Homeostasis Notes-Class 10th KPK
HOMEOSTASIS
Q No# 1
Define homeostasis? Give various forms of Homeostasis?
Homeostasis:
Homeostasis is a key concept in understanding how our body works. It means keeping things constant and comes from two Greek words: 'homeo,' meaning 'similar,' and 'stasis,' meaning 'stable.' A more formal definition of homeostasis is a characteristic of a system that regulates its internal environment and tends to maintain a stable, relatively constant condition of properties.DEFINATION:-
Homeostasis may be defined as the maintenance of the internal conditions of body at equilibrium, despite changes in the external environment.
OR
The tendency of an organism to maintain its internal environment against external environment is known as homeostasis.
OR
The ability of living organisms to maintain or nearly maintain constant internal condition.EXAMPLES:
The core temperature of human body remains at about 37°C despite fluctuations in the surrounding air temperature.
The blood glucose level remains about 1 g per litre despite eating meal rich in carbohydrates. Body cells need the internal environment in which conditions do not Change much. Stable internal conditions are important for the efficient functioning of enzymes.
Claude Bernard, a French Physiologist over a century ago describes two types of environment:
Internal Environment- The environment in which an organism cell activity starts.
External Environment- The environment surrounds an organism
Various processes of Homeostasis
1. Osmoregulation:
It is maintenance of the amounts of water and salts in body fluids (i.e. blood and tissue fluids). The relative amounts of water and salts in body fluids and inside cells control the processes of diffusion and osmosis, which are essential for the functioning of cells.2. Thermoregulation:
The maintenance of internal body temperature is called thermoregulation. The enzymes of body work best at particular temperatures. Any change in body temperature may affect the functioning of enzymes.3. Excretion:
Excretion is also a process of homeostasis. In this process, the metabolic wastes are eliminated from body to maintain the internal conditions at equilibrium.Metabolic waste means any material that is produced during body metabolism and that may harm the body.
Question No # 02How homeostasis does occur in Plants? Explain the various modes of homeostasis.
Homeostasis in Plants:
Plants respond to environmental changes and keep their internal conditions constant homeostasis. They apply different mechanisms for the homeostasis of water and other chemicals (oxygen, carbon dioxide, nitrogenous materials etc.).1. Removal of Extra Carbon dioxide and Oxygen:
In daytime, the carbon dioxide produce during cellular respiration is utilized in photosynthesis and hence it is not a waste product. At night, it is surplus because there is no utilization of carbon dioxide. It is removed from the tissue cells by diffusion. In leaves and young sterns, carbon dioxide escapes out through stomata. In young roots, carbon dioxide diffuses through the general root surface, especially through root hairs.Role of Mesophyll
Oxygen is produced in mesophyll cells only during daytime, as a by-product of photosynthesis. After its utilization in cellular respiration, the mesophyll cells remove the extra amount of oxygen through stomata.2. Removal of Extra Water:
The plants obtain water from soil and it is also produced in the body during cellular respiration. Plants store large amount of water in their cells for turgidity. Extra water is removed from plant body by transpiration. At night, transpiration usually does not occur because most plants have their stomata closed. If there is a high water content in soil, water enters the roots and is accumulated in xylem vessels.Guttation
Some plants such as grasses force this water through special pores, present at leaf tips or edges, and Form drops. The appearance of drops of water on the tips or edges of leaves is called guttation3. Removal of other Metabolic Wastes:
Plants deposit many metabolic wastes in their bodies as harmless insoluble materials. For example, calcium oxalate is deposited in the form of crystals in the leaves and stems of many plants e.g. in tomato.(4) Shedding of Leaves
In trees winch shed their leaves yearly, the excretory products are removed from body during leaf fall. Other waste materials that are removed by some plants are resins by coniferous trees, gums by keekar, latex by rubber plant and mucilage by carnivorous plants and ladyfinger etc. Resin drops from a cut tree Latex being extracted from a tree Mucilage drops on carnivorous plant.
Q No : 03
Write a note on Osmotic adjustments in Plants.
