2.2 Animal Tissues, Organs and Systems (heart+lungs) Flashcards
What is the heart?
An organ that pumps blood around the body
What is the purpose of the circulatory system?
Carries oxygen and other useful substances to bodily tissues, and removes waste substances.
How does the double circulatory system work?
● One pathway carries blood from the heart to the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place.
● One pathway carries 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?
Body tissues
Why is the double circulatory system important?
It makes the circulatory system more efficient - for example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.
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.
● The atria contract, 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?
Heart rate is 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?
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
How are arteries adapted for their function?
● Function: carry blood away from the heart.
● Thick muscle layer - adds strength to resist high pressure.
● Thick elastic layer - allows arteries to stretch and recoil - in order to withstand high pressure.
How are veins adapted for their function?
● Function: carry blood towards the heart
● Wide lumen - enables low pressure
● Valves - prevent backflow of blood
How are capillaries adapted for their function?
● Function: enable transfer of substances between the blood and tissues.
● Walls are one cell thick - short diffusion path.
● Permeable walls - substances can diffuse across.
● Narrow lumen - blood moves slowly - 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?
The lungs are located in the thorax (within the chest). They are protected by the ribcage and separated from the rest of the abdomen by the diaphragm.
What tissues and organs make up the gas exchange system?
● Trachea ● Bronchi ● Bronchioles ● Alveoli ● Intercostal muscles ● Diaphragm
Explain how the lungs are ventilated by the action of intercostal muscles
● Intercostal muscles contract
● Ribcage moves upwards and outwards
● Diaphragm flattens and volume of the chest increases
● Increased volume results in decreased pressure
● Air is drawn into lungs down pressure gradient
The inverse occurs when air moves out of the lungs.
Describe how gas exchange occurs at the alveoli
● 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
● 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?
● 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?
Transport of oxygen around the body
How are red blood cells adapted for their function?
● 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?
● Have a nucleus - contains DNA which codes for proteins
● Can produce antibodies and antitoxins
● Can engulf and digest pathogens (phagocytosis)
Describe what platelets are.
Platelets are small cell fragments which aid the clotting of blood at the site of a wound.
Why is the function of platelets important?
They help the blood to clot at a wound, preventing excessive bleeding.
Scab formation (after the clot has dried) prevents bacteria from entering the wound.
Lack of platelets can cause excessive bleeding and bruising.
What is coronary heart disease?
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
- It 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?
- The insertion of a stent can be carried out without general anaesthetic.
- Quick recovery time
- Lower the risk of a heart attack
What are disadvantages of stents?
Disadvantages
● Risk of infection
● Risk of blood clots at stent
What are statins?
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?
Advantages
● Reduce risk of strokes, coronary heart disease and heart attacks
● Increase level of HDL (good) cholesterol
What are disadvantages of statins?
Disadvantages
● 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 and disadvantages of mechanical valves?
Advantages
● Last for a very long time Disadvantages
● Need to take medication to prevent blood clotting around valve
What are the advantages and disadvantages of biological valves?
Advantages
● Work very well - no medication required Disadvantages
● 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?
Advantages
● Less likely to be rejected by immune system
● Allows damaged heart to rest to help recovery
What are the disadvantages of artificial hearts?
Disadvantages
● Risk of infection due to surgery
● Risk of blood clots
● Have to take blood-thinning drugs
