Week 2 formative quiz questions

Question 1

Liver disease and kidney disease can both cause hyperproteinaemia

Answer 1

FALSE - liver disease and kidney disease can both cause HYPOproteinaemia (less protein in the blood than normal). The liver is the main site of production of plasma proteins, so loss of function impairs production of plasma proteins. The kidney on the other hand does not normally filter protein out of the blood as these molecules are too large to cross the filtration barrier. However when the kidney becomes damaged the filtration barrier becomes more “Leakey” and protein is lost in the urine. Normally no protein is excrete in the urine

Question 2

Integral membrane proteins have an extracellular and an intracellular domain

Answer 2

TRUE - integral proteins are, as the name suggests, integral to the membrane. They span the whole width of the membrane and project on both the intra - and extra- cellular sides. Often the extracellular side acts as a receptor to bind extracellular ligands such as neurotransmitters or hormones, which brings about a conformational change in the protein and a change in behaviour of the cell as a result

Question 3

It is possible for a solution to be both hyperosmotic and hypotonic

Answer 3

TRUE - osmolarity describes the number of total solutes in solution without describing whether they can cross the cell membrane or not. Tonicity describes the number of solutes in a solution that cannot readily cross the membrane (non-penetrating particles). A solution may be hyperosmotic if, for example, it contains a higher level of urea than normal plasma, but if at the same time it contains a lower level of sodium than normal plasma it would also be hypotonic

Question 4

Activation of T and B lymphocytes and the production of immune response takes place in the thymus

Answer 4

FALSE - the activation of T and B lymphocytes through the exposure to foreign antigens takes place in the second lymphoid organs including the lymph nodes and spleen, this leads to the production of an immune response that is transported to the site of infections, the thymus is a primary lymphoid organ responsible for the maturation of T cells

Question 5

Average circulating volume in an adult male is 5 Litres

Answer 5

True - It is generally slightly less in women

Question 6

A glycoprotein is a molecule made up of lipid and protein

Answer 6

FALSE - “glyc” relates to carbohydrate (often but not always glucose) so a glycoprotein is a molecule made up of carbohydrate and protein

Question 7

Glucose crosses the cell membrane by active transport

Answer 7

FALSE - Glucose uses transporter proteins but it enters cells down a conc. gradient so active transport (using energy to drive the movement of a substance against a conc. gradient) is not required.

Question 8

The cell membrane is a lipid bilayer. The outer layers are composed of phosphate groups and the inner core is lipid

Answer 8

TRUE- The hydrophobic (water hating) lipid part of the membrane is “hidden” from the aqueous environment of the intracellular and extracellular fluid, deep inside the membrane, while the hydrophilic (water loving) phosphate heads are in contact with the aqueous ICF and ECF

Question 9

In terms of the electrochemical gradient, the electrical gradient and conc. gradient of a substance are always going in the same direction, but with different magnitudes

Answer 9

False – the electrical gradient and concentration gradient for any substance may be in the same direction or they may oppose each other. Potassium, for instance, has a concentration gradient favouring outward movement but because the inside of the cell is negative compared to the outside, the electrical gradient favours inward movement of the positively charged potassium ion. However, because the concentration is much greater than the electrical gradient, potassium moves out of a cell when the potassium ion channels open

Question 10

Antibodies have a Y shape structure and can be seen as two parts, the lower part is responsible for biding to the antigen.

Answer 10

FALSE - - Antibodies are proteins that are produced against antigens.

Because we have different antigens, each antigen will induce different antibodies.

