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Segmentation and migrating motility complexes & Gastroileal reflex

By: HWC, Views: 6584

• Within a few hours, most of the stomach contents are in the duodenum. • Distension of stretch receptors in the small intestine activates a reflex that stimulates segmentation, a mixing movement. • During segmentation, sections of the intestine are constricted. • This movement incr...

Osmosis - water transport

By: HWC, Views: 6749

Osmosis is the flow of water down its concentration gradient, across a semi-permeable membrane. Osmosis is an example of diffusion, which is when molecules tend to distribute themselves evenly in a space. what is a semi-permeable membrane? It is a membrane or barrier that allows some molec...

Oxygen transport - methods and oxyhemoglobin

By: HWC, Views: 6450

• 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...

New DNA Strand Replication

By: HWC, Views: 6149

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...

Peptide Bond Formation Animation

By: HWC, Views: 515

During protein synthesis, peptide bonds link amino acids together in the order specified by DNA instructions. In this case, the first two amino acids in the protein are methionine and alanine. Here are ball-and-stick models of these amino acids. Peptide bond formation is a type of condensatio...

Cellular slime mold life cycle Animation

By: HWC, Views: 883

Life cycle of Dictyostelium discoideum, a cellular slime mold Animation. Amoeba-like slime mold cells live in the soil, where they feed on bacteria. The free-living cells grow and reproduce by mitosis. When food dwindles, the amoebas stream toward one another in response to a chemical...

Haustral churning, Gastrocolic reflex and mass peristalsis & Defecation

By: HWC, Views: 6797

• As the cecum becomes filled and distends, a local reflex causes: • Closure of the ileocecal valve. • Activation of haustral churning. • Haustral churning mixes the chyme, which helps absorption of water, salts, and vitamins. • Haustral churning propels the contents of the colo...

Gastrin (protein digestion)

By: HWC, Views: 6664

The endocrine system maintains many body conditions within normal limits with feedback loops. Each endocrine feedback loop maintains homeostasis using the following components: • Stimulus - a change in a body condition. • Production cell - an endocrine cell that produces a hormone after b...

ETC Protein Complexes & Chemiosmosis (Total ATP Production and ATP Synthase)

By: HWC, Views: 6366

You will notice that FADH2 donates two electrons further downstream than NADH. This results in only two protons being pumped across the inner membrane. The final electron acceptor for these transported electrons is oxygen. Oxygen receives these electrons, plus protons from the aqueous matrix. ...