Unit 3: Muscular system Pt.1 Flashcards
What is the purpose of your muscular system?
Regulates homeostasis by stabilizing body positions, producing movements, regulating organ volume, moving substances within the body, and producing heat.
What composes your muscular system and how does it work?
The voluntary controlled muscles of your body compose the muscular system.
Skeletal muscles that produce movements do so by exerting force on tendons, which in turn pull on bones or other structures.
What are muscles attached to?
Muscles are attached to bones by tendons at their origins and insertions.
What happens when skeletal muscle contracts?
When a skeletal muscle contracts, it moves one of the articulating bones. The two articulating bones usually do not move equally in response to contraction. One bones remains stationary or near its original position.
Differentiate between origin and insertion in regards to muscles.
The attachment of a muscles tendon to the stationary bone is called the origin.
The attachment of the muscles other tendons to the moveable bone is the insertion.
The origin is usually proximal and the insertion is distal, the insertion is usually pulled towards the origin.
Define the belly of the muscle.
The fleshy portion of between the tendons is called the belly.
Define action and the relation to reverse muscle action.
The actions of a muscle are the main movements that occur when the muscle contracts.
Certain muscles are also capable of reverse muscle action (RMA), meaning during specific movements of the body the actions are reversed.
Define lever in relation to muscles and joints.
In producing movements, bones acts as levers, and joints function as the fulcrum.
A lever is a rigid structure that can move around a fixed point called a fulcrum.
Differentiate between effort and load.
A lever is acted on at two different forces, the effort, which causes movements, and the load or resistance, which opposes movement.
How does motion occur?
Motion occurs when the effort applied to the bone at the insertion exceed the load.
Differentiate between mechanical advantage and mechanical disadvantage.
The relative distance between the fulcrum and load and the point at which the effort is applied determine wether a given lever operates at a mechanical advantage or a mechanical disadvantage.
If the load is closer to the fulcrum and the effort farther from the fulcrum, then only a relatively small effort is required to move a large load over a small distance. This is called a mechanical advantage.
If the load is farther from the fulcrum and the effort is applied closer to the fulcrum, then a relatively large effort is require to move small load. This is called a mechanical disadvantage.
What are the three types of levers?
- First class lever
- Second class lever
- Third class lever
Define first class levers.
The fulcrum is between the effort and the load. A first class lever can produce either a mechanical advantage or a mechanical disadvantage.
Define second class levers.
The load is between the fulcrum and the effort. They always produce a mechanical advantage because the load is always closer to the fulcrum than the effort. This type of lever produces the most force. This class of lever is uncommon in the human body.
Define third class lever.
The effort is between the fulcrum and the load. These levers operates like a pair of forceps and are the most common levers in the body. Third class levers always produce a mechanical disadvantage because the effort is always closer to the fulcrum than the load.
Define what fascicles are.
Within a muscle are arranged in bundles known as fascicles. Within a fascicle, all muscle fibers are parallel to one another.
What are the five patterns of fascicles.
- Parallel
- Fusiform
- circular
- Triangular
- Pennate
Define what parallels in fascicles are.
Fascicles parallel to longitudinal axis of muscle; terminate at either end in flat tendon.
Define what circular patterns are in fascicles.
Fascicles in concentric circular arrangement form sphincter muscles that encloses an orifice.
Define what pennate patterns are. Define the three types.
Short fascicles in relation to total muscle length; tendon extends nearly entire length of muscle
- Unipennate: Fascicles arranged on only one side of the tendon.
- Bipennate: Fascicles arranged on both sides of centrally positioned tendons.
- Multipennate: Fascicles attach oblique from many directions to several tendons.
Define what fusiform in fascicles are.
Fascicles nearly parallel to longtitudinal axis of muscles; terminate in flat tendons; muscle tapers towards tendons, where diameter is less than at belly.
Define what triangular fascicles are.
Fascicles spread over broad area converge at thick central tendon; gives muscle a triangular appearance.
Differentiate between prime mover and antagonist.
Most skeletal muscles are arranged in opposing pairs at joints. Within opposing pairs, one muscle called the prime mover or agonist, contracts to cause an action while the other muscle, the antagonist stretches and yields the effects of the prime mover.
If a prime mover and its antagonist contract at the same time with equal force, there will be no movement.
The muscle primary responsible for a movement is called the primary mover.
A muscle with the opposite action of the prime mover is called an antagonist.
Define synergists.
