Search results for: 'small%20intestine'

Watch Later 1:24

By: HWC, Views: 6681

Endocytosis is the process by which a substance is brought inside a cell without having to pass through the cell membrane. It is the opposite of endocytosis, the process by which substances exit the cell without having to pass through the cell membrane. Exocytosis – membrane-enclosed secret...

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Primate Evolutionary Tree Animation

By: HWC, Views: 2791

Presumed evolutionary branchings in the primate family tree. The first primates arose between 85 and 65 million years ago. The common ancestor of apes and hominids branched off from Old World monkeys about 23 million years ago. The hominid lineage, which includes humans and earlier humanlik...

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Oxygen transport - methods and oxyhemoglobin

By: HWC, Views: 6420

• The blood is the medium used for gas transport throughout the body. • Oxygen is only available in the lungs. Because the partial pressure of oxygen is higher in the alveoli than in the blood, oxygen diffuses into the blood and is transported to systemic cells. • At the tissues the par...

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New DNA Strand Replication

By: HWC, Views: 6135

First step: strands are separated • Helicase unwinds the DNA double helix at the replication fork • SSBs coat the single strands to prevent reannealing • Polymerase attaches nucleotide at 3' end • Synthesis is in 5' to 3' direction DNA Polymerase: • Only extends nucleic ac...

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Origin of organelles Animation

By: HWC, Views: 286

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...

Watch Later 5:36

How does asthma work?And How do you treat asthma?

By: HWC, Views: 5595

These are the parts of the respiratory system. Sinuses and Nasal Passages Mouth Windpipe (Trachea) Lungs Airways (Bronchial Tubes) Airsacs (Alveoli) When we breathe, air moves easily in and out of the lungs. The small airways are also called bronchial tubes. The side of the tube is...

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Types of disease resistance: innate defenses & immunity

By: HWC, Views: 6858

Our immune system protects us and helps fight off disease. Microorganisms, small microscopic organisms, and viruses are everywhere. Ever thought about how many are on that door you just opened? Many microbes and viruses can cause disease and are termed pathogens. Plants and animals have what i...

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Methods of carbon dioxide transport - carbaminohemoglobin and bicarbonate ions

By: HWC, Views: 6692

• Carbon dioxide is transported three ways: • As bicarbonate ions in the plasma. • Bound to hemoglobin. • As a dissolved gas in the plasma. • A small percent of carbon dioxide is transported as a dissolved gas. • Some of the carbon dioxide is bound to hemoglobin, in the fo...

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Cell mediated immune response to a viral infection Animation

By: HWC, Views: 2690

Intracellular pathogens are the targets of cell-mediated immune response. The process begins when a virus infects a macrophage. Another macrophage engulfs the same virus or an antigen from it. In both cells, enzymes cleave the viral antigens into small bits. The fragments move to the cell sur...

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