Organisation Flashcards
What are tissues?
Groups of specialised cells with similar structure and function to perform a particular function
What are organs?
Made from a group of different tissues working together to perform a particular function
What are cells?
Basic functional and structural units in a living organism
What are organ systems?
Made from a group of organs with related functions which work together to perform body functions within the organism
What is the role of the stomach?
To start protein digestion
How is pepsin produced?
Pepsin, a protease is produced by the stomach to digest proteins into AMINO ACIDS
What is the role of the digestive system?
To break down large insoluble molecules into smaller soluble food molecules to provide the body with nutrients
What is digestion?
- Process where large, insoluble food molecules (starch and proteins) are broken down into smaller, soluble ones
- Which can now be absorbed into the bloodstream and delivered to cells in the body
How can the small soluble molecules (produced after digestion of food) be used in the body?
- To provide cells with energy (via respiration)
- Building other molecules to grow, repair or function
What is the alimentary canal?
The channel through which food flows through the body and starts at the mouth and ends at the anus. Digestion occurs within this alimentary canal
What are accessory organs?
- Organs which produce substances that are needed for digestion to occur, (enzymes or bile) but food does not directly pass through these organs.
- Examples are the Liver, pancreas, gall bladder or salivary glands
What happens at the mouth?
- Mechanical digestion takes place
- Amylase enzymes in saliva start digesting starch into maltose
- Food shaped to bolus by tongue and lubricated by saliva so it can be swallowed
What happens at the oesophagus?
- A tube connecting the mouth to the stomach
- Contracts after we have swallowed to push bolus down into stomach
What happens at the stomach?
- Food is mechanically digested through churning
- Protease enzymes start to chemically digest proteins
- HCL kills bacteria in food and provides optimum pH for protease enzymes to work
What happens at the small intestine?
- First section is called the duodenum, and is where food coming out of the stomach finishes being digested by enzymes
- pH of small intestine is slightly alkaline (pH 8-9)
- Second section is ileum and is where absorption of digested food molecules takes place
- Second section is long and lined with villi to increase SA where absorption can take place
What happens at the large intestine?
- Water is absorbed from remaining material
What happens at the pancreas?
Produces all 3 types of digestive enzyme -
- amylase
- protease
- lipase
- These enzymes are secreted in an alkaline fluid into the duodenum for digestion
What happens at the liver?
- Produces bile to emulsify fats
- Amino acids which weren’t used to make protein are broken down here producing urea as waste
What happens at the gall bladder?
- Stores bile to release into duodenum as required
Why is bacteria important to digestion?
- The large intestine is home to hundreds of species of bacteria
- They form a microbial ecosystem, playing an essential role in human digestion
- they break down substances we cant digest (cellulose)
- supply essential nutrients
- synthesising vitamin k
- providing competition with any harmful bacteria
What do digestive enzymes do?
- Biological catalysts made of protein
- Digest large, insoluble food molecules into smaller, soluble molecules
- These can be absorbed into the bloodstream
What is metabolism?
The sum of all the reactions happening in a cell or organism in which molecules are broken down
What are substrates?
- Temporarily bind to the active site of an enzyme
- Leads to a chemical reaction and the formation of a product
What is the lock and key model?
- A model where the lock is the enzyme, and the key is the substrate (fits perfectly into the active site of the enzyme)
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How does the relationship with enzymes and substrates work?
- Randomly move about in a solution
- Enzyme and its COMPLEMENTARY substrate collide randomly
- Enzyme-substrate complex is formed, so reaction occurs
- A product (or products) forms from the substrate which are released from the active site
What do proteases do?
Break down proteins to amino acids
How does temperature affect enzymes?
- Too low and the enzymes will not be effective and work too slow (less kinetic energy so lower rate of reaction)
- Optimum, and the enzymes will work at a good rate (collision theory)
- Too high, and enzymes will become DENATURED where the active site loses shape so substrates cannot lock on
How does pH affect enzymes?
- Too low OR too high, the bonds holding the amino acids chain together to make up the protein can be destroyed
- This changes the shape of the active site so the substrate can no longer fit in
See RP 4 and 5 about enzymes
do it
What are the 3 main digestive enzymes?
Carbohydrases, proteases and lipases
What do carbohydrases do?
- Enzymes which break down carbohydrates into SIMPLE SUGARS
- eg. Amylase breaks down STARCH into maltose
- Maltose is then broken down to glucose by the enzyme MALTASE
Where is amylase made?
Salivary glands, pancreas and small intestine
What do proteases do?
- Enzymes which break down proteins into AMINO ACIDS in the stomach and small intestine
Where is protease made?
Stomach, small intestine, pancreas
What are lipases?
- Enzymes which break down lipids (fats) into GLYCEROL and FATTY ACIDS
Where are lipases produced?