When a prime mover crosses other joints before it reaches the joint at which its primary action occurs. To prevent unwanted movements at intermediate joints or to otherwise aid the movement of the prime mover, muscles called synergists contract and stabilize the intermediate joints.
Synergists are usually located close to the prime mover.
Muscles that assist in this action are called synergist.
Define fixators.
Some muscles in a group also act as fixators, stabilizing the origin of the prime mover so that the prime mover can act more efficiently. Fixators steady the proximal end of a limb while movements occur at the distal end.
A synergist that makes the insertion site more stable is called a fixator.
Define compartments in muscles.
In the limbs, a compartment is a group of skeletal muscles, their associated blood vessels, and associated nerves all of which have a common function.
What are the seven characteristics used to name muscles?
- Direction
- Size
- Shape
- Action
- Number of origins
- Location
- Origin and insertion
How are facial expressions contract?
Muscles of facial expression move the skin rather than a joint.
What are the three scalp muscles that make up facial expressions? Explain them.
- Occiptofrontalis
- Frontal belly: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of the forehead horizontally as in locks of surprise.
- Occipital belly: Draw scalp posteriorly.
What are the four mouth muscles responsible for facial expression? Explain them.
- Orbicularis oris: Closes and protrudes lips, as in kissing: compresses lips against teeth; and shapes lips during speech.
- Zygomaticus major: Draws angle of mouth superiorly and laterally, as in smiling.
- Buccinator: Presses cheeks against teeth and lips
What is the orbit and eyebrow muscle responsible for facial expression? Explain it.
Orbicularis oculi: closes eyes.
Explain what muscles of mastication is. What are the two powerful closers of the jaw and account for the strength of the bite? Explain the origin, insertion, and action.
The muscle that move the mandible at the tempomandibular joint are known as the muscles of mastication also known as chewing.
Masseter:
- Origin: Maxilla and zygomatic arch
- Insertion: Angle and ramus of mandible
- Action: Elevates mandible, as in closing mouth
Temporalis:
- Origin: Temporal bone
- Insertion: Coronoid process and ramus of mandible
- Action: Elevates and retracts mandible
What is the head attached to?
The head is attached to the vertebral column at the atlanto-occipital joints formed by the atlas and occipital bone.
What is the muscle responsible for the movement of the head? Explain the origin, insertion, and action.
Sternocleidomastoid: Divided into two principle triangles (anterior and posterior)
- Origin: Sternal head, manubrium of sternum, clavicular
head, medial third of clavicle.
- Insertion: Mastoid process of temporal bone and
lateral half of superior nuchal line of occipital bone.
- Action: Acting together, flex cervical portion of
vertebral column, extended head at atlanto-occipital
joints. Acting singly, laterally flex neck and head to
same side and rotate head to side opposite contracting
muscle. Laterally rotate and flex head to opposite sides
of muscle. Posterior fibers of muscle can assist in
extension of head. Elevates sternum during forced
inhalation.
What are the four muscles protecting the abdominal visceras and moves the vertebral column? Explain the origin, insertion, and action.
Rectus abdominis:
- Origin: Pubic crest and pubic symphysis
- Insertion: Cartilage of ribs 5 - 7 and xiphoid process.
- Action: Flexes vertebral column, especially lumbar
portion and compresses abdominal to aid in
defecation, urination, forced exhalation, and childbirth.
External oblique:
- Action: Acting together, compress abdomen and flex
vertebral column. Acting singly, laterally flex vertebral
column, especially lumbar portion and rotate vertebral
column.
Internal oblique:
- Action: Same as external oblique.
Transversus abdominis:
- Insertion: Xiphoid processes, linea alba, and pubis.
- Action: Compresses abdomen.
Describe the purpose of the anterolateral abdominal muscles.
The anterolateral abdominal muscles protect the abdominal viscera, move the vertebral column, and assist in forced exhalation, defecation, urination, and childbirth.
Describe the rectus sheath. How is it related to linea alba?
The aponeuroses (sheathlike tendon) of the external oblique, internal oblique, and transverse abdominis muscles form the rectus sheath. It encloses the rectus abdominis muscles.
The sheaths meet at the midline to form the linea alba, a tough fibrous band that extends from the xiphoid process of the sternum to the pubis symphysis.
In the later stages of pregnancy, the linea alba stretchs to increase the distance between the rectus abdominis muscles.
What are the two types of muscles most important in breathing?
The diaphragm and the intercostals.
Describe what the diaphragm is. How does it work?