Antibodies have a Y shape structure that can be divided into two regions, the upper region is called antigen binding region /fab, and this is in fact the specific part of the antibody that recognises and interacts with antigen. The lower region is called Fc region

Question 11

Aquaporin channels allow ions to move between the intracellular fluid and extracellular fluid compartments in a regulated manner

Answer 11

FALSE - aquaporins only allow the free movement of water. They do not permit ions to cross the membrane. Ions must use gated ion channels in order to cross the membrane and these are tightly regulated. It is this tight regulation that maintains the concentration gradients and marked differential distribution of ions either side of the cell membrane, or in other words the significant difference in composition between the ICF and ECF

Question 12

T helper cells can be further divided into different subsets based on the help they provide, and the cell they target for this help: Th1, Th2, Th17

Answer 12

True - T helper cells can be further divided into different subsets based on the help they provide, and the cells they target for this help. This help is achieved through the action of different cytokines

Th1: for example, activate macrophages,

Th2: activate Eosinophil, mast cells

Th17: activate neutrophil particularly in their phagocytic activity

Question 13

Insulin can bind to all cells of the body, but only stimulates a response in some.

Answer 13

False – insulin, and other hormones and neurotransmitters, can only bind to cells expressing receptors for those ligands. Most cells do not express receptors for most ligands, there is a specificity that allows for very specific ligand- receptor interaction to ensure responses are only generated in the appropriate tissues. Insulin receptors are found on fat and muscle tissue, most other tissues are insensitive to insulin and take glucose up via other means. Follicle Stimulating Hormone (FSH) is another example – its receptors are localised to the gonads and other tissues just ignore FSH because it cannot bind to them

Question 14

Albumin is the most abundant of all plasma protein

Answer 14

True – 60% of plasma protein is albumin, 38% is globulin and the remaining 2% are clotting factors

Question 15

One of the important features of adaptive immunity is that the immune response is fast and immediate

Answer 15

False - The immune response of adaptive immunity is slow and requires days to develop as the immune cells of this part of immunity must interact with and adapt to the pathogen/antigen to produce immune response

Question 16

G proteins are an example of peripheral proteins and are involved in cell communication

Answer 16

True – G proteins are peripheral proteins. They are found only on the inner leaf of the membrane (they do not span the width of the membrane like integral proteins do). Their role is to translocate through the inner leaf of the membrane carrying signals for receptor proteins to other membrane bound proteins e.g. enzymes or ion channels.

Question 17

Components of the innate immunity include: phagocytes, mast cells, basophils, T lymphocytes.

Answer 17

False - Phagocytes, mast cells, basophils are components of the innate immunity, while T lymphocytes are components of the adaptive immunity as they differentiated to cytotoxic T cells and helper T cells

Question 18

There is only one type of T cell lymphocytes, namely Cytotoxic T cells, whose main function is to destroy infected cells.

Answer 18

FALSE - T cell lymphocytes, in fact, can be divided into two main types mainly based on their role in the immune response.

Cytotoxic T cells (CD8 T) cells because they have CD8 receptors on their surface

These cells recognize pathogens antigens /components only when these antigens are bound to MCH I,

The main role of these cells is to kill pathogens or cells that are infected with pathogens or even damaged or abnormal cells such as tumor cells.

The other type of T cells are called helper T cells (CD4) T cells because they have CD4 receptors on their surface. These cells recognize pathogens antigens /components only when these antigens are bound to MCH II. These cells do not kill but as the name suggests that they help other cells mainly B cells to complete their functions

Question 19

A 2mM solution of urea has an osmolarity of 2 milliosmoles

Answer 19

True – as urea does not dissociate in solution, a 2mM solution of urea gives an osmolarity of 2mM

Question 20

Class l, II molecules are a group of proteins that are found on the surface of cells whose main function is to bind to specific components of pathogen called peptides or antigens and present them to immune cells

Answer 20

True - Class l molecules are a group of proteins that are found on the surface of virtually all nucleated cells.

Their main function is to bind to specific components of pathogen called peptides or antigens and present them to CD8+ T to trigger cytotoxic response against these pathogens or the cells containing these pathogens. Note that MHC I present antigens that are obtained from pathogens inside cells and present them only to CD8.

