Exam 2 Part two Flashcards
Prime movers are
Also called agonist. A muscle that contracts to produce a particular movement, such as extending the forearm. The triceps brachii of the posterior arm is an agonist that causes forearm extension
Antagonists are
A muscle whose actions oppose those of the agonist. The contraction of the agonist stretches the antagonist, & vise versa
Synergists are
A muscle that assists the agonist in performing its action. The contraction of a synergist usually either contributes to tension exerted close to the insertion of the muscle or stabilized the point of origin
How are the biceps brachia & triceps brachia act as agonist & antagonist?
When the triceps brachia acts as an agonist to extend the forearm, the biceps brachia on the anterior side of the humerus acts as an antagonist to stabilized the movement & produce the opposing action, which is flexion of the forearm
When are synergists most useful?
At the start of a movement when the agonist is stretched & cannot exert more power
What are some examples of synergist muscles?
The biceps brachii & brachialis muscles of the arm. Both muscles work synergistically “together” to flex the elbow joint
Synergists may also assist an agonist by?
Preventing movement at a joint & thereby stabilizing the origin of the agonist
How many levers are found in the human body?
Three classes of levers; first-class, second-class, and third-class
First-class levers
Has a fulcrum in the middle, between the effort & the resistance
An example of first-class levers are?
A pair of scissors. The effort is applied to the handle of the scissors while the resistance is at the cutting end of the scissors. The fulcrum (pivot for movement) is along the middle of the scissors, between the handle & the cutting ends
What is an example of a first-class lever in the body?
The atlanto-occipital joint of the neck, where the muscles on the posterior side of the neck pull inferiorly on the nuchal lines of the skull & oppose the tendency of the head to tip anteriorly
The resistance in a second-class lever is between the
Fulcrum & the applied effort
A common example of second class lever is
Lifting the handles of a wheelbarrow, allowing it to pivot on its wheel at the opposite end & lift a load in the middle.
An example of second-class lever in the body is?
They are rare, but occurs when the foot is depressed so that a person can stand on tiptoe. The contraction of the calf muscles causes a pull superiorly by the calcaneal tendon attached to the heel (calcaneus)
Third class levers are
An effort is applied between the resistance & the fulcrum, as when picking up a small object with a pair of forceps. These are the most common levers in the body
An example of third class levers found in the body is?
Found at the elbow, where the fulcrum is the joint between the humerus & ulna. The effort is applied by the biceps brachii muscle, & the resistance is provided by any weight in the hand, or by the weight of the forearm itself
How does the mandible act as a third class lever?
When you bite w/ your incisors on a piece of food. The temporomandibular joint is the fulcrum, & the temporal is muscle exerts the effort, while the resistance is the item of food being bitten
What are the 3 types of pennate muscles?
Unipennate muscle, bipennate, & multipennate
Unipennate muscle is
All of the muscle fibers are on the same side of the tendon. The extensor digitorum, a long muscle that extends the fingers, is a unipennate
Bipennate muscle is
The most common type, has muscle fibers on both sides of the tendon. The palmar & dorsal interosseous muscles that attach to the metacarpals are composed of bipennate muscle that helps adduct and abduct the digits
Multipennate muscle
Has branches of the tendon w/in the muscle. The triangular deltoid that covers the shoulder joint is a multipennate muscle
Convergent muscle
Has widespread muscle fibers that converge on a common attachment site. This attachment site may be a single tendon, a tendinous sheet, or a slender band of collagen fibers (raphe). These muscle fibers are often triangular in shape, resembling a broad fans/a tendon at the tip
How is convergent muscle versatile?
The direction of its pull can be modified merely by activating a single group of muscle fibers at one time
An example of a convergent muscle is?
The pectoralis major of the chest
Red fibers are
Also called slow fibers. They are called red fibers because they contain the pigmented myoglobin which is a globular O2 binding, reddish-appearing protein that is structurally related to hemoglobin
White fibers are
Also called fast fibers. They are white because they are pale in color due to their lack of myoglobin
Intermediate fibers are
Exhibit properties that are somewhere between those of slow fibers & fast fibers. These fibers contract faster than the slow & slower than the fast fibers. They resemble fast fiber, however, they have a greater resistance to fatigue
Lever is
An elongated, rigid object that rotates around a fixed point called a fulcrum. They have the ability to change the speed & distance of movement produced by a force, the direction of an applied force, & the force strength
Aerobic is
Both slow & intermediate fibers require O2 to produce ATP, so the metabolic reactions w/in these fibers are termed aerobic
Central nervous system (CNS)
Composed of the brain & spinal cord. Command center of the nervous system that integrates & processes nervous information
Where are the brain & spinal cord housed?
The brain is protected & enclosed w/in the skull, while the spinal cord is housed & protected w/in the vertebral canal
Peripheral nervous system (PNS)
Includes the cranial nerves (nerves that extend from the brain), spinal nerves (nerves that extend from the spinal cord), & ganglia, which are clusters of neuron cell bodies located outside the CNS. Projects information to and receives information from CNS mediates some reflexes
Oligodendrocytes are
Large cells w/a bulbous body & slender cytoplasmic extensions or processes. The processes ensheath portions of many different axons, each repeatedly wrapping around part of an axon. This protective covering around the axon is called myelin sheath
Neurolemmocytes are
Also called schwann cells. They are associated w/PNS axons. Responsible for myelinating PNS axons.
Sensory (afferent) nervous system is responsible for
Receiving sensory info. from receptors & transmitting to CNS. Responsible for input. Contains both PNS & CNS components; nerves of the PNS transmit the sensory info, & certain parts of the brain & spinal cord interpret info. Has two components; Somatic sensory & visceral sensory
Motor (efferent) nervous system is responsible for
Transmitting motor impulses from CNS to muscles or glands. Also for output. Contains both CNS & PNS components; parts of the brain & spinal cord initiate nerve impulses, which travel through motor nerves that in turn transmit impulses to effector organs. Subdivided into somatic motor & autonomic motor components
Somatic sensory
The components are the general somatic senses-touch, pain, pressure, vibration, temp. & proprioception, & the special senses (taste, vision, hearing, balance, & smell). These functions are considered voluntary because we have some control over them & we tend to be conscious of them
Visceral sensory components transmit…
Nerve impulses from blood vessels & visceral to the CNS. The visceral senses include temp. & stretch (muscles of the organ wall). These functions are involuntary because we don’t have control over them & are not conscious of them
Somatic motor
Component conducts nerve impulses from the CNS to the skeletal muscles, causing them to contract. Called the voluntary nervous system division because the contractions of the skeletal muscles are under conscious control
Autonomic motor
This component is called the autonomic nervous system (ANS), because it innervates internal organs & regulates smooth muscle, cardiac muscle, & glands w/out our control. Also known as the visceral motor system or the involuntary nervous system. Has two further subdivisions: parasympathetic & sympathetic
The cell body of a neuron is
Also called a soma, serves as the neurons control center & responsible for receiving, integrating, & sending nerve impulses. It is enclosed by a plasma membrane & contains cytoplasm surrounding a nucleus
Dendrites tend to be
Shorter, smaller processes that branch off the cell body. Some neurons have only one dendrite, while others have many. They conduct nerve impulses toward the cell body; they receive input & then transfer it to the cell body for processing. The more dendrites a neuron has, the more nerve impulses that neuron can receive from other cells