Osmotic adjustments in Plants:
On the basis of the available amount of water and salts, plants are divided into four groups:1. Hydrophytes: (Hydro= Water and Phytes=Plants)
Hydrophytes are the plants which live completely or partially submerged in freshwater. Such plants do not face the problem of water shortage. They have developed mechanisms for the removal of extra water from their cells. Hydrophytes have broad leaves with a large number of stomata on their upper surfaces. This characteristic helps them to remove the extra amount of water.Examples
The most common example of such plants is water lily, Lotus, Sea weeds, and Pistia.
2. Halophytes: (Halo= Saline and Phytes=Plants)
Halophytes live in sea waters and are adapted to salty environments. Salts enter in the bodies of such plants due to their higher concentration in sea water.On the other hand, water tends to move out of their cells into the hypertonic sea water. When salts enter into cells, plants carry out active transport to move and hold large amount of salts in vacuoles. Salts are not allowed to move out through the semi -permeable membranes of vacuoles. So the sap of vacuoles remains even more hypertonic than sea water. In this way, water does not move out of cells. Many sea grasses are included in this group of plants.3. Xerophytes: (Xero= Desert and Phytes=Plants)
Xerophytes live in dry environments. They possess thick, waxy cuticle over their epidermis to reduce water loss from internal tissues. They have less number of stomata to reduce the transpiration. Such plants have deep roots to absorb maximum water from soil.4. Mesophytes:(Meso= Moderate and Phytes= Plants)
Mesophytic plants are marked by average to hot temperatures and soil that is neither too dry nor too wet. Most mesophytic plants don’t do well in soggy, poorly drained soil. Mesophytes commonly grow in sunny, open areas such as fields or meadows, or shady, forested areas. Examples are Pinus tree, Berberis plant etc.Osmosis is the movement of water from hypotonic solutions (less solute concentration) to hypertonic solutions (higher solute concentration), through semipermeable membrane.
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Q.4: What is Homeostasis in Humans? Explain various organs of homeostasis?
Homeostasis in Humans:
Like other complex animals, humans have highly developed systems for homeostasis. The following are the main organs which work for homeostasis: Lungs remove excess carbon dioxide and keep it in balance. Skin performs role in the maintenance of body temperature and also removes excess water and salts. The kidney filters excess water, salts, urea, uric acid etc. from the blood and form urine.(i) Role of Skin in Homeostasis:
Human's skin consists of two layers.(a) Epidermis:
Epidermis is the outer protective layer without blood vessels.(b) Dermis:
While dermis is the inner layer containing blood vessels, sensory nerve endings, sweat and oil glands. hairs and fat cells.Regulation of body temperature
Skin performs important role in the regulation of body temperature. The thin layer of fat cells in the dermis insulates the body. Contraction of small muscles attached to hairs forms 'Goosebumps'. It creates an insulating blanket of warm air.Functions of Skin
Skin helps in providing cooling effect when sweat is produced by sweat glands and excess body heat escapes through evaporation. Metabolic wastes such as excess water, salts, urea and uric acid are also removed in sweat.Lungs:
Our cells produce carbon dioxide when they perform cellular respiration. From cells, carbon dioxide diffuses into tissue fluid and from there into blood. Blood carries carbon dioxide to lungs from where it is removed in air.Q No # 05
What is Urinary System of Humans and explain the structure of Kidney.
URINARY SYSTEM OF HUMANS:
The excretory system of humans is also called the urinary system. It is formed of one pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys filter blood to produce urine and the ureters carry urine from kidneys to urinary bladder. The bladder temporarily stores urine until it is released from body. Urethra is the tube that carries urine from urinary bladder to the outside of body.Structure of Kidney:
Kidneys are dark -red, bean shaped organs. Each kidney is 12 cm long, 6 cm wide and 4 cm thick and weighs about 150 grams. They are placed against the dorsal side of abdominal cavity just below diaphragm, one on either side of vertebral column. They are protected by the last 2 ribs. The left kidney is a little higher than the right.
