Chapter 4: Animal tissues, organs and organ systems Flashcards
What is digestion?
The breakdown of food into smaller molecules that can diffuse into the blood
What is the function of the salivary glands?
To produce saliva, especially when you’re hungry and sense food. Saliva acts as a lubricant, making it easier to swallow food. It also contains AMYLASE, an enzyme that breaks down starch (a carbohydrate) into glucose
What is the oesophagus?
The tube that connects the mouth to the stomach. It pushes boluses of food downwards using rhythmic contractions
What is the function of the stomach?
Produces PROTEASE, an enzyme that breaks down protein into amino acids. It also releases hydrochloric acid, which kills pathogens and reduces the pH of the stomach to the optimal level for protease to work
What is the function of the liver in the digestive system?
Produces bile, a non-enzyme that helps to break down lipids (fats). Bile is stored in the gall bladder before being released into the small intestine
What is the function of the pancreas?
Produces 3 types of enzymes found in the digestive system: CARBOHYDRASE enzymes, LIPASE enzymes and PROTEASE enzymes
What is the rule for enzymes?
_____-ose is broken down by the enzyme _____-ase
What is the function of the small intestine?
Absorbs the products of digestion into the blood. Longer and narrower than the large intestine
How is the small intestine adapted to its function?
It contains villi, which are microscopic finger-like projections which massively increase the surface area for absorption. It also contains muscles which contract rhythmically to push food along (peristalsis)
What is the function of the large intestine?
Absorbs water and salts from the remaining digested food
What is a substrate?
A molecule which an enzyme acts on
What is lipase?
An enzyme which breaks down lipids into 3 fatty acid molecules and 1 glycerol molecule
What is the function of bile?
Breaks down large globules of fat into small droplets (it acts as an emulsifier). It increases the surface area of the fat so the lipase enzymes can break it down more quickly. Bile is alkaline so neutralises HCl entering the small intestine, allowing the enzymes there to work optimally
How do enzymes work?
The substrate fits into the active site (unique to the substrate) and the enzyme breaks its bonds.
How are enzymes destroyed?
High temperatures and extreme pH values can permanently change the shape of the active site, meaning the substrate no longer fits.
When are enzymes most effective (highest enzyme activity)?
At their optimal temperature and pH. If the temperature gets too low, they won’t have enough energy to break the bonds and if it gets too high they’ll become denatured
What are synthesis enzymes?
Enzymes which make complex molecules from simpler substances. For example, the enzyme found in protein synthesis joins amino acids to make proteins
What is an artery?
A large blood vessel that takes blood AWAY from the heart. They have thick elastic walls which can stretch to cope with the high-pressure blood
What is a vein?
A large blood vessel that returns blood to the heart. They have thinner walls than arteries because the blood is at a lower pressure. They also have one-way valves to prevent blood flowing in the wrong direction
What are capillaries?
Tiny blood vessels that spread out into tissues and organs to deliver blood and oxygen to them. They have thin walls to maximise diffusion. They connect arteries to veins
How does the heart pump blood around the body?
It contains pacemaker cells, which regularly generate electrical impulses. These electrical impulses travel along neurons to the cardiac muscle, causing it to contract
What path does blood take around the body?
Lungs (gains oxygen) Pulmonary vein Left atrium Left ventricle Aorta Body (loses oxygen) Vena cava Right atrium Right ventricle Pulmonary artery Lungs
Atria = input, Ventricle = output
How is the heart adapted to its function?
It contains valves at the top of the atria to prevent blood from being pumped backwards and to force it into the ventricles. The walls of the left ventricle are thicker than in the right ventricle. This is because the left ventricle needs to pump blood further to the extremities of the body, while the right ventricle only needs to pump it to the lungs
What is double circulation?
When blood goes through the heart twice on every circulation
What is the composition of blood?
55% plasma (which in turn is 92% water), 45% cells and platelets
How are red blood cells adapted to their function?
