B2 - Organisation Flashcards
What is a tissue?
A group of similar cells working together to perform a particular function
What is an organ?
A group of different tissues working together to perform a particular function
What is an organ system?
A group of organs with related functions working together to perform a specific function
What is the stomach made up of?
- Muscle = Contracts to churn
- Glandular tissue = Made from cells that secrete chemicals such as enzymes and hormones
- Epithelial tissue = Covers the inside and outside parts of the body
Journey food takes?
Mouth - Oesophagus - Stomach - Small intestine - Large intestine - Rectum - Anus
Complimentary organs or the digestive system?
Salivary glands, liver, gall bladder, pancreas
Function of mouth?
- Mechanical digestion - teeth break down food into smaller pieces to increase SA to volume ratio
- Amylase in saliva starts digesting starch to maltose
Function of the oesophagus?
- Connects mouth to stomach
- Contracts to push food down
Function of stomach?
- Mechanical digestion by churning
- Protease enzymes start to digest proteins
- HCL kills bacteria and gives optimal pH for protease enzymes
Function of small intestine?
Absorption of nutrients and digested food molecules
Function of large intestine?
Water absorption
Function of pancreas?
- Produces amylase, lipase and protease
- Secretes enzymes into small intestine to raise Ph of fluid coming out of the stomach
Function of liver?
- Produces bile to emulsify fats
Function of gall bladder?
Stores bile to release into small intestine as needed
Role of bacteria in digestion?
- Breaking down substances we can’t digest
- Supplying essential nutrients
- Synthesising vitamin K
- Providing competition with harmful bacteria to restrict their growth
What are enzymes?
Biological catalysts made from protein
Why are enzymes specific 3D shapes?
They are formed from protein molecules
How does the lock and key model work?
- Enzymes and substrates move about in a solution
- When an enzyme and it’s complimentary substrate collide, an enzyme-substrate complex forms and the reaction occurs
- A product/products are formed which are released form the active site
What happens to the enzyme after it has been used?
It is unchanged and catalyse further reactions
What is the induced-fit model?
When the substrate and active site change shape slightly to fit more perfectly when they bind
Optimal enzyme temperature in humans?
Around 37 degrees
What is denaturation?
High temperatures will start to break the bonds that hold the enzyme together and it will start to lose its shape. Eventually the active site is lost completely and the substrate cannot bind
Why does increasing temperature up to a point increase enzyme activity?
The molecules have more energy so move faster and the number of collision with substrate molecules increases
What happens at low temperatures?
Denaturation does not occur but there is less kinetic energy so the substrates collide at a lower rate
What is the best pH for enzymes?
Mostly 7 but some are produced in acidic conditions which have a lower optimum pH (stomach) and some that have higher (small intestine)
What can cause denaturation?
Wrong pH or too high temperatures
What is the purpose of digestion?
To break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream
What are three types of digestive enzymes?
Carbohydrases, proteases and lipases
What do carbohydrases do?
Break down carbohydrates into simple sugars
What does amylase do?
A carbohydrase which breaks starch into maltose
Where is amylase made?
Salivary glands, pancreas, small intestine
What do proteases do?
Break down proteins into amino acids in the stomach and small intestine
Where is protease made?
Stomach (pepsin), pancreas and small intestine
What do lipases do?
Break down lipids into glycerol and fatty acids
Where is lipase made?
Pancreas
Where is lipase secreted?
Small intestine (Duodenum)
Roles of bile?
- Neutralise HCl from the stomach because the enzymes in the small intestine have a higher optimum pH
- Emulsifies fats
What is glucose used for in humans?
Some that is released from carbohydrate breakdown is used in respiration to release energy
What are amino acids used for in humans?
To build proteins such as enzymes and antibodies
What are the products of lipid digestion used for?
To build new cell membranes and hormones
How have the lungs adapted for gas exchange?
- Large surface area for faster diffusion
- Thin walls for a short diffusion pathway
- Good ventilation for concentration gradients
- Good blood supply for concentration gradients
Structures of the lungs?
Nasal cavity, trachea, pleural cavity, lung, bronchus, bronchiole, alveoli, intercostal muscle, ribs, diaphragm
Function of the rib?
- Bone structures to surround and protect lungs
- Aid breathing
Function of the intercostal muscles?
Muscles between ribs which control movement, causing inhalation and exhalation
Function of the diaphragm?
Sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax
Function of the trachea?
- Windpipe that connects the mouth and nose to the lungs
- Lined with ciliated epithelial cells (to move mucus up to the mouth)
Function of the bronchi?
Tubes branching off the trachea with one for each lung
Function of the bronchioles?
Bronchi split to form smaller tubes called bronchioles that connect to the alveoli
Function of alveoli?
Tiny moist air sacs where gas exchange takes place that are covered in capillaries
What happens when you breathe in?
- External intercostal muscles contract
- Rib cage moves up and out
- Diaphragm contracts and flattens
- Volume of thorax increases
- Pressure inside thorax decreases
- Air is drawn in
What happens when you breathe out?
- External intercostal muscles relax
- Rib cage moves down and in
- Diaphragm relaxes and becomes dome shaped
- Volume of thorax decreases
- Pressure inside thorax increases
- Air is forced out
What does the right side of the heart do?
Brings blood from the body and takes to the lungs
What does the left side of the heart do?
Brings blood from the lungs and takes to body
Benefits of a double circulatory system?
- Blood travelling through small capillaries in the lungs loses a lot of pressure which reduces the speed it flows
- Returning oxygenated blood to the heart, pressure can be raised before sending to the body so cells can be supplied more quickly
Order of blood through the heart?
Body - Vena cava - Right atrium - Right ventricle - Pulmonary artery - Lungs - Pulmonary vein - Left atrium - Left ventricle - Aorta - Body
How have the ventricles adapted?
They have thicker walls so they can pump with pressure
Why is the wall of the left ventricle thicker?
It has to pump the blood to the rest of the body
What are the two types of valves in the heart?
Atrioventricular valves - separate the atria from the ventricles
Semilunar valves - found in the two arteries that come out the top of the heart
What separates the two sides of the heart?
Septum (atrial septum and ventricular septum)
What is the heart made of?
Cardiac muscle which does not fatigue like skeletal muscle
What do the coronary arteries do?
Supply the tissue of the heart wit oxygenated blood - the heart needs a supply of oxygen and glucose for energy
What are where is the pacemaker?
A group of cells that control the natural resting heart rate in the right atrium
What does the pacemaker do?
Sends an electrical impulse causing the cardiac muscles to contract which it does everytime it needs to beat
What happens if the pacemaker stops functioning properly?
An artificial pacemaker may need to be implanted to correct irregularities in heart rate. Implanted just under the skin and delivers an electrical current to the heart with a wire
Three types of blood vessels?
- Veins
- Arteries
- Capillaries
Order of blood vessels?
Arteries -> Capillaries -> Veins
Features of arteries?
- Thick wall with layers of collagen, smooth muscle and elastic fibres
- Elastic fibres allow the artery wall to expand around surging blood at high pressure
- Narrow lumen maintains high blood pressure
Features of veins?
- Thin wall with thinner layers of collagen, smooth muscle and elastic fibres
- Larger lumen than arteries
- Valves to prevent backflow of blood
Features of capillaries?
- 1 cell thick wall to reduce diffusion distance
- Cells of the wall have pores to allow blood plasma to leak out and form tissue fluid
Features of red blood cells?
- Biconcave disc shape for large surface area to volume ratio
- No nucleus
- Cytoplasm is packed with haemoglobin which binds to oxygen
Role of white blood cells?
Recognising and destroying pathogens
Three ways that white blood cells defend the body?
- Phagocytes
- Lymphocytes producing antibodies
- Lymphocytes producing antitoxins
What do phagocytes do?
Engulf and digest pathogens to destroy them
What do lymphocytes do?
- Produce specific antibodies that enhance phagocyte activity by disabling pathogens
- Producing antitoxins which bind to toxic substances produced by pathogens to neutralise them
Adaptations of white blood cells?
- Phagocytes have a lobed nucleus and are autonomous
- Lymphocytes have a large nucleus and can produce antibodies very quickly
What are platelets?
Fragments of cells that have cytoplasm but no nucleus
What is the role of platelets?
- Forming blood clots at a wound to prevent blood loss
- Insufficient platelets cannot clot blood effectively which can be life threatening
Cause of CHD?
A build up of fatty material inside the coronary arteries
What is the fatty material in CHD made of?
- Dietary cholesterol
- Cholesterol synthesised by the liver
Why is it bad for the coronary arteries to be blocked?
