Unit 2: Transport Systems

Question 1

Describe the ratio of surface area: volume in cells

Answer 1

As a cell grows, it’s volume increases much more than the surface area. Therefore, the SA:V ratio decreases. A cell wants to have a large SA:V ratio.

Question 2

Why is a small surface area:volume ratio bad?

Answer 2

Cells need to import molecules and expel waste products through the plasma membrane in order to survive. If the surface area is too small compared to the volume, not enough necessary molecules can get in and not enough waste (including heat) can get out.

Question 3

How is a large surface area:volume ratio achieved?

Answer 3

mitosis allows cells to divide into 2 smaller cells, which allows a larger ratio to be restored. Microvilli (small folds on the cell membrane) increase the surface area even more and this allows nutrients to be absorbed more efficiently.

Question 4

What is the importance of the surface area to volume ratio as a factor for limiting cell size? (8 mark question)

Answer 4

As a volume of a cell increases, the SA:V volume decreases
food/oxygen enters through the surface of cells
Waste leaves through the surface of cells
The rate of substance crossing the membrane depends on surface area
More metabolic activity in a larger cell means more food and oxygen required
Larger volume:
longer diffusion time
more waste produced
Excess heat generated will not be lost efficiently (with low SA:V ratio)
Eventually sa can no longer serve the requirements of the cell
This critical ratio stimulates mitosis
The size of the cell is reduced and kept within size limits

Question 5

What is cell differentiation?

Answer 5

a process in which unspecialised cells develop into cells with a more distinct structure and function

Question 6

What are emergent properties?

Answer 6

Emergent properties: a complex system possesses properties that its constituent parts do not have; the whole is more than the sum of its parts (due to the interaction between the different parts)

Question 7

What is a genome?

Answer 7

The complete set of genes, chromosomes or genetic material present in a cell or organism.

Question 8

Describe the steps of cell evolution.

Answer 8

Life started out with unicellular organisms.

Through evolution: cells clumped together and started working together to form multicellular organisms

For organism growth: needs either giant cells or more cells. Due to SA:V ratio, the cell cannot grow too much, which is why cells become multicellular

Steps of evolution:

1. Organisms were no longer limited by the size of the cell and grew larger
2. Cells in such an organism specialised through differentiation
3. Multicellular organisms displayed emergent properties

Question 9

What is the role of arteries?

Answer 9

carry blood AWAY from the heart to the body

Question 10

What is the role of pulmonary arteries?

Answer 10

transport blood with low oxygen content from the right ventricle to the lungs.

Question 11

What is the role of systemic arteries?

Answer 11

transport oxygenated blood from the left ventricle to the body tissues

Question 12

Describe the Tunica Intima (in arteries)

Answer 12

Tunica intima: innermost layer and is in direct contact with the blood in the lumen. Includes the endothelium that lines the lumen of all vessels, therefore forming a smooth, friction reducing lining.

Question 13

Describe the Tunica Media (in arteries)

Answer 13

• middle coat
• mainly made up of smooth (involuntary) muscle cells and elastic fibres arranged in roughly spiral layers
• usually the thickest of the 3 layers

Question 14

Describe the tunica adventitia / externa (in arteries)

Answer 14

• outermost coat
• tough layer consisting of loosely woven collagen fibres that protect the blood vessel and anchor it to surrounding structures.

Question 15

What is Diastolic pressure?

Answer 15

When the cardiac muscle is relaxing.

Question 16

What is systolic pressure?

Answer 16

when the cardiac muscle contracts.

Question 17

How does the structure of the artery help it?

Answer 17

Arteries can cope with the pressure as the walls (tunica externa/adventitia) are elastic:

• Contain elastic fibres formed by elastic protein
• Stretched with every heartbeat
• Back at normal shape they recoil to propel the blood forward

Muscular walls (tunica media) help with the propulsion of the blood

Tunica media and externa/adventitia help maintain high blood pressure

Smooth muscle arounds arteries can also relax which is called vasodilation

Question 18

What is the role of veins?

Answer 18

Transport blood back to the heart and return it to the atria

Question 19

Describe how the structure of a vein helps it fulfil its function.

Answer 19

veins have low blood pressure and travel at a slower pace

Don’t have as thick tunica medias
Skeletal muscles and valves keep the blood flowing
Skeletal muscles provide pressure which squeeze the veins
Movement is required to keep the blood flowing
Due to gravity there is a danger of backflow
Valves close to prevent backflow
These make sure blood only flows towards the heart

Question 20

What is the role of capillaries?

