Nervous System Flashcards
Nervous system
Responsible for sensing and responding to the environment
Where does the nervous system receive info from?
Receptor cells
What can receptor cells be activated by
Internal/external stimuli
Nervous system responds to stimuli by transmitting info to what effectors?
Mechanical/chemical effectors
Neurons
Primary cells of nervous system and biological basis for sensory/response
Sensory/afferent neurons
Carry messages from rest of body to brain; allows us to sense environment
Motor/efferent neurons
Carry messages from brain to rest of body; allows us to respond to environment
Dendrites
Ends of neurons which receive chemical messages
Axons
End of neuron which send messages to other cells
Glial cells
Exist to support neurons; Pass nutrients from capillaries to neurons, trap bacteria/other particles and produce myelin
Myelin sheath
Layer of fatty tissue that surrounds axon; insulates electrochemical signal making nervous system more efficient
What would happen if you didn’t have myelin in your nervous system?
Signals would get lost and you would lose the ability to sense/respond to environment
What kind of signals do the dendrites receive?
Excitatory and inhibitory signals
Excitatory signals
Encourage dendrite to send a message
Inhibitory signals
Encourage dendrite to not send a message
Where is a message sent if excitatory signals exceed inhibitory signals?
Along the neuron
Synapse
The short gap between the dendrites and axons of separate neurons
What happens when an electrochemical signal reaches end of axon?
Causes release of neurotransmitters into synapse
Where do neurotransmitters go once released?
Jump across synapse and bind to receptor site on opposite dendrite
Electrochemical
The electrical signal is result of chemical differences across neurons cell membrane
What causes a negative voltage across cell membrane?
Resting neuron has more positive charge outside of cell than inside cytoplasm
What are the majority of positive charges?
Sodium ions
What does the net negative voltage result from?
Higher sodium and potassium concentration outside of measuring than inside
Polarized neuron
Neuron in its resting state
Activation of a neuron results in what?
Opening of sodium ion channels in cell membrane, allowing positive charged sodium to flood into neuron
Depolarization
The movement of sodium ions into neuron causing the voltage to temporarily turn positive inside neuron
Sodium-Potassium pump
Uses active transport to swap intercellular sodium ions with extracellular potassium ions
What does sodium-potassium pump result in?
Repolarization of neuron
What does the reversal of charge of a neuron trigger?
An action potential which moves down the neuron
Refractory period
No new action potential can be initiated
Central nervous system
Contains brain and spinal cord; receives and responds to sensory information
Peripheral nervous system
Contains all neurons located outside of central nervous system
Where are neurons in the PNS packed into?
Nerves
Nerves
Cords containing multiple axons bundled together
Somatic nervous system
Part of the PNS that controls voluntary muscle movement
Autonomic nervous system
Part of the PNS that controls all involuntary actions in the body
Sympathetic nervous system
Controls response to stress (fight or flight response)
What does the SNS increase?
Increases blood pressure, heart rate, blood sugar and sweat
These actions increase energy, allowing you to deal with conflict
Parasympathetic nervous system
Opposite effect of SNS, lowering heart rate and blood sugar causing you to conserve energy
Endocrine system
Transmits chemical messages by releasing hormones instead of using nerves
Where does the endocrine system send messages through?
Blood stream
What are hormones released by?
Glands
What system is located above the brain stem?
Limbic system
What does the limbic system contain?
Pituitary gland, hippocampus, amygdala, hypothalamus
Pituitary gland
Responsible for regulating body’s hormones
Hippocampus
Responsible for making new memories out of experiences/facts
Cerebellum
Creates muscle memory
Amygdala
Controls fear and aggression, plays important role in sympathetic nervous system and how you respond to conflict
Hypothalamus
Connects part of brain responsible for thought (cerebrum) to pituitary gland
What does this linkage between the cerebrum and pituitary glands do?
Hypothalamus can monitor body chemistry and thoughts; can order pituitary gland to activate appropriate hormones
Dopamine
Neurotransmitter most commonly used by hypothalamus
Cerebrum (cerebral cortex)
Largest brain structure for humans; thought centre for brain where sensory info is interpreted
What lobes are contained within the cerebrum?
Parietal lobe
Occipital lobe
Temporal lobe
Frontal lobe
Parietal lobe
Specializes in sensing touch
Occipital lobe
Specializes in vision
Temporal lobe
Specializes in hearing
Frontal lobe
Specializes in thought/reasoning
