Biology

Cells - foundation of all living organisms 

Tissues - group of cells with a similar structure and function

Organs - group of tissues working together to perform a specific function

Organ Systems - group of organs working together to perform a specific function

Organism - organ systems working together

Mouth

• teeth chews food (mechanical digestion), cuts and crushes the food
• the pieces are mixed with saliva (special gland under the tongue that produces saliva)
• helps to break down and lubricates food so it goes down the gullet smoothly
• enzymes are released acting as a catalyst to make chewing faster

Oseophagus

• food broken down through digestive system by process called peristalsis
• peristalsis is the contraction of 2 sets of muscles in the walls of the gut
• one set runs along the gut
• other circles it
• creates wave-like contractions creating squeezing action - moving down gut

Stomach

• organ that digests food (can store food)
• muscular tissue (contracts to bring movement) churns food and other contents of stomach
• glandular tissue (can produe enzymes and hormones)
• epithelial tissue (covers some part of body) covers inner and outer surfaces of stomach
• contains hydrochloric acid (HCl) - has pH of 1.5 - 3.5

Pancreas & Liver

• liver produces bile, pancreas produces digestive juices
• bile=alkaline substance stored in gall bladder and secreted into small intestine 
• bile (in small intestine) emulsifies (breaks down) fats
• pancreas produces enzymes and insulin to help break down/store food

Small Intestine

• food digested & nutrients absorbed
• is long as it needs large surface area to absorb food & nutrients
• absorptino across surface is quicker if surface=thin and surface area=large
• inner wall of small intestine adapts so substances can cross quick&efficiently->
• thin wall=one cell thick
• many tiny villi=big surface area
• blood capillaries to carry away absorbed food molecules

Large Intestine

• absorbs water&undigested food
• reabsorption of water occurs & formation of faeces
• not enough water absorbed=diarrhoea & too much=constipation

Rectum & Anus

• stores faeces until it comes out of anus
• rectum connects large intestine to anus and temporarily stores faeces until defaction
• anus regulates discharge of waste & indigestable substances out of body
• can hold faeces from escaping till individual finds appropriate place to release it

Red blood cells

• job is to transport oxygen around body
• have large surface area for absorbing oxygen - oxygen carried in haemoglobin
• when oxygen binds to haemoglobin it's alled oxy-haemoglobin

White blood cells

• different types but same function
• function=to defend against microorganisms that cause disease
• do this by: phagocytosis, producing antibodies to fight them & produce antitoxins to neutralise any toxins
• larger than red blood cells (has nucleus unlike red blood cell)

Platelets

• small fragments of cells - no nucleus
• helps blood clot together at wound, stops from losing too much blood&stops from microorganisms getting in at wound
• lack of platelets=excessive bleeding and bruising

Plasma

• pale-straw coloured liquid - carries everything in blood

Carries:

• red, white blood cells(antitoxins, antibodies) & platelets
• nutrients (glucose, amino acids, water) - soluble products of digestion absorbed from small intestine&taken to cells of body
• carbon dioxide from organs to lungs, urea from liver to kidneys
• hormones and proteins

Pulmonary artery carries deoxygenated blood away from heart

Pulmonary vein carries oxygenated blood to heart

Right Atrium (RA)

• Deoxygenated blood enters via vena cava
• RA contracts pushing blood into right ventricle
• ventricle contracts forcing blood into plumonary artery and out of heart
• blood flows to organs through arteries and returns again through veins 

Left Atrium (LA)

• Oygenated blood enterss via the plumonary vein in the left atrium
• LA contracts pushing blood into left ventricle
• ventricle contracts pushing blood into aorta and out of heart
• blood flows to organs through arteries and returns again through veins 

Arteries

• job=carry blood away from heart (towards organ)
• structure=walls are strong to help transport blood at high pressure

Capillaries

• Arteries branch into capillaries
• job=carry blood to every cell in body to exchange substance with them-supply food and oxygen to cells/take away waste (carbon dioxide)
• really tiny, permeable walls (one cell thick), narrow=increases rate of diffusion/large surface area

Veins

• capillaries join up to form veins/job=carry blood to heart
• blood pressure lower in veins=walls not thick
• have valves to keep blood flowing in right direction

Our lungs are found in thorax (top part of body), separated from digestive organs by diaphragm, and are full of bronchi that split into smaller tubes called bronchioles, full of air sacs called alveoli where gaseous exchange occurs. 

We have lungs so that gas exchange can occur, so it can get oxygen into bloodstream and remove carbon dioxide out of bloodstream

Gas exchange system=two way process as O2 taken in and CO2 needs to be removed (build up of CO2 in body is harmful)

The alveoli provide a large surface area to speed up rate of diffusion of oxygen and carbon dioxide. They also have good blood supply due to network of capillaries. 

There's always concentration gradient provided as arriving blood is little in oxygen and more in carbon dioxide, making gas exchange quick and effective.

The larger cells between the alveoli and capillaries is one cell thick, providing a short diffusion distance.

Non-communicable diseases=diseases that can't be spread from one to another

Examples=allergies, cancer, diabetes, tubercolosis, arthritis, pneumonia, cardiovascular disease and CRD (chronic respiratory disease)

Communicable diseases=contagious diseases that can be spread to others (animal/object)

Examples=cold, chicken pox, flu and hepatitis

Pathogens (microorgansims) cause communicable/infectious diseases

Pathogens=viruses, bacteria, fungi, parasites, protists and microbes

Bacteria

• very small cells (1/100th size of body cells)
• can reproduce rapidly inside body (doesn't divide inside your cells & can survive outside body)
• make you feel ill by producing toxins that damage cells and tissues
• e.g. Salmonella - causes food poisoning

Viruses

• not cells (1/100th size of bacteria)
• reproduce rapidly inside body (divides inside cells & can't survive outside body)
• cell wall usually burst releasing new viruses-->cell damage makes us feel ill
• e.g. HIV - infects and damages cells apart of our immune system

Protists

• many different types of protists (all eukaryotic & mostly single-celled)
• some=parasites (live in/or organisms)
• often transferred to organism by vector (vector doesn't get disease)
• e.g. vectors=insects such as mosquitoes (malaria)

Fungi

• some fungi=single-celled, others=hyphae (hyphae=penetrate human skin&plant surfaces causing disease)
• hyphae=causes spores & can spread to plants/animals

Air

• droplets containing microbe fly into air when people sneeze/cough
• microbes can be breathed in e.g. chicken pox, colds, measles

Animals

• carry harmful microbes
• microbes can get into person who's scratched/bitten by such animals (mosquito-malaria)

Food

• can have harmful microbes in/on it & get into body when food eaten (food poisoning)

Touch

• microbes passed when infected person touches another or object infected person touched

Water - can have harmful microbes - get into body when swallowed e.g. chloera