Unlike MHC Class l molecules, MHC II molecules are a group of proteins that are found on the surface of only few cells including APCs (macrophages for example). Again, they bind to specific components of pathogen called peptides or antigens and present them to CD4+ to trigger immune response against these pathogens or the cells containing these pathogens. Also Note that MHC II present pathogenic antigens that are obtained from pathogens outside the cells and present them only to CD4 not CD8

Question 21

The Na+/K+ ATPase pumps 3 sodium ions into the cell for every 2 potassium ions it pumps out

Answer 21

False – it’s the other way around. It pumps 3 sodium ions out of the cell for every 2 potassium ions it pumps in. In doing so it helps to maintain the negative charge inside the cell (by pumping more positive charge out than it brings in) i.e. it is electrogenic – it generates a difference in electrical charge across the membrane

Question 22

Membranes are always impermeable to ions

Answer 22

False – membranes are impermeable to ions most of the time but critically, they do become permeable for very short periods of time (milliseconds) and these short periods of permeability are vitally important for changing cell activity - this change in permeability forms the foundations by which a nerve cell sends electrical messages along its cell membrane

Question 23

Anaemia, heart and lung disease will all stimulate the production of thrombopoietin

Answer 23

False – Thrombopoietin stimulates the production of platelets, and will not be affected by anaemia, heart or lung disease. Release of erythropoietin, which stimulates the production of red blood cells, will on the other hand, be stimulated by these conditions in an effort to increase the oxygen carrying capacity of the blood (remember the primary stimulus for erythropoietin release is a reduction in oxygen delivery to the kidney, and the primary job of the red blood cell is to carry oxygen, so increasing RBC number should, in theory, restore oxygen delivery to the kidney, and subsequently switch off erythropoietin production – a nice example of negative feedback)

Question 24

Lymphocytes are the most abundant of all the white blood cells.

Answer 24

False – neutrophils are the most abundant white blood cells (68%), with lymphocytes coming second (25%)

Question 25

Both active transport and facilitated diffusion can work via carrier mediated transporter proteins

Answer 25

True – both active transport and facilitated diffusion can use protein transporters. In addition, facilitated diffusion, but not active transport, can also use ion channels. Carrier mediated transport proteins, unlike channels, are only open to one side of the membrane at any one time. The difference between active transport and facilitated diffusion is that the former requires energy to pump the substance being moved against a concentration gradient, while the latter needs no energy as the substance crossing the membrane moves passively down a concentration gradient

Question 26

Both active transport and facilitated diffusion can work via carrier mediated transporter proteins

Answer 26

True – both active transport and facilitated diffusion can use protein transporters. In addition, facilitated diffusion, but not active transport, can also use ion channels. Carrier mediated transport proteins, unlike channels, are only open to one side of the membrane at any one time. The difference between active transport and facilitated diffusion is that the former requires energy to pump the substance being moved against a concentration gradient, while the latter needs no energy as the substance crossing the membrane moves passively down a concentration gradient

Question 27

The complement system is a group of cells of the innate immunity responsible for allergy

Answer 27

False - The complement system is not a cell, it consists of more than 30 proteins/factors that are found in the plasma and has important roles in the defence mechanisms of innate immunity. The vast majority of complement factors are present in an inactive form and get activated due to many conditions including infections. The final result of Complement activation is the production of membrane attack complex (MAC ) which basically makes a hole in the target cells and eventually leads to direct lysis and destruction of these targets

Question 28

The main stages of development of an adaptive immune response against a pathogen in the correct order is as follows:

• Recognition of a pathogen.
• Production of specific weapons against this pathogen.
• Transport of these weapons to site of attack.

Answer 28

True -The development of an adaptive immune response against a pathogen can be divided into three main stages:

• Recognition of a pathogen: a pathogen must first be recognised by the immune system
• Production of specific weapons against this pathogen (this occurs in the form of Abs and Cytotoxic T cells)
• Transport of these weapons to site of attack: these Abs and T cells are then transported to the site of infection to eliminate it.

