List #6 Flashcards
fascia
-layers of dense connective tissue that holds individual skeletal muscle in position.
myosin
-thick protein filament (dark)
actin
-thin protein filament (light)
sacromeres
- The striations form a repeating pattern of units along tac muscle fiber
I-bands
- The light bands, composed of thin actin filaments held by direct attachments to structures called Z lines
Z-lines
-Found in the center of I-bands
H-zones
- A slightly lighter central region consisting only of thick filaments found in the A-band
A-bands
-The second part of the striation pattern, which composes thick myosin filaments overlapping thin actin filaments
M-lines
- Consists of proteins that help hold the thick filaments in place, found in the A band in a thicker section.
myosin crossbridges
-A myosin head can attach to an actin binding site forming a cross-bridge, and bend slightly, pulling on the actin filament
ATPases
- An enzyme found in myosin heads
- it catalyzes the breakdown of ATP to ADP and a phosphate
tropomyosin
-rod-shaped and occupy the longitudinal grooves of the actin helix
troponin
-three protein subunits and are attached to actin
sarcoplasmic reticulum
- corresponds to the endoplasmic reticulum. Membranous channels in the sarcoplasm of a muscle fiber that surrounds each myofibril and runs parallel to it.
transverse tubules
- A set of membranous channels that extends into the sarcoplasm as invaginations continuous with the sarcolemma and contains extracellular fluid
triads
-Region where the actin and myosin filaments overlap
sliding filament theory
- When sarcomeres shorten, the thick and thin filaments do not change length
neuromuscular junction
- The synapse where a motor neuron axon and a skeletal muscle fibers.
- Here the muscle fiber membrane is specialized to form a motor end plate, where nuclei and mitochondria are abundant and the sarcolemma is extensively folded.
lower motor neurons
- Neurons that control effectors, including skeletal muscle fibers.
- Normally a skeletal muscle fiber contracts only upon stimulation by its motor neuron
motor end plates
- Where nuclei and mitochondria are abundant and the sarcolemma is extensively folded.
motor unit
- Together a motor neuron and a muscle fiber control it
synaptic cleft
- A small gap that separates the membrane of the neuron and the membrane of the muscle fiber
neurotransmitters
- Biological messenger molecules that convey neural information
synaptic vesicles
-tiny vesicles that stores neurotransmitters
acetylcholine (ACh)
- The neurotransmitter that motor neurons use to control skeletal muscle contraction.
acetylcholinesterase
- An enzyme that rapidly decomposes acetylcholine remaining in the synapse.
myasthenia gravis
- grave muscular weakness
- The body produces antibodies that target receptors for the neurotransmitter acetylcholine on skeletal muscle cells at neuromuscular junctions
peristalsis
- Alternare contractions and relaxations of the longitudinal and circular muscles.
- In the intestines it pushes food down the digestive tract
dendrites
- Small cellular processes that receive input
axons
- A longer process than dendrites(nerve fiber) , and carries the information away from the cell in the form of impulses
cell body(perikaryon) of neuron
- It contains granular cytoplasm, mitochondria, lysosomes, a Golgi apparatus, and many microtubules.
chromatophilic substance (Nissl substance)
- consist mainly of rough endoplasmic reticulum
Schwan cells
-neuroglia that encase the large axons of peripheral neurons in lipid-rich sheaths (PNS)
myelin
- layers that consist of several types of lipids and proteins
nodes of Ranvier
-Narrow gaps in the myelin sheath between Schwann cells
trigger zone (axon hillock)
- In a multipolar neron, the first part of the axon the cone-shaped axon hillock or initial segment
astrocytes
- provide support and hold structures together with abundant cellular processes
- aid metabolism of certain substances, and they may help regulate the concentrations of important ions in the interstitial space of nervous tissues
oligodendrocytes
- A type of neuroglia that produces myelin rather than a Schwann cell. (CNS)
microglia
- Small cells that have fewer processes than other types of neuroglia
ependyma
- Cuboidal or columnar cells in shape and may have cilia.
- They form the inner lining of the central canal that extends downward through the spinal cord
ventricles
-Ependymal cells also form a one-cell-thick epithelial-like membrane that covers the inside of spaces in the brain
central canal
-Extends downward from the spinal cord
choroid plexuses
- Specialized capillaries associated with the ventricles of the brain
- They regulate the composition of the cerebrospinal fluid
buccinator
origin: Alveolar processes of maxilla and mandible
insertion: orbicularis oris
action: compresses cheeks
platysma
origin: Fascia in upper chest
insertion: skin and muscles below mouth; mandible
action: depresses lower lip and angle of mouth as when pouting
levator scapulae
origin: transverse processes of cervical vertebra
insertion: medial border of scapula
action: elevates scapula
pectoralis major
origin: clavicle, sternum, and costal cartilages of upper ribs
insertion: intertubercular groove
action: flexes shoulder, adducts, and rotates arm medially
coracobrachialis
origin: coracoid process of scapula
insertion: medial mid-shaft of humerus
action: flexes shoulder and adducts arm
teres major
origin: lateral border of scapula
insertion: intertubercular groove
action: extends shoulder, adducts, and rotates arm medially
subscapularis
origin: anterior surface of scapula
insertion: lesser tubercle of humerus
action: rotates are medially
infraspinatus
origin: infraspinous fossa of scapula
insertion: greater tubercle of humerus
action: rotates arm laterally
brachioradialis
origin: distal lateral end of humerus
insertion: lateral surface of radius above styloid process
action: flexes elbow
triceps brachii
origin: tubercle below glenoid cavity and lateral and posterior surfaces of the humerus
insertion: olecranon process of ulna
action: extends the elbow
plantaris
origin: femur
insertion: calcaneus
action: plantar flexion of foot, flexes knee