Biconcave shape for high surface area to volume ratio, no nucleus means more space for haemoglobin
What is haemoglobin?
The protein in red blood cells that can bind to oxygen and carry it around the body. When it’s carrying oxygen, it becomes oxyhaemoglobin. Oxygenated blood is a brighter red than deoxygenated blood
What are white blood cells?
Immune system cells also found in the blood. They have a nucleus and are rarer than red blood cells (more details in Chapter 6)
What are platelets?
Small cell fragments in the blood that join together to form scabs and clots
What happens when the skin is cut?
Platelets start the clotting process by releasing chemicals called clotting factors. These convert the fibrinogen in the blood into fibrin. This forms a mesh and acts as a glue to stick the platelets together, forming a scab
What are coronary arteries?
The arteries that supply the heart muscle with oxygenated blood
What is atherosclerosis?
A medical condition resulting from an unhealthy lifestyle that reduces the flexibility of arteries
What is coronary heart disease?
A disease where fatty deposits of cholesterol in the coronary arteries stops oxygenated blood from reaching the cells of the heart. Without oxygen, these cells die, causing heart attacks
What is cholesterol?
A biological molecule for cell membranes that leads to atherosclerosis if found in high levels in the blood
What is a heart bypass?
The traditional method for treating coronary heart disease, in which a section of a less important artery is moved to allow blood to flow around a blockage in a more important one
What is a stent?
A small device made from mesh which is inserted into the arteries to keep them open. This operation is less dangerous and easier to recover from than a heart bypass
What are some of the symptoms of faulty valves?
Breathlessness, tiredness, dizziness caused by less oxygen and glucose reaching the cells that need them due to blood flowing more slowly or in the wrong direction
Describe some other heart problems
Pacemaker cells don’t work correctly, causing an irregular heartbeat. Solution: Artifical pacemaker
Gap between left and right sides of heart causes oxygenated and deoxygenated blood to mix and cause a lack of oxygen and glucose reaching cells. This can be fixed with an operation
What are the issues with heart-and-lung transplants?
Risky, long recovery period, need to find organs that won’t be destroyed by the recipient’s immune system. These are only carried out in the case of heart failure
How can physical and mental health be maintained?
Eating a well-balanced diet according to the food pyramid: Prevents coronary heart disease and diabetes, encourages growth, prevents vitamin deficiency, strengthens bones, prevents getting fat
Regular exercise: Burns off fat, prevents heart disease, builds muscle, strengthens cardiovascular system
Seeing a doctor about mental health issues: Prevents suicide, improves quality of life
How does cancer develop?
Cell differentiation or division occurs incorrectly and cells divide rapidly, forming tumours (lumps). Cancerous cells can travel to other organs via the bloodstream, forming a secondary cancer. This is called metastasis
What is the difference between a malignant and a benign tumour?
Malignant tumours are cancerous and can spread. Benign tumours are the opposite
What are the signs of cancer?
Lumps, unexplained bleeding, loss of weight, long-term cough
What is screening?
Checking for cancer. Screening can be done by: X-rays, blood tests, monoclonal antibodies. Screening for breast (mammogram X-ray) and cervical (smear test) cancer is offered to all adult women on the NHS
What are the causes of cancer?
Obesity, smoking, UV radiation, HPV, carcinogenic chemicals
How is cancer treated and prevented?
Prevention: Healthy lifestyle, avoiding things known to cause cancer
Treatment: Radiotherapy, chemotherapy, palliative care (when cancer is terminal)
Describe the effects of obesity
Diabetes (see Chapter 12)
Describe the effects of excessive alcohol consumption
Liver damage (cirrhosis), depression caused by altered levels of neurotransmitters, underdevelopment of unborn babies whose livers cannot detoxify the dangerous compounds
Describe the effects of smoking
Cancer, asthma, underdevelopment of unborn babies whose livers cannot detoxify the dangerous compounds
