Exam 3 Flashcards
questions from study guide #3
What are the 5 functions of the muscular system?
movement stability control body openings heat production glycemic control
What are the connective tissues in muscle?
endomysium
perimysium
epimysium
fascia
What is a fascicle?
sheet of connective tissue
determine the strength of a muscle and the direction of pull
What is the difference between endomysium, perimysium, and epimysium?
endomysium: thin sleeve of loose connective tissue that surrounds each muscle fiber
perimysium: thicket connective tissue sheath that wraps muscle fibers into fascicles (bundles)
epimysium: fibrous sheath that surrounds the entire muscle
What is the difference between deep fascia and superficial fascia?
answer
What is the difference between the origin, insertion, and belly of a muscle?
answer
What are the 5 muscle shapes?
fusiform, parallel, triangular, pennate, circular
What is the trade-off in strength versus range of motion?
answer
What are direct and indirect attachments of muscles?
indirect: muscle ends before the bone, gap is bridged by a tendon
direct: red muscular tissue seems to directly emerge from the bone
What is a tendon?
answer
What is an aponeurosis?
answer
What is a retinaculum?
answer
What are the 4 muscle actions?
prime mover
synergist
antagonist
fixator
For a specific motion, what is an example of each muscle action in the body?
answer
What are intrinsic and extrinsic muscles?
intrinsic: contained within a particular region; both the origin and the intersection are there
extrinsic: acts upon a certain region but its origin is elsewhere
What are the 5 characteristics of muscle tissue?
responsiveness conductivity contractility extensibility elasticity
What are the elastic components of muscle tissue?
endomysium
perimysium
epimysium
What are the sarcolemma, sarcoplasm, sarcoplasmic reticulum, and sarcomeres?
sarcolemma: plasma membrane
sarcoplasm: cytoplasm
sarcoplasmic reticulum: smooth ER
sarcomeres:
What is being stored inside the sarcoplasmic reticulum?
answer
What is a transverse tubule?
tubular infolding that penetrate through the cell and open onto the other side
What is a myofibril?
long protein bundles
What are myofilaments?
each myofibril bundled; parallel protein filaments
From what precursor cells are muscle cells formed?
answer
What are the names of thin and thick filaments?
thick (myosin molecules)
thin- F actin
G actin
What is titin?
answer
What is dystrophin?
answer
What filaments are troponin and tropomyosin attached to?
thin
Function of troponin
answer
Function of tropomyosin
answer
How do actin and myosin act upon one another in a sarcomere?
answer
Draw a sarcomere with all the bands and zones.
draw
What is the difference between a motor neuron and a motor unit?
answer
What is the difference between large and small motor units?
small motor units: for fine control
large motor units: for strength
where will you find a large motor unit
gastrocnemius
where will you find a small motor unit
muscles of eye movement
What is the point of connection between a neuron and a muscle fiber?
nueromuscular junction (NMJ)
What are the structures of a synapse?
nerve fiber and target cell
How is a nerve impulse transferred across a neuromuscular junction?
answer
What is acetylcholine and acetylcholinesterase?
acetylcholine: (ACh) key molecule, ligand
acetylcholinesterase: (AChE) enzyme, decomposes ACh
How is an action potential created in a cell membrane?
answer
What are the steps involved in Excitation?
- A nerve signal arrives at a synaptic knob and stimulates voltage-regulated Ca2+ gates to open; calcium ions enter the synaptic knob.
- Ca2+ stimulates exocytosis of synaptic vesicles, which release ACh into the synaptic cleft.
- ACh diffuses across the synaptic cleft and binds to receptor proteins on the sarcolemma.
- The receptors are ligand-gated ion channels that bind two ACh molecules to open.
a. When the gates are opened, Na+ diffuses into the cell and K+ diffuses out. The sarcolemma reverses polarity from –90 mV to +75 mV, it then falls back again as K+ diffuses out.
b. This rapid fluctuation in membrane voltage at the motor end plate is called end-plate potential (EPP). - Areas adjacent to the NMJ have ion-specific voltage-gated ion channels that open in response to the EPP, allowing flow of Na+ in and K+ out, generating an action potential.
