Nervous system 1 Flashcards
What is the central nerves system?
Brain and spinal cord
Wich division of the peripheral NS carries signals TO the CNS from sensory receptors?
Sensory (afferent)
Wich division of the PNS carries signals from the CNS?
What kind things do they signal?
Motor (efferant)
Muscles contract, glands secrete
What branch of the Motor division carries signals to skeletal muscles, that you have concious control over?
Somatic
What branch of the motor division do you have no concious control over?
Autonomic
The ______________division – sends signals that cause “fight or flight” responses in body organs and systems, i.e. increased heart rate, breathing rate, redirection of blood to muscles and away from the gut etc.
Sympathetic
The ____________division generally acts to restore the resting state, i.e. maintain the “status quo”, bringing activity levels back to “normal”.
Parasympathetic
How many types of cells are there in the nervous system and what are they called?
Neuroglia and neurons
What do neuroglia do? (4)
protect and support neurons segregate and insulate neurons secrete chemicals to guide young neurons to their proper connections. promote neuron health and growth.
What are the 4 types of neuroglia in the CNS?
- Astrocytes
- Microglia
- Ependymal cells
- Oligodendrocytes
Astrocytes
Astrocytes – most common, radiating processes attach to neurons and their endings,
cover capillaries in the brain and provide support to neurons.
They regulate the chemical environment around neurons by controlling exchange between
neurons and capillaries.
Microglia –
small cells that monitor the health of neurones and carry out a defense role within the CNS. (immune cells cannot normally enter the CNS).
Ependymal cells
epithelial like cells found within the central cavities of the brain and spinal cord that produce and circulate cerebrospinal fluid.
Oligodendrocytes
wrap around neuron fibers, forming insulating myelin sheaths in the CENTRAL ns
What are the 2 types of neuroglia of the PNS?
satelite cells and schwann cells
Schwann cells
surround nerve fibers, to form myelin sheath
What 4 things do all neuron cells have?
- Cell body
- Dendrites
- Axons
- Synaptic boutons
What are Dendrites?
– short, tapering, branching extensions of the cell which typically act as the receptive part of the cell.
- Part of neuron cells
What are axons?
long narrow tubes that extend out from the cell and “carry” the nerve signal from “A to B”.
What are Synaptic boutons?
swellings at the end of the axon that contain a chemical - NEUROTRANSMITTER, that is released when a signal arrives. The neurotransmitter acts on the target cell to switch it on or switch it off.
Since membranes present a significant barrier to charged solutes (ions) if they are crossing the membrane they must be doing so via special routes. These routes are a special group of membrane proteins called _____________.
CARRIER OR CHANNEL PROTEINS
If there is a concentration difference for an ion across a membrane because ions are charged there will be a charge difference too. Differences in charge are known as _____.
Voltage
voltages across the cell membrane, called _______ can affect___________.
membrane potentials
how ions move
if the inside of a cell is +ve and the outside -ve, what will happen?
–ve ions will want to enter and +ve ions will want to leave
if holes are opened in the membrane that allow ions to cross, then ions will move across the membrane in what direction?
Down CONCENTRATION GRADIENTS Along ELECTRICAL (CHARGE) GRADIENTS (voltages).
nerve and muscle cells at rest we see a small voltage across the cell membrane; what is this called?
the membrane potential (PDm).