10. Osmoregulation

10.1 Gaining Water
Today’s Learning Objectives:
State three ways by which water is gained by humans.
State the meaning of the term ‘ metabolism ’.
State the meaning of the term ‘ metabolic water’ .
State the word equation for aerobic respiration.

Water is required for life to provide
A medium for chemical reactions
To allow compounds and elements to dissolve
Lubricant
To keep objects firm
To cool our body

How We Gain Water Drinking Eating Chemical Reactions

Metabolic Water - Metabolism describes all the chemical reactions in the cells of the body. - Metabolic water means water that is a product of metabolic reactions. e.g. aerobic respiration… Glucose + Oxygen Water + Energy + Carbon dioxide

10.2 Losing Water
State four ways by which humans lose water.
State the need for water loss in urine.
Be able to use bar charts and pie charts to present information on water loss.
Be able to use data to calculate percentage increase.

How We Lose Water Faeces Sweat Breathing Urine

Water Gained = Water Lost It is essential to keep a water balance in your tissues and blood stream or your cells would shrink or burst! Water gain/ 24 hr Food/ drink: 2300 cm 3 Metabolic water: 300 cm 3 Total: ? cm 3 Water lost/ 24 hr Sweat: 1000cm 3 Breath: 400cm 3 Faeces: 100cm 3 Urine: ? cm 3 Total: ? cm 3

10.3 Role of the Kidneys
State the typical volume of water per kilogram of body mass in a human.
Describe the ways in which the water content of the body is kept constant.
Describe the role of the kidney in regulating water content and name its connecting vessels.
Define the term ’ osmoregulation ’ and name the main organ in the body responsible for this process.
Name the waste product produced from the breakdown of amino acids and state where this happens.
Describe how urea is transported to the kidneys for removal.
Define the term ‘ excretion ’.

The Human Urinary System Aorta Left Kidney Ureter Bladder Urethra Right Kidney Renal vein Vena cava

The Functions of the Renal System Sac that is the site of temporary storage of urine Bladder Tube that carries urine from a kidney to the bladder Ureter The vein that takes blood away from the kidney containing purified blood. Renal vein The artery that supplies the kidney with unpurified blood Renal artery One of two bean shaped organs that excrete urine and maintain water balance by regulating the water content of the body Kidney Function Part

The kidneys: - regulate the water content of the body. - get rid of nitrogenous waste from the blood. Osmoregulation is the process controlling water content of the body. Excretion is the removal of waste which has been synthesised within the body.

10.4 Kidney in Detail
Describe the structure of a nephron and identify the glomerulus, Bowman’s Capsule, tubule and collecting duct.
Describe the functions of the glomerulus and Bowman’s capsule.
State what is meant by glomerular filtrate and describe its composition.
Describe how the structure of the glomerulus assists filtration.
Explain what is meant by reabsorption and state which components of glomerular filtrate are reabsorbed.
Explain the differences in the composition of glomerular filtrate and urine.

Once inside the kidney the artery splits into many capillaries . Each capillary supplies blood to one of thousands of tiny nephrons.

Nephron Branch of renal artery Glomerulus Bowmans capsule Kidney tubule Blood capillaries Collecting Duct

The Glomerulus and Bowman's Capsule The blood entering the glomerulus is under pressure, forcing small soluble molecules through the capillary wall into the bowman's capsule. The small soluble molecules, urea, glucose, salts are called the glomerular filtrate.

10.5 Marine Bony Fish
Explain in terms of habitat and skeleton what is meant by a marine bony fish.
Explain the use of the term ‘hypotonic’ in comparing sea water with the body tissues of a marine bony fish.
Describe the regulation problems for a marine bony fish.
State two mechanisms that help marine bony fish to maintain their water balance.
Describe how the kidney in a marine bony fish is adapted to assist in one of these mechanisms.
State where most of the nitrogenous waste in the blood of a marine bony fish is removed.
Describe where and how excess salt in the blood is removed.

- Fish live in aquatic surroundings and breathe dissolved oxygen from the water. - They use the thin, selectively permeable surface of their gills. - Diffusion ensures oxygen passes across the gills and into the bloodstream. - But diffusion ( osmosis ) creates problems for marine fish due to sea water with high salt concentrations ( hypertonic solution ). Marine Water Bony Fish

Maintaining Water Balance Only small volumes of urine due to few glomeruli and less filtrate Loss of water by osmosis through gills. Drinking seawater. Extra salt consumed excreted through gills against a concentration gradient by salt secretory cells (requires energy).

10.6 Freshwater Bony Fish
Explain in terms of habitat and skeleton what is meant by a fresh water bony fish.
Explain the use of the term ‘hypertonic’ in comparing fresh water with the body tissues of a fresh water bony fish.
Describe the regulation problems for a fresh water bony fish.
Describe how the kidney in a fresh water bony fish is adapted to assist in maintaining water balance.
Describe the composition and volume of urine produced by fresh water bony fish
State where and how freshwater bony fish gain additional salt and explain why this requires energy.

- Fresh water fish live in surroundings that have a much lower salt concentration than their bodies. - Fresh water bony fish have the problem of their surroundings being hypotonic relative to their bodies. - These fish therefore have a water balance problem opposite to the marine bony fish. Fresh Water Bony Fish

Maintaining Water Balance Gain water through mouth and gills. Kidneys have many large, glomeruli. Large volumes of filtrate leads to large volumes of urine. Specialised cells in gills to absorb salts against the concentration gradient. (requires energy)

10.7 Corrective Control
Explain why conditions in the external environment are important and name the cells that detect these changes.
Say what is meant by ‘effectors’ and ‘negative feedback control’.
Name the cells which detect changes in the water concentration of the blood and name their locaton.
Name the gland which releases ADH, and state ADH effect on kidney tubules and collecting ducts.
Describe the steps by which negative feedback control returns water concentration of blood to normal, and the effect on urine.

Internal Environment:
Immediate surroundings of cells within the body.
The body has to control the conditions within the internal environment .
Cells work best when conditions are ‘normal’.
Control Mechanism:
When a condition in the internal environment
changes, a mechanism is triggered to correct it.

Receptor cells: detect changes in internal environment Effector cells: respond to messages from receptors by producing a corrective mechanism. When normality returns, receptor and effector cells are no longer triggered and the corrective mechanism ceases. Negative feedback control

Controlling Water Concentration -changes in blood water concentration stimulates osmoreceptors in the hypothalamus of the brain. -hypothalamus sends nerve impulses to the pituitary gland which lies below. - pituitary gland releases more or less of a hormone called antidiuretic hormone (ADH). - ADH controls the permeability of the cells of the kidney tubules and collecting ducts, regulating the volume of water reabsorbed into the bloodstream.

Water content of the blood normal Water content of the blood HIGH Water content of the blood LOW Too much water drunk Too much salt or sweating Brain produces More ADH Urine output LOW Brain produces Less ADH Urine output HIGH High volume of water reabsorbed by kidney Low volume of water reabsorbed by kidney (small volume of Concentrated urine) (large volume of dilute urine)

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10. Osmoregulation

by rossbiology on Dec 16, 2008

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10. Osmoregulation — Presentation Transcript