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Muscle Twitch and Muscle Tension - Motor unit size and force

By: HWC, Views: 6921

• 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...

Origin of organelles Animation

By: HWC, Views: 305

Possible origins of the nucleus and other organelles. Some prokaryotic cells have infoldings of their plasma membrane. These infoldings may have served as channels from the cytoplasm to the cell surface. These membranous folds may have evolved into the endoplasmic reticulum and the nuclear e...

Premenstrual Syndrome

By: Administrator, Views: 9859

Premenstrual syndrome (PMS) refers to physical and emotional symptoms that occur in the one to two weeks before a woman's period. Symptoms often vary between women and resolve around the start of bleeding. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mo...

Muscle cell structures - actin, myosin and titin filaments

By: HWC, Views: 6790

Once the muscle cell has been excited it will contract. • A muscle action potential will trigger the release Of Ca2+ ions into the sarcoplasm. • The Ca2+ ions bind to the regulatory proteins and trigger contraction. • Within skeletal muscle cells are structures that provide the ability...

Contraction cycle of a sarcomere

By: HWC, Views: 7185

• A single nervous signal releases Ca2+ ions into the sarcoplasm and initiates the contraction cycle. step 1. ATP hydrolysis • ATP provides the to move myosin molecules back into the energized configuration necessary to perform the power stroke. Step 2. Crossbridge attachment • Myosin...

Type of Cell Junctions - Desmosome, Hemidesmosomes and Gap Junctions

By: HWC, Views: 7020

Cell Junctions: Cell junctions are found in some multi-cellular organisms. They exist of complexes and are found between cells and between cells and other structures. The junctions provide a way for cells to connect and exchange signals. What are tight junctions, desmosomes, and gap junctions...

Introduction to Pre-eclampsia

By: Administrator, Views: 9739

Pre-eclampsia (PE) is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe disease there may be red blood cell breakdown, a low blood platelet c...