Hilus:
The concave side of kidney faces vertebral column. There is a depression, called hilus, near the centre of the concave area of kidney. This is the area of kidney through which ureter leaves kidney and other structures including blood vessels, lymphatic vessels and nerves enter and leave kidney.The longitudinal section of the kidney shows two regions:
The longitudinal section of the kidney
(a) Renal Cortex:
Renal cortex is the outer part of kidney and it is dark red in colour.(b) Renal Medulla:
Renal medulla -is the inner part of kidney and is pale red in colour.Pyramids
Renal medulla consists of several cone shaped structure Ureter called renal pyramids.Pelvis
Renal pyramids projects into a funnel shaped cavity called pelvis, which is the base of ureter.Nephron:
The functional unit of the kidneys is called nephron. There are over one million nephrons in each kidney. There are two parts of a nephroni.e. (a) renal corpuscle and (b) renal tubule
Renal Corpuscle:
The renal corpuscle is not tubular and has two parts i.e. glomerulus and Bowman's capsule.(a) Glomerulus:
Glomerulus is a network of capillaries.(b) Bowman's capsule:
Bowman's capsule is a cup -shaped structure that encloses glomerulus.(2) Renal Tubule:
The renal tubule is the part of nephron which starts after Bowman's capsule.Proximal Convoluted Tubule:
It cosists of following parts:i. The first portion of Renal Tubule is called the proximal convoluted tubule:
ii. Next portion of renal tubule is U-shaped and is called the Loop of Henle.
iii. The last portion of renal tubule is the distal convoluted tubule.
Collecting Duct: The distal convoluted tubules of many nephrons open in a single collecting duct. Papillary Ducts: Many collecting ducts join together to form several hundred papillary ducts which drain into renal pelvis.
Q No # 06 Lungs are homeostasis organ? Explain.
LUNGS AS HOMEOSTASIS ORGANS
Co2 and water vapours are produced in every cell as by product during respiration. CO2 and water require to be eliminated from the body because CO2 is an acidic gas can change the pH of the blood, making it more acidic. This may cause the disturbance of the chemical reaction in the body. Lungs excrete this by product and maintain the homeostatic balance of the body. CO2 gas dissolved in the plasma of the blood and reaches the lungs from where CO2 is removed during exhalation.
Q No # 07
How skin help in homeostasis?
SKIN AS HOMEOSTSIS ORGAN:
Skin is a homeostasis organ which maintains the body temperature. We can regulate the body temperature by metabolic heat production. Walking, running, shivering or any other muscle activities increase the rate of heat. Thyroid and adrenal hormone also increase heat production. During overcooling, vasoconstriction takes place and the blood supply to the skin is reduced. This decrease the rate of heat loss. Similarly, the sweat production is stopped which further decrease the heat loss by evaporation
During overheating, vasodilation takes place and blood supply to the skin is increased. This causes more heat loss. The sweat glands of the skin start releasing excessive sweat which results in a cooling effect on evaporation.
Q.No # 08
What are the functions of Kidney? Also explain Osmoregulatory Function of Kidney?
Functioning of Kidney:
The main function of kidney is urine formation, which takes place in three steps.1. Pressure Filtration:
The first step is pressure filtration. When blood enters the kidney via the renal artery, it goes to many arterioles, and then to the glomerulus.Glomerular Filtrate:
The pressure of blood is very high and so most of the water, salts, glucose and urea of blood is forced out of glomerular capillaries. This material passes into the Bowman's capsule and is now called glomerular filtrate.2. Selective re -absorption:
The second step is the selective re- absorption. In this step about 99% of the glomerular filtrate is reabsorbed into the blood capillaries surrounding renal tubule. It occurs through osmosis, diffusion and active transport.Proximal convoluted tubules
Some water and most of the glucose is reabsorbed from the proximal convoluted Reabsorption of salts tubule. Here, salts are reabsorbed by active transport and then water follows by osmosis.Descending limb
The descending limb of loop of Henle allows the reabsorption of water .Ascending limb
The ascending limb of Loop of Henle allows the reabsorption of salts. The distal convoluted tubule again allows the reabsorption of water into the blood.3. Tubular Secretion:
The third step is the tubular secretion. Different ions, creatinine, urea etc. are secreted from blood into the filtrate in renal tubule. This is done to maintain blood at a normal pH (7.35 to 7.45).Urine: After the above mentioned steps, the filtrate present in renal tubules is known as urine. It moves into collecting ducts and then into pelvis.