Question 29

A drop in colloid oncotic pressure will result in oedema

Answer 29

plasma proteins (mainly albumin) generate colloid oncotic pressure that favours movement of fluid into the capillary. In cases of hypoproteinaemia where circulating levels of plasma protein falls, there is a loss of oncotic pressure. Fluid is therefore no longer pulled into the capillary and instead pools in the interstitial space, causing oedema(fluid retention in the body that results in the swelling of tissue)

Question 30

Phagocytes are important component of the innate immunity whose main function is to engulf and kill pathogens

Answer 30

True - Phagocytes are the cells of the immune system that track down, engulf and destroy bacteria, other pathogens as well as own damaged or dead cells, and so participate in the clearance of microbes and the restoration of the damaged tissues, they contain lysosomes that are filled with destructive enzyme and chemical to destroy the engulfed pathogens

Question 31

The cell membrane is freely permeable to gases

Answer 31

True - it is

Question 32

Active immunity is produced as part of the action of the adaptive immunity, while passive immunity is achieved through the transfer of antibody from immune individual

Answer 32

True - Protective immunity against a pathogen may be induced through the host’s own response to that pathogen this is called active immunity, obviously because individual own host immune system plays an active part in responding to the antigen

Protective immunity against a pathogen can also be induced through the transfer of antibodies or lymphocytes specific for that microbe from another individual this is called passive immunity Individuals who have not yet encountered a particular antigen are said to be susceptible to that pathogen

Question 33

Membranes involved with high levels of metabolic function have a high protein content

Answer 33

True – the mitochondrial membrane is a very metabolically active membrane. Many chemical reactions take place on this membrane. Proteins form enzymes, receptors, transporters etc, so any membrane with high metabolic function must contain relatively high amounts of protein to carry out that metabolic function

Question 34

A differential cell count showing a raised neutrophil count indicates bacterial infection

Answer 34

True – neutrophils are well designed to target bacteria. They phagocytose and digest them hence a bacterial infection will usually present with a raised white cell count generally, and a proportionally greater increased neutrophil count

Question 35

Erythropoietin is primarily produced by the liver

Answer 35

False – erythropoietin is primarily produced by the kidney (85%) with the liver contributing a relatively small amount (15%)

Question 36

Glucose enters cells via aqueous channels in their membranes

Answer 36

False - Glucose molecules are too large to pass through channels (only mineral ions and water can do this). Glucose is transported by carrier mediated transport proteins

Question 37

Aquaporin channels allow water to freely move between interstitial fluid and intracellular fluid

Answer 37

True - while water cannot move directly through the hydrophobic (water hating), lipophilic (lipid loving) cell membrane, the membrane is studded with aquaporin channels that are permanently open and allow water to move freely between ISF and ICF. As water can also easily cross the capillary wall and thus freely move between plasma and ISF, water can effectively “Access All Areas

Question 38

The GMC may sometimes grant conditional registration to a graduating doctor, if there are unresolved fitness to practice concerns

Answer 38

False - The law doesn’t let the GMC make a conditional grant of registration, or register a doctor and consider their fitness to practise afterwards. At the time of application, a doctor is either fit to practise or not fit to practise

Question 39

It is possible for a solution to be hypo-osmotic and hypertonic

Answer 39

False - Osmolarity describes the number of total solutes in a solution without describing whether they can cross the cell membrane or not. Tonicity describes the number of solutes in a solution than cannot readily cross the membrane (non-penetrating particles). If a solution is hypo-osmotic it must contain a lower number of total solutes than normal plasma. It therefore cannot simultaneously contain more non-penetrating particles than normal plasma, so cannot be both hypo-osmotic and hypertonic.

Question 40

A haematocrit result of 45% means that blood cells account for 45% of whole blood volume

Answer 40

False – a haematocrit of 45% means red blood cells (only) account for 45% of whole blood volume. Haematocrit only refers to red blood cell volume. It tells you nothing about white cell volume or platelets.

