Related Concept Videos

Dosage Compensation02:50

Dosage Compensation

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one Y chromosome, whereas C.elegans with one X chromosome is a male, and the one with two X chromosomes is a hermaphrodite.
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with  distinct numbers of X chromosomes will...
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Compensation Mechanisms01:28

Compensation Mechanisms

The human body employs intricate mechanisms to counteract changes in blood pH, preventing conditions like acidosis (pH < 7.35) and alkalosis (pH > 7.45). These compensatory responses aim to restore normal arterial blood pH by engaging respiratory or renal systems, depending on the source of the imbalance.
Respiratory Compensation
This mechanism addresses metabolic-induced pH imbalances by adjusting breathing rates. Respiratory compensation begins within minutes of detecting a pH...
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Renewal of Intestinal Stem Cells01:23

Renewal of Intestinal Stem Cells

The intestinal epithelial lining rapidly renews every 4 to 5 days. The renewal is facilitated by intestinal stem cells (ISCs) located at the base of the crypt– a gland located at the bottom of each villus. ISCs divide asymmetrically to form new stem cells and progenitor daughter cells. The daughter cells are called transit-amplifying (TA) cells which move upwards along the crypt and either differentiate into absorptive cells– the enterocytes or secretory cells– including the...
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Tissue Renewal without Stem Cells01:23

Tissue Renewal without Stem Cells

After cellular or tissue damage, the resident stem cells present in the human body can locally repair and regenerate the damaged tissue or organ. However, even though some tissues do not have stem cells, they can repair and regenerate with the help of pre-existing cells. For example, beta cells of the pancreas and hepatocytes of the liver can divide to renew and regenerate the tissue. Here, both cell division and cell death are well regulated by homeostasis.
However, failure of such a system...
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Renewal of Skin Epidermal Stem Cells01:12

Renewal of Skin Epidermal Stem Cells

The skin is divided into epidermis, dermis, and hypodermis, the skin's outermost, middle, and inner layers. The human epidermal layer regularly undergoes renewal, where old, dead cells are replaced by new cells. Epidermal stem cells or EpiSCs divide and differentiate to restore the lost cells. For the renewal process, some EpiSCs continuously self-renew. In contrast, few others differentiate into transit-amplifying cells, which later form prickle or spinous cells, followed by granular...
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Role Of Notch Signalling In Intestinal Stem Cell Renewal01:12

Role Of Notch Signalling In Intestinal Stem Cell Renewal

Notch signaling was first discovered in Drosophila melanogaster, where it is involved in cell lineage differentiation. Notch signaling regulates the maintenance and differentiation of intestinal stem cells or ISCs by controlling the expression of atonal homolog 1 or Atoh1. Atoh1 directs cells to differentiate into secretory cells.
Direct cell-to-cell contact is needed for the activation of Notch signaling. The signal is initiated when a notch ligand binds to a receptor on an adjacent cell, also...
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