At the final stage urine is only 1% of the originally filtered volume. The typical volume of urine produced by an average adult is around 1.4 litres per day.
OSMOREGULATORY FUNCTION OF KIDNEY
Osmoregulation is defined as the regulation of the concentration of water and salts in blood and other body fluids. Kidneys play important role in osmoregulation by regulating the water contents of blood. It is an important process as excessive loss of water dilutes them.Hypotonic Medium:
When there is excess water in body fluids, kidneys form dilute (hypotonic) urine. For this purpose, kidneys filter more water from glomerular capillaries into Bowman's capsule. Similarly less water is reabsorbed and abundant dilute urine is produced. It brings down the volume of body fluids to normal.Hypertonic Medium:
When there is shortage of water in body fluids, kidneys filter les water from glomerular capillaries and the rate of reabsorption of water is increased. Les filtration and more reabsorption produce small amount of concentrated (hypertonic) urine. It increases the volume of body fluids to normal. This whole process is under hormonal control.Q No # 09
What are the disorders of kidneys? Write a note on
(a) Kidney Stones (b) Kidney Failure
Disorders of Kidney:
The process by which a Kidney is unfit for its functions is called disorder of kidney. There are many different kidney disorders.1. Kidney Stones:
When urine becomes concentrated, crystals of many salt e.g. calcium oxalate, calcium and ammonium phosphate, uric acid etc. are formed in it. Such large crystals cannot pass in urine and form hard deposits called kidney stones. Most stones start in kidney. Some may travel to ureter or urinary bladder.Causes of Kidney Stones:
The major causes of kidney stones are age, diet (containing more green vegetables, salts, vitamins C and D, recurring urinary tract infections, less intake of water, and alcohol consumption.Symptoms of Kidney Stones:
The symptoms of kidney stones include severe pain in kidney or in lower abdomen, vomiting, frequent urination and foul-smelling urine with blood and pus. About 90% of all kidney stones can pass through the urinary system by drinking plenty of water. In surgical treatment, the affected area is opened and stone(s) are removed.
Removal of Kidney Stones
Lithotripsy
Lithotripsy is another method for the removal of kidney stones. In this method, non-electrical shock waves from outside are bombarded on the stones in the urinary system. Waves hit the dense stones and break them. Stones become sand -like and are passed through urine.Abu Nast- al-Farabi (872-951) was a prominent scientist who wrote many books that contained information about kidney diseases, The genius Abu Al-Qasim Al-Zahrawi (known as Albucasis: 936-1013), is considered to be Islam's greatest surgeon who invented many surgical procedures including the surgical removal of stones.from the urinary bladder. His encyclopedia Al- Tasrif ("The Method"), contained over 200 surgical medical instrument that he personally designed.
2. Kidney (Renal) Failure:
Kidney failure means a complete or partial failure of kidneys to function.Causes of Kidney Failure:
Diabetes mellitus and hypertension are the leading causes of kidney failure. In certain cases, sudden interruption in the blood supply to kidney and drug overdoses may also result in kidney failure.
Symptom of kidney Failure:
The main symptom of kidney failure is the high level of urea and other wastes in blood, which can result in vomiting, nausea, weight loss, frequent urination and blood in urine. Excess fluids in body may also cause swelling of legs, feet andface and shortness of breath.Treatment or Kidney Failure:
The kidney failure is treated with dialysis and kidney transplant.(a) Dialysis:
Dialysis means the cleaning of blood by artificial ways. There are two methods of dialysis:Peritoneal Dialysis
In this type of dialysis, the dialysis fluid is containing pumped for a time into the peritoneal cavity which is the space around gut.This cavity is lined by peritoneum. Peritoneum contains blood vessels. When we place dialysis fluid in peritoneal cavity, waste materials from peritoneal blood vessels diffuse into the dialysis fluid, which is then drained out. This type of dialysis can be performed at home, but must be done every day.
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