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Carbon fixing adaptations Animation

By: HWC, Views: 1811

Different plants trap carbon by different pathways. Most C3 plants evolved in moist, temperate zones. On hot dry days they close their stomata to conserve water and oxygen accumulates. Under these circumstances, the enzyme rubisco uses oxygen in an inefficient reaction that competes with t...

Role of the urinary system - acidosis and alkalosis

By: HWC, Views: 7963

• Tubular cells of the proximal convoluted tubule and collecting tubules can alter filtrate pH and therefore blood pH. • These cells can affect blood pH with two coupled mechanisms: • Reabsorption of bicarbonate ions. • Secretion of hydrogen ions. • The reabsorption of bicarbonate...

Alternative Energy Sources

By: HWC, Views: 1978

Points at which organic compounds enter the reaction stages of aerobic respiration. Complex carbohydrates are broken down into simple sugars, such as glucose. They become the substrates for glycolysis. If your body doesn't need to burn glucose for energy, glucose-6-phosphate can be co...

Definition of heart rate

By: HWC, Views: 7873

• 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 ...

Second Messengers in the Inositol-lipid Signaling Pathway

By: HWC, Views: 7009

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...

How does an animal choose what food to eat?

By: HWC, Views: 7192

One might assume that natural selection has influenced the foraging behaviors of animals, and that most animals forage efficiently, spending the least energy to gain the most nutrients. This is the underlying assumption of optimality modeling, a scientific approach to studying foraging behavior. ...

Primary and secondary response to infection

By: HWC, Views: 7485

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...

Barriers - eye structures, digestive mucosa, respiratory mucosa & genitourinary mucosa

By: HWC, Views: 8038

• Eyebrows, eyelids, eyelashes and conjunctiva serve to trap microbes preventing their invasion. • Tearing (lacrimation) is a protective mechanism that washes away microbes that attempt to enter the eyes. • Salts, mucus, and lysozymes in tears neutralize substances and bacteria. â€...

Methods of carbon dioxide transport - carbaminohemoglobin and bicarbonate ions

By: HWC, Views: 7792

• 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...