Accessory excretory organs-biology

Carbon dioxide is a catabolic waste product formed due to oxidation of food releasing energy.
It is carried by the blood to the lungs.
During expiration this carbon dioxide along with a small quantity of water vapour is expelled out of the lungs.
Lungs which are the main respiratory organs of vertebrates, help to eliminate the entire volume of carbon dioxide produced in the body, as well as some moisture, during expiration .
The lungs maintain the blood-gas homeostasis through elimination of carbon dioxide.

1. ACCESSORY EXCRETORY ORGANS

2. Man is a highly evolved vertebrate and so the excretory organs are well developed.

3. Carbon dioxide is a catabolic waste product formed due to oxidation of food releasing energy. It is carried by the blood to the lungs. During expiration this carbon dioxide along with a small quantity of water vapour is expelled out of the lungs. Lungs which are the main respiratory organs of vertebrates, help to eliminate the entire volume of carbon dioxide produced in the body, as well as some moisture, during expiration . The lungs maintain the blood-gas homeostasis through elimination of carbon dioxide. LUNGS

4. When lungs fail to eliminate enough carbon dioxide, the kidneys attempt to compensate. They change some of the carbon dioxide into sodium bicarbonate, which becomes part of the blood buffer system.

5. The skin of aquantic animals is permeable and excretory wastes pass out by diffusion. In terrestrial animals, the skin is less permeable and excretory products pass out only through ducts and pores. Human skin has two kinds of glands that perform the function of excretion. Human skin possesses glands for secreting two fluids on its surface, namely sweat from the sweat glands and sebum from sebaceous gland . SKIN

6. Sweat is a watery fluid containing in solution primarily contains sodium-chloride, lactic acid, urea, amino acids and glucose. It helps in excreting mainly water and sodium chloride, and a small amount of urea and lactic acid. Sebum is a wax-like secretion which helps to excrete some lipids such as waxes, sterols, other hydrocarbons and fatty acids on the skin.

7. Sweat glands are long lubular glands, coiled at their ends, located in the dermis of the skin, embedded in the subcutaneous tissue . They produce a watery fluid called sweat which consists of 98% water and 2% solid residue. Organic :Urea, uric acid, creatinine , volatile fatty acids. Inorganic : Sodium chloride, potassium chloride and glucose. Sweat glands in the skin secrete a fluid waste called sweat or perspiration, however, its primary functions are temperature control and pheromone release . SWEAT GLAND

8. Therefore, its role as a part of the excretory system is minimal. Sweating also maintains the level of salt in the body

9. It is a microscopic exocrine glands in the skin that secreate an oily or waxy matter,called sebum. Sebum lubricate and waterproof the skin and hair of mammals. Excretory substances make waxes, sterols ,fatty acids and traces of other hydrocarbons are eliminated along with the sebum. Sebum in human primarily composed of triglycerides(41%),wax esters(26%), squalene (12?%),and free fatty acids(16%). SEBACEOUS GLANDS

10. Bile pigments ( biliverdin and bilirubin ) are produced as a result of break down of haemoglobin in the worn out red blood cells in the liver and excreted with the bile into the duodenum and removed along with the faeces . Liver also excretes cholesterol, various inactivated products of steroid hormones and harmful products like alcohol , nicotine and several drugs. The liver is also responsible for converting ammonia produced by deamination into less to less urea by combining it with carbon dioxide. LIVER

11. SKIN STRUCTUE

12. The skin has three layers * Epidermis * Dermis * Fat layer (also called the subcutaneous layer) Each layer performs specific tasks Beneath the surface of the skin are nerves, nerve endings glands, hair follicles, and blood vessels

13. The skin is the largest organ of the body, with a total area of about 20 square feet. The skin protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold The skin's color is created by special cells called melanocytes , which produce the pigment melanin. Melanocytes are located in the epidermis.

14. Epidermis The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone. Dermis The dermis, beneath the epidermis, contains tough connective tissue, hair follicles and sweat glands. Hypodermis The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue

15. Other components of the skin include Blood vessels To help keep your body a constant temperature,blood vessels in the skin dilate in response to heat or constract in response to cold. Sebaceous glands The sebaceous glands secrete sebum, an oily substance that helps keep skin from drying out. Most of the glands are located in the base of hair follicles.

16. Acne starts when the tiny hair follicles become plugged with these oily secretions. Sweat glands When your body gets hot or is under stress, these glands produce sweat, which evaporates to cool you. Sweat glands are located all over the body but are especially abundant in your palms, soles,forehead , and underarms.

17. Sweat Glands These are highly vascular, coiled, simple tubular glands These separate the wastes from the blood and send it out in the form of sweat . Sweat is formed of water (99%), sodium chloride, lactic acid,some urea and carbon dioxide. Function of sweat (a) Excretion of excess of sats and water. (b) Evaporation of sweat causing a cooling effect and helping to maintain body temperature. These are branched glands opening into the hair follicles. These secrete an oily secretion called as sebum formed of lipids like waxes .

18. Hair follicle Every hair on your body grows from a live follicle with roots in the fatty layer called subcutaneous tissue. Collagen Collagen is the most abundant protein in the skin making up 75% of your skin. This is also your fountain of youth as it's responsible for warding off wrinkles and fine lines . Over time, environmental factors and ageing diminish your body`s ability to produce collagen.

19. Elastin When you hear the word elastin , think elastic. This protein is found with collagen in the dermis and is responsible for giving structure to your skin and organs . As with collagen, elastin is affected by time and the elements . Dimininshed levels of this protein cause your skin to wrinkle and sag.

20. Keratin Keratin is the strongest protein in our skin. It`s also dominant in your hair and nails . Keratin is what forms the rigidity of your skin. Colour The skin’s colour is created by special cells called melanocytes , which produce the pigment melanin. Melanocytes are located in the epidermis.

21. SUMMARY

22. The skin releases toxins from the blood via the sweat glands and pores, these highly vascular,coiled , tubular glands remove waste products from the blood and discharge them from the body in the form of sweat Sweat is a transparent acidic fluid that contains sodium chloride, water and some urea. The liver helps with digestion and also helps remove toxins from the body . Among the substances it makes is bile, which helps digest fats, oils and fat-soluble vitamins like vitamin A . The bile the liver makes is either taken up by the small intestine or stored in the gallbladder .

23. Lungs which are the main respiratory organs of vertebrates, help to eliminate the entire volume of carbon dioxide produced in the body, as well as some moisture, during expiration

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