Arteries lose elasticity and cannot stretch to accommodate blood
What does a partial blockage cause?
Restricted blood flow to the cardiac muscle cells that results in angina
What does a complete blockage cause?
Cells of the heart cannot respire aerobically so results in a heart attack
Possible treatments of CHD?
Stents or statins
How do stents work?
- A narrow tube is threaded up through the groin to the blocked vessel
- A tiny balloon is inflated
- The balloon pushes the stent against the artery wall, widening the lumen
- The balloon and tube are removed
Advantages of stents?
- Very effective to increase blood flow
- Simple procedure
- Long lasting
Disadvantages of stents?
- Risk of thrombosis (clots)
What are statins?
Drugs that reduce the levels of cholesterol in the blood by blocking an enzyme in the liver needed to make cholesterol
Advantages of statins?
- Reduces the risk of plaque building up so lowers the risk of CHD, heart attacks and strokes
- Statins can increase the levels of HDL (good) cholesterol in the blood
Disadvantages of statins?
- Must be taken regularly and long term
- Can take a while to have an effect
- Can cause side effects such as muscle pains, kidney problems and neurological issues
Why might heart valves become faulty?
- Illness
- Old age
- Heart attack
Why is it bad if valves become stiffer?
- Prevents them fully opening
- Reduces volume of blood pumped by the heart
- Could develop a leak which gives backflow of blood
Replacements for faulty valves?
Pig, cow or mechanical valves
What is an artificial heart for?
Short term solution to keep the patient alive while waiting for a heart transplant
Advantages of artificial hearts?
- Less wait for one to be available
- Less chance of rejection
Disadvantages of artifical hearts?
Don’t always work as well as real hearts
- Increased risk of blood clots
Function of the upper epidermis?
Thin and transparent to allow light to enter the layer underneath
Function of the palisade mesophyll?
Column shaped cells tightly packed with chloroplasts to absorb more light
Function of the spongy mesophyll?
Contains internal air spaces that increase the surface area to volume ratio for diffusion of gases
Function of the lower epidermis?
Contains guard cells and stomata
Function of the guard cell?
Absorbs and loses water to open and close the stomata
Function of the stomata?
Where gas exchange takes place, opens during the day, closes at night, water evaporation also takes place here
Function of the vascular bundle?
Contains xylem and phloem to transport substances to and from the leaf
Function of the xylem?
Transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
Function of the phloem?
Transports sucrose and amino acids around the plant
Order of structure of leaf?
Upper epidermis - Palisade mesophyll - Spongy mesophyll - Lower epidermis - Guard cells and Stomata
Adaptations of leaves?
- Large surface area
- Thin
- Chlorophyll
- Network of veins
- Stomata
- Thin and transparent epidermis
- Thin waxy cuticle
- Palisade cell layer at top
- Spongy layer
- Vascular bundles
Factors that affect transpiration?
- Air movement
- Humidity
- Light intensity
- Temperature
How does air movement affect transpiration?
Good airflow removes water vapour from the air surrounding the leaf which increases the concentration gradient so increases water loss
How does humidity affect transpiration?
When the air is full of water vapour, the concentration gradient decreases so decreases water loss
How does light intensity affect transpiration?
Guard cells are responsive to light intensity, when it is high, they are turgid and the stomata open so more water is lost
How does temperature affect transpiration?
At higher temperatures, particles have more kinetic energy so transpiration occurs at a faster rate
What is the aorta?
The main artery that takes oxygenated blood away from the heart and to the body
What is an artery?
A blood vessel that carries blood at high pressure away from the heart
What is a benign tumour?
An abnormal cell growth that is contained within one area
What is blood?
A tissue containing red blood cells, white blood cells, platelets and plasma
What is cancer?
A non-communicable disease cause by changes in the cell that lead to uncontrolled growth and division
What is a cell?
The basic building block or all living organisms
What is health?
The state of physical and mental wellbeing
What is a malignant tumour?
A cancerous cell growth that invades neighbouring tissues and can spread to different parts of the body in the blood
What is metabolism?
All the chemical reactions occurring in an organism
What is translocation?
The movement of food molecules through the phloem tissue
What is transpiration?
The movement of water through the plant via the xylem tubes from root to leaf that includes the evaporation of water out of the plant and osmosis into the plant
