Bio107-ch11,12,13lab15 Flashcards
Irritability
ability to perceive stimuli
Excitability
ability to respond to stimuli
Primary functions of nervous system (3)
- transmit info from one part of the body to another
- coordinate activities within the body
- produce hormones and neurotransmitters
Examples of neurotransmitters
ACh, norepinephrine, epinephrine
Transmit sensory receptors to the
CNS
brain and spinal cord
Transmit from CNS and send it to
muscles, glands, organs
Central nervous system containts
brain and spinal cord
like axial skeleton
Peripheral nervous system contains
cranial and spinal nerves
branches out to limbs
2 types of PNS
- Somatic ns
2. Autonomic ns
Somatic nervous system (2)
skeleton, skeletal muscles, most of skin
VOLUNTARY
Autonomic nervous system (2)
smooth and cardiac muscle, glands, part of skin
INVOLUNTARY
2 divisions of autonimic ns
- Sympathetic division: fight or flight
2. Parasympathetic division: body returns to homeostasis
All senses get heightened using the sympathetic division except
the GI tract shuts down
Neurons (4)
- 20-25% of total nerve cells
- respond to stimuli
- conduct action potentials
- release chemical regulators
Sensory neurons
afferent
Motor neurons
efferent
Glial cells (3)
- 75-80% of nerve cells
- structural support for neurons
- do NOT produce action potentials
Types of glial cells:
Schwann cells
produce myelin sheath in PNS
myelin insulates the axon
Oligodendrocytes
produce myelin sheath in CNS
Astrocytes
anchor neurons to their nutrient supplies
MOST COMMON TYPE
Microglia
monitors health of neurons
gobbles up waste in neuron
Ependymal cells
CNS ONLY
on ventricles of the brain
produce cerebrospinal fluid
Neuron structure:
Cell body/soma
cont. organelles
Dendrites
receive info
Axon
conducts action potential
Axon hillock
responsible for the initiation of the action potential
Neurilemma (myelin sheath)
insulates the axon
PNS
Axon terminal
secretes neurtransmitters
Multipolar neurons (2)
- Most common
2. Found: CNS to skeletal muscle
Bipolar neurons (2)
- Least common
2. Found: retina of eye
Unipolar neurons
Found: visual and auditory senses
Depolarization
cell becoming more POS
Repolarization
cell becoming more NEG
Hyperpolarization
cell becoming SUPER NEG
Effector
muscle, organ, or gland
2 types of potentials
- Graded potential
2. Action potential
Graded potential (3)
- steps 1-2 on drawing
- short-lived
- decrease in intensity with distance
Action potential (3)
- steps 2-6 on drawing
- does NOT decrease in strength over distance
- “All or none” law (with threshold)
Node of Ranvier
the gaps along the myelin sheath
Non-myelinated takes _____ to conduct velocity
longer (because of the gaps)
Synapses
a GAP that mediates TRANSFER from one neuron to
- another neuron
- an effector cell
2 classifications of synapses
- Presynaptic neuron
2. Postynaptic neuron
Presynaptic neuron
the neuron BEFORE the synapse
sends impulse
Postsynaptic neuron
the neuron AFTER the synapse
received impulse, sends new message
Types of synapses (5)
- Axodendritic: axon-dendrite
- Axosomatic: axon-soma
- Axoaxonic: axon-axon
- Dendrodendritic: dendrite-dendrite
- Dendrosomatic: dendrites-soma
Removal of neurotransmitters occur when they (3)
- Are degraded by enzymes
- reabsorbed by astrocytes or presynaptic terminals
- diffuse from the synaptic cleft *
2 types of POSTsynaptic potentials
- EPSP
- IPSP
(before the threshold)
EPSP - excitatory postsynaptic potentials
determines if action potential will reach threshold
CAN generate action potential
IPSP - inhibitory postsynaptic potentials
NEVER get an action potential from IPSP
basically hyperpolarization
Excitatory neurotransmitters (4)
- ACh- excites muscles, nerves
- Norepinephrine- fight/flight hormones
- Epinephrine- fight/flight ^
- Dopamine- pain relief
Excitatory AND Inhibitory neurotransmitters (2)
- Histamine- triggers inflammation
2. P-substances- pain relief
Spatial summation (2)
- postsynaptic potential
2. almost will NEVER induce an action potential in a neron
Temporal summation (2)
- postsynaptic potential
2. RAPID FIRE
