Chapter 1 - The Structure and Function of Body Systems Flashcards
A-Band
The section of the sarcomere that corresponds with the alignment of myosin and actin filaments.
Acetylcholine
A neurotransmitter released when an action potential arrives at the nerve terminal. The Acetylcholine diffuses across the neuromuscular junction causing excitation of the sarcolemma.
Actin
A protein that forms actin myofilaments. Actin filaments consist of two thin strands about 6nm in diameter arranged in a double helix.
Action potential
An electrical impulse from a motor nerve that signals the release of calcium from the sarcoplasmic reticulum into the myofibril, causing tension development in the muscle.
All-or-none principle
The phenomenon that a stimulus from the motor neuron will cause all fibers in that motor unit to contract. As such, stronger action potentials do not result in bigger contractions.
Alveolar pressure
Pressure inside the alveoli when the glottis is open and no air is flowing into or out of the lungs.
Alveoli
The final passages in the respiratory system where gases are exchanged from the lungs.
Aortic valve
Valve in the heart that prevents backflow of blood from the aorta into the ventricle.
Appendicular skeleton
Bones of the shoulder/pectoral girdle (left and right scapula and clavicle), bones of the arms, wrists, and hands (left and right humerus, radius, ulna, carpals, metacarpals, and phalanges); the pelvic girdle (left and right coxal or innominate bones), and the bones of the legs, ankles, and feet (left and right femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges). (ESC p. 2)
Arterial system
System of tubes that carries blood away from the heart. Due to the high pressure of the blood from the heart, arteries have strong walls.
Arteriole
Smaller branches of the arterial system that deliver blood to the capillaries.
Artery
Strong tubes that rapidly transport blood from the heart.
Atrioventricular (AV) bundle
Conducts the impulse in the heart to the ventricles.
Atrioventricular (AV) node
Node in the heart that slightly delays the impulse from the SA node.
Atrioventricular (AV) valves
One-way valves that prevent the backflow of the blood from the ventricles into the atria.
Atrium
Chambers of the heart that receive blood and pump it to the ventricles. The left and right atria pump blood to the left and right ventricle, respectively.
Axial Skeleton
Bones of the skull (cranium), vertebral column (C1-coccyx), ribs, and sternum.
Biaxial joints
Joints such as the ankle and wrist that allow movement around two perpendicular axes.
Bone periosteum
A specialized connective tissue covering all bones. The tendons attach to the bone periosteum.
Bradycardia
Heart rate less than 60 bpm.
Bronchi
Second generation passages in the respiratory system that deliver air to the bronchioles.
Bronchiole
The third generation passages in the lungs that deliver air to the alveoli, where gases are exchanged.
Capillary
Small end-tubes of the arterial system that facilitate exchange of oxygen, fluid, nutrients, and other substances between the blood and other fluids in various body tissues.
Cartilaginous joints
joints that allow limited movement - i.e. intervertebral disks. (ESC p. 2).
Crossbridge
The connections between the globular heads on myosin filaments that bind with actin. The strength of a muscle contraction is directly related to the number of myosin crossbridges bound to actin.
Depolarization
The reversal of the heart membrane electrical potential and results in contraction of the atria or ventricles in the case of the P-Wave and QRS complex, respectively.
Diastole
Ventricular relaxation.
Diffusion
The simple random motion of molecules moving in opposite directions through the alveolar-capillary membrane.
Distal
The attachment of a limb muscle that is further from the trunk relative to the proximal attachment.
Electrocardiogram (ECG)
Graphic representation of heart electrical activity.
Endomysium
The connective tissue that surrounds each muscle fiber and is contiguous with the muscle fiber membrane known as the sarcolemma.
Epimysium
The outer layer of fibrous connective tissue covering the body’s more than 430 skeletal muscles. The epimysium is contiguous with the tendons at the ends of the muscle.
Extrafusal fibers
Normal muscle fibers.
Fasciculi
Bundles of muscle fibers located under the epimedium. The fasciculi can consist of up to 150 fibers and each fascicle is individually surrounded by connective tissue called perimysium.
Fast-twitch fiber
The fibers in a fast-twitch motor unit that develops force and relaxes rapidly, resulting in a short twitch time. Fast-twitch fibers are further broken into Type IIa fibers and type IIx fibers. Type II fibers and motor units can produce force rapidly but are inefficient and quick to fatigue. Type IIa fibers are more resistant to fatigue than type IIx fibers due to a greater capacity for aerobic metabolism. Type IIa fibers are still far less aerobically efficient than type I fibers.
Fibrous joint
Joints that allow little to no movement such as the sutures of the skull.
Golgi tendon organ
Proprioceptors located in the tendons attached to extrafusal muscle fibers. Golgi tendon organs relay information regarding tension in the muscle and are though to protect against the development of excess tension in the muscle.
Hemoglobin
The iron-protein molecule carried by red blood cells. Hemoglobin transports oxygen as well as provides an acid-base buffer in the blood to regulate H+ ion concentration.
Hyaline cartilage
The smooth covering on the ends of articulating bones. (ESC p. 2)
H-Zone
The area in the center of the sarcomere containing only myosin filaments. The H-zone decreases during muscle contraction as actin slides over the myosin toward the center of the sarcomere.
