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Contraction and Relaxation Animation

By: Administrator, Views: 12233

Muscles are responsible for movement. The types of movement are: - Locomotion, when chemical energy is changed into mechanical energy. - Propulsion of substances through tubes, as in circulation and digestion. - Changes in the sizes of openings, as in the contraction and relaxation of the iris...

Definition of heart rate

By: HWC, Views: 9491

• Heart rate is determined by the rate of depolarizations of the sinoatrial (SA) node. • Cardiac output is directly proportional to heart rate, the greater the heart rate the greater the cardiac output. • Changes in heart rate are associated with exercise, stress or injury. Nervous ...

Causes of Angina

By: Administrator, Views: 12735

Angina is a type of chest pain caused by reduced blood flow to the heart. Angina (an-JIE-nuh or AN-juh-nuh) is a symptom of coronary artery disease. Angina, which may also be called angina pectoris, is often described as squeezing, pressure, heaviness, tightness or pain in your chest.

Muscle Twitch and Muscle Tension - Motor unit size and force

By: HWC, Views: 9573

• 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...

Labor and Delivery - Placenta Cord

By: Administrator, Views: 380

Soon after a baby is conceived, a support system, comprised of the placenta and umbilical cord, begins to develop. These two structures are essential for sustaining a healthy pregnancy, explains Donald Davis, an obstetrician in Medicine Hat, Alta., and past president of the Society of Obstetricia...

Autonomic Nervous System Animation

By: Administrator, Views: 12612

Parasympathetic Division Works to conserve energy and innervate the digestive system. When activated, it: stimulates the salivary and digestive glands. decreases the metabolic rate. slows the heart rate. reduces blood pressure. promotes the passage of material through the intestines along...

Structures that affect circulation - kidneys and blood volume and skeletal muscle pumping

By: HWC, Views: 9931

• Kidneys regulate blood volume and blood osmolarity via salt and water reabsorption. • Increased reabsorption increases blood volume and venous return (and CO). • Decreased reabsorption Increases urine production, which decreases blood volume and venous return (and CO). • Systemi...

Simple Diffusion - gases and nonpolar compounds transport

By: HWC, Views: 9700

Gases and some molecules can diffuse through the phospholipid bilayer because they are small or non-polar. Oxygen gas. Carbon dioxide gas. Lipid based hormones. Plasma membranes are selectively permeable: The lipid bilayer is always permeable to small, nonpolar, uncharged molecules ...

Angiotensin II - kidneys, adrenal glands and dehydration

By: HWC, Views: 9400

• Angiontensin II targets cells in the proximal convoluted tubule of the nephron. ■ The reabsorption of Na+ and Cl- ions sets up an osmotic gradient favoring the retention of water. • Decreases urine production and increases blood volume and pressure. • Angiontensin II targets zon...