A2 Biology Topic 7 Hormones

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A2 Biology Topic 7
Performance enhancing drugs
Banned substances and practices
Anabolic steroids
Stimulants
Hormones and releasing factors
Beta-2 agonists
Narcotics
Beta blockers
Hormone agonists
Diuretics
Blood doping
Gene doping
Is it an infringement of athletes human rights to be required to give blood and urine samples?
Page reference: 178-179 Edexcel A2 Biology (concept) textbook
Steroid hormones
Pass through the plasma membrane and stimulate protein synthesis
Steroid
hormones
Other steroid
molecules
Mechanism of action of steroid hormones:
steroid hormone
cell surface membrane
Hormone enters
cell and binds with
receptor
Complex binds to DNA
and acts as a
transcription factor
receptor
nuclear
membrane
enters nucleus
hormone-receptor
complex
Switches on a gene for
synthesis of a protein
Testosterone
Stimulates protein synthesis
Results in bigger and stronger
muscles
Anabolic steroids
Natural testosterone is quickly
broken down.
testosterone
Testosterone is modified to
produce drugs that remain for
longer in the body
These synthetic anabolic
steroids are illegal.
nandrolone
Side-effects of using anabolic steroids
Infertility due to disruption of normal
hormone production:
- disrupted menstrual cycle
- reduced sperm production
-impotence
In addition:
- liver damage
- high blood pressure
- heart attacks
- increased aggression
21 year old body builder: A and B Severe
acne conglobata C After 8 weeks off
steroids and with antibiotics
Peptide hormones
Peptide hormones do not
enter the cell.
They bind to receptors on
the cell surface membrane.
They also act to switch
genes on or off.
Human erythropoietin
Mechanism of action of peptide hormones:
peptide hormone
receptor
cell surface membrane
Inactive secondary
messenger eg. cAMP
Secondary messenger
activated: initiates a
protein kinase cascade
acts as a transcription
factor which switches
on gene for a specific
protein
Erythropoietin
Erythropoietin is synthesised in the
kidneys
Causes the synthesis of enzymes
required for synthesis of red blood cells
(erythrocytes) in bone marrow.
Useful for treating anaemia.
Use of erythropoeitin
Increases number of blood cells and
therefore enhances oxygen supply to
muscles.
Improvement of 10% in aerobic
performance
Use is popular with endurance
athletes and cyclists
Side-effects of overuse of erythropoietin
Excess of red blood cells can lead
to strokes and heart attacks .
Attacks most common at night
due to low heart rate.
Thought to have caused the
unexpected deaths of 18
european cyclists between 1987 1991 .
Abuse difficult to prove as it is
naturally occurring.
Ethics of performance-enhancing drugs
Problems with deciding on what is illegal:
Ethical questions:
Creatine is not banned:
Classed as a nutritional supplement
Can cause kidney damage and high blood pressure
Is everything acceptable in
the pursuit of sporting
excellence?
Erythropoietin is banned:
Is a naturally occurring hormone
Can cause strokes and heart attacks
Isn´t it the choice of the
athlete to risk using drugs
or not?
Blood doping banned:
Donating, storing and transfusing own blood before
competition
Do use of performanceenhancing drugs improve
or ruin competition?
High altitude training not banned:
Increases number of red blood cells.
Caused by natural increase in erythropoietin production.
Are there circumstances
when drug use is
acceptable?
Essay
Read pages 182 – 183 (of concept approach textbook) and
answer question 2 on page 183:
Describe an absolutist and a relativist ethical position on the
proposal to set a maximum total red blood cell count for athlete
rather than measure erythropoietin levels.

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