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Gastrulation: cross section of the frog

By: HWC, Views: 6813

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...

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

By: HWC, Views: 8041

• 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€...

Embryonic development - Week 3

By: HWC, Views: 7774

Week 3 (gastrulation) • Three primary germ layers are formed which provide cells for organ formation in the following months. • These germ cell layers are formed by a process known as gastrulation, which involves rearranging epiblast cells. • As cells from the epiblast migrate, a fain...

Role of the respiratory system - effect of altered ventilation rates

By: HWC, Views: 8271

• The respiratory system regulates blood pH by controlling the amount of carbon dioxide removed from the blood. • Near systemic cells, carbon dioxide forms bicarbonate ions in the blood. H+ ions are also released, thereby decreasing blood pH. • At the alveolar capillaries, bicarbonate io...

Muscular System Animation

By: Administrator, Views: 10651

Three basic types of muscles: - Skeletal - Smooth - Cardiac Composed of striated or smooth muscle tissue and classified according to their functions and appearance. Skeletal Muscle: - Also known as voluntary or striated muscle. - Controlled by the conscious part of the brain and attach...

Oxygen transport: association and dissociation & Factors that affect hemoglobin's saturation with O2

By: HWC, Views: 7691

• The production of oxyhemoglobin can be illustrated through the following reaction: 02 + Hb-H --) Hb-02 + H+ • This equation represents the binding of oxygen to the iron ions in heme groups in hemoglobin molecules. • Oxygen binding or loading occurs at the lungs • The dissociatio...

Parathyroid hormone (bone resorption) & Calcitonin (bone deposition)

By: HWC, Views: 7708

• Cellular needs for calcium may cause blood calcium concentrations to decline below the normal range. • This decrease stimulates cells in the parathyroid gland to secrete parathyroid hormone. • Binding of parathyroid hormone to osteoclasts in bone tissue promotes bone resorption and th...

Vascular tissues in a corn stem and a buttercup root

By: HWC, Views: 2240

Vascular tissues in a corn stem and a buttercup root. The cells that make up each tissue. Xylem conducts water and dissolved ions. It also helps mechanically support a plant. The cells, called vessel members and tracheids, are dead at maturity. Their lignified walls interconnect and serve as p...

Role of ATP in muscle movement

By: HWC, Views: 7835

• Muscle cells use ATP to power contraction and movement. • The hydrolysis of ATP to ADP releases • ATP can be regenerated by adding to ADP. • During muscular contraction, ATP molecules: • Energize the myosin head • Detach myosin from actin • ATP must be then regenerat...