The dome shapes diaphragm is the most important muscle that powers breathing. It also separates the thoracic and abdominal cavity.
It peripheral muscular portion of the diaphragm originates on the xiphoid process of the sternum, the inferior six ribs and their costal cartilages, and the lumbar vertebrae and their intervertebral discs and the twelfth ribs.
Breathing in contracts the diaphragm and causes it to flatten and increase in vertical dimension.
Breathing out causes the diaphragm to expand.
Define what intercostal muscles are.
Also involved in breathing. They span the intercostal spaces, which are the spaces between the ribs. These muscles are arranged in three layer but two are the most important which are the external intercostal and internal intercostal muscles.
The external intercostal runs diagonally on the surface of the muscle.
The main purpose of these muscles is to help expand and deflate the thoracic cage when breathing. `
Name the two anterior thoracic muscles that move the pectoral girdle. Explain the origin, insertion, and action.
Pectoralis minor
- Action: Abducts scapula and rotates it downwards.
Elevates ribs 3 - 5 during forced inhalation when
scapula is fixed.
Serratus anterior
- Origin: Ribs 1 - 8 or 1 - 9
- Insertion: Vertebral border and inferior angle of
scapula.
- Action: Abducts scapula and rotates it upward. Elevates
ribs when scapula is stabilized. Known as ‘boxers
muscle’ because it is important in horizontal arm
movements such as punching and pushing.
Name the three posterior thoracic muscles that move the pectoral girdle. Explain the origin, insertion, and action.
Trapezius
- Origin: Superior nuchal line of occipital bone,
ligamentum nuchae and spine of C7 - T12.
- Insertion: Clavicle and acromion and spine of scapula.
- Action: Superior fibers upward rotate scapula. Middle
fibers adduct scapula. Inferior fibers depress and
upward rotates scapula. Superior and inferior fibers
together rotate scapula upward. Superior fibers can
help extend the head.
Levator scapulae
- Origin: Transverse processes of C1 - C4.
- Insertion: Superior vertebral border of scapula.
- Action: Elevates scapula and rotates it downward.
Rhomboid major
- Action: Elevates and adducts scapula and rotates it
downward stabilizes scapula.
Where does the muscles that move the pectoral girdle originate from?
Muscles that move the pectoral girdle originate on the axial skeleton and insert on the clavicle or scapula.
Describe the two axial muscles that move the humerus. Explain the origin, insertion, and action.
Pectoralis major
- Origin: Clavicle, sternum, and costal cartilages of the
ribs 2 - 6
and sometimes the ribs 1 - 7.
- Insertion: Greater tubercle and lateral lip of inter
tubercular sulcus of humerus.
- Action: As a whole, adducts and medially rotates arm at
shoulder joint. Clavicular head flexes arm, and
sternocostal head extends flexed arm to side of trunk.
Latissimus dorsi
- Action: Extends, adducts, and medially rotates arm at
shoulder joint. Draws arm inferiorly and posteriorly.
Elevates vertebral column and torso.
What are the six scapular muscles that move the humerus? Explain the origin, insertion, and action.
Deltoid
- Origin: Acromial extremity of clavicle, acromion of
scapula, and spine of scapula.
- Insertion: Deltoid tuberosity of humerus.
- Action: Lateral fibers abducts arm at shoulder joint.
Anterior fibers flex and medially rotate arm at
shoulder. Posterior fibers extend and laterally rotate
arm at shoulder joint.
Subscapularis
- Action: Medially rotates arm at shoulder joint.
Supraspinatus
- Origin: Supraspinous fossa of scapula.
- Insertion: Greater tubercle of humerus.
- Action: Assists deltoid muscle in abducting arm at
shoulder joint.
Infraspinatus
- Action: Laterally rotates arm at shoulder joint.
Teres major
- Action: Extends arm at shoulder joint and assists in
adduction and medial rotation of arm at shoulder joint.
Teres minor
- Action: Laterally rotates and extends arm at shoulder joint.
How is the rotator cuff related to the shoulder joint?
The strength and stability of the shoulder joint are provided by the tendons that form the rotator cuff.
Explain the three forearm flexors that moves the radius and ulna. Explain the origin, insertion, and action.
Biceps brachii
- Origin: Long head originates from tubercle above
glenoid cavity of scapula.
- Insertion: Radial tuberosity of radius and bicipital
aponeurosis.
- Action: Flexes forearm at elbow joint, supination
forearm at radioulnar joints, and flexes arm at shoulder
joint.
Brachialis
- Action: Flexes forearm at elbow joint.
