Exam 4 Flashcards
what is a twitch?
a single cycle
what is a latent period?
delay between muscle action potential and beginning of muscle tension
-time required for Ca2+ release and binding to troponin
what is rigor mortis?
no ATP being produced
then you decompose
what is a single twitch?
muscle relaxes between stimuli
what is summation?
interval between action potential is shortened and muscle cannon fully relax
-produces more forceful contractions
what is tetanus?
state of maximal contraction
complete or incomplete
how much ATP is stored in muscle?
only a little bit
what does the muscle use for back up energy?
phosphocreatine (PCr)
how long is anaerobic glycolysis?
short term
how long is aerobic metabolism?
long term
what is muscle fatigue?
muscle no longer able to generate/sustain expected power
when can muscle fatigue occur?
at each step of muscle contraction
how is movement orchestrated?
by the CNS through control of motor unit
what is a motor unit?
single motor neuron and all of the muscle fibers it controls
what are isotonic contractions?
creates force and moves a load
what are isometric contractions?
creates force without moving a load
-carrying groceries
what are concentric contractions doing?
shortening
what are eccentric actions doing?
lengthening
how do isometric contractions occur?
due to series elastic element
-sarcomeres still contract and create tension
what does contraction speed depend on?
muscle fiber type
load
when will contractions be fastest?
type 2B fiber
what are the different classifications of neural reflexes for the efferent divisions?
somatic
autonomic
what are the different classifications of neural reflexes for the CNS where information is processes?
spinal
cranial
what are the different classifications of neural reflexes at the time reflexes develop in life?
innate
learned
what are the different classifications of neural reflexes for the number of neurons in loop?
monosynaptic
polysynaptic
what is the input signal for a skeletal muscle reflex?
proprioceptor
what does the CNS determine for a skeletal muscle reflex?
determines if muscle should contract or relax
what is the output signal for a skeletal muscle reflex?
based on CNS decision
what does a somatic motor neuron do?
only contraction
do inhibitory neurons synapse on skeletal muscle?
no
where can you inhibit a contraction?
integrating center
what are the three types of proprioceptors?
muscle spindle
golgi tendon organ
joint receptors
what does the muscle spindle do?
detects muscle length
what does the goldi tendon organ do?
detects muscle tension
what does the joint receptors do?
detects changes in bone position
what do stretch receptor do?
signal brain about muscle length
what are stretch receptors made of?
specialized muscle fibers in a fusiform configuration intrafusal fibers
what is fusiform?
feather shaped
what are extrafusal fibers?
normal contractile muscle fibers
-alpha motor neurons
what does the muscle spindle do as they are being stretched?
send action potentials
what is muscle tone?
tonic activity
what happens when there is a stretch reflex?
- input signal is sent to CNS
- output signal is sent to muscle - contraction occurs
what does the stretch reflex prevent?
overstretching
how do you change the signal for muscle length?
change frequency for signal
how do you get an output signal?
action potential though somatic motor neuron (alpha or gamma)
where does the sensory neuron travel to?
integrating center
what does alpha-gamma coactivation do?
keeps the spindle stretched when muscle contracts
-decreases in length
what is the Golgi tendon organ?
junction of muscle fibers and tendons
what does a junction of muscle fibers and tendons contain?
free nerve endings woven between collagen fibers
what does afferent input from the Golgi tendons do?
excites inhibitory interneurons
what do inhibitory interneurons do?
trigger a reflex to reduce/end muscle contractions
-stop signals from CNS going to skeletal muscle
where are joint receptors found?
in joint capsules and ligaments around joints
what do joint receptors respond to?
joint movement velocity
joint position
inflammation and pain
what are the three different types of movement?
reflex
voluntary
rhythmic
what is a reflex movement?
- least complex
- mainly in spinal cord
ex: knee jerk, cough
what is a voluntary movement?
- most complex
- mainly in cerebral cortex
ex: playing piano
what is a rhythmic movement?
- intermediately complex
- in spinal cord and cerebral cortex
ex: walking
what is special about rhythmic movement?
they have no stimulus, sensor, or input signal
what do rhythmic movements have?
central pattern generations (CPGs)
what factors influence movement?
how complex the movement is
- number of spinal cord segments needed
- use of upper or lower motor neurons
- section of CNS controlling movement
what are the different spinal cord segments?
segmental
intersegmental
what is the segmental part of the spinal cord?
reflex only passes through spinal portion of the spinal cord
ex: knee jerk
what is the intersegmental part of the spinal cord?
reflex passes through many segments of the spinal cord or brain
ex: most movement, voluntary, rhythmic
what is a lower motor neuron?
alpha motor neuron
-cell body in CNS and axon synapses on skeletal muscle fibers
what are upper motor neurons?
