Search results for: 'Four Giant Convection Cells oF Earth'

Watch Later 5:14

By: Administrator, Views: 10650

An electrocardiogram (ECG or EKG) is a test that checks how your heart is functioning by measuring the electrical activity of the heart. With each heartbeat, an electrical impulse (or wave) travels through your heart. This wave causes the muscle to squeeze and pump blood from the heart. Sinoat...

Watch Later 2:10

Hormonal regulation of pregnancy - weeks 17 through 38

By: HWC, Views: 8039

• Estrogens increase uterine blood flow, maintaining the endometrium during pregnancy. • High levels of estrogen and progesterone inhibit the synthesis of milk. Progesterone inhibits myometrial contractions of the uterus to prevent premature birth. • Relaxin inhibits myometrial contract...

Watch Later 2:31

Factors that influence muscle tension - Sarcomere length and force, understretched and overstretched

By: HWC, Views: 7820

• Muscle tension generated through the contraction of muscle cells provides the force necessary for the muscular system to function. • The amount of tension produced depends on several factors: • Sarcomere length Frequency of stimulation • Motor unit size • Recruitment of moto...

Watch Later 1:29

Mitosis step-by-step

By: HWC, Views: 5787

During interphase, the chromosomes will be duplicated in preparation for mitosis, which divides the chromosomes, and cytokinesis, which divides the cell's cytoplasm. In early prophase, the duplicated chromosomes begin to condense. Each chromosome consists of two sister chromatids joined at the...

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Isovolumetric VC, Ventricular ejection, Isovolumetric & Passive ventricular filling

By: HWC, Views: 7758

• Isovolumetric means that blood volume does not change. • Ventricular blood volume and cell length remain constant. • With valves closed and contraction continuing, ventricular pressure continues to rise. • Ventricular pressure rises above arterial pressure. • Increased ventr...

Watch Later 1:42

Second Messengers in the Inositol-lipid Signaling Pathway

By: HWC, Views: 7072

Extracellular signals produce specific responses in target cells through the action of intracellular second messengers. Here, we focus on three second messengers, IP3, DAG, and Ca2+, all involved in the inositol-lipid signaling pathway. A hormone-receptor signal on the cell surface leads to the a...

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Bone elongation - processes at the epiphyseal plate

By: HWC, Views: 8042

• Interstitial lengthening occurs in only certain bones, primarily those of the appendages. • Such lengthening takes place at the epiphyseal plate, a layer of hyaline cartilage in the metaphysis of a growing bone. 1. Zone of resting cartilage. • Consisting of a hyaline cartilage pa...

Watch Later 1:44

Fermentation - When Oxygen Is Absent, Pyruvate to Lactate & Pyruvate to Ethanol

By: HWC, Views: 7360

Pyruvate is the end product of glycolysis. If oxygen is present, pyruvate enters the mitochondrion where further energy yielding reactions of the Krebs cycle will take place. However, if oxygen is not present, pyruvate will enter a pathway called fermentation. This pathway regenerates NAD+ fro...

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Lactation and Breast Feeding

By: HWC, Views: 8597

Regulation of lactation - breast preparation • Pregnancy hormones trigger breast changes to prepare for feeding the new baby. • The amount of the hormone prolactin, essential to the initiation of lactation, increases steadily throughout pregnancy. • However, high levels of both estroge...

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