Brachioradialis
- Action: Flexes forearm at elbow joint, supinates and
pronates forearm at radioulnar joints to neutral
position.
Explain the two forearm extension muscles that move the radius and ulna. Explain the origin, insertion, and action.
Tripes brachii
- Origin: Long head originates from infraglenoid tubercle,
a projection inferior to glenoid cavity of scapula.
Lateral head originates from lateral and posterior
surface
of humerus. Medial head originates from entire
posterior surface of humerus inferior to a groove for
the radial nerve.
- Insertion: Olecranon of ulna.
- Action: Extends forearm at elbow joint and extends
arm at shoulder joint.
Anconeus
- Origin: Lateral epicondyle of humerus.
- Insertion: Olecranon and superior portion of shaft of
ulna.
- Action: Extends forearm at elbow joint.
Explain the forearm pronator muscles that move the ulna and the radius. Explain the action.
Pronator teres
- Action: Pronates forearm at radioulnar joints and
weakly flexes forearm at elbow joint.
Explain the forearm supinator muscles that move the ulna and the radius. Explain the action.
Supination
- Action: Supinates forearm at radiaulnar joints.
How does the forearm extend and flexes?
The anterior arm muscle flexes the forearm and the posterior arm muscles extends it.
Explain the four superficial anterior compartment of the forearm. Explain the origin, insertion, and action.
Flexor carpi radialis
- Origin: Medial epicondyle of humerus.
- Insertion: Metacarpals 2 and 3.
- Action: Flexes and abducts hand at wrist joint.
Palmaris longus
- Action: Weakly flexes hand at wrist joints
Flexor carpi ulnaris
- Origin: Medial epicondyle of humerus and superior
posterior border of ulna.
- Insertion: Pisiform, hamate, and base of metacarpal 4.
- Action: Flexes and adducts hand at wrist joint.
Flexor digitorum superficialis
- Origin: Medial epicondyle of humerus, coronoid
process of ulna, and ridge along lateral margin or
anterior surface of radius.
- Insertion: Middle phalanx of each finger.
- Action: Flexes middle phalanx of each finger at
proximal interphalangeal joint, proximal phalanx of
each finger at metacarpophalangeal joint, and hand at
wrist joint.
Explain the three superficial posterior compartment of the forearm. Explain the origin, insertion, and action.
Extensor carpi radialis longus
- Action: Extends and abducts hand at wrist joint.
Extensor digitorum
- Origin: Lateral epicondyle of humerus.
- Insertion: Distal and middle phalanges of each finger.
- Action: Extends distal and middle phalanges of each
finger at interphalangeal joints, and hand at the wrist
joint.
Extensor carpi ulnaris
- Origin: Lateral epicondyle of humerus and posterior
border of ulna.
- Insertion: Metacarpal 5.
- Action: Extends and adducts hand at wrist joint.
Whats the main difference between the anterior compartment muscles and the posterior compartment muscles?
The anterior compartment muscle functions as flexors, and the posterior compartment muscles function as extensors.
What are the three erector spinae that move the neck and back that move the vertebral column? What is the action?
Ileocostalis cervicis, iliocostalis thoracis, and iliocostalis lumborum.
- Action: Acting together, muscles of each region extend
and maintain erect posture of vertebral column of their
respective regions.
Explain the three scalene muscles. Explain their actions.
Anterior scalene
- Action: Acting together, right and left anterior scalene
and middle scalene muscles elevate first ribs during
deep inhalation.
Middle scalene
- Action: Flex cervical vertebrae. Acting singly, laterally
flex and slightly rotate cervical vertebrae.
Posterior scalene
- Action: Acting together, right and left posterior scalene
elevate second ribs during deep inhalation. Flex cervical
vertebrae. Acting singly, laterally flex and slightly rotate
cervical vertebrae.
Explain what the erector spinae muscle groups are.
The erector spinae group is the largest muscular mass of the back and is the chief extensor of the vertebral column.
Explain the six muscles included in moving the gluteal region that move the femur.
Iliopsoas psoas major
- Origin: Transverse processes and bodies of lumbar
vertebrae.
- Insertion: With iliacus into lesser trochanter of femur.
- Action: Psoas major and iliacus muscles acting together
flex thighs at hip joints, rotate thigh laterally, and flex
trunk on hip as in sitting up from supine position.
Iliacus
Gluteus maximus
- Origin: Iliac crest, sacrum, coccyx, and aponeurosis of
sacrospinalis.