lie entirely within the CNS
- control lower motor neurons
- -if they are going to the brain
what is white matter?
myelinated axon
what is myelinated axon?
bundles of axons known as tracts
what is ascending tract?
carry sensory info to brain
what is a descending tract?
carry efferent signals from brain to spinal cord
what does simple motor control come from?
spinal cord
what are the two divisions of the ventral horns of the spinal cord?
medial
lateral
what does the medial tract do?
controls axial and proximal muscles
what does the medial tract include?
tectospinal tract
vestibular tract
reticulospinal tract
what is the tectospinal tract?
head orientation to environmental stimuli
what is the vestibular tract?
muscle control against gravity
what is the reticulospinal tract?
controls muscle tone in axial and proximal muscles
where do tectospinal tract, vestibular tract, and reticulospinal tract originate?
in mesencephalon, pons, and medulla
what does the lateral tract do?
controls distal muscles
what does the lateral tract include?
rubrospinal tract
what does the rubrospinal tract do?
voluntary muscle control
implicated in control of skilled, repetitive movement
where is the mesensephalon?
midbrain
what does the corticospinal tract do?
controls the most skilled voluntary muscle movements
what does the corticospinal tract connect?
it connects motor cortex in parietal lobe of the brain with lower motor neurons
where does the corticospinal tract cross?
at pyrimdal decussation
what are the five tracts that control movement?
rubrospinal tract corticospinal tract x 2 tectospinal tract vestibular tract reticulospinal tract
what are the basics of smooth muscle anatomy?
no striations uninucleated small spindle shaped no motor end plate
what five things come with smooth muscle anatomy?
- more variety
- anatomy makes research difficult
- contrations controlled by hormones, paracrines, and NTs
- variable electric properties
- lots of pathways influence contraction and relaxation
what are the two types of smooth muscle tissue?
single unit
multi unit
what does single unit muscle tissue do?
forms walls of internal organs
in single unit smooth muscle tissue, how are cells joined?
gap junctions
what do single unit smooth muscle tissues contain?
internal pace makers
do multi unit smooth muscle tissues have gap junctions?
no
do multi unit smooth muscle tissues have internal pace makers?
no
where are multi unit smooth muscle tissues found?
in iris and ciliary muscle
male repro tract
uterus
why is the uterus special?
large muscle contractions
what are the parts of the contractile element structure?
actin
myosin
sarcoplasmic reticulum
what are the characteristics of actin for contractile element structure?
longer
high ratio A:M ratio
filaments are crosshatched
what are the characteristics of myosin for contractile element structure?
longer
myosin light chain
what is a myosin light chain?
regulatory protein chain in myosin head
how are contractile element structure arranged?
diagonal bundles
-fibers become globular when contracted
what are the characteristics of sarcoplasmic reticulum for contractile element structure?
less overall than skeletal
IP3 - receptor channel - no T-tubules
most Ca2+ comes from extracellular space
what are the characteristics of dense bodies for contractile element structure?
the z-lines in smooth muscle
where actin attaches
what are some characteristics of contractions for contractile element structure?
very slow contractions
how long is the latent period for contractions for contractile element structure?
about 200 milliseconds
what is tetanus?
muscles not relaxing
sustained contractions
what is a twitch?
one muscle contraction
what is depolarization caused by?
Ca2+ entry
when are membrane potentials unstable?
slow wave
pacemaker
how much do resting potentials vary?
-40 to -80mV
what are slow wave potentials?
cyclic depolarization and repolarization
what are pacemaker potentials?
cyclic but always reaches threshold and fire AP
what is the definition of a contraction?
AP or GP or no change in membrane potential
what controls E-C coupling?
calcium
where does the calcium come from for E-C coupling of smooth muscle?
extracellular space
little from SR
is there any troponin or tropomyosin function for E-C coupling for smooth muscle?
no
what two enzymes for E-C coupling for smooth muscle rely on?
myosin light chain kinase
myosin light chain phosphatase
what does myosin light chain kinase do?
attaches P to myosin to start contraction
what does myosin light chain phosphatase do?
removes P from myosin to stop contraction and begin relaxation
tension development is…
all or none
what does tension development depend on?
amount of calcium influx
in tension development, what happens when there is more calcium activity?
more light chain kinase
stronger contractions occur
what are the four different types of activating stimuli for smooth muscle?
nervous
stretch
hormonal
internal pacemaker
what is the nervous activating stimuli for smooth muscle like?
similar to skeletal
but no direct synapse
what is the stretch activating stimuli for smooth muscle like?
mechanically gated Ca2+ channels
what kind of contractions do stretch activating stimuli for smooth muscle have?
myogenic contraction
what is the hormonal activating stimuli for smooth muscle like?
ligand gated Ca2+ channels
what is the internal pacemaker activating stimuli for smooth muscle responsible for?
rhythmic contractions of GI tract
what is the basic anatomy for cardiac muscle?
striated with sarcomeres unincleated branched intercalated disc regulatory proteins intermediate contraction speed
what are some differences that cardiac muscle has from skeletal muscle?
