Chapter 43: Muscles, Bones, and Body Movements Flashcards
Which types of muscle are under voluntary control?
skeletal
Which types of muscle are under involuntary control?
smooth and cardiac
What connects bone to bone?
ligaments
What connects muscle to bone?
tendons
Which nervous system controls the skeletal muscle?
somatic nervous system
Are skeletal muscles multinucleated?
yes
What is a fasicle?
bundle of muscle fibers
What are myofibrils? composition?
make up muscle fibers
made of thin and thick filaments
What gives skeletal muscle a striated appearance?
alternating pattern of thin and thick filaments
What are A bands?
Dark bands at both ends of stacked thick filaments where thin filaments overlap
Where ACTION takes place
What is the H zone?
Lighter middle region of an A band, which contains only thick filaments
What is the M line?
A disc of proteins in the center of the H zone, which holds the stack of thick filaments together
MIDDLE of the sarcomere
What are I bands?
Light bands consisting of the parts of the thin filaments not in the A band
connects 2 sarcomeres
What is the Z line?
A thin disc in the center of each I band to which the thin filaments are anchored
end, edge, boundary
What is a sarcomere?
the basic unit of contraction in a myofibril
What are thick filaments?
are parallel bundles of myosin molecules, each consisting of two subunits that form a head connected to a long double-helix tail – the head bends toward the adjacent thin filament to form a crossbridge
heads away from middle and towards the Z-line
What are thin filaments?
contain two linear chains of actin molecules twisted into a double helix
tropomyosin and troponin are found here
What happened to the sarcomere when a muscle is fully contracted?
-Z lines get closer together, doesn’t change shape just
moves
-actin and myosin overlap
-actin doesn’t change shape or move
What does interdigitated mean?
(of two or more things) interlock like the fingers of two clasped hands.
What are the steps in forming a cross-bridge/muscle contraction?
1) myosin head binds to ATP, detaches from actin
2) Myosin head catalyzes (breaks down) ATP forming ADP which cocks the myosin head back
3) Myosin head hinds to actin forming a cross-bridge
4) ADP and Pi are released which created a power stroke that causes thin filament to slide which shorten the sarcomere
What is rigor mortis?
Can tell time of death by presence of ATP, For a while after death ATP is still produced which allows for cross-bridge formation still.
Within a few hours after death, Ca2+ diffuses into the cytoplasm of muscle cells and initiates the crossbridge cycle, producing rigor mortis
What is the sarcoplasmic reticulum?
complex system of vesicles modified from smooth ER that encircle the sacromeres
Segments of sarcoplasmic reticulum wrap around each A and I band, separated from T tubules by small gaps
What are T tubules?
At the junction of an A band and I band, the plasma membrane folds to form a T (transverse) tubule
on top of Z line, hollow tube that plunges down into the tissue
What neurotransmitter is responsible for neural muscular control? what does this cause?
acetylcholine, causes the release o f Na+ ions that depolarize the membrane which then release Ca2+ ions from voltage gated channels
What role does Ca2+ play in skeletal muscle contraction control?
In low Ca2+ levels, tropomyosin inhibits cross-bridge formation
In high Ca2+ levels, Ca2+ binds to troponin, Tropomyosin is displaced, and formation of actin-myosin cross-bridges
What is the difference between troponin and tropomyosin?
tropomyosin is the rope and troponin is the globular proteins that Ca2+ binds to
What is botulinum?
Botulinum toxin blocks acetylcholine release in neuromuscular junctions – body muscles, including the diaphragm, become paralyzed and the victim dies of respiratory failure
What is curare?
Curare blocks acetylcholine from binding to its receptors in muscle fibers – body muscles, including the diaphragm, become paralyzed and the victim dies of respiratory failure
What will a single action potential arriving at a neuromuscular junction causes a single, weak contraction produce?
muscle twitch
What is a twitch summation?
If a muscle fiber is restimulated before it has relaxed completely, the second twitch is added to the first, producing twitch summation
What is tetanus?
If action potentials arrive so rapidly (about 25 msec apart) that the fiber can’t relax at all between stimuli, twitch summation produces a peak level of continuous contraction (tetanus)
What are slow muscle fibers?
where in the body would they be found in?
-contract slowly for longer periods of times.
breakdown ATP slowly.
-has a lot of mitochondria that makes ATP by oxidative
phosphorylation.
-high concentrations of myoglobin = tissue is redder
found in postural muscles
What is myoglobin? found more in?
enhances oxygen supply
found more in slow muscle fibers and fast aerobic muscle fibers
What are the 2 types of fast muscle fibers? where in the body would they be found in?
aerobic and anaerobic
found in finger muscles
What is similar between aerobic and anaerobic fast muscle fibers?
both contract quickly and paler than slow muscle fibers
both more fatigue quicker than slow muscle fibers
What is different between aerobic and anaerobic fast muscle fibers?
aerobic has more mitochondria = ATP, and high concentration of myoglobin. Uses oxidative phosphorylation, and an intermediate capacity for making ATP by anaerobic glycolysis
Anaerobic muscle fibers has high concentrations of glycogen, relatively few mitochondria, and a more limited blood supply than fast aerobic fibers. uses GLYCOLYSIS and has short bursts of rapids contractions
Which fast muscle fiber is more susceptible to fatigue?
anaerobic
Which muscle fiber would runners have more of?
slow twitch fibers
What does working out do? in muscle fibers?
increases muscle mass via feedback
particular types of exercise can convert some fast muscle fibers between aerobic and anaerobic types
Can you create fine motor control?
nope, can’t build more motor units
can only get better via coordination
What is a motor unit?
