Biology

1. Lifestyle
   1. Smoking

      Annotations:

      • Carbon Monoxide: combines with haemoglobin, REDUCES the OXYGEN-CARRYING capacity of the blood, meaning the heart has to work harder (beat faster) to supply the same amount of oxygen to the tissues, therefore raising BP Nicotine: stimulates ADRENALINE, which increases the heart rate and raises blood pressure. Also makes blood "STICKY" increasing the chance of thrombosis
   2. Diet

      Annotations:

      • High levels of salt: raise BP High levels of saturated fat: increase LDL and hence blood cholesterol concentration
      1. Blood Cholesterol

         Annotations:

         • An essential component of membranes, so must be transported through the blood. HIGH-DENSITY LIPOPROTEINS remove cholesterol from the blood by transporting it to the liver for excretion LOW-DENSITY LIPOPROTEINS transport cholesterol to the artery walls, leading to risk of atheroma and heart disease.
2. Pathogens
   1. Bacteria

      Annotations:

      • Produce toxins
   2. Fungi
   3. Viruses

      Annotations:

      • Inserting their DNA (or RNA) into  a host cell

1. Phagocytosis

   Annotations:

   • *Chemicals produced by pathogens attracts phagocytes *Phagocytes attach themselves to the surface of the pathogen *They then engulf the pathogen to form a vesicle (phagosome) *Enzymes within lysosomes then break the pathogen down (by hydrolysis). *The products of the breakdown are then absorbed by the phagocyte.
2. T Cells
3. B Cells
4. Antibodies

1. Lung Disease
   1. TB

      Annotations:

      • Spread through the air by droplets (coughing, sneezing etc.) *The bacteria grow and divide in upper region of lungs (high levels of oxygen) *Immune system causes accumulation of white blood cells, leading to inflammation and blockage of lymph nodes (PRIMARY INFECTION). This clears up within a few weeks, however sometimes bacteria remain. *Bacteria may re-emerge, however, and cause POST-PRIMARY INFECTION *Also in upper region of lungs, bacteria destroy lung tissue resulting in cavities and scaring.  *Suffers cough up blood and bits of damaged lung
   2. Emphysema

      Annotations:

      • Permanent stretching of the lungs, preventing air being forced out of alveoli. ALso a recuced surface area of the alveoli due to bursting. This all causes little or no gas exchange.
   3. Asthma

      Annotations:

      • Localised allergic reaction, causing white blood cells on the lining of the bronchi to release histamine. *The airway lining becomes inflamed  *The epithelial cells secrete more mucus *Fluid leaves the capillaries and enters the airways *The muscles surrounding constrict
   4. Fibrosis

      Annotations:

      • Caused by scar tissue forming on  epithelial lining of the lungs, leading to irreversible thickening. This increases the diffusion pathway of the lungs, meaning oxygen doesn't diffuse as quickly and also leads to reduced elasticity of the lungs, making it harder to breathe out and hence ventilate the lungs.
2. Heart Disease
   1. Atheroma

      Annotations:

      • Fatty deposits (cholesterol, fibres, dead muscle cells, etc.) that form within the walls of the arteries (usually larger), building up into atheromatous plaques.  They bulge into the lumen of the artery, causing it to narrow and restricting blood flow.
   2. Thrombosis

      Annotations:

      • Can be caused by an atheroma breaking through the artery wall creating a rough surface around which a blood clot (thrombus) can be formed. The thrombus can then block the artery, causing any tissue beyond it to die from lack of oxygen.
   3. Aneurysm

      Annotations:

      • Caused by a weakening of an artery wall (often by an atheroma). The weakened point swells and fills with blood. If the aneurysm bursts it can cause haemorrhage and loss of blood to that area. A brain aneurysm is called a cerebrovascular accident.
   4. Myocardial Infarction (Heart Attack)

      Annotations:

      • Reduced supply of oxygen to the heart muscle due to a blockage of the coronary arteries.
3. Cholera

   Annotations:

   • Prokaryotic bacteria cause it. They're ingested (most are killed by the stomach acid). Once in the small intestine they propel themselves by their flagella into the mucus lining of the intestine wall. They produce a toxic protein which causes chloride ion channels to open, causing them to diffuse into the intestine. This causes water to move by osmosis  from the small intestine cells into the lumen of the intestine (because of a reduction in water potential). 
   1. Oral Rehydration Therapy

      Annotations:

      • Water: to rehydrate tissues Sodium: To replace sodium ions lost and to make use of sodium-glucose channels Glucose: To stimulate the uptake of sodium ions and to provide energy Potassium: to replace lost potassium ions and to stimulate appetite Other electrolytes: to help prevent electrolyte imbalance

1. DIffusion

   Annotations:

   • The net movement of molecules or ions from a region where they are of high concentration to one where their concentration is lower
   • Rate: *Concentration gradient *Surface area - a large SA means faster diffusion *Thickness - a thinner surface means faster diffusion
   1. Facilitated Diffusion

      Annotations:

      • A passive process (no ATP needed). Occurs down a concentration gradient. Specific carrier proteins will allow WATER SOLUBLE molecules to diffuse through them across the phospholipid bilayer. The carrier proteins change shape in the presence of certain molecules, allowing them to be selective about what travels across
2. Osmosis

   Annotations:

   • The passage of water from a region of higher water potential to a region of lower water potential, through a partially permeable membrane.
3. Active Transport

   Annotations:

   • The movement of molecules or ions out of a cell from a region of lower concentration to a region of higher concentration using energy or carrier molecules. ATP is needed

Annotations:

• DIFFUSION: carbohydrates are being digested constantly so the conc of glucose is usually higher in the small intestine than in the blood. Glucose therefore diffuses into the blood and can be taken to cells for respiration.
• ACTIVE TRANSPORT:  *Sodium ions are actively transported out of epithelial cells bt the Na/K pump, creating a much higher conc of Na+ in the lumen of the intestine. *The Na+ ions therefore diffuse back into the epithelial cells down a conc gradient, however they do this through a CO-TRANSPORT PROTEIN taking gliucose with them. 

1. Single-celled organisms
2. Fish
3. Leaves

1. Through Roots
2. Up Stems
3. Transpirstion