Answer 20

Capillaries are the connection between arteries and veins

This is because nutrients and oxygen must be transported to everywhere in the body

Question 21

How are capillaries formed?

Answer 21

Arteries form arterioles which then form capillaries

Capillaries then form venules which fuse together to form veins

Question 22

Describe the structure of capillaries.

Answer 22

Have walls that are only one-cell thick (diameter of 3–4 µm)

The wall is made up of endothelial cells.

Question 23

What are the similarities / differences in structure between arteries, veins and capillaries?

Answer 23

Number of layers: Veins and arteries both have 3 layers (intima, media, externa) whereas capillaries have one layer of endothelial cells.

Tunica media: thicker in an artery than in a vein (due to blood pressure), nonexistent in capillaries

Muscle and elastin fibres: thicker layer in arteries than in veins, don’t exist in capillaries

Valves: only exist in veins

Wall thickness and lumen: arteries generally have thicker walls with narrower lumens than veins. Capillaries have a wall that is 1 cell thick and a lumen that is around 5 µm

Look at image in google doc.

Question 24

Describe the differences in blood pressure, blood velocity and surface area in arteries, veins and capillaries.

Answer 24

Blood pressure: high in arteries, low in veins, lowest in capillaries

Blood velocity: highest in arteries, lowest in veins, high in capillaries

Surface area: smallest in arteries, largest in veins and small in capillaries

Question 25

Explain the structures and functions of arteries and veins | 8 mark question

Answer 25

A. arteries and veins have 3 layers in their walls B. walls of arteries and veins have tunica externa, media and intima C. arteries receive blood from heart and carry blood away from the heart D. lumen of artery is small to keep pressure high E. arteries have thick (muscular) walls with elastic fibres to withstand pressure F. elastic fibres recoil in response to ventricle/heart contraction G. muscle / elastic fibres help propel blood towards capillary beds H. veins receive blood from capillaries and carry blood to the heart I. large lumen of veins = less resistance to blood flow J. valves in veins keep blood flowing towards heart / prevent backflow

Question 26

Describe the structure of a water molecule

Answer 26

Water consists of 2 hydrogen atoms and one oxygen atom - joined by covalent bonds The oxygen atom is more electronegative than the 2 hydrogen atoms Oxygen has a greater pull on the electron clouds that exists between atoms oxygen acquires a slightly negative charge, whilst hydrogens have a slightly positive charge Water is therefore polar - positive and negative charges act as small magnets

Question 27

How does blood transport molecules?

Answer 27

a. Water is the universal solvent b. Blood is 90% water c. Water is polar d. Oxygen in water is slightly negatively charged and hydrogens slightly positive e. Hydrogen bond forms between individual water molecules f. Water forms hydrogen bonds with polar substances (eg glucose) g. These polar substances dissolve in water h. Ionic substances dissolve in water and are transported as ions i. Water cannot dissolve hydrophobic molecules j. Lipids must be transported as lipoproteins k. Hydrophilic protein on the outside and hydrophobic lipid on the inside

Question 28

What are the key molecules in blood?

Answer 28

Glucose: - Polar molecule - Soluble in water (can be transported in blood) Amino acids: - Both negatively and positively charged - Most are soluble in water - Depends on size and R group - With hydrophilic r group: easily dissolved in water and transported - Hydrophobic r group: not easily dissolved, transported in lower concentrations of blood Fats: - Nonpolar - Generally insoluble in water - Transported in structures called lipoproteins Oxygen: - Nonpolar - Due to small size: soluble to a limited extent - Oxygen transported in blood is bound to a protein called hemoglobin Sodium chloride: - Ionic compound - transported in blood in the form of Na+ and Cl- ions . - These ions are easily dissolved in water

Question 29

Draw a diagram of an unsaturated fatty acid

Answer 29

Check google document.

Question 30

Draw an IB heart

Answer 30

Check google document.

Question 31

What is electronegativity?

Answer 31

the tendency of an atom to attract shared electrons to itself

Question 32

describe circulation on the right side of the heart

Answer 32

Blood enters the heart through the inferior and superior vena cava, with oxygen-poor blood from the body tissues flowing into the right atrium of the heart. As the atrium contracts, blood flows from the right atrium into the right ventricle through the open tricuspid valve. When the ventricle is full, it begins to contract. The increased pressure of blood against the tricuspid valve forces it shut. This prevents blood from flowing backwards into the atrium. As the ventricle contracts, blood leaves the heart through the pulmonary valve, into the pulmonary artery and flows to the lungs where it is oxygenated.

