1. 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.
2. 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
3. How We Gain Water
Drinking Eating
Chemical Reactions
4. 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
5. 10.2 Losing Water
Today’s Learning Objectives:
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.
7. 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 cm3
Metabolic water: 300 cm3
Total: ? cm3
Water lost/ 24 hr
Sweat: 1000cm3
Breath: 400cm3
Faeces: 100cm3
Urine: ? cm3
Total: ? cm3
8. 10.3 Role of the Kidneys
Today’s Learning Objectives:
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’.
9. The Human Urinary System
Aorta
Left Kidney
Ureter
Bladder
Urethra
Right Kidney
Renal vein
Vena cava
10. 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
FunctionPart
11. 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.
12. 10.4 Kidney in Detail
Today’s Learning Objectives:
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.
13. Once inside the kidney the artery splits into many
capillaries. Each capillary supplies blood to one of
thousands of tiny nephrons.
15. 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.
16. 10.5 Marine Bony Fish
Today’s Learning Objectives:
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.
17. - 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
18. 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).
19. 10.6 Freshwater Bony Fish
Today’s Learning Objectives:
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.
20. - 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
21. 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)
22. 10.7 Corrective Control
Today’s Learning Objectives:
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.
23. 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.
24. 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
25. 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.
26. 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)