What are the steps involved in Excitation-contraction coupling?
steps from excitation and then…
- A wave of action potentials spreads from the end plate in all directions, and enters the T tubules, continuing down them into the sarcoplasm.
- Action potentials open voltage-gated ion channels in the T tubules.
a. These gates are linked to calcium channels in the terminal cisternae of the sarcoplasmic reticulum (SR).
b. When the channels in the SR open, Ca2+ diffuses out of the SR and into the cytosol down its concentration gradient. - Calcium binds to the troponin of the thin filaments.
- The troponin–tropomyosin complex changes shape, exposing active
What are the steps involved in Contraction?
steps from excitation- contraction followed by…
- Myosin ATPase hydrolyzes ATP that is bound to the myosin head. The energy released activates the head by changing its shape into a “cocked” position.
- With ADP and phosphate still bound, the activated myosin head binds to an exposed active site on the thin filament, forming a cross bridge.
- Myosin releases the ADP and phosphate and flexes into a bent, low energy shape, tugging the thin filament along with it. This is called the power stroke.
- Upon binding to another ATP, myosin releases the actin. It is now prepared to repeat the process by hydrolyzing the ATP and recocking (the recovery stroke). It will then attach to a new active site farther down.
a. When one myosin releases an actin, many other heads on the same thick filament are still bound to actin on the thin filament so it does not slide back.
b. Even though the muscle fiber contracts, the myofilaments do not become shorter; instead, the thin filaments slide over the thick ones.
c. The cycle of power and recovery is repeated many times by each myosin head, at a rate of about five strokes per second, and each stroke consumes one molecule of ATP.
What are the steps involved in relaxation?
- Nerve signals stop arriving at the NMJ, so the synaptic knob stops releasing ACh.
- As ACh dissociates from the receptor, AChE breaks it down; the synaptic knob reabsorbs the fragments, but now no new ACh replaces that which is broken down.
- Active transport pumps in the SR begin to pump Ca2+ from the cytosol back into the cisternae.
a. The Ca2+ in the cisternae binds to a protein called calsequestrin and is stored until stimulation occurs again. - As Ca2+ dissociates from troponin, it is pumped into the SR and not replaced.
- Tropomyosin moves back into position, blocking the active sites of the actin filament and preventing myosin binding.
What is the length-tension relationship of muscle?
the amount of tension a muscle generates depends on how stretched or contracted before it was stimulated
What is muscle tone?
continual adjustment of length of resting muscles in a state of partial contraction
What is a muscle twitch?
answer
What is the latent period?
a delay between the onset of the stimulus and the onset of a twitch
What is internal tension and external tension?
internal tension: force generated in the onset of a twitch
external tension: when the muscles are taut
What affects the contraction strength of a muscle twitch?
varies with stimulation frequency
stimuli arriving closer together
amount of Ca2+
how stretched the muscle was before stimulation
What is recruitment?
continual stimulation to get more nerve cells to fire
What is treppe?
staircase phenomenon
What is tetanus?
sustained muscle contraction
What is the difference between isometric and isotonic contraction?
isometric: muscle stays the same length, there is no movement
isotonic: muscle tension stays the same
What is the difference between concentric and eccentric isotonic contraction?
concentric: muscle shortens
eccentric: muscle lengthens
What is the difference between aerobic and anaerobic respiration?
aerobic respiration: requires a constant supply of oxygen; produces more ATP
anaerobic: no oxygen
Which is more efficient at generating ATP for each glucose molecule- aerobic or anaerobic respiration?
aerobic
Which is faster- aerobic or anaerobic respiration?
anaerobic
Which produces more toxic waste products- aerobic or anaerobic respiration?
anaerobic
What is the phosphagen system?
atp and CP
What is the difference in anatomy and function between slow and fast twitch fibers?
slow twitch muscles last longer
slow twitch muscles are red, fast twitch muscles are white
What are the sources of muscular fatigue?
build up of lactic acid accumulation of K+ in the ECF ADP/ Pi accumulation fuel depletion loss of electrolytes
What factors affect strength of muscular contraction?
answer
How do smooth muscle fibers differ from skeletal muscle fibers in anatomy?
