Animal Tissues, Organs and Systems Flashcards
What is the main function of the digestive system?
To digest food and absorb the nutrients obtained from digestion.
What is the role of the pancreas and the salivary gland in the digestive system?
To release enzymes to break down large insoluble food molecules into small soluble food molecules.
What is the role of the stomach in the digestive system?
- Produces hydrochloric acid - which kills any bacteria present
- Provides the optimum (acidic) pH for the protease enzyme to function.
What is the role of the small intestine in the digestive system?
The site where soluble food molecules and nutrients are absorbed into the bloodstream.
What is the role of the liver in the digestive system?
Produces bile (stored in the gallbladder) which:
- emulsifies lipids
- allows the lipase enzyme to work more efficiently.
What is the role of the large intestine in the digestive system?
Absorbs water from undigested food, producing faeces.
What is an enzyme?
A biological catalysts
What is the role of enzymes in the digestive system?
To speed up the rate of reactions (the breakdown of food) without being used up.
How does the shape of an enzyme affect its function?
Enzymes have a specific active site which is complementary to their substrate.
What is metabolism? (NN)
The sum of all the reactions in a cell or an organism.
What is the lock and key hypothesis of enzyme function?
The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex.
How does temperature affect enzyme action? Why?
Up to a certain point, increasing temperature increases enzyme action; as molecules have a higher kinetic energy. Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured (so it can no longer catalyse the reaction).
What is the optimum temperature for enzyme activity?
The optimum temperature is around 37°.
What is the optimum pH for enzyme activity? (2)
The optimum pH for most enzymes is 7 (apart from proteases in the stomach).
How does pH affect enzyme function? (1)
If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.
Where are carbohydrases, proteases and lipases produced in the body?
● Carbohydrase: salivary gland, pancreas (amylase), and small intestine (maltase).
● Protease: stomach (pepsin), pancreas, and small intestine (others).
● Lipase: pancreas and small intestine.
What is the role of carbohydrases in the digestive system?
Carbohydrases (amylase) breaks down starch into glucose.
What is the role of proteases in the digestive system?
Proteases break down proteins into amino acids.
What is the role of lipases in the digestive system?
Lipases break down lipids into fatty acids and glycerol.
Where is bile made and stored in the body?
Bile is made by the liver and stored in the gallbladder
What is the role of bile in the digestive system?
● Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.
● Bile emulsifies lipids to form smaller droplets - this increases the surface area for the lipase enzyme to work on more efficiently.
What is the heart?
An organ that pumps blood around the body.
What is the purpose of the circulatory system? (2)
Carries oxygen and other useful substances to bodily tissues, and removes waste substances.
How does the double circulatory system work?
● One pathway carries (deoxygenated) blood from the heart to the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place.
● One pathway carries (oxygenated) blood from the heart to the tissues.
Where does blood pumped by the right ventricle go?
The lungs
Where does blood pumped by the left ventricle go?
Around the body (tissues).
Why is the double circulatory system important and how?
It makes the circulatory system more efficient; the pressure of the blood stays quite high (higher in the left ventricle) so it can flow faster around the body.
How many chambers does the heart have and what are they called?
4 - right atrium, right ventricle, left atrium, left ventricle.
Why is the wall of the left ventricle thicker?
The left ventricle has to pump blood at a higher pressure around the whole body.
What are the four main blood vessels associated with the heart?
● Aorta (left) - carries oxygenated blood from the heart to the body.
● Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart.
● Vena cava (right) - carries deoxygenated blood from the body to the heart.
● Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.
What is the purpose of valves in the heart?
Prevent the backflow of blood.
What is the purpose of coronary arteries?
Coronary arteries supply the heart muscle with oxygenated blood.
Describe the process of blood flow through the heart.
● Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
● Pressure builds up in the atria and it contracts, forcing blood into the ventricles and causing valves to shut.
● After the ventricles contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body).
What is the approximate value of the natural resting heart rate?
70 beats per minute
How is the heart rate controlled? (2)
Heart rates are controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle to contract.
How can an abnormal heart rhythm be treated? (2
Irregular heart rhythms can be treated using an artificial pacemaker, which sends out electrical signals to correct the heart’s rhythm.
What are the three types of blood vessel in the body?
● Arteries
● Veins
● Capillaries
What is the function of the arteries?
Carry blood away from the heart.
How are arteries adapted for their function? (2)
● Thick muscle layer adds strength to resist high pressure.
● Thick elastic layer allows arteries to stretch during and recoil in between surges of blood, keeping the blood moving.
What is the function of the veins?
To carry blood towards the heart.
How are veins adapted for their function? (2)
● Wide lumen maintains low pressure
● Valves to prevent backflow of blood
What is the function of the capillaries?
To enable the transfer of substances between the blood and tissues.
How are capillaries adapted for their function? (3)
● One cell thick walls providing a short diffusion path.
● Permeable walls allows substances to diffuse across.
● Narrow lumen causes slow blood flow leaving more time
for diffusion.
