2.2 Animal tissues, organ, organ systems Flashcards
2.2.1 The human digestive system
What is the digestive system?
- an example of an organ system in which several organs work together to digest and absorb food.
2.2.1 The human digestive system
How does the human digestive system work?
- mouth (saliva): amylase is broken down
- chewing: breaks up food (mechanical), increases SA for digestive enzymes
- stomach: pepsin breaks down proteins into amino acids. Hydrochloroic acid provides optimal pH conditions for pepsin to work effectively.
- liver: bile is produced (neutralises acids, emulsifies fats)
- gall bladder: bile is stored (neutraises acids, emulsifies fats)
- small intestine: food is broken down, absorbs nutrients/minerals
- large intestine: absorbs excess water
2.2.1 The human digestive system
Enzymes
Amylase: breaks down starch into glucose. found in mouth, pancreas, small intestine
Protease: breaks proteins into amino acids. found in stomach (pepsin), small intestine, pancreas
Lipase: breaks down lipids into fatty acids + glycerol. Found in pancrease, and small instestine.
2.2.1 The human digestive system
Lock and key model
enzymes
- substrate is specific to the enzyme’s active site
- substrate and the enzyme bind creating an enzyme-substrate complex
- products are formed when substrate is released from active site. enzyme stays unchanged.
2.2.1 The human digestive system
Factors of enzymes
optimum pH for enzymes: pH 7. if it is too high, then it can denature and will be irreversible.
optimum temp for enzymes: 37 degrees. if it too high, it can denature and will be irreversible.
2.2.2 The heart and blood vessels
The heart
- deoxygenated blood enters through the vena cava to the right atrium
- RA contracts, and blood enters the right ventricle.
- RV contracts, and blood enters pulmonary artery
- blood from PA goes to the lungs to get oxygenated.
- oxygenated blood come through the pulmonary veins (from lungs) and to left atrium
- LA contracts, blood enters left ventricle
- LV contracts, blood enters aorta
- blood from aorta gets transported throughout the body (to transport energy/minerals to cells)
Valves: prevent backflow, opens and closes.
2.2.2 The heart and blood vessels
Blood vessels
Arterties: carry blood away from the heart.
* thick, muscular walls with elastic fibres - withstand high pressure without being damaged
* small lumen so it creates high pressure
Veins: carry blood into the heart
* thinner walls - doesn’t have a lot of pressure to withstand
* large lumen - blood moves slower, creating low pressure
* valves: prevents backflow of blood
Capillaries: tiny blood vessels which connect veins and arteries
* one cell thick
* contain small holes (pores) which allows substances to pass through them easily.
2.2.2 The heart and blood vessels
Lungs
- nose/mouth - trachea - bronchi - alveoli
- diffusion occurs in the alveoli. oxygen in, carbon dioxide out.
adaptations of aveoli:
* good blood supply: creates steep concentration gradient for carbon dioxide and oxygen
* capillary walls are one cell thick: short diffusion distance
* layer of moisture
2.2.3 Blood
Blood components
- Red blood cells: the haemoglobin in RBC binds to oxygen. RBCs do not have a nucleus – this provides more space to store oxygen.
- White blood cells: detect any pathogens which are circulating in the blood and initiate an immune response
- Platelets: form a blood clot at the site of a wound to prevent excessive blood loss and entry of microorganisms through the skin.
- Plasma: a liquid containing carbon dioxide, digested food molecules, urea, hormones and heat energy
2.2.4 Coronary heart disease: non-communicable
Coronary heart disease
- layers of fatty material build up inside the coronary arteries, narrowing them
- reduces the flow of blood through the coronary artery, resulting in a lack of oxygen for the heart muscles.
2.2.4 Coronary heart disease: non-communicable
How can a coronary heart disease be treated?
Stents: stretches the artery wall, holds it open and maintains a flow of blood. used when drugs are less effective, they are a long term solution.
Statins: drugs which reduce how much chloesterold the liver makes, prescribed for those who are at high risk of the disease.
2.2.4 Coronary heart disease: non-communicable
Artificial hearts
- used when the heart fails, keeps the patients alive whilst waiting for heart transplant or uses it to rest as an aid to recovery
- patients immune system can recognise the heart as foreign, and start an immune response (rejection).
- if rejected, patient needs to take immunosuppressant drugs, making them at risk from other infections (due to weakened immune system)
2.2.4 Coronary heart disease: non-communicable
Faulty valves
Faulty valves may not open properly, which means that :
* less blood enters the heart chambers
* less blood is delivered to the body
* pressure builds up, lungs swell with fluid
faulty valves may not close properly, meaning that
* blood will leak back.
Faulty valves can lead to heart failure. Can be replaced using biological or mechanical valves.
2.2.5 Health issues
Relationship between health and disease
Disease is a major cause of a lack of health.
Lack of health arise from diet, stress, life situation (smoking, drinking etc)
Diseases also cause a lack of health. Eg:
- Defects in the immune system mean that an individual is more likely to suffer from infectious diseases.
- Viruses living in cells can be the trigger for cancers.
- Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
- Severe physical ill health can lead to depression and other mental illness.
2.2.6 The effect of lifestyle on some non-communicable disease
Risk factors
effects of diet: increase of fatty food creates build up of fatty material, reduces body’s sensitivity to insulin. increase of healthy food deposits more minerals and nutrients in the blood.
effect of smoking: damages the lining of arteries, encouraging build up of fatty material. inhalation of carbon monoxide reduces the amount of oxygen that can be carried by blood. damages alveoli lining.
effect of alcohol: produces toxic substances for liver cells, in high concentrations. neurones of brain are damaged by alcohol, reducing brain function
effect of exercise: improves muscles ability to pull oxygen out of blood, reducing need for the heart to pump more blood to muscles
exposure to carcinogens: exposure to ionising radiation, damaging DNA in cells leading to uncontrolled cell division, causing cancer
smoking/alcohol when pregnant: smoking reduces amount of oxygen transported around mother, reducing oxygen delivered to the foetus. alchohol can damage development of the brain in a foetus.
