Chapter 1 Key Terms Flashcards
A-band
muscle striation containing myosin filaments; appears dark under light microscope & light in polarized light
acetylcholine
a neurotransmitter that stimulates nicotinic receptors in autonomic ganglia, at the motor endplates of skeletal muscle, & in the central nervous system as well as muscarinic receptors in smooth myscle, in exocrine glands & int he central nervous system
actin
one of the protein components into which actomyosin can split
action potential
sequence of electrical changes that occurs in a portion of a nerve cell membrane that is exposed to a stimulus that exceeds the membrane’s threshold
all-or-none principle
theroy that when a muscle contracts completely or not at all
alveolar pressure
is the pressure inside the alveoli when the glottis is open & no air is flowing into or out of the lungs
alveoli
1 - one of the terminal secretory portions of an alveolar or racemose gland.
2 - one of the honeycomb pits in the wall of the stomach
aortic valve
the valve between the left ventricle & the ascending aorta, consisting of three fibrous semilunar cusps (valvules)
arterial system
which carries blood away from the heart
arteriole
a minute artery with a tunica media comprising only one or two layers of smooth muscle cells
artery
thick-walled, muscular blood vessel conveying blood away fromt eh heart & pulsating with each heartbeat. with the exception of the pulmonary & umbilical arteries, the arteries convey red or oxygenated blood
atrioventricular (AV) bundle
group of specialized fibers that conducts impulses from the atrioventricular node to the Purkinje fibers in the ventricular muscle of the heart
atrioventricular (AV) node
specialized mass of cardiac muscle fiibers located in the interatrial septum of the heart; transmits cardiac impulses from the sinoatrial node to the A-V bundle
atrioventricular (AV) valves
cardiac valve located between an atrium & a ventricle
atrium
chamber of the heart that recieves blood from veins
bone periosteum
a specialized connective tissue covering all bones
bradycardia
slowness of the heartbeat, usually a rate less than 60 beats per minute
bronchi
one of the two subdivisions of the trachae serving to convey air to & from the lungs
bronchiole
small brnach of a bronchus within the lung
capillary
a small blood vessel that connects an arteriole & a venule
cross-bridges
globular heads that protrude away from the myosin filament at regular intervals
depolarization
the loss of an electrical charge on the surface of a cell membrane
diastole
phase of the cardiac cycle when a heart chamber wall relaxes
diffusion
random movment of molecules from a region of higher concentration toward one of lower concentration
distal
farther from the trunk or origin; opposite of proximal
electrocardiogram (ECG)
recording of the electrical activity associated with the heartbeat
endomysium
sheath of connective tissue surroundign each skeletal muscle fiber
epimysium
outer sheath of connective tissue surroundign a skeletal muscle
extrafusal fibers
served by axons of the alpha motor neurons (serve multiple muscle fibers); contraction of these muscle provides movement
fasciculus
small bundle of muscle fibers
fast-twitch fiber
histologically distinct skeletal muscle fibers that generate energy rapidly & are active in quick, powerful actions
Golgi Tendon Organ (GTO)
sensory receptors in tendons close to muscle attachments that are involved in reflexes that help maintian posture
heart
a hollow chmabered muscular organ that recieves the blood from the veins & propels it inot the arteries
hemoglobin
oxygen-carrying pigment in red blood cells
H-Zone
the area in the center of the sarcomere where only myosin filaments are present
I Band
a light band on each side of the Z line of striated muscle fibers, comprising a region of the sarcomere where thin filaments are not overlapped by thick filaments
inferior
situated below something else; pertaining to the lower surface of a part
insertion
end of a muscle attached to a movable part
intrafusal fibers
specialized sensory organs served by 2 axons, one sensory & one motor
mitral valve
heart valve located between the left atrium & the left ventricle; bicuspid valve
motor neuron
neuron that transmits impulses form the central nervous system to an effector
motor unit
a motor neuron & its associated muscle fibers
muscle fiber
muscle cell
muscle spindle
modified skeletal muscle fiber that can respond to changes in muscle length
myocardium
muscle tissue of the heart
myofibril
contractile fiebrs within muscle cells
myofilament
the ultramicroscopic threads of filamentous proteins making up myofibrils in striated muscle
myosin
protein that, with actin, contracts & relaxes muscle fibers
neuromuscular junction
synapse between a motor neuron & a skeletal muscle fiber
origin
end of a muscle that attaches to a relativley immovable part
parasympathetic nervous system
the branch of the autonomic nervous system that sends motor signals to glandular smooth muscle, & cardiac tissue, during recovery from threat
perimysium
sheath of connective that encloses a bundle of skeletal muscle fibers or a fascicle
pleura
the serous membrane envelopign the lungs & lining the walls of the pleural cavity
pleural pressure
is the pressure in the narrow space between the lung pleura & the chest wall pleura
proprioceptor
nerve ending that senses changes in muscle or tendon tension
proximal
closer to the trunk or origin; opposite of distal
pulmonary valve
valve leading from the right ventricle ot the pulmonary trunk (artery); pulmonary semilunar valve
purkinje fibers
specialized muscle fibers that conduct the cardiac impulse from the A-V bundle into the ventricular walls
P Wave
waveform in an electrocardiographic tracing representign arterial depolarization
QRS complex
segment is ventricular depolarization
recruitment
increase in number of motor units activated as stimulation intensity increases
red blood cell
disc-shaped cell, lacking a nucleus, that is packed with the oxygen-carrying molecule hemoglobin; erythrocyte
repolarization
returning the cell membrane potential to resting potential
sarcolemma
cell membrane of a muscle fiber
sarcomere
structural & functional unit of a myofibril
sarcopenia
progressive reduction in muscle cross-section & mass with aging
sarcoplasm
cytoplasm within a muscle fiber
semilunar valve
a heart valve composed of a set of three semilunar cups (valvules); hence, both the aortic & pulmonary vlaves are semilunar valves
sinoatrial (SA) node
specialized tissue in the wall of the right artrium that initiates cardiac cucles; the pacemaker
sliding-filamnet theory
muscles contract when the thin (actin) & thick (myosin) filaments move past each other, shortening the skeletal muscle cells
slow-twitch fiber
develop force & relax slowly & have a long twitch time
superior
structure higher than another structure
sympathetic nervous system
portion of the autonomic nervous system that arises from the thoracic & lumbar regions of the spinal cord
systole
phase of the cardiac cycle duirng a heart chamber wall contracts
tachycardia
abnormally rapid heartbeat
tendon
cordlike or bandlike mass of white fibrous connective tissue that connects a muscle to a bone
tetanus
a stimuli may be delivered at so high a frequency that the twitches begin to merge & eventually completely fuse
trahea
tubular organ that leads from the larynx to the bronchi
triad
group of three things
tricuspid vlave
heart valve located between the right artrium & the right ventricle
tropomyosin
protein that blocks muscle contraction until calcium ions are present
Troponin
protein that functions with tropomyosin to block muscle contraction until calcium ions are present
T-tubule
the transverse tubule that passes from the sarcolemma across a myofibril of striated muscle; it is the intermediate tubule of the triad
T-Wave
the next deflection in the electrocardiogram after the QRS complex; represents ventricular repolarization
twitch
brief muscular contraction followed by relaxation
type I fiber
slow twitch
type IIa fiber
fast twitch
type IIb fiber
fast twitch
vein
vessel that carries blood toward the heart
venous sytem
returns blood toward the heart
venule
vessel that carries blood from capillaries to a vein
Z-line
a cross-striation bisecting the I band of striated muscle myofibrils & serving as teh anchoring point of actin filaments at either end of the sarcomere
