Chapter 2 Flashcards
_____. specialized cells that convery sensory info into brainl carry out operations involved in thought, feeling, and action, and transmit commands out into body to control muscles and organs
Neurons
how many neurons in humans brain? what percentage of brain do they make up? what are the other cells?
86 billion
half your brain
the other half are glial cells
the most prominent part of the neuron
the cell body/ soma
the largest organelle In the cell body
the nucleus which contains cell chromosomes
purpose of a motor neuron
carries commands to the muscles and organs
parts of the neuron
dendrites: extensions that branch out from the cell body to receive info from other neurons
axon: extends like a tail from the cell body and carries info to other locations
myelin sheath: wraps around the axon
axon terminals: contain neurotransmitters wich the neuron releases to communicate with a muscles, an organ, or the next neron in the chain
the cell body (largest part) of enuron in mammals is _______ big (mm)
0.0005 - 0.1 mm
giant squid axons size
1mm in diameter
typical axons in mammals size
0.002 to 002 mm in diameter
axons can be as short as ___ or as long as ___ in the tallest giraffes
0.1mm or 5m
____ neurons carry info from the body and from the outside world into the brain and spinal cord
sensory neurons
what’s difference in configuration between sensory neurons and motor neurons
motor neurons axons and dendrites extend in several directions from the cell body (multipolar neuron)
a sensory neuron can be either unipolar or bipolar
unipolar is when a single short stalk from the cell body divides into two branches
bipolar is when you have an axon on one side and a dendritic process on the other
____ neurons connect one neuron to another in the same part of the brain or spinal cord. Are multipolar
interneurons
what are the most numerous type of neuron
interneurons
What neurons are multipolar
interneurons and motor neurons
what kind of neurons are sensory neurons? explain
unipolar and bipolar
unipolar means that there is a single short stalk that divides into two branches
bipolar: axon and dendrites process are on opposite sides of the cell body
form and location of each type of neuron
motor neurons - multipolar, located throughout nervous system
sensory neurons. - unipolar ( outside brain) - bipolar (outside brain and spinal cord)
interneurons - multipolar; brain and spinal cord
the most critical factor in the neurons ability to communicate
the membrane that encloses the cell
describe the neuron cell membrane
8 micrometers thin
is made of lipid and protein
the lipid molecules have a head (water soluable, attract sealike fluid) and tail end (water insoluble (repelled by sea water fluid)
so heads orient towards the fluid and tails away. the moledules turn their tails toward each other and form a double layer membrane
examples of molecules that can go through the cell membrane freely
water, oxygen, and carbon dioxide
polarization
a difference in electrical charge between the inside and outside of the cell. also called a voltage
resting potential
the difference in charge between the inside and outside of the membrane of a neuron at rest ~ -70 but can be anywhere from -40 to -80
what is the resting potential from
the unequal distribution of electrical charges on the two sides of the mmebrane. Caused by atms that have gained or lost electons and thus given a charge (Na+, K+, Cl-, A-)
what makes the resting potential negative
the fluid outside neron contains mostly Na+ and Cl- ions and inside the neuron is mostly K+ and A. The inside has more negative than positive and on outside has mostly positive
