biology 3.2

Question 1

What are the advantages and disadvantages of the single and double circulation?

Answer 1

Single Advantages: less complex so doesn’t require complex organs
Single Disadvantages: low blood pressure, slow movement of blood so activity of animal tends to be low
Double Advantages: Heart can pump blood further around body with high pressure and fast
Double disadvantages: None

Question 2

What is the function of elastic fibres in blood vessels?

Answer 2

-Made of the protein elastin, provides flexibility enabling vessel to stretch
-Evens out the surges from the pumping of the heart so there is a continuous flow of blood

Question 3

What is the function of smooth muscle in blood vessels

Answer 3

-Provides strength, contracts, and relaxes to control the size of lumen to alter the flow of blood to particular tissue

Question 4

What is the function of collagen in the blood vessels?

Answer 4

-Provides structure and support
-Limits stretch to maintain shape and volume of vessel

Question 5

What is the function of the arteries, Lumen and components?

Answer 5

-Direction of blood flow is away from heart to the body, the pressure is high
-Lumen is narrow so the blood pressure is high
-Contains many elastic fibres and collagen amount of them decrease as the blood pressure decreases
-Contain smooth muscle which controls the size of lumen, vasodilation/vasoconstricion

Question 6

What is the function, size and components of the capillaries?

Answer 6

-Allow the exchange of substances between blood and surrounding cells
-One cell thick walls for short diffusion, lumen is so small that red blood cells travel in a single file line for shorter diffusion distance and are leaky
-Small so provide large surface area
-No elastic fibres, smooth muscle or collagen

Question 7

What is the function, size of lumen and components of the veins?

Answer 7

-Blood flow is back to heart, pressure is low and they have a big capacity
-Large lumen to reduce resistance/friction
-Contain elastic fibres(thin as they don’t need to stretch),smooth muscle and collagen

Question 8

How is a varicose vein formed and how do veins get blood back to heart?

Answer 8

-If a vein becomes weakened its valves won’t work properly, which allows blackflow of blood this causes the vein to become enlarged and bumpy (varicose)
-Big veins run near active muscles when the muscles contract this causes blood to beforced towards the heart
-Veins also have valves

Question 9

What is the composition of the blood?

Answer 9

-Plasma, erythrocytes(RBC), leukocytes(white blood cells) and thrombocytes(platelets)

Question 10

What are the adaptations of erythrocytes?

Answer 10

-Flattened biconcave shape: large S/A
-Large amount of haemoglobin
-No nucleus or organelles
-Small diameter

Question 11

What is albumin?

Answer 11

-Found in Plasma and helps maintain osmotic pressure of blood by dissolving in blood plasma increasing solute potential and causing water to flow into blood by osmosis(oncotic pressure)

Question 12

What is the fluid in the lymphatic system?

Answer 12

-Fluid in lymphatic system is called lymph this is similar to tissue fluid but also contains lymphocytes

Question 13

What is the function of the heart, where is it located and it’s size?

Answer 13

-Pumps blood continuously around the body to enable gas exchange.
-Located between the lungs in the thorax
-Its size is approximately the size of a fist

Question 14

Describe the function and adaptation of cardiac muscle cells?

Answer 14

-heart is composed mainly of cardiac muscle tissue, contraction is involuntary
-Cells contain lots of mitochondria and myoglobin (oxygen binding protein)

Question 15

What is the function of intercalated discs?

Answer 15

-Cardiac muscles are separated by them and they allow electrical impulses to pass through tissue and cause synchronised contraction

Question 16

What is the structure and function of the Pericardium and function of the coronary arteries?

Answer 16

-Pericardium: tough fibrous sac that protects the heart
-Coronary arteries: supply oxygen to the heart for aerobic respiration through blood

Question 17

What side of the heart contains oxygenated and deoxygenated blood?

Answer 17

-Left oxygenated(right in diagram),right deoxygenated (left in diagram)

Question 18

What is the septum and its function?