- t-tubules are larger with more branches
- SR is smaller
- mitochondria is 1/3 total cell volume
- nervous control comes from ANS and autorhythmic cells
what is myocardium?
bulk of the heart
- the muscle
what do autorhythmic cells do?
create signals for heart contractions
-pacemakers
where does the vena cava get blood from?
the body
where do pulmonary veins get blood from?
lungs
what does the right ventricle do?
pumps blood to lungs
what does the left ventricle do?
pumps blood to body and coronary arteries
why is there fibrous contractive tissue between the atria and ventricles?
structural support
electrical insulation
what is valve closure caused by?
blood back pressure
what does chordae tendinae do?
works together with papillary muscles to prevent valve erosion
what is a valvular heart murmur?
leaky/narrow valve
systolic and diastolic
what is a nonvalvular heart murmur?
PDA
what kind of tissue is cardiac muscle?
excitable
what are the two types of cells in cardiac muscle?
myocardial contractile cells
myocardial autorhythmic cells
how can you prevent tetanus in the heart?
AP longer in cardiac contractile cells
why is it important to prevent tetanus in the heart?
needs to be beating constantly
-must fill ventricles with blood
what can myocardial autorhythmic cells create?
their own AP
in what two ways does the ANS control the heart?
sympathetic - increase HR
parasympathetic - decrease HR
what is tachycardia?
increase HR
what is bradycardia?
decrease HR
what is the pathway for electrical conduction through the heart?
- SA node
- internodal
- AV node
- pathways of Bundle of His
- Bundle Branches
how do ventricular myocardium contract?
from apex to base
why is there a time delay at the AV node?
let atria finish contracting
for cardiac EC coupling what do t-tubules have?
voltage gated Ca2+ channels
for cardiac EC coupling what is RyR operated by?
Ca2+ binding
what initiates cardiac EC coupling?
AP
- originated in pacemaker cells
what is cardiac EC coupling similar to?
skeletal muscle EC coupling
what does the electrocardiogram record?
electrical activity of the heart
-cardiac cycle
what is the P wave?
atrial depolarization
what is the QRS complex?
ventricular depolarization
-atrial repolarization
what is the T wave?
ventricular repolarization
what does the cardiac cycle consist of?
systole
diastole
what is systole?
contraction
what is diastole?
relaxation
what is the PR interval?
delay of AV node allowing for filling of ventricles
what is the ST segment?
beginning of ventricle repolarization
what is end systolic volume?
mL remaining in ventricles
-ventricles do not empty completely during systole
what is end diastolic volume?
volume of ventricles after diastole is large
what are arteries?
vessel that carries blood away from the heart
what does an artery become?
arterioles
what is a vein?
vessel that carries blood toward the heart
what do venules become?
veins
how much blood do veins carry?
50% of the blood in a body
what are capillaries?
thin walled vessels that connect arterioles with venules
what do capillaries do?
exchange nutrients and gases
what are the 3 basic layers of a blood vessel?
inner tunica intima
middle tunica media
outer tunica externa
what are the 4 types of tissue in blood vessels?
endothelium - inner
elastic connective tissue - inner
smooth muscle - middle
fibrous connective tissue - outer
do all veins have valves?
no
what do valves in veins do?
prevent backflow of blood
-force blood toward the heart
where does blood flow?
down a pressure gradient
what happens to pressure over distance?
it decreases
what is flow rate?
volume of blood that passes a given point in the system per unit time (L/min)
what is velocity of flow?
how fast the blood flows
what is resistance?
tendency of the CV system to oppose blood flow
when does resistance increase?
when there is an increase in length and velocity
when does resistance decrease?
when there is an increase in radius
where does pressure gradient begin?
in ventricles
what is a pulse?
pressure wave felt as blood is pushed into the aorta
what happens to pressure gradient as it goes through the circulatory system?
decrease
when is pressure gradient the lowest?
point of ventricle filling
what 3 factors influence blood pressure?
volume - increase volume, increase pressure
flow rate - increase flow rate, increase pressure
resistance - influenced by vessel radius
what is blood flow rate influenced by?
blood velocity and CSA of vessels
what happens if a vessel has a wider diameter?
faster the velocity
how do arterioles provide resistance?
reducing vessel radius
what are arterioles controlled by?
metabolites
paracrine
what are metabolites?
O2, CO2
-cause dilatation
what are paracrine?
NO, histamine, adenosine -cause dilatation
serotonin - cause constriction
what does stretching of smooth muscle cause?
constriction
-remyogenic
