BIO 110 --> Exam 2

Actin filaments

Thin filaments that provide site for myosin attachment.

Myosin filaments

Thick filaments with heads that bind to actin.

Troponin and tropomyosin

Regulatory proteins that control interaction between actin and myosin.

Threshold stimulus

Depolarizing stimulus that reaches a certain threshold to cause action potential.

Sodium ion influx

Voltage-gated sodium channels open allowing Na+ ions to enter, which depolarizes the neuron.

Motor neuron activation

Process by which motor neuron releases acetylcholine at the neuromuscular junction.

Action potential propagation

Acetylcholine binding to receptors on muscle cell membrane leads to action potential traveling along the sarcolemma and down T-tubules.

Muscle fiber

Basic cellular unit of a muscle.

Fascicles

Bundles of muscle fibers.

Tendon

Connects muscle to bone.

Sarcomere

Functional unit of muscle contraction.

Z-lines

Define the boundaries of each sarcomere.

A-band

Contains myosin filaments and overlaps with actin.

I-band

Contains only actin filaments.

H-zone

Area where only myosin is present.

Muscle contraction

Muscle activity generates heat as a byproduct.

Isotonic contractions

Muscle changes length while contracting, producing movement and work.

Isometric contractions

Muscle length remains the same while tension increases, maintaining posture and stabilizing joints.

Sarcomere function

Basic contractile unit of muscle responsible for muscle contraction through interaction of actin and myosin filaments.

Nasal cavities

Filter, warm, and humidify air.

Pharynx

Passageway for air and food.

Larynx

Houses vocal cords and protects trachea against food aspiration.

Alveoli

Tiny air sacs where gas exchange occurs.

Diaphragm

Separates thoracic and abdominal cavities.

Pulmonary veins

Bring oxygenated blood from lungs to left atrium.

Right atrium

Receives deoxygenated blood from body.

Right ventricle

Pumps blood into lungs via pulmonary artery for oxygenation.

Bronchi

Conducts air into lungs and branches into smaller bronchi and bronchioles.

Peristalsis

Wave-like muscle contractions that move food throughout the digestive tract.

Enzymes in digestion

Speed up chemical reactions that break food into small pieces.

Basal metabolic rate

Energy expenditure of an individual at rest necessary to maintain vital functions.

Homologous chromosomes

Pairs of chromosomes that carry the same genes but may have different alleles.

Dominant alleles

Express a trait even when only 1 copy is present.

Recessive alleles

Only expressed when 2 copies are present.

Homozygous

Organism has 2 identical alleles for a gene.

Heterozygous

Organism has 2 different alleles for a gene.

Law of segregation

Two alleles for a gene separate so each gamete carries only 1 allele.

Linked genes

Located close to each other on the same chromosome and tend to be inherited together.