Question 41

A solution of 3mM urea is iso-osmotic when compared with a solution of 1mM CaCl2

Answer 41

True – 3mM urea has an osmolarity of 3 mosmoles (urea does not dissociate in solution). 1mM CaCl2 on the other hand dissociates to give 1 mmole Ca+ and 2 mmoles of Cl-, thus also giving an osmolarity of 3 mosmoles

Question 42

Mast cells are a type of white blood cells involved in combating parasites and have a role in allergy

Answer 42

True - Mast cells are also a type of white blood cells and they have granules that contain substances that are toxic to parasites and host tissues. They have on their surfaces, receptors that are specific to IgE antibodies (IgE Abs) and can bind to them, this class of Abs are usually produced against some parasites and some allergens. When these antibodies that are bound to mast cells interact and bind with these substances which are called allergen, mast cells release their granules` content which includes many chemicals mainly histamines. this leads to local effects like runny rose, watery eyes, itching, which are characteristic to allergic diseases such hay fever, but if the amount of histamine released is larger, then this might lead to constriction of airway which might cause breathing difficulties, the main symptom of Asthma, or dilation of blood vessels which cause low blood pressures and sometimes death

Question 43

The body is always in osmotic equilibrium

Answer 43

True – water has access all areas and thus will always move to ensure water concentration is the same in all compartments. The concentration of non-penetrating particles, such as ions, will not be the same, but the concentration of water always will be. We cannot stop the movement of water

Question 44

A differential cell count showing a raised white blood cell count indicates viral infection

Answer 44

False – it might do, but not necessarily. Not all viruses bring about a generalised increase in white blood cell number but they do generally show an increase the proportion of lymphocytes

Question 45

The body is typically in a state of electrical and chemical disequilibrium

Answer 45

True – the chemical composition of fluids in the different compartments (Plasma, ISF, ICF) are not identical – in fact they are very different. Equally the electrical charge across a membrane differs with the inside of the cell typically being negative compared to the outside. This state of disequilibrium is important for normal function and homeostasis operates to maintain these normal, but different, conditions in different compartments

Question 46

One of the dangers of hypothermia is decreased blood viscosity

Answer 46

False – blood viscosity increases (becomes thicker) in the cold. This makes it harder for the heart to pump blood around the body, increasing the strain on this organ and decreasing oxygen delivery to tissues

Question 47

If colloid oncotic pressure exceeds capillary hydrostatic pressure, interstitial fluid will move into the capillary

Answer 47

True – colloid oncotic pressure favours movement of fluid into the blood vessel, while capillary hydrostatic fluid favours the movement of fluid out of the blood vessel

Question 48

If body sodium intake exceeds sodium output, there would be a decrease in intracellular fluid volume

Answer 48

True - The increase in ECF osmolarity caused by the presence of the non-penetrating Na+ would lead to an osmotic efflux of water from the ICF leading to a decrease in its volume

Question 49

Sodium leaves a cell via active transport

Answer 49

True – the concentration of sodium is greater outside the cell than inside, and it is important that it stays that way. However sodium enters a cell down its concentration gradient when the sodium ion channels open. These sodium ions then need to be redistributed back to the outside of the cell. This requires moving them against their concentration gradient and thus energy is required to do that, the use of energy to move substances against a concentration gradient is known as active transport

Question 50

A 2mM solution of NaCl has an osmolarity of 2 milliosmoles

Answer 50

False – a 2 mM solution of NaCl has an osmolarity of 4 milliosmoles, as each millimole of NaCl dissociates into one millmole of Na ions and one millimole of chloride ions when in solution, thus giving an osmolarity of 2 milliosmoles per mmole

Question 51

difference between active immunity and passive immunity is that passive immunity is immediate, while active immunity takes weeks to develop

Answer 51

True - The main differences between active immunity and passive immunity are

Active immunity:

• Produced by hosts own immune system
• Takes weeks to develop
• Memory cells produced
• Protection is permanent

Passive immunity:

• Transfer of Abc/cells from another individual
• Effective immediately
• No memory cells
• Protection is short lived

Question 52

The phospholipid bilayer forms a barrier to polar molecules.