answer
How is a smooth muscle cell stimulated by the nervous system?
answer
What are varicosities?
beadlike swellings on the nerve fibers of smooth muscle
What are dense bodies?
protein plaques that take the place of z discs
What are multiunit smooth muscle and single-unit smooth muscle?
multiunit: in some large arteries and pulmonary air passages (bronchioles)
single-unit: myocites are electrically couple to each other by gap junctions
Where is the calcium kept for smooth muscle contraction?
extracellular fluid
What is the difference between sensory, motor and interneurons?
sensory:
motor:
interneurons:
What are the 3 characteristics of nervous tissue?
answer
What is the difference between a neuron, a nerve and a ganglion?
neuron is a nerve cell
nerve is
What is the difference between the CNS and PNS?
central and peripheral
central contains brain and spinal cord
peripheral contains everything else except the brain and spinal cord
Which of these divisions are part of the autonomic nervous system?
answer
Draw a multipolar neuron and label all of its structures.
DRAW
What is the difference between multipolar, bipolar, unipolar and anaxonic neurons?
multi- 1 axon, multiple dendrites
bipolar- 1 axon, 1 dendrite
unipolar- 1 process
anaxonic- no axon, multiple dendrites
What are the neuroglia?
supportive cells
neuroglia- What do each of them do and where are they found?
oligodendrocytes: makes myelin, wraps around nerve fibers
microglia: small macrophages for the CNS
ependymal: lines the internal cavities of the brain and spinal cord, produce CSF
astrocytes: form framework for nervous tissue, tissue of the brain
satellite: surround the somas of the ganglia, regulate chemical environment
schwann: envelope fibers of the PNS, produce myelin
Why is myelin so important in the nervous system?
speeds up nerve conduction
How does an axon regenerate in the PNS?
answer
How is a membrane potential changed in a neuron?
answer
What is the difference between local and action potentials?
their location, gate type, and propterties
Where are action and local potentials found and what are their characteristics?
action: found on the axon, all or none, non decremental, irreversible, voltage gated ion channels
local potentials: found on the dendrites and soma, reversible, ligand gated ion channels
What is the refractory period?
a period of time after a nerve or muscle cell has responded to a stimulus in which it cannot be re-excited by a threshold stimulus
What is a synapse?
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter
Where are the synapses on a neuron cell?
the ends of the neuron
What are the four forms of neurotransmitters and what is the difference between them and neuromodulators?
acetycholine (Ach), amino acids, monoamines, neuropeptides.
Neuromodulators are hormones
What are the steps involved in cholinergic synaptic transmission?
answer
What is the difference between ionotropic and metabotropic effects?
answer
What are the three means of removing neurotransmitters from a synapse?
re-uptake
diffusion
degradation
What is an EPSP?
excitatory postsynaptic potential
any voltage change that raises the membrane potential closer to the threshold
What is an IPSP?
inhibitory postsynaptic potential
any voltage change that hyper polarizes the membrane and makes it more negative than the RMP
What is summation?
process of adding up the EPSP’s and IPSP’s and responding to their net effect
What is the difference between temporal and spatial summation?
temporal: a single synapse generates EPSP’s so quickly that there is a cumulative effect
spatial: EPSP’s from multiple synapses add up to the threshold
How are qualitative and quantitative information encoded in neural signals?
Quantitative (2): recruitment, another neuron is stimulated
Qualitative:
What are the anatomical structures of the brain? (Check the lab list of structures)
answer
What are the three meninges?
dura mater forms
arachnoid mater
pia mater
Which of the meniges is most superficial and deepest?
superficial:
What are the ventricles?
fluid filled chamber of the brain or heart
What are the choroid plexi?
spongy masses of blood capillaries
What are the 3 functions of cerebrospinal fluid?
bouyancy
protection
chemical stability
Where does cerebrospinal fluid come from?
epedmya, a type of nueroglia
Why is it important to keep whole blood from touching the CNS?
answer
What is the difference between the blood-brain barrier and the blood-CSF barrier?
answer
What are the anatomical structures of the spinal cord and spinal nerves?
answer
How many spinal nerve pairs are there?
31
