Class 6 Flashcards
Chapter 9
The nervous and endocrine systems
Neurons
Neutrons are specialized cells that transmit and process information from one part of the body to another.
Action potentials
Information takes the form of electrochemical impulses known as action potentials.
synaptic transmission
action potential reaches the end of an axon at a synapse, the signal is transformed into a chemical signal with the release of neurotransmitters into synaptic cleft, a process called synaptic transmission.
Neuron
The basic structural and functional unit of the nervous system is the neuron.
These cells neurones) transmit and process action potential.
Soma
Neutrons have a mental cell body called soma.
It contains the nucleus, and this is where most of the biosynthetic activity of the cell takes place.
Neutrons have only ____ axon but many ____
One
dendrites
bipolar
Neutrons with one dendrite are termed bipolar.
Multipolar
neutrons with many dendrites are multipolar.
direction of action potential in axon
away from the cell body
What is the difference between neutron and nerve?
neutron is a single cell.
a nerve is a large bundle of many different axons from different neutrons.
kinesin
a motor protein called kinesin is one of the several different proteins that drive movement of vesicles and organelles along microtubules in axons.
anterograde movement
movement from the soma toward the axon terminus.
This is how kinesin drives movement.
atrophy
(of body tissue or an organ) waste away, typically due to the degeneration of cells, or become vestigial during evolution.
If a chines inhibitor is added to neutrons in culture, what is the likely result?
If materials can not be transported through through the axon from the cell body, atrophy of axons will occur.
The resting membrane potential
the resting membrane potential is an electric potential across the plasma membrane of approximately - 70 millivolts (mV), with the interior of the cell negatively charged with respect to the exterior of the cell.
What are the two primary membrane proteins that are required to establish the resting membrane potential?
The Na+/K+ ATPase and
the potassium leak channels
Na+/K+ ATPase
The Na+/K+ ATPase pumps three sodium ions out of the cell and two potassium ions into the cell with the hydrolysis of one ATP molecule.
What form of transport is carried out by the Na+/K+ ATPase?
The Na+/K+ ATPase uses ATP to drive transport against a gradient; this is primary active transport.
What is the result of pumping three sodium ions out of the cell and two potassium ions into the cell?
The result is a sodium gradient with high sodium outside of the cell and a potassium gradient with high potassium inside the cell.
Leak channels
Leak channels are channels that are open all the time. This allows the ions to leak across the membrane based on their gradient. Eg. Potassium leak channels allow potassium but no other ions to flow down their concentration gradient.
If the potassium leak channels are blocked, what will happen to the membrane potential?
The flow of potassium out of the cell makes the interior of the cell more negatively charged. Blocking the potassium leak channels would reduce the magnitude of the resting membrane potential, making the interior of the cell less negative.
What would happen to the membrane potential if sodium ions were allowed to flow down their concentration gradient?
Sodium ions would flow into the cell and reduce the potential across the plasma membrane, making the interior of the cell less negative and even relatively positive if enough ions flow into the cell.
Why are the cells described as polarized?
The resting membrane potential establishes a negative charge along the interior of axons.Thus the cell can be described as polarized; negative on the inside and positive on the outside.
