Exam 3 Study Guide Flashcards
What is the epimysium?
surrounds the muscle; “overcoat” of dense irregular connective tissue that surrounds entire muscle
What are fascicles?
grouped muscle fibers; resemble bundle of sticks
What is the perimysium?
layer of dense irregular connective tissue that surrounds each layer of the fascicle
What is insertion?
movable bone
What is origin?
the less movable bone
What are the three basic types of muscle tissue? Which are voluntary and involuntary?
skeletal, smooth, and cardiac; skeletal is voluntary, smooth and cardiac are involuntary
How do actin and myosin interact?
myosin and actin drive skeletal muscle contraction; myosin binds to actin to contract muscle
Why is calcium important?
Calcium binds to troponin to change shape and remove tropomyosin; Ca provides the final “go signal” for contraction
What is the sarcolemma?
plasma membrane of the muscle fiber
Describe the sliding filament model of muscle contraction.
states that during the contraction, the thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree
How are muscle fibers stimulated to contract?
an action potential travels along the nerve, down the sarcolemma, through its t tubules, and the sarcoplasmic reticulum releases Ca to to bind to troponin
Describe the events that occur at the neuromuscular junction.
-the motor neuron releases ACh that stimulates the skeletal muscle fiber, causing a local depolarization
-muscle fiber excitation; EPP triggers an action potential that travels across sarcolemma
-excitation contraction coupling; AP in sarcolemma propogates along the t tubules and causes release of Ca from terminal cisterns of the SR.
-cross bridge cycling; muscle contracts as a result of a repeating cycle of steps that cause myofilaments to slide relative to each other
What does ACh do?
binds to receptor proteins on the sarcolemma and triggers an action potential
What does acetylcholinesterase do?
breaks down ACh
What is the difference between oxidative slow twitch muscle fibers and glycolytic muscle fibers?
Oxidative slow twitch muscle fibers are for low intensity long lasting muscle contractions. Glycolytic muscle fibers are best suited for short term rapid intense movements
Why are gap junctions important for smooth muscle?
gap junctions are communicating junctions between adjacent cells. In smooth muscle, they coordinate changes in both membrane potential and intracellular Ca between adjacent smooth muscle cells
What protein binds calcium in smooth muscle?
calmodulin
What are the structural divisions of the nervous system?
-central nervous system(brain & spinal cord); the control center of the nervous system
-peripheral nervous system(nerves that branch off and extend throughout the body); they carry impulses to and from the brain
What is the afferent pathway?
information traveling across the afferent pathway approaches the control center
Efferent pathway
output flows from the control center along the efferent pathway to the third component
What are the types of neuroglia in the CNS?
-astrocytes
-microglial cells
-ependymal cells
-oligodendrocytes
What are the types of neuroglia in the PNS?
-satellite cells
-schwann cells
Astrocytes
most abundant and versatile glial cells; support and brace neurons and anchor them to their nutrient supply lines
Microglial cells
small and ovoid with relatively long thorny processes; processes touch nearby neurons, monitoring their health and migrate towards neurons that are injured
Ependymal Cells
many are ciliated; line the central cavities of the brain and spinal cord to form a fairly permeable barrier
Oligodendrocytes
line up along the thicker nerve fibers in the CNS and wrap their processes tightly around the fibers, producing and insulating covering called myelin sheath
Satellite cells
surround neuron cell bodies located in the peripheral nervous system
Schwann cells
surround all nerve fibers in the PNS and form myelin sheath around the thicker nerve fibers
What neuroglia makes myelin in the CNS?
the oligodendrocytes
What neuroglia makes myelin in the PNS?
Schwann cells
Explain the importance of the myelin sheath
the myelin sheath protects and electrically insulates fibers; also increases the transmission speed of nerve impulses
How is the myelin sheath formed in the PNS?
formed by Schwann cells, which indent to receive an axon and then wrap themselves around it in a jelly roll fashion; form only one segment of a myelin sheath
How is the myelin sheath formed in the CNS?
Oligodendrocytes form the CNS; they have multiple flat processes that can coil around as many as 60 axons at the same time
What is a synapse?
a junction that mediates information transfer from one neuron to the next, or from a neuron to an effector cell, it is where the action begins
How do neurons communicate with each other?
through the neuromuscular junctions(I think)
Sensory/afferent neurons
transmit info from sensory receptors to CNS; typically unipolar
Motor/efferent neurons
transmit from CNS to muscle/glands; all multipolar
Interneurons
sit between and help shuttle signals around; typically multipolar and very common in CNS
ATP is required for the myosin head to _____ from actin.
release
ADP+P is released from the myosin head, resulting in the
power stroke
What neurotransmitter is used at the neuromuscular junction to send a signal from the motor neuron to the skeletal muscle
acetylcholine
What occurs during muscle relaxation?
ATP binds to the myosin head
the troponin-tropomyosin complex covers the myosin binding sites
membrane potential chart
- resting potential
- depolarization
- repolarization
- hyperpolarization
Describe the resting membrane potential
-more sodium outside the cell
-more potassium inside the cell
-ACh binding
Describe depolarization
-sodium goes into the cell
-voltage gated channels open
-action potential
Describe repolarization
-Na channels close and K channels open
-negative charge restored in cell
Describe hyperpolarization
-further efflux of potassium
-redistribution of ions and resting potential restored
