extending from cell body.
Carry messages to skeletal muscles
Interneurons found in the brain and spinal cord, and in motor neurons
Bipolar (Structure + function + where it is found)
1 axon and 1 dendrite
Take impulses from the receptor cells to other neurons
eyes, ears, nose, and other senses
Unipolar (Structure + function + where it is found)
1 axon
They carry messages around the body
Not found in vertebrates they are found in insects
Pseudounipolar (Structure + function + where it is found)
1 axon that divides into 2, and 0 dendrites
Carry messages to the spinal cord
Sensory neurons and spinal cord
Conduction of a nerve impulse
Nerve impulses are electrochemical change that travel along an axon.
It involves a change in electrical voltage and changes in the concentration of ions inside and outside the cell membrane of the neuron.
Membrane potential
The fluid outside the cell contains a high concentration of sodium chloride, while the fluid inside the cell has a high concentration of potassium =. This difference creates a membrane potential of -70 mV in unstimulated nerve cells
Ion channels
Ions move through protein channels in the cell membrane. Leakage channels are always open, while voltage-gated channels are open when the nerve is stimulated.
The sodium-potassium pump moves ions against the concentration gradient using ATP or energy
Active transport (Sodium-potassium pump)
The sodium-potassium pump moves theee sodium ions out of the cell for every two potassium ions that move into the cell, resulting in a net reduction
