Search Results

Semidiscontinuous DNA replication

By: HWC, Views: 7339

During DNA replication, one of the two DNA strands, the leading strand, is replicated continuously, or all at once, in the 5' to 3' direction. The other strand, called the lagging strand, is replicated discontinuously, or in pieces, in the 3' to 5' direction. This is necessary because DNA poly...

Action potentials - electrical characteristics and generation

By: HWC, Views: 7569

• An action potential is the nervous impulse or signal for long distance communication. Each action potential is generated at the cell's trigger zone. • Action potentials are considered an all-or-nothing phenomena because they are either generated or not. • The generation of an action...

Atrophy

By: Administrator, Views: 10559

Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, excessive amount of apoptosis of c...

Muscle Twitch and Muscle Tension - Motor unit size and force

By: HWC, Views: 7964

• A motor unit is a group of muscle cells controlled by a single neuron. • A stimulus of sufficient intensity will cause all the cells in the motor unit to contract. • A single contraction, caused by a single action potential, is called a muscle twitch. • Latent period: A brief per...

Effect of blood chemistry - stimuli, hyperventilation response and hypoventilation response

By: HWC, Views: 7442

• Respiratory rate is effected by changes in: • Blood pH. • Blood Pco2. • Blood P02. • Chemoreceptors in the central and peripheral nervous systems closely monitor the Fr, CO2 and 02 levels in blood. • Changes in frequency of impulses from Chemoreceptors affect respiratory r...

How proteins function? How do proteins work?

By: HWC, Views: 7383

How proteins function is really about how proteins "do work" in cells. How do proteins work? Let's start thinking about protein function by looking at something important to you: your hair. Keratin is a structural protein that is composed of 2 intertwined or helical strands. Keratin is also f...

Homologous chromosomes during prophase I - Animation

By: HWC, Views: 5597

The chromosomes were duplicated during interphase and the sister chromatids are now in thin threadlike form. Each chromosome becomes zippered to its homologue, so that all four chromatids are closely aligned. The chromosomes are tightly aligned, but we will show them as separate so that y...

Male Reproductive System - Testosterone

By: HWC, Views: 8330

• Under the influence of FSH and testosterone, Sertoli cells produce androgen-binding protein (ABP) that binds to testosterone and maintains high levels of the hormone near spermatogenic cells. • Testosterone stimulates the final stages of spermatogenesis. • In addition, testosterone is...

Bone cells and tissues - tissue composition and cells

By: HWC, Views: 8556

Bone tissue consists of bone cells secreting bone matrix. • The extracellular bone matrix is a connective tissue that is hard, yet flexible. • Collagen fibers provide flexibility. • Inorganic mineral salts (primarily calcium phosphate, or hydroxyapatite) provide hardness. • Togethe...