- Insertion: Iliotibial tract of fascia lata and superior
lateral part of the linea aspera under greater trochanter
of femur.
Gluteus medius
- Action: Abducts thigh at hip joint and medially rotates
thigh.
Adductor longus
- Action: Adducts and flexes thigh at hip joint and rotates
thigh. Extends thigh.
Where does the muscles that move the femur originate from?
Most muscles that move the femur originate on the pelvic girdle and insert on the femur.
Explain the five anterior compartment quadriceps femoris muscles that move the femur, tibia, and fibula. Explain the origin, insertion, and action.
Rectus femoris
- Origin: Anterior inferior iliac spine.
- Insertion: Patella via quadriceps tendon and then tibial
tuberosity via patellar ligaments.
- Action: All four heads extend leg at knee joint. Rectus
femoris muscle acting along also flexes thigh at hip
joints.
Vastus lateralis
- Origin: Greater trochanter and linea aspera of femur
- Insertion: Same as Rectus femoris
- Action: Same as Rectus femoris
Vastus medialis
- Origin: Linea aspera of femur
- Insertion: Same as Rectus femoris
- Action: Same as Rectus femoris
Vastus intermedius
- Origin: Anterior and lateral surfaces of femur
- Insertion: Same as Rectus femoris
- Action: Same as Rectus femoris
Sartorius
- Action: Weakly flexes leg at knee joint. Weakly flexes, abducts, and laterally rotates thigh at hip joint.
Define what hamstrings are.
A collective designation for three separate muscles.
Define the three hamstring muscles. Explain the origin, insertion, and action.
Biceps femoris
- Origin: Long head arises from ischial tuberosity
- Insertion: Head of fibula and lateral condyle of tibia
- Action: Flexes leg at knee joint and extends thigh at hip
joint.
Semitendinosus
- Action: Same as Biceps femoris
Semimembranous
- Action: Same as Biceps femoris
Name the two anterior muscle compartments of the legs that move the foot and toes.
Tibialis anterior
- Origin: Lateral condyle and body of tibia and
interosseous membrane.
- Insertion: Metatarsal 1 and first cuneiform.
- Action: Dorsiflexes foot at ankle joint and inverts foot at
intertarsal joint.
Extensor digitorum longus
- Origin: Lateral condyle of tibia, anterior surface of
fibula, and interosseous membrane.
- Insertion: Middle and distal phalanges of toes
- Action: Dorsiflexes foot at ankle joint and extends distal
and middle phalanges of each toe at interphalangeal
joints and proximal phalanx of each toe at
metatarsophalangeal joint.
Name the lateral muscle compartment of the leg. Explain its action.
Fibularis
- Action: plantar flexes foot at ankle joint and erects foot
at intertarsal joint.
Name the two superficial posterior compartment of the leg that move the toes. Explain the origin, insertion, and action.
Gastrocnemius
- Origin: Lateral and medial condyles of femur and
capsule of knee
- Insertion: Calcaneus by way of calcaneal (achilles)
tendon
- Action: Plantar flexes foot at ankle joint and flexes leg
at knee joint.
Soleus
- Action: Plantar flexes foot at ankle joint
What characteristics allow nerve impulse to generate?
The excitable characteristics of nervous tissue allows for the generation of nerve impulse (action potential) that provide communication with and regulation of most body organs.
Define what nervous system is.
The nervous system is one of the smallest and yet the most complex of the 11 body system.
Differentiate between a neurologist and neurology.
Neurologist is a physician who diagnosis and treats disorders of the nervous system. Neurology deals with normal functioning and disorders of the nervous system.
Define what the central nervous system is.
Consists of the brain and the spinal cord. The brain is located in the skull, and the spinal cord is connected to the brain through the foramen magnum. The CNS processes sensory information. It is also the source of thoughts, emotions, and memories.
Define what the peripheral nervous system is.
Consists of all nervous tissue outside the CNS. Components of the PNS includes nerves and sensory receptors.
Define what a nerve is.
A nerve is a bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord.
Differentiate between cranial nerve and spinal nerve.
Twelve pairs of cranial nerves emerge from the brain and thirty one pairs of spinal nerve emerge from the spinal cord.
Define what the sensory receptor is.
The term sensory receptor refers to a structure of the nervous system that monitors changes in the external or internal environment.
What is the PNS divided into?
The sensory and motor division.
Differentiate between the sensory and motor division.