Question 33

Describe circulation on the right side of the heart

Answer 33

Blood enters the heart through the inferior and superior vena cava, with oxygen-poor blood from the body tissues flowing into the right atrium of the heart. As the atrium contracts, blood flows from the right atrium into the right ventricle through the open tricuspid valve. When the ventricle is full, it begins to contract. The increased pressure of blood against the tricuspid valve forces it shut. This prevents blood from flowing backwards into the atrium. As the ventricle contracts, blood leaves the heart through the pulmonary valve, into the pulmonary artery and flows to the lungs where it is oxygenated.

Question 34

Describe circulation on the left side of the heart

Answer 34

The pulmonary vein carries oxygen-rich blood from the lungs into the left atrium of the heart. As the atrium contracts, blood flows from the left atrium into the left ventricle, through the open bicuspid (also called mitral) valve. When the ventricle is full, it begins to contract. The increased pressure of blood against the bicuspid valve causes it to close. This prevents blood from flowing backward into the atrium while the ventricle contracts. As the ventricle contracts, blood leaves the heart through the aortic valve, into the aorta and to the body.

Question 35

Describe circulation on the right side of the heart

Answer 35

Blood enters the heart through the inferior and superior vena cava, with oxygen-poor blood from the body tissues flowing into the right atrium of the heart. As the atrium contracts, blood flows from the right atrium into the right ventricle through the open tricuspid valve. When the ventricle is full, it begins to contract. The increased pressure of blood against the tricuspid valve forces it shut. This prevents blood from flowing backwards into the atrium. As the ventricle contracts, blood leaves the heart through the pulmonary valve, into the pulmonary artery and flows to the lungs where it is oxygenated.

Question 36

Describe circulation on the left side of the heart

Answer 36

The pulmonary vein carries oxygen-rich blood from the lungs into the left atrium of the heart. As the atrium contracts, blood flows from the left atrium into the left ventricle, through the open bicuspid (also called mitral) valve. When the ventricle is full, it begins to contract. The increased pressure of blood against the bicuspid valve causes it to close. This prevents blood from flowing backward into the atrium while the ventricle contracts. As the ventricle contracts, blood leaves the heart through the aortic valve, into the aorta and to the body.

Question 37

Label a heart

Answer 37

Look at google document.

Question 38

Describe a graph showing pressure related to a heartbeat.

Answer 38

look at google document. Atrial contraction begins (atrial systole). 2. Atria eject blood into ventricles (atrial systole). 3. Atrial systole ends; AV valves close ('lubb' sound). 4. Isovolumetric contraction of the ventricles occurs (ventricular systole). 5. Ventricular ejection occurs. 6. Semilunar valves close ('dupp' sound). 7. Isovolumetric relaxation of the ventricles occurs (ventricular diastole). 8. AV valves open; passive ventricular filling occurs.

Question 39

What is the SA node?

Answer 39

The sinoatrial node (SA) initiate each heartbeat and sets the heart rate. It sends electrical signals at regular intervals to cause the heart to beat of around 60-70 beats per minute

Question 40

Describe the cardiac cycle.

Answer 40

The SA node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria. The signal then passes via interatrial septum to reach the atrioventricular (AV) node. From the AV node, the signal is relayed via the bundle of His located in the interventricular septum to the top of each ventricle (confusingly, the top of the heart, or apex, is the bottom-most part where the two ventricles meet in a shape somewhat like a point). At the top of the ventricles, the signal spreads from the bundle of His (also called the atrioventricular (AV) bundle), to the ventricles via the Purkinje fibres located in its wall.

Question 41

Label where the SA node, atrioventricular node, bundle of His, purkinje fibres, AV bundle and interatrial septum are in the heart.

Answer 41

look at google document.

Question 42

Describe how Epinephrine (adrenaline) works

Answer 42

Adrenaline → ‘fight or flight’ hormones By the medulla of the adrenal glands Strong emotions cause epinephrine to enter the bloodstream → to the whole body Increases the heart rate Stimulating faster impulses from the sinoatrial and the atrioventricular node Prepare for vigorous physical activity

Question 43

How does doing activity change heart rate?