How would you calculate the rate of blood flow?
Volume of blood / number of minutes
Where are the lungs found in the body? (2)
The lungs are located in the thorax (within the chest) and are separated from the rest of the abdomen by the diaphragm.
What is the function of the ribcage?
To protect the ribcage.
What tissues make up the gas exchange system? (7)
● Mouth and nose
● Trachea
● Bronchi
● Bronchioles
● Alveoli
● Intercostal muscles
● Diaphragm
Explain how the lungs are ventilated through inflation by the action of intercostal muscles.
● Intercostal muscles contract
● Ribcage moves upwards and outwards
● Diaphragm contracts (flattens) and volume of the chest increases
● Increased volume results in decreased pressure
● Air is drawn into lungs down pressure gradient.
Explain how the lungs are ventilated through exhalation by the action of intercostal muscles.
● Intercostal muscles relax
● Ribcage moves downwards and inwards
● Diaphragm relaxes (dome-shaped) and volume of the chest decreases
● Decreased volume results in increased pressure
● Air is drawn out of the lungs down pressure gradient.
Describe how gas exchange occurs at the alveoli. (2)
● Oxygen diffuses from the alveoli into the capillary bloodstream down its concentration gradient.
● Carbon dioxide diffuses from the capillary into the alveoli down its concentration gradient.
Describe how alveoli are adapted for gas exchange
(3).
● Small and arranged in clusters - larger surface area.
● Rich blood supply - maintains concentration gradient.
● Thin alveolar wall - short diffusion pathway.
How would you calculate the breathing rate?
Number of breaths / number of minutes
What substance carries the different components of blood around the body?
Plasma
What substances are transported by plasma? (6)
● Red blood cells
● White blood cells
● Platelets
● Carbon dioxide
● Urea
● Products of digestion
What is plasma?
A yellow liquid within blood that transports substances around the body.
What is the purpose of red blood cells in blood?
To transport oxygen around the body
How are red blood cells adapted for their function? (3)
● Biconcave shape - increased surface area to volume ratio.
● No nucleus - more room for haemoglobin to bind to oxygen.
● Contain haemoglobin - binds to oxygen
What is the purpose of white blood cells in blood?
They form part of the immune system, which protects the body from invading pathogens.
How are white blood cells adapted for their function? (4)
● Have a nucleus - contains DNA which codes for proteins
● Can produce antibodies
● Can produce antitoxins
● Can engulf and digest pathogens (phagocytosis)
What is the purpose of platelets in blood?
Platelets are small cell fragments which aid the clotting of blood at the site of a wound.
Why is the function of platelets important?
● Platelets aid in the process of blood clotting (conversion of fibrinogen to fibrin). As a result, red blood cells are trapped in the fibrin network, forming a clot which prevents excessive bleeding. Scab formation (after the clot has dried) prevents bacteria from entering the wound.
What is coronary heart disease and what may it result to?
Coronary heart disease occurs when the coronary arteries that supply the heart muscle become blocked with a buildup of fatty material; This restricts the supply of oxygen to the heart, possibly leading to a heart attack or death.
What is a stent and how does it work?
A stent is a metal mesh tube that is inserted into a blocked artery so that it remains open; The stent is inflated using a balloon, which is later removed to allow blood to flow freely.
What are the advantages of stents?
● Insertion can be carried out without general anaesthetic
● Quick recovery time
● Lower the risk of a heart attack
What are the disadvantages of stents?
● Risk of postoperative infection
● Risk of blood clots at site of stent
What are statins? (N?)
Statins are drugs which reduce the level of LDL (bad) cholesterol which contributes to the development of coronary heart disease.
What are the advantages of statins?
● Reduce risk of strokes, coronary heart disease and heart
attacks
● Increase level of HDL (good) cholesterol
What are the disadvantages of statins?
● Have to be taken continuously
● May have side effects
● Effect may not be immediate
What is a heart bypass surgery?
A surgery where blocked coronary arteries are replaced with sections of veins taken from other parts of the body.
What are the consequences of leaky heart valves?
Blood flows in the wrong direction, causing the heart to become less efficient. Patients may become breathless and die as a result.
What types of valves can replace leaky valves?
● Mechanical - made of metal or polymers
● Biological - taken from animals (pigs,
sometimes humans)
What are the advantages of mechanical valves?
● Last for a very long time
What are the disadvantages of mechanical valves?
Disadvantages
● Need to take medication to prevent blood
clotting around valve
What are the advantages of biological valves?
● Work very well - no medication required.
What are the disadvantages of biological valves?
● Only lasts 12-15 years
What is the purpose of an artificial heart?
Artificial hearts are intended to support a patient’s heart while they wait for a suitable donor heart.
What are the advantages of artificial hearts?
● Less likely to be rejected by immune system
● Allows damaged heart to rest to help recovery
What are the disadvantages of artificial hearts?
● Risk of infection due to surgery
● Risk of blood clots
● Have to take blood-thinning drugs
