Search results for: 'alpha cells'

Watch Later 2:01

By: HWC, Views: 6795

Gastrulation Most animals enter a phase early in development called gastrulation. In this phase, a tiny ball or disc of cells rearranges to form three embryonic layers of tissue, called germ layers. The germ layers of the embryo—now called a gastrula—are called the endoderm, mesoderm, and eco...

Watch Later 2:14

Four Giant Convection Cells oF Earth

By: HWC, Views: 7042

Earth Has Four Giant Convection Cells Earth's climates range from dry and cold at the poles to wet and warm at the equator. These climates are dictated largely by the amount of solar radiation that a region receives. Solar radiation warms the Earth and the surrounding air, setting up convection c...

Watch Later 1:56

Renin/Angiotensin (water gain from urine & Na ion and water reabsorption)

By: HWC, Views: 7649

• Sensing declining blood pressure or blood volume, juxtaglomerular cells of the nephron release renin, an enzyme that promotes the formation of angiotensin II. • Angiotensin II targets smooth muscle cells in blood vessels that provide blood to the nephron. • Angiotensin II causes thes...

Watch Later 1:16

Amniocentesis and CVS Animation

By: HWC, Views: 4635

Amniocentesis and chorionic villus sampling (CVS) are prenatal diagnostic tools. In amniocentesis, which can be performed as early as 14 weeks into the gestation period. A syringe needle is inserted through the abdominal and uterine walls to withdraw some amniotic fluid. The fluid contains...

Watch Later 1:29

Spermatogenesis Animation

By: Administrator, Views: 11075

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. T...

Watch Later 1:42

Atrial natriuretic peptide (vasodilation) & Aldosterone

By: HWC, Views: 7350

• Certain situations will cause the body's stress level to rise. • increased blood pressure will stretch the atria of the heart, stimulating the secretion of atria natriuretic peptide (MP). • ANP causes muscle cells in blood vessels to relax. • Blood pressure is lowered as a result ...

Watch Later 0:23

Stress and Immune System Animation

By: Administrator, Views: 10923

How stress and the immune system are linked. Immune response declines with age, limiting body's ability to identify and fight foreign substances. Loss of thymus cortex leads to reduced production of T lymphocytes, including T cells, NK cells, B lymphocytes. Frequency and severity of infectio...

Watch Later 1:11

Bone processes - resorption and deposition, remodeling and response to stress in adult bones

By: HWC, Views: 7920

• The process of remodeling bone tissues involves bone cells resorbing or depositing minerals into bone tissue. • During resorption, bone cells break down bone tissue and release calcium and other minerals for use by other cells in the body. • Bone cells also rebuild bone tissue by depo...

Watch Later 1:29

Oxygen - hemoglobin dissociation curve & Hemoglobin's affinity with oxygen - acidity

By: HWC, Views: 8350

• The partial pressure of oxygen is a primary factor influencing the degree of saturation of hemoglobin. • The Po2 determines the number of oxygen molecules that can bind or dissociate from hemoglobin. • Blood in vessels coming from the lungs is very high in Po2 so saturation is high. ...

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