Answer 18

-Wall of muscle tissue in heart that ensures blood doesn’t mix

Question 19

What valves closing cause the lub and dub sounds?

Answer 19

Lub: atrioventricular valves
Dub: semilunar valves

Question 20

What happens during Atrial systole?

Answer 20

-Atria contracts, volume decreases so the pressure increases blood is forced out of arteries
-Atrioventricular valve is open
-Ventricles are relaxed and fill with blood
-Semilunar valve stays closed

Question 21

What happens during ventricular systole?

Answer 21

-Atria relaxes and passively fills with blood from veins
-AV is initially open but closes when there is a higher pressure in ventricles than atrium
-Ventricles contract, volume of blood decreases so pressure increases and blood is forced out into arteries
-Semilunar valve is initially closed but open when there is more pressure in ventricle than atrium

Question 22

What happens during diastole?

Answer 22

-Atria is relaxed and passively fills with blood
-AV valve is initially closed but opens when pressure in atria is above ventricle (same for semilunar except they close)
-Ventricles also relax and passively fill with blood

Question 23

How does the heart control its own rhythmic contractions

Answer 23

-The heart contains myocytes(cells in the heart) which are polarised they have a slight electrical charge across their membranes and an opposite negatively charged inside
-The charge can be reversed(depolarised) which causes them to contract
-These contractions are controlled by the Sinoatrial node (SAN)

Question 24

How does the SAN control atrial systole?

Answer 24

-SAN Indicates a wave of depolarisation through the atria causing the walls to contract and forcing blood into ventricles
-There is a layer of non conducting tissue that prevents ventricle from being depolarised

Question 25

How does the SAN control ventricular systole?

Answer 25

-Atrioventricular node picks up wave from sinoatrial node and delays before starting its own wave of polarisation
- Wave of polarization is sent to a bundle of His this triggers a contraction of the ventricles starting at the bottom of the heart so there is efficient emptying of the ventricles

Question 26

How do artificial pacemakers work and what are the problems?

Answer 26

-Devices implanted in peoples hearts which stimulate the atria and ventricle to contract when necessary
-Problems include SAN not firing and disruption between SAN and AVN or in the bundle of His

Question 27

How is a haemoglobin adapted to carry oxygen?

Answer 27

-Made of four polypeptide chains each bound to one haem group
-Within each haem group is a single iron ion which can reversibly join onto one oxygen molecule
-So each haemoglobin molecule can combine to four oxygen molecules

Question 28

What is the effect of carbon dioxide on haemoglobins dissociation curve?

Answer 28

-Bohrs shift, co2 levels increase when you perform excercise, this causes Ph to reduce and affeccts haemoglobins tertiary structure lowering its affinity for oxygen
-This increases the release of oxygen as its needed

Question 29

What is the effect of temperature on the haemoglobin dissociation curve?

Answer 29

-Decrease in temperature causes haemoglobins affinity to increase so hypothermia for example reduces the blood ability to release oxygen to metabolising tissue

Question 30

What is the difference between foetal haemoglobin and adult haemoglobin

Answer 30

-Foetal haemoglobin has a higher affinity for oxygen than adult

Question 31

What is myoglobin and why is it useful?

Answer 31

-Similar structure to haemoglobin
-Has a very high affinity for oxygen so will only release when oxygen levels are very low
-Acts as an oxygen reserve only dissociating oxygen when really needed

Question 32

How does carbon dioxide enter the blood and exit

Answer 32

1. Dissolves into plasma
2. Some carbon dioxide diffuse into RBC and forms carbaminohaemoglobin
3. It is then converted into hydrogen carbonate ions as it reacts slowly with water, erythrocytes speed up this reaction with the enzyme carbonic anhydrase
4. Hydrogen carbonate splits up into hydorgen ions and carbonate ions the carbonate ions move out of the cell and chloride goes in, this is known as chloride shift
   -It is the same procces but into the oposite direction for co2 exiting