Muscle fibers are organized into motor units, each controlled by branches of the axon of a single efferent neuron
will be the same type of muscle fiber
What happens to the motor until when it contracts?
When a motor unit contracts, its force is distributed throughout the entire muscle because the fibers are dispersed throughout the muscle, not concentrated in one segment
What is recuritment?
you can use a different amount of muscle units depending on the task—strength
How do motor units differ in different areas of the body?
Muscles that can be precisely and delicately controlled, such as finger movements, have many motor units in a small area
Muscles that produce larger body movements, such as leg movements, have fewer motor units in the same volume of muscle, but thousands of muscle fibers in each unit
What is fatigue?
muscle failure, multivariable problem
What is creatine?
released in muscle tissue breakdown and can be used to look at kidney function
What are the 3 types of skeletons?
hydrostatic skeletons, exoskeletons, and endoskeletons
How do hydrostatic skeletons work?
consists of a body compartment or compartments filled with water or body fluids – which are incompressible liquids
If muscles in one part of the compartment are contracted and another part is relaxed, pressurized fluid moves to the relaxed part of the compartment, distending it
uses pressure and density of H2) to build structure
How do hydrostatic skeletons work in earthworms?
- Circular muscles reduce diameter and increase length
- Longitudinal muscles shorten length and increase diameter
- “feet”/keta provide friction
Where do hydrostatic skeletons occur?
Hydrostatic skeletons are the primary support systems of cnidarians, flatworms, roundworms, and annelids
Many arthropods have hydrostatic skeletal elements (e.g., larvae of flying insects and legs of spiders)
Some structures of echinoderms are supported by hydrostatic skeletons (e.g., tube feet of sea stars and sea urchins)
In vertebrates, the erectile tissue of the penis is a fluid-filled hydrostatic skeletal structure
What is an exoskeleton?
is a rigid external body covering that supports and protects internal tissues – the force of muscle contraction is applied against the exoskeleton
What are the two types of exoskeletons? What organisms are they found in?
Many mollusks, such as clams and oysters, have an exoskeleton consisting of a hard [calcium carbonate] shell secreted by glands in the mantle
Arthropods, such as insects, spiders, and crustaceans, have a [chitinous cuticle] secreted by underlying tissue – joints are moved by muscles that extend across the inside surfaces
found in smaller organisms
What is an endoskeleton?
consists of internal body structures, such as bones, that support and protect soft tissues – the force of muscle contraction is applied against the bones
What type of skeletons do echinoderms have?
Echinoderms have an endoskeleton consisting of ossicles formed from calcium carbonate crystals
What type of skeletons do sea urchins and sand dollars have for thier shells?
endoskeletons
What is the difference between the axial and appendicular skeleton?
axial= skull, spine, ribcage
appendicular= appendages and pelvis
What are they 2 types of bone? where are they found?
spongy and dense compact
dense compact bone, which generally forms the outer surfaces, and more open spongy bone, found in interior regions
Is the bone vascular in humans? birds?
yes in humans, allows for repair
nope in birds
What is osteoporosis?
loss of bone matirx
How can you tell if you have broken a bone?
very quickly there will be a dark colored bruise where blood from the broken bone is collecting
What is red marrow and where is it found?
The interior of some flat bones, such as hip bones and ribs, are filled with red marrow, a tissue that is the primary source of new red blood cells in mammals and birds
What is yellow marrow and where is it found?
The shaft of long bones such as the femur is opened by a large central canal filled with adipose tissue called yellow marrow, which is a source of some white blood cells
What hormones are involved in calcium levels in the bone? function?
calcitonin decreases blood calcium levels by stimulating osteoblasts to build bone
Parathyroid hormone decreases blood calcium levels by stimulating calcium reabsorbtion
What are the 3 types of joints?
fibrous, cartilaginous, and synovial
What are synovial joints?
consist of the cartilage covered ends of two bones, enclosed by a capsule of connective tissue filled with synovial fluid, and held together by ligaments
freely movable
What are cartilaginous joints?
the ends of bones are covered with cartilage, but have no fluidfilled capsule surrounding them – the bones are connected by fibrous connective tissue
semi movable
Are fibrous joints movable? what type of bone?
nope, they are flat and compact bone
What is a hinge joint?
The elbow and the knee are hinge joints
This type of joint can move only in one direction to open or close the angle between the bones flanking it.
What is a ball-and-socket joint?
Shoulder and the hip joints exemplify ball-and-socket joints
This type of joint can rotate about its axis, providing the greatest range of motion of any joint in the body
What is a fulcrum? example?
pivot point that bones move around
The elbow joint has the fulcrum at one end, the
load at the opposite end, and force applied between the ends
What is an agonist muscle?
A muscle that causes movement in the joint when it contracts
What is an extensor muscle?
extend joint
What is a flexor muscle?
opposite of extensor muscle
What are the antagonistic muscle pairs?
extensor and flexor
What do we see in evolution about bones?
animals have the same bones in the differnet order but they vary from one another creating different adaptation and advantages for the organism
