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Cell mediated immune response to a viral infection Animation

By: HWC, Views: 3747

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...

Endocytosis -Types and Phagocytosis

By: HWC, Views: 7759

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...

Phases of mitosis

By: HWC, Views: 5669

Prophase is the first step in the mitotic process. During prophase, the chromosomes condense. The centrosomes begin to form a spindle and move into position on opposite sides of the cell. Sister chromatids are held together by a protein called cohesin at the centromere. Prometaphase is the sec...

Male Reproductive System - Testosterone

By: HWC, Views: 8330

• Under the influence of FSH and testosterone, Sertoli cells produce androgen-binding protein (ABP) that binds to testosterone and maintains high levels of the hormone near spermatogenic cells. • Testosterone stimulates the final stages of spermatogenesis. • In addition, testosterone is...

Neural regulation of blood pressure - baroreceptor and chemoreceptor reflexes

By: HWC, Views: 7988

• The nervous system regulates blood pressure with two reflex arcs: baroreceptor and chemoreceptor. ■ Baroreceptors (pressure) and chemoreceptors (chemical) are located in the carotid sinus and aortic arch. • Carotid sinus reflex helps maintain normal blood pressure in brain. • Ba...

DNA Replication

By: HWC, Views: 4588

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell.

Muscle cell structures - actin, myosin and titin filaments

By: HWC, Views: 7873

Once the muscle cell has been excited it will contract. • A muscle action potential will trigger the release Of Ca2+ ions into the sarcoplasm. • The Ca2+ ions bind to the regulatory proteins and trigger contraction. • Within skeletal muscle cells are structures that provide the ability...

Origin of organelles Animation

By: HWC, Views: 1365

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...

Female Reproductive System - Hormonal regulation (GnRH) الجهاز التناسلي للأنثى - التنظيم الهرموني

By: HWC, Views: 8146

• There is a complex interaction between the anterior pituitary gland, the hypothalamus, the ovaries and the uterus that leads to the monthly changes that women experience during their monthly reproductive cycle. • Two monthly cycles constitute these changes: • Ovarian cycle. • Uter...