Muscular System Flashcards
What are the 3 types of muscles?
- smooth
- cardiac
- skeletal
Where is smooth muscle located?
wall of hollow organs, vessels, respiratory, passageways
Where is cardiac muscle located?
wall of the heart
Where is skeletal muscle located?
attached to bones
What type of muscle is tapered at each end?
smooth
What type of muscles are nonstriated?
smooth
What type of muscles are striated?
cardiac and skeletal
What 2 types of muscles are in branching networks?
smooth and cardiac
What are the special membranes between cells in cardiac muscle?
intercalated disks
What type of muscle is multinucleated?
skeletal
What type of muscle is long and cylindrical?
skeletal
Which types of muscles are involuntary and which voluntary?
- involuntary: smooth & cardiac
- voluntary: skeletal
What is the action (contraction) of smooth muscle?
- produces peristalsis
- contracts and relaxes slowly
- may sustain contraction
What is the action of cardiac muscle?
- pumps blood out of heart
- self excitatory but influenced by nervous system and hormones
What is the action of skeletal muscle?
- produces movement at joints
- stimulated by nervous system
- contracts and relaxes rapidly
What are some properties of smooth muscle?
- single nucleus per cell
- no visible bands (striations)
- tapered at each end
- involuntary contractions
- located within walls of hollow organs (stomach, small intestine), blood vessels (arteries, veins), and bronchioles of lungs
Is smooth muscle voluntary or involuntary?
involuntary
What is peristalsis?
muscular waves of contraction that propel food along the digestive tract
What does smooth muscle contract in response to?
- nerve impulses
- hormones
- stretching
Does smooth muscle contract fast or slow?
- contracts and relaxes slowly
- can remain contracted for a long time
What are some properties of cardiac muscle?
- single nucleus per cell
- branching cells that communicate with each other
- striated (visible bands due to overlapping contractile proteins)
- involuntary contractions
- in heart wall only (myocardium)
- autorhythmic (contract on own without need for nervous system stimulation)
What is autorhythmic (cardiac muscle)?
means they contract on their own without need for nervous system stimulation
What are some properties of skeletal muscle?
- multinucleated
- long, large cylindrical cells (muscle fibres)
- striated
- sarcoplasmic reticulum prevalent (membranous structures that store calcium ions)
- voluntary contraction
- contracts and relaxes rapidly
What is sarcoplasmic reticulum?
membranous structures that store calcium ions - prevalent in skeletal muscle
Is skeletal muscle voluntarily or involuntarily contracted?
voluntary
- conscious stimulation to contract
- nervous system control
- some involuntary actions such as posture
What are 3 main functions of skeletal muscle? Name any others.
- movement (w/ bones & joints)
- maintenance of posture
- maintenance of body temperature
- vocalizations (muscles of speech), chewing (mastication), initial part of swallowing
How does skeletal muscle maintain body temperature?
- skeletal muscles generate heat
- heat is natural byproduct of muscle cell metabolism
- shivering (rapid small muscle contractions)
What are two primary properties of muscle tissue?
- excitability (stimulated to generate an action potential, which is a form of electrical impulse/electrical current)
- contractility (ability of muscle to shorten, generate force, and pull on a bone
What is excitability?
- stimulated to generate an action potential, which is a form of electrical impulse/electrical current
What characteristic of muscle tissue is described here:
stimulated to generate an action potential, which is a form of electrical impulse/electrical current
excitability
What characteristic of muscle tissue is described here:
steady, partial contraction that keeps the body in posture, holding head upright
muscle tone
What characteristic of muscle tissue is described here:
ability of the muscle to shorten, generate force, and pull on a bone (lever)
contractility
What characteristic of muscle tissue is described here:
ability to return to original resting length or stretch
extensibility
What is muscle tone?
steady, partial contraction that keeps the body in posture, holding head upright
What is contractility?
ability of the muscle to shorten, generate force, and pull on a bone (lever)
What is extensibility?
ability to return to original resting length or stretch
Describe the structure of a whole muscle?
- connective tissue coverings (endomysium covers individual muscle fibers, perimysium surrounds fascicles, epimysium outer covering or sheath of entire muscle)
- deep fascia wraps around a group of muscles that work together (eg quadriceps group, hamstrings)
- tendons form at either end of a muscle from the merging of fibers from all these CT layers (attach muscles to the CT periosteum of bone)
- bursa (cushioning sacs that prevent rubbing of tendons
What are the 3 components of connective tissue coverings of a whole muscle?
- endomysium covers individual muscle fibers
- perimysium surrounds fascicles (bundles of muscle fibres)
- epimysium outer covering or sheath of entire muscle
What is the deep fascia in regard to muscles?
wraps around a group of muscles that work together (eg quadriceps, hamstrings)
Where are tendons formed?
at either end of a muscle from the merging of fibers from connective tissue layers (attach muscles to the connective tissue periosteum of bone)
What are bursa?
cushioning sacs that prevent rubbing of tendons
What is a synapse?
a point of communications between two cells (neuromuscular junction or between two neurons)
What is a neuromuscular junction?
a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction.
What is the ultimate effect of the NMJ (neuromuscular junction)?
to cause release of calcium ions in the muscle cell (calcium needed for contraction)
What direction do nerve impulses travel? Motor impulses? Sensory impulses?
- nerve impulses come from the brain and spinal cord to stimulate the muscle fibers
- motor impulses travel away from the brain/spinal cord
- sensory impulses travel toward the brain/spinal cord
What carries impulses away from the neuron cell body?
axons
What is the receiving end of the neuron called?
dendrite
What is a motor unit?
a single neuron plus all of the muscle fibres it stimulates (a single action potential or nerve impulse causes all muscle fibres to contract simultaneously)
Do muscles that carry out fine motor control or those that carry out large/gross muscles have more fibres per motor unit?
- muscles that carry out large/gross muscle actions (have many fibres per motor unit - quadriceps, hamstrings)
- those that carry out fine motor control have few fibres per motor unit (fingertips)
Describe structure of muscle cell/fibre.
- composed of many overlapping threadlike filaments (or proteins)
- thin filaments (light bands composed mainly of actin)
- thick filaments (dark bands composed of myosin)
- filaments arranged in repeated 3D subunits called sarcomeres (arranged end to end)
