2.69 Urinary system

describe the structure of the urinary system, including the kidneys, ureters, bladder and urethra

Source: www.biochem.co, www.medicalartlibrary.com

1. Right and left kidney
Each with its own separate blood supply
Excretion, filtration, osmoregulation

2. Ureter
Carries urine from the kidney to the bladder
Each kidney has a tube that leads into the common bladder

3. Bladder
Stores urine

4. Urethra
Where urine is carried out of the body
Travels down through either the vagina or the penis

2.68b Osmoregulation

understand how the kidney carries out its roles of excretion and of osmoregulation

The kidney can control the amount of water and salts in the bloodstream, keeping the blood and tissue fluid isotonic and therefore maintaining the function of the cells

Osmoregulation
Osmo - osmosis (less conc. ==> more conc.)
Regulation - control

[1]
The blood circulating into the tissue could be very concentrated or dilute, causing the tissue fluid to be hypertonic or hypotonic - both of these conditions could remove or add too much water to the cells, causing the cells to lose its function

[2]
The kidneys keep the tissue fluid isotonic - controlling the composition of the blood
(Blood forms the tissue fluid)
Excess water and salts removed and excreted down into the ureter

2.68a Excretion

understand how the kidney carries out its roles of excretion and of osmoregulation

Both the liver and kidneys remove toxic amino acids and urea from the body by breaking the amino acids down into urea (in the liver) and converting the urea into urine (in the kidneys), finally excreting it out of the body through the bladder in the form of urine

Urea, contains nitrogen
Nitrogen toxic to body - unable to store

Amino acids - Normally used for growth
Excess amino acids must be excreted (liver and kidneys)

1. Liver
- Blood circulates to the liver
- Amino acids in blood broken down
- Converted into urea
- Returns to the bloodstream

2. Kidneys
- Blood circulates to both kidneys
- Kidneys filter urea from blood
- Urea added to water to form urine

- Urine flows down into the bladder via ureters
- Filtered blood returns to the bloodstream in veins without toxic amino acids and urea

2.67b Human organs of Excretion

recall that the lungs, kidneys and skin are organs of excretion

1. Lungs
- Carbon dioxide (waste from respiration)

2. Kidneys
- Excess H2O
- Urea (nitrogen waste from amino acids, because of inability to store amino acids)
- Salts

3. Skin
- Sweat (H2O and salts)
- to a lesser extent, urea

2.67a Excretion in plants

recall the origin of carbon dioxide and oxygen and waste products of metabolism and their loss from the stomata of a leaf

Plants excrete oxygen (O2) and carbon dioxide (CO2) depending on whether they are carrying out photosynthesis or respiration

1. Photosynthesis
- Leaf absorbing light energy, producing oxygen
- CO2 + H2O -> C6H12O6 + O2 (Excretion - the release of metabolic waste)
- Waste excreted through the stomata

2. Respiration
- C6H12O6 + O2 -[Enzyme reactions]-> ATP + CO2 + H2O
Aerobic respiration

CO2 is metabolic waste - excretion

3.30 Mutation

Rare, random change in genetic material that can be inherited

Mutation changes the base sequence of the genes (e.g. ACT to AAT)
Allele - form of gene

Alleles exist because of mutation
i.e. A and a (dominant and recessive genes)

Mutation creates a new version of alleles
Creates new protein
Entirely different effect on phenotype

3.29 Species Variation

Variation within a species can be
- Genetic
- Environmental
- Both

Variation -> differences in phenotype (determined by Variation = Genotype + Environment)
[Continuous variation]

1. Variation entirely dependent on genotype.
e.g. blood group (A, AB, B, O...)

2. Variation modified by the environment

e.g. tallness (inherited with genotype but diet may influence it)








3. Environmental variation
Entirely dependent on environment
Cannot be inherited genetically

e.g. home language

3.31 Evolution

describe the process of evolution by means of natural selection

Evolution - Change in the form of organisms / Change in the frequency of alleles

Natural selection - Mechanism of evolution (Proposed by Charles Darwin)

Change in allele frequency by means of natural selection
-> e.g. Skin / lung infections by Staphylococcus aureus

Original form is susceptible to being killed by metheciline (antibiotic)

Random mutation - gives it ability to break down metheciline (resistant)

2 forms - (1st definition of evolution)
2nd form increases because the 1st form dies out

Natural selection:

• Random mutation - Produces MRSA form
• Non-random selection - Antibiotic selecting MRSA to be killed

3.33 Antibiotic resistance

Understand how resistance to antibiotics can increase in bacterial populations

Staphylococcus aureus
- Skin infections
- Lung infections

Can be treated with metheciline
Antibiotic - Chemical can kill staph.

Type of staph. that can be killed with metheciline is called the susceptible form
MSSA - metheciline susceptible staph. aur.

----

Random mutation to the genotype of the staph.
Bacteria does not die when given methe.
Resistant

MRSA - metheciline resistant staph. aur.

----

Effects of use of antibiotics

MRSA increasing survival rate
Becomes more common

Resistance becoming an increasing problem within hospitals

3.34 Causes of mutation

Mutation - change of base sequence

1. Radiation
Ionising radiation (e.g. gamma rays, X-rays, ultraviolet UV-B)
UV-B causes mutation causing skin cancer

2. Chemicals
Tars, tobacco
Mutagens - Chemicals which cause mutations
Carcinogens - Mutagens which also cause cancer

3.32 Types of Mutation

Understand that many mutations are harmful but some are neutral and few are beneficial

Gene ==> New alleles [mutation]
Alleles are responsible for phenotype
New phenotype could be:
- Beneficial e.g. enzyme
- Neutral (neutrality may not last forever - +environmental changes may affect it and turn it beneficial or neutral)
- Harmful e.g. non functional enzyme

3.21a Genetic Probabilities

3.20 Family Pedigrees

Finding out if the condition is caused by a dominant or recessive allele

Write out genotypes and look for evidence in the diagram:

3.18c Codominance

3rd (distinct) phenotype appears: Blue x White -> Orange

Codominance -> B = W both contribute to phenotype