The muscular system Flashcards
What are the 3 functions of muscle?
Movement, maintaining posture and heat generation.
What are the 3 types of muscles and indicate whether they are under voluntary or involuntary control?
Skeletal - voluntary
Cardiac - involuntary
Smooth - involuntary
When referring to muscles what do voluntary and involuntary mean?
Voluntary means that the muscle is under conscious control
Involuntary means that the muscle is not under conscious control
Describe the primary differences between skeletal, cardiac and smooth muscles
Skeletal muscles are under conscious control, are attached to the skeleton, serve to move the skeleton and generate heat.
Cardiac muscle is located in the heart, serves to pump blood and is not under conscious control.
Smooth muscle is located in multiple internal organs such as the stomach, intestines and blood vessels, serve to bring about movements in those organs and is not under conscious control.
What is the name of the fibrous tissue sheath that surrounds an individual muscle fibre(cell)?
The endomysium
What is the name of the fibrous tissue sheath that surrounds an entire muscle?
The epimysium
What is the name of the fibrous tissue band that runs between the abdominal muscles? What is the scientific term for this structure?
The linea alba
It is an aponeurosis
What is the difference between the origin of a muscle and its insertion?
The origin is the attachment of the muscle to the skeleton that is relatively stable that allows the contraction of that muscle to move the part of the skeleton that is attached at the site termed the insertion.
What is the definition of an agonist muscle? Give and example and describe what part of the skeleton it moves.
An agonist is a muscle that directly produces a desired movement. The Biceps brachii is an agonist. It brings about upward movement of the forearm (radius and ulna). The triceps brachii is also an agonist and brings about the downward movement of the forearm.
What is the definition of an antagonist? Give an example and describe part of the skeleton it controls.
An antagonist is a muscle that directly opposes the movement of an agonist. The triceps brachii is the antagonist to the biceps brachii. It opposes the upward movement of the forelinmb brough about by contraction of that muscle.
Based on the naming conventions of muscles approximately where would the deep digital flexor muscle be located and what would be its function?
It would be located deep to other muscles in other words closer to the bone in the limbs and its function would be to flex the digits.
What does the masseter muscle do?
It is the main muscle of chewing
What are the names of the abdominal muscles listed in order from most superficial to deepest?
External abdominal oblique, internal abdominal oblique, rectus abdominis and transverse abdominis.
What is the basic contractile unit of skeletal muscle called?
Sarcomere
Define myofibril
It is a structure within a muscle cell that is made up of sarcomeres laid end to end
What are the main components of muscle fibres (cells)?
Myofibrils, mitochondria, sarcoplasmic reticulum and Transverse tubules
What substances give skeletal muscle a striated appearance?
Actin, myosin and Z-lines
Define a motor unit
One nerve fiber and all the muscle fibers it innervates
What is the neurotransmitter that works in the neuromuscular
Acetylcholine
What ion, released from the sarcoplasmic reticulum by a nerve impulse, starts the contraction process in a muscle fiber?
Calcium
What are the names of the 2 fibres in the sarcomere that contract against each other to bring about muscle contraction
Actin and myosin
What molecule provides the power for the sliding of actin and myosin against each other?
ATP
What does ATP convert to once it has released its power?
ADP
In muscles, what molecule allows ADP to be recharged to ATP in preparation to power further muscle contractions?
Creatine Phosphate
What is the name of the molecule that stores oxygen in the muscle?
Myoglobin
Why does an animal breathe heavily for a while after heavy exercise?
Anaerobic exercise leads to the production of lactate that can be converted back to glucose in the liver but requires oxygen necessitating panting until this process is complete.
How do muscles work?
When a muscle contracts every cell in that muscle shortens. When a muscle relaxes every cell in that muscle lengthens.
How do muscles generate heat?
They undergo spasmodic contractions that generate heat. Also known as shivering. Not under voluntary control.
What is the name of the group of muscles that is the main adductor of the forelimb?
The pectoral muscles
Name the muscles that flex and extend the elbow joint.
Flex biceps brachii. Extend triceps brachii.
What movements do contraction of the muscles on the cranial aspect of the distal forelimb (below the elbow) bring about?
Extension of the digits and the carpus
What movements do contraction of the muscles on the caudal aspect of the distal forelimb (below the elbow) bring about?
Flexion of the carpus and digits
What main muscle groups extend the hip?
The gluteals and the hamstrings
What muscles do we use for intramuscular injections in dogs and cats?
Quadriceps, Lumbar,Triceps, Semimembranosus/semitendinosus
What muscles do we use for intramuscular injections in horses?
Neck,Semimembranosus/semitendinosus, Pectoral muscles
What are the unique characteristics of cardiac muscle?
Cells contract spontaneously with no external stimulation. Groups of cells contract at the rate of the most rapid cell in the group.
What effect does stimulation by the sympathetic nervous system have on cardiac muscle?
It increases heart rate.
What are the functions of intercalated discs in cardiac muscle?
The represent a physical attachment between cardiac muscle cells and they allow electrical impulses to pass between cardiac muscle cells.
What structure generates the impulse that starts each heart beat?
The Sinoatrial node.
List where visceral smooth muscle is located
Stomach, intestines, uterus, urinary bladder
In the wall of the gastrointestinal tract (GIT) what triggers smooth muscle to contract?
Stretching of the walls of the GIT
What effect does stimulation from the sympathetic nervous system (fight or flight) have on visceral smooth muscle?
It decreases activity
List where multiunit smooth muscle is located
Iris and ciliary body of eye, walls of small blood vessels, and small air passageways in lungs