In the pancreas and secreted into the duodenum
What is bile?
- Alkaline to neutralise HCL in stomach
- It also breaks down large drops of FAT into smaller ones, increasing the SURFACE AREA, called EMULSIFICATION
- These alkaline conditions and larger surface area allow LIPASE to bread down fats (lipids) into GLYCEROL and fatty acids FASTER
What are the products of digestion used for?
- Production of new carbohydrates, lipids and proteins
- Glucose is used in respiration
- Amino acids are used to build proteins like enzymes and antibodies
Where is bile produced and stored?
- Produced in liver
- Stored in gall bladder
See RP 5
Investigate the effect of pH on the rate of reaction of amylase enzymes
Adaptations of lungs
- Thin walls for short diffusion distance
- Large surface area for faster diffusion of gases
- Excellent blood supply maintain a high concentration gradient so diffusion occurs faster
Ribs
Bone structure surrounding and protecting the lungs
Intercostal muscles
Muscles between ribs causing inhalation and exhalation
Diaphragm
Thin sheet of muscle separating chest cavity from abdomen and responsible for ventilation in the lungs
Trachea
Windpipe connecting the mouth and nose to the lungs
Bronchii
Tubes branching off the trachea
Bronchioles
Smaller tunes in lungs which connect to alveoli
Alveoli
Tiny, moist air sacs where gas exchange occurs, and covered in capillaries
How does the diaphragm work?
- Diaphragm contracts and increases volume of thorax (chest cavity), DECREASING AIR PRESSURE IN LUNGS, and drawing air in
- Diaphragm relaxes so moves upwards causing increased pressure inside lungs forcing air out
What is the heart?
An organ which pumps blood around the body in a double circulatory system
What does the right ventricle do?
Pumps blood to the lungs where gas exchange takes place
What does the left ventricle do?
Pumps blood around the rest of the body
Circulatory system
System of blood vessels with a pump and valves to maintain a one way flow of blood around the body
What do veins do?
Carry blood towards heart
What do arteries do?
Carry blood FROM heart to the rest of the body
What is the path of blood in the body?
- Deoxygenated blood enters vena cava
- Into right atrium
- Into right ventricle
- Right ventricle pumps deoxygenated blood through to pulmonary artery
- Through to lungs where blood becomes oxygenated
- Then flows to pulmonary vein
- Into the left atrium
- Into the left ventricle
- Where the ventricle contracts
- Blood is pumped through the aorta into rest of body
Adaptations of the heart
- Walls of ventricles are thicker because they are responsible for pumping blood around the body at high pressures
- Wall of left ventricle is much thicker than right because it pumps blood to ENTIRE BODY
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What is special about the tissue of the heart?
Cardiac muscle does not fatigue like skeletal muscle
What do the coronary arteries do?
- Supplies the tissue of the heart with oxygenated blood
- The heart needs a constant supply of oxygen for aerobic respiration to release energy to allow continued muscle contraction
What is special about the pulmonary vein and artery?
- Pulmonary vein is the only vein to carry oxygenated blood
- Pulmonary artery is the only artery to carry deoxygenated blood
What is a pacemaker?
- Cells located in the right atrium
- Which coordinates contraction of the heart muscles
- Therefore REGULATES HEARTRATE
What happens to the heart when we exercise?
- Heart rate increases
- Because there is a greater demand for oxygen
How does the pacemaker work?
- REGULATES HEART BEAT
- By sending out an electrical impulse spreading to surrounding muscle cells
- CAUSING THEM TO CONTRACT
What are artificial pace makers?
- Electrical devices used to correct irregularities in heartbeat
What are the 3 types of blood vessel in the body?
Arteries, veins, capillaries
Adaptations of arteries?
- Walls are relatively thick
- Elastic fibres allow artery wall to expand around blood at high pressures
Adaptations of veins?
- Walls are thin
- Layers of muscle and elastic fibres
- Lumen of vein is much larger than that of an artery
- Veins contain valves which prevent backflow of blood
Adaptations of the capillaries?
- Walls are 1 cell thick
- Cells of the wall have pores to allow blood plasma to leak out and form tissue
What is the role of blood in the body?
- To transport useful substances to every cell of the body
- To remove waste substances
What is blood?
Blood is a tissue, consisting of plasma, in which red blood cells, white blood cells and platelets are suspended
What are adaptations of RBCs?
- Bi-concave shape so large SA : V ratio for maximum efficiency of diffusion
- No nucleus
- Packed with HAEMOGLOBIN
What are white blood cells?
Immune cells responsible for defending the body from infection by recognising and destroying pathogens
Which arteries supply blood to the heart?
Coronary arteries supply blood to the heart (for oxygen, glucose, etc)
What is CHD?