Answer 43

Increase in activity will increase your heart rate - Cells in your body will need more oxygen and nutrients when activity increases, heart beats faster in response to these increased demands Increased activity means more respiration - Greater need for oxygen - Increased production of waste products, such as carbon dioxide Increased carbon dioxide in the blood will decrease the pH - Sensed by the cardiovascular centre - Signal sinoatrial node via. cardiac accelerator nerve to increase heart rate - Result = more oxygen

Question 44

What does the cardiac accelerator nerve do?

Answer 44

originates in the medulla oblongata of your brain in the cardiovascular centre and signals the sinoatrial node to release impulses FASTER

Question 45

What does the vagus nerve do?

Answer 45

originates in the medulla oblongata of your brain in the cardiovascular centre and signals the sinoatrial node to release impulses SLOWER

Question 46

What does the cardiovascular centre monitor?

Answer 46

Blood pressure pH Carbon dioxide concentration of the blood - Determine whether impulses should be sent along the cardiac accelerator nerve or vagus nerve to the heart

Question 47

What are atheromas?

Answer 47

Fatty deposits Cause → high blood concentrations of low density lipoprotein (LDL) - In arterial walls next to the endothelial cells - LDL consists of cholesterol and fats Eventually block the artery

Question 48

what is thrombosis?

Answer 48

Clot in blood vessel Can block blood vessel completely If it were a coronary artery (artery supplying the heart with oxygen and nutrients) - Cells in that part of the heart will die Result is a myocardial infarction (heart attack) Buildup of plaque takes time Restricted flow of blood in such an artery will cause pain: angina - Due to heart cells being deprived of oxygen and nutrients

Question 49

What are causes of plaque formation?

Answer 49

High blood concentrations of LDL Diabetes causing high blood glucose concentrations Smoking and stress causing high blood pressure Diets containing high levels of trans fats Recent research indicates that certain infections with bacteria, such as Chlamydia pneumoniae, can also play a role.

Question 50

Describe the process of blood clotting.

Answer 50

a. Platelets detect skin/blood vessel damage b. Platelets release clotting factors c. Clothing factors trigger a chain of reactions d. Leading to formation of thrombin e. Thrombin causes fibrinogen conversion into fibrin f. Blood clot seals the wound due to fibrin network of fibres

Question 51

What are platelets?

Answer 51

Tiny blood cells (the glue) Plug to fix damage Plasma (factors including calcium, vitamin K) Fibre is the net, platelet is the plug

Question 52

What is plaque and how does it lead to the formation of blood clots?

Answer 52

plaque is fatty deposits They can turn chunky, hardened or inflamed Plaques turn into blockages, ruptures or cracks Red blood cells get stuck in the platelets, cascade occurs Blood flow cut off the the heart oxygen starved cells die

Question 53

What are some clotting problems?

Answer 53

``` TIA: A “mini stroke” transient ischaemic attack Lasts only a few minutes When the blood supply to part of the brain is briefly blocked ``` Deep Vein Thrombosis Blood clot forms in a vein deep inside your body Usually in one's leg Can be caused by injuries (causing damage to a vessel's wall), surgery (vessels can be damaged and staying in bed too long), as well as minimal activity and specific medications

Question 54

What is a stem cell?

Answer 54

An undifferentiated cell of a multicellular organism that can form more cells of the same type indefinitely, and from which certain other kinds of cells arise by differentiation.

Question 55

What types of cells can be made from stem cells?

Answer 55

liver, nerve, cardiac, blood, intestinal, bone, skin, and muscle cells

Question 56

What types of stem cells are there?

Answer 56

totipotent: the first cells formed after fertilisation of an egg cell pluripotent: eg. embryonic stem cells multipotent: eg. umbilical cord stem cells unipotent:

Question 57

What types of cells can be made from stem cells?

Answer 57

totipotent: can differentiate into any type of cell including placental cells. Can give rise to a complete organism pluripotent: can differentiate into all body cells but cannot give rise to a whole organism multipotent: can differentiate into a few closely related types of body cell. unipotent: can only differentiate into their associated cell type (eg. liver stem cells can only make liver cells)

Question 58

describe leukemia.

Answer 58

a

Question 59

describe stargardts disease.

Answer 59

a

Question 60

How are stem cells created?

Answer 60

egg cell - totipotent morula - blastocyst - pluripotent inner mass cells - into immune system, nervous system or circulatory system