Neuromuscular Muscle System Flashcards
What are the four big picture functions of the nervous system?
- Control of internal environment
- voluntary control of movement
- spinal cord reflexes
- assimilation of experiences necessary for memory and learning
The nervous system is organized into what two parts?
central nervous system (CNS) and peripheral nervous system (PNS)
The central nervous system (CNS) primarily consists of:
brain and spinal cord
What are the two divisions of the peripheral nervous system?
sensory division (incoming) and motor division (outgoing)
which division of the peripheral nervous system uses afferent fibers to transmit impulses from receptors to CNS?
sensory division (incoming)
which division of the peripheral nervous system uses efferent fibers to transmit impulses from CNS to effector organs?
motor division (outgoing)
in the motor division of the PNS, which nervous system is voluntary to skeletal muscles and which is involuntary?
somatic: voluntary, to skeletal muscles
autonomic: involuntary
What is somatic sensory?
sensory input that is consciously perceived from receptors (e.g., eyes, ears, skin)
What is visceral sensory?
sensory input that is not consciously perceived from receptors of blood vessels and internal organs (e.g., heart)
The somatic and visceral sensory systems are a part of which nervous system?
sensory nervous system
What does the sensory nervous system do?
detects stimuli and transmits information from receptors to the CNS
What is somatic motor?
motor output that is consciously or voluntarily controlled; effector is skeletal muscle
what is autonomic motor?
motor output that is not consciously or is involuntarily controlled; effectors are cardiac muscle, smooth muscle, and glands
somatic motor and autonomic motor are part of which nervous system?
motor nervous system
what does the motor nervous system do?
initiates and transmits information from the CNS to effectors
What is the basic functional unit of the nervous system?
neuron
What are the three primary regions of a neuron?
cell body (soma
dendrites
axon
What structure in the neuron contains the nucleus?
cell body
What structure in the neuron conducts impulses toward the cell body?
dendrites
What structure in the neuron carries electrical impulses away from the cell body?
axon
Axons may be covered by what?
schwann cells
What structure of a neuron has end branches, terminal, and neurotransmitters?
axon
The ability of a neuron to respond to a stimulus and trigger a neural impulse is called:
irritability
the ability of a neuron to transmit the impulse along the axon is called:
conductivity
What is a nerve impulse?
electrical signal which enables communication between periphery and brain
What three things must happen for a nerve impulse to occur?
- must be generated by a stimulus
- must be propagated down an axon
- must be transmitted to next cell in line
What are two types of synaptic transmission?
neuron - synapse - neuron
neuron - synapse - muscle
What is the resting potential of a cell membrane?
-70 mV
Why is the resting potential of a cell membrane -70 mV?
- Difference in ion concentrations across membrane
- high concentration of Na+ outside
- medium concentration of K+ inside
- inside more negative relative to outside
How does the cell membrane maintain its resting potential?
- cell membrane more permeable to K+ than Na+
- Na+ - K+ ATPase pumps
How many K+ and Na+ are moved in the Na+/K+ ATPase pumps?
2 K+ in and 3 Na+ out
Depolarization occurs when:
a stimulus of sufficient strength depolarizes the neuron
What happens to Na+ during depolarization?
Na+ channels open and Na+ diffuses into the cell (inside becomes more positive 70mV > 0mV)
What is repolarization?
returns to resting membrane potential
What happens to K+ and Na+ during repolarization?
K+ leaves the cell rapidly, Na+ channels close
What is the All-or-none principle?
once a nerve impulse is initiated, it will travel the length of the neuron
What is a synapse?
small gap between presynaptic neuron and postsynaptic neuron
What are the two types of postsynaptic potential?
excitatory (EPSP) and Inhibitory (IPSP)
What is a neurotransmitter?
chemical messenger released from presynaptic membrane
What does a neurotransmitter bind to?
receptor on a postsynaptic membrane, then causing depolarization of postsynaptic membrane
What is a motor unit?
alpha-motor neuron and all of the muscle fibers it innervates
What does the neuromuscular junction do?
allows the neuron and muscle fiber to communicate
synapse: allows for the communication of electrical and chemical signals
The synapse initiates:
muscle action
What is the most basic functional unit?
motor unit
The site of neuron-to-muscle communication uses what neurotransmitter?
acetylcholine (ACh)
A postsynaptic cell is equivalent to:
muscle fiber
What happens at a postsynaptic cell?
ACh binds to receptor at motor end plate which causes depolarization. AP moves along plasmalemma, down T-tubules. Undergoes repolarization, refractory period
What comes in to push NTs out to receptors in order to start depolarization?
calcium
what is the basic function of t-tubules?
carry signal deep into the muscle
When does the signal stop?
when enough NTs have broken off of their receptors
What triggers graded potentials on a new cell (neuron/muscle)?
neurotransmitters
What serves as an excitatory signal in muscle cells?
ACh
Where can ACh be inhibatory?
heart
Is Norepinephrine excitatory or inhibitory?
can be either depending on the tissue