Chapter 3 The Biological Bases of Behaviour Flashcards
Neurons
specialized cells that make up the nervous system
cell body (soma)
structures that keep the cell alive (nucleus)
dendrites
“branches” from cell body, recieve signals
axon
conducts electrical impulses away from soma and towards axon terminals
- axon terminals
sends signals to other cells
Glial cells
hold neurons in place
- make and move nutrients
- from the Myeline Sheath
- Remove toxins
blood-brain barrier
a bunch of glial cells that form a wall between the blood and neurons because blood kills neurons
- allows nutrients to be taken out of the blood for the neurons
2 functions of neurons
- generate electricity
- create nerve impulses
- goes down the cell never the other way!
- Release chemicals
- communicate with other cells
Neural Impulses
ctivation occurs in the three steps:
cell is at rest with electrical resting potential
. -70mV on average
2. means inside of cell is more negative than outside of the cell
3. this is due to ions.
Na+
(positives ion. Lots in outside of cell)
. K+
(potassium is also positive and inside the cell, less potassium than sodium, therefore outside is more positive than inside which is more negative. Difference is 70 mV)
. resting potential
neither one of channel is open.
cell is stimulated and electrical charged (ions) flows across cell membrane
- reverse charge of resting potential
2. produces action potential, or neural impulses
when the sodium channels open
all the positive ions flood into the inside of the cell and makes the inside of the cell positive. Ex/ -70mV to +40 mV
depolarization
when we go more positive. sodium enters (more positive, less negative)
Restore distribution of ions, cell at rest again.
potassium opens now, but sodium is closed. potassium stars flooding outside of the cell. Turns inside of the cell negative again.
2. as one part of the axon repolarizes the next one depolarizes.
repolarization
potassium leaves (less positive, more negative)
hyperpolarization
: extra negative
The all-or-none law:
action potentials occur at a uniform and maximal intensity, or they do not occur at all
- stronger signals DO NOT cause stronger action potential
- it just means it will cause action potential
- you can increase number of action potential in a period of time, and it send a signal of more important message
Absolute refractory period:
cell cannot fire again
- impossible to have a second action potential
- limits how often nerve impulses can occur
- ensures that impulses only travel in a single direction
- cell has to reset
- always a small gap in which nothing can happen
The myelin sheath:
created by glial cells
- a fatty, whitish insulation layer derived from glial cells during development
- i.e., support (help protect from damage) and surround neurons
- insulated neurons (quick signals)
- in-between each myelin sheath is the nodes of ranvier
- only around the axon
- not all neurons myelinated
Node of Ranvier
places here the myelin is either extremally thin or absent
- allows conduction to “skip ahead”
- foster signals
Synapses
where axon terminals meet dendrites
- neurons do not make physical contact
- communicate across gaps called synaptic cleft
Synaptic gap
functional (not physical) connections between neurons and their target (contracts muscles). They are not toucing, but very close to its other
Neurotransmitters
chemcial substance shat carry messages across the synapse toeither excite otehr nerons, or inhibit their firing
- five stages fo chemcial communcation:
- five stages fo chemcial communcation:
- five stages fo chemcial communcation:
- synthesis - make them oin the neuron
- stoarge - held in synaptic vessels
- release - into synaptic space
- binding - attach to receptor sites
- deactivation - stop the neurotransmitter signal
excitation vs inhibition
- inhibitory neurotransmitter:
decreases resting postential of post-synaptic neuron; hypopoloarization
- chill eurons out
hypopoloarizes neruon’s membrane -> DECREASES likelihood of action potential
- exitary neurotrasnmitter:
increases resting potentail of post-synaptic neuron; may even fire
- it rev neurons up
depolarizes neruon’s membrane -> INCREASES likelihood of action potential
Specific neurotransmitters: glutamate (glutamic acid)
exitaory
- expressed in whoel brain
- control fo behaviours
- especially learning and memor
- GABA (gamma-aminobutyric acid)
inhibitory
- expressed in whole brain
- control of behaviours
- especailly anxietyt and motor control
- huntington’s deisease
Acetylcholine (ACh)
exitaroy
- function at synapses invovled in muscle movement and memory
- memory in loss in Alzhemier’s disesase
Norepinephrine
exitaory and inhibitoary
- functions at various sites
- invovled in learning, memory, wakefyllnes, eating
- depression and panic disorders
Seretonin
- Inhibitory (mostly)
- functions at various sites
- mood, eating, sleep, arousal
- I.e., depression, sleeping, and eating disorders