MITOCHONDRIA:

• Mitochondria are known as the powerhouses of the cell.
• They are organelles that act like a digestive system which takes in nutrients, breaks them down, and creates energy rich molecules for the cell.
• Mitochondria are a part of eukaryotic cells.
• The main job of mitochondria is to perform cellular respiration.
• This means it takes in nutrients from the cell, breaks it down, and turns it into energy.
• This energy is then in turn used by the cell to carry out various functions.

LYSOSOMES:

• Lysosomes are specialized vesicles within cells that digest large molecules through the use of hydrolytic enzymes.
• A simple description of lysosomes is that they are tiny sacs filled with fluid containing enzymes.
• Which enable the cell to process its nutrients and are also responsible for destroying the cell after it has died.

• Lysosomes are only found in animal cells; a human cell contains around 300 of them.
• Not only do they digest large molecules, they are also responsible for breaking down and getting rid of waste products of the cell
• Lysosomes digest many complex molecules such as carbohydrates, lipids, proteins, and nucleic acids, which the cell then recycles for other uses.
• The pH of lysosomes is acidic (around pH 5) because their hydrolytic enzymes function best at this pH instead of at the neutral pH of the rest of the cell.

CYTOPLASM:

• Cytoplasm consists of all of the contents outside of the nucleus and enclosed within the cell membrane of a cell. It is clear in color and has a gel-like appearance.
• Cytoplasm is composed mainly of water but also contains enzymes, salts, organelles, and various organic molecules.

• The cytoplasm functions to support and suspend organelles and cellular molecules. Many cellular processes also occur in the cytoplasm.
• Some of these functions include protein synthesis, the first stage of cellular respiration (known as glycolysis), mitosis, and meiosis.
• In addition, the cytoplasm helps to move materials, such as hormones, around the cell and also dissolves cellular waste.

ENDOPLASMIC RETICULUM:

• The endoplasmic reticulum (ER) is an important organelle in eukaryotic cells.
• It plays a major role in the production, processing, and transport of proteins and lipids.
• The rough endoplasmic reticulum manufactures membranes and secretory proteins.

• The ribosomes attached to the rough ER synthesize proteins by the process of translation.
• The smooth ER has a wide range of functions including carbohydrate and lipid synthesis.
• Lipids such as phospholipids and cholesterol are necessary for the construction of cell membranes.

EPIDERMIS:

• The outermost layer of the skin is composed of epithelial tissue and is known as the epidermis.
• It contains squamous cells or keratinocytes, which synthesize a tough protein called keratin.
• Keratin is a major component of skin, hair, and nails.
• Keratinocytes on the surface of the epidermis are dead and are continually shed and replaced by cells from beneath.

DERMIS:

• The layer beneath the epidermis is the dermis.
• This is the thickest layer of skin composing almost 90 percent of its thickness. Fibroblasts are the main cell type found in the dermis.
• The dermis also contains specialized cells that help regulate temperature, fight infection, store water, and supply blood and nutrients to the skin.

SENSATION OF SKIN:    

• Sensations on the skin are detected by cutaneous receptors. These receptors may feel sensations such as pain, tickle, cold, hot, soft, and rough.
• Mechanoreceptors detect light pressure (e.g., caress), vibration, and texture, nociceptors detect strong pressure (e.g., pain), and thermoreceptors detect temperature.

CATHERINE SHALINI RAJA
M.P.T.,MIAP.,PGDYN
CARDIO RESPIRATORY PHYSICAL THERAPIST
FITNESS & SPORTS REHABILITATION SPECIALIST.