- Layers of fatty material build up inside coronary arteries, NARROWING THEM
- Blood flow is reduced in the coronary arteries
- Resulting in lack of oxygen for heart muscle
Where are the two main sources of cholesterol in the body?
- Dietary cholesterol (animal products eaten)
- Cholesterol synthesised by the liver
How can we treat CHD?
Stents and Statins
What are stents?
- Narrow tubes threaded to blocked vessel
- Tiny balloon inflated
- Balloon stent against wall of artery, increasing width of lumen
- Balloon and tube are removed but stent stays which keeps the artery open
- USED TO KEEP THE CORONARY ARTERIES OPEN
Advantages and Disadvantages of stents
- Reduces risk of heart attack
- Procedure is relatively simple
- Stents last a long time
- Risk of blood clots
What are statins?
- Drugs used to reduce cholesterol levels in the blood
- block an enzyme in the liver needed to make cholesterol
- slowing rate of fatty material building in blood
- reducing risks of CHD
Advantages of statins
- Reduce levels of BAD cholesterol in blood
- Can be used to reduce risks of CHD
Disadvantages of statins
- Must be taken regularly and long term
- Take a long time to have an effect
- Can cause side effects, such as joint pain, kidney problems and neurological issues
What are heart valves?
Ensure blood is pumped from ventricles to arteries
What happens if heart valves STIFFER?
Prevents valve from opening so reduces volume of blood pumped by heart
What happens if heart valves develop a LEAK?
- Blood may flow from ventricles to atria or arteries to ventricles
- Reducing effectiveness of the heart in pumping oxygenated blood around the body
How can heart valves be replaced?
Via surgery using biological or mechanical valves, eg.
- Cow valves
- Pig valves
- Mechanical valves
What are heart transplants?
- In the case of a heart failure, a heart transplant is required
- So a dead donor’s lungs or heart can be transplanted to the patient
- However waiting lists can be long, so often a heart needs to be replaced by an artificial one (plastic and metal)
How can artificial hearts be used?
- To keep patients alive until a biological heart can be supplied
- To allow the patients heart to rest as an aid to recovery
Advantages and disadvantages of artificial hearts
- Higher availability than biological hearts
- Less chance of patient’s immune system rejecting it
- Artificial hearts don’t pump blood around the body as well as biological hearts
- When using stents with an artificial heart, there is an increased likelihood of a stroke due to blood clots
What is cellular respiration?
- An exothermic reaction
- Continually occurring in organisms
- Releasing energy
- The energy supplied allows the living processes to occur within cells and organisms
What is aerobic respiration?
- Respiration which requires OXYGEN for energy transfer
Glucose + Oxygen –> Carbon Dioxide + Water
- Reaction takes place in the mitochondria
What is anaerobic respiration?
- Respiration which does not require oxygen to transfer energy
- Occurs when the body cannot supply enough oxygen for aerobic respiration
Glucose –> Lactic Acid
- Supplies much less energy than in aerobic respiration due to glucose breakdown being incomplete
How does anaerobic respiration work in yeast?
FERMENTATION
- Glucose is broken down producing ethanol and CO2
Why is fermentation important?
- Economically important in manufacturing bread
- Production of CO2 makes dough rise
- Alcoholic drinks can be produced from the ethanol
Why do organisms need energy?
- Chemical reactions to build larger molecules
- Movement
- Keeping warm
How can the body react to excecise?
- Breathing rate and breath volume increases (to increase oxygen absorbed into blood stream and CO2 removed)
- To provide oxygen to cells for respiration to release energy required
- Heart rate increases to supply body with sufficient oxygen
- If exercising vigorously, the body may not be able to supply sufficient oxygen from aerobic respiration
- So ANAEROBIC respiration takes place
- It releases much less energy and forms lactic acid as a result of glucose being incompletely oxidised
- An oxygen debt is created by the presence of this lactic acid
- This is why we breathe vigorously and have a high heart rate AFTER exercise as well as during it
What happens after a build up of lactic acid?
- Muscles become fatigued and cannot contract as efficiently
- Oxygen needs to be supplied due to oxygen debt
What is oxygen debt?
When lactic acid needs to be oxidised by extra oxygen to form CO2 and water
Blood flowing through the muscles can transport the lactic acid to the liver where it is converted back to clucose
Metabolism
The sum of all the reactions in a cell or the body
How can energy be used from respiration in terms of metabolism?
- Continual enzyme controlled processes of metabolism
- Synthesising new molecules
Metabolism includes -
- Conversion of glucose to cellulose
- Conversion of glucose into glycogen
- Formation of lipid molecules from glycerol
- use of glucose and nitrate ions to form amino acids which are used to synthesise proteins
- Breakdown of excess proteins to form urea for excretion