The sensory division also called afferent of the PNS conveys input into the CNS from sensory receptors in the body. This division provides the CNS with sensory information about the somatic senses and special senses.
The motor division also called efferent of the PNS conveys output from the CNS to effectors.
Differentiate between the somatic senses and special senses.
Somatic senses is tactile, thermal, pain, and proprioceptive sensations.
Special senses are smell, taste, vision, hearing, and equilibrium.
What two subdivision is motor division split into?
The somatic nervous system and the autonomic nervous system.
Define the somatic nervous system.
The somatic nervous system conveys output from the CNS to skeletal muscles only. It is voluntary.
Define the autonomic nervous system.
The autonomic nervous system conveys output from the CNS to smooth muscles, cardiac muscles, and glands. It is involuntary.
What are the two main branches of the autonomic nervous system.
The two branches are the sympathetic and the parasympathetic nervous system.
Differentiate between the sympathetic and the parasympathetic nervous system.
The parasympathetic nervous system takes care of the ‘rest and digest’ activities. The sympathetic nervous system helps support exercise or emergent actions, also called your fight or flight.
Define what the enteric nervous system is.
A network of neurons confined in the walls of the gastrointestinal tract. It helps regulate the activity of the smooth muscle tissue and glands of the GI tract and it also functions independently.
Define the three basic functions of the nervous system.
Sensory function: Detects internal stimuli, or external stimuli. This sensory information is then carried into the brain and spinal cord through cranial and spinal nerve.
Integrative function: The nervous system process sensory information by analyzing it and making decisions for appropriate responses. An activity known as integration.
Motor function: Once sensory information is integrated, the nervous system may elicit an appropriate motor response by activating effectors through cranial and spinal nerves.
What type of cells is the nervous tissue comprised of?
Neurons and Neuroglia.
Differentiate between neurons and neuroglia.
As a result of their specialization, most neurons have lost the ability to undergo mitotic division. Neuroglia are smaller cells, but they greatly outnumber neurons. Neuroglia continues to divide throughouts a persons lifetime.
What is the function of neuroglia?
They nourish, support, and protect neurons and maintain the interstitial fluid that bathes them.
What does it mean when neurons possess electrical excitability?
Like muscle cells, neurons possess electrical excitability, which is the ability to respond to a stimulus and convert it into action potential.
Define what is meant by stimulus.
A stimulus is any change in the environment that is strong enough to initiate an action potential.
What is an action potential?
An action potential is an electrical signal that propagates along the surface of the membrane of a neuron. It begins and travels due to the movement of ions between the interstitial fluid and the inside of a neuron through specific ion channels in its plasma membrane.
What are the three parts of a neuron?
- Cell body
- Dendrites
- An axon
Define what the cell body is in a neuron?
A cell body, also called soma, contains a nucleus surrounded by cytoplasm that includes typical cellular organelles. The cell body also contains free ribosomes and prominent clusters of rough ER called nissl bodies.
What are the function of the nissl bodies?
Newly synthesized proteins produced by the nissl bodies are used to replace cellular components, as material for growth of neurons, and to regenerate damaged axons in the PNS.
Differentiate between neurofibrils and microtubules.
The cytoskeleton includes both neurofibrils and microtubules. Neurofibrils are composed of bundles of intermediate filaments that provide the cell shape and support. Microtubules assists in moving materials between the cell body and axon.
Define what lipofuscin is.
Aging neuron also contains lipofuscin, it is a pigment that occurs as clumps of yellowish-brown granules in the cytoplasm.
Lipofuscin is a product of neuronal lysosomes that accumulates as the neuron ages, but does not seem to harm the neuron.
Define what ganglion is.
A collection of neuron cell bodies outside the CNS is called a ganglion.
Define what nerve fibers are.
A nerve fiber is a general term for any neuronal process that emerges from the cell body of a neuron.
Define the function of dendrites.
Dendrites are the receiving or input portions of the neuron. The plasma membrane of dendrites contain numerous receptor sites for binding chemical messages from other cells.
Define what the axon is.
A single axon of a neuron propagates nerve impulses towards another neuron, a muscle fiber, or a gland cell. An axon is a long, thin, cylindrical projection that often joints to the cell body at a cone shaped elevation called the axon hillock.
Define what the axon hillock is.
The part of the axon closes to the axon hillock is the initial segment. Nerve impulse arise at the junction of the axon hillock and the initial segment, an area called the trigger zone, from which they travel along the axon to their destination.
Why does protein synthesis not occur in the axon?
Rough ER is not present on the axon.