Answer 52

True - Lipophilic molecules can dissolve straight through the phospholipid bilayer, polar (hydrophilic) molecules must generally travel through protein channels or with the aid of transport proteins

Question 53

An increase in plasma urea concentration will cause haemolysis of erythrocytes in vivo

Answer 53

False - Urea is a penetrating solute which can freely cross cell membranes. It will therefore equilibrate across the membrane and cause no osmotic effect. Urea is not an “effective osmole”. Critically, in vivo, the presence of non-penetrating solutes in the plasma (primarily Na+) determines water movement

Question 54

Platelets are critical for blood clot formation

Answer 54

True – Platelets form the foundations on which a blood clot (thrombus) is formed, although they do not take part in the blood clotting process directly. The prefix “thrombo” relates to blood clots. Platelets are sometimes known as thrombocytes. Their formation is stimulated by the hormone thrombopoietin

Question 55

Erythroblasts are immature red blood cells found in the circulation

Answer 55

False – erythroblasts are immature red blood cells found in the bone marrow. Once released into the circulation they are called reticulocytes. Reticulocytes circulate and mature over the next 24 hours to become fully mature red blood cells (erythrocytes)

Question 56

Plasma is 50% water and 50% formed components

Answer 56

False – Plasma is 95% water and 5% protein, ions, nutrients and waste products. Blood is 50% plasma and 50% formed components (blood cells and platelets).

Question 57

Cytokines are one of the immune cells involved in engulfing pathogen like phagocytes

Answer 57

False - Cytokines are not cells, they are a group of small proteins that are produced and secreted by immune and non-immune cells in response to a stimulus, a pathogen for example. They communicate with other cells by binding to specific receptors on these cells producing a signalling molecules that lead to many biological effects. Many of these effects are important in the innate and adaptive immune response.

Examples of biological effects induced by cytokine include:

Differentiation, of immune cells into effector cells to eliminate pathogens

Activation, activating the phagocytic and destructive activities of phagocytes.

Chemotaxis which mean recruiting more immune cells to the site of infection to enhance the immune response against infection and accelerate recovery

Enhancing the cytotoxic activity of immune cells.

Question 58

Oxygen, nitrogen and carbon dioxide can equilibrate easily between plasma and interstitial fluid compartments but not between extracellular fluid and intracellular fluid compartments

Answer 58

False – gases can cross the cell membrane easily. Oxygen and nitrogen are small and lipophilic, and the lipophilicity greatly enhances their ability to cross the membrane. Carbon dioxide is lipophonic but because it is small and uncharged it can also readily cross the membrane so these three important gases equilibrate across all three compartments – plasma + interstitial fluid (ECF) and intracellular fluid (ICF)

Question 59

Neutrophils, platelets and monocytes are all examples of myeloid cells

Answer 59

True – all blood cells other than lymphocytes are myeloid in origin. Lymphocytes are lymphoid in origin

Question 60

ISF volume may be measured directly using sucrose

Answer 60

False - ISF volume cannot be measured directly. It can be found by subtracting plasma volume (measured by dye or I125 albumin tag on plasma proteins) from the ECF volume measured by sucrose.

Question 61

There is only one type of T cell lymphocytes, namely Cytotoxic T cells, whose main function is to destroy infected cells

Answer 61

False - T cell lymphocytes, in fact, can be divided into two main types mainly based on their role in the immune response.

Cytotoxic T cells (CD8 T) cells because they have CD8 receptors on their surface

These cells recognize pathogens antigens /components only when these antigens are bound to MCH I,

The main role of these cells is to kill pathogens or cells that are infected with pathogens or even damaged or abnormal cells such as tumor cells.

The other type of T cells are called helper T cells (CD4) T cells because they have CD4 receptors on their surface. These cells recognize pathogens antigens /components only when these antigens are bound to MCH II. These cells do not kill but as the name suggests that they help other cells mainly B cells to complete their functions

Question 62

Phagocytes are important component of the innate immunity whose main function is to engulf and kill pathogens

Answer 62

True - Phagocytes are the cells of the immune system that track down, engulf and destroy bacteria, other pathogens as well as own damaged or dead cells, and so participate in the clearance of microbes and the restoration of the damaged tissues, they contain lysosomes that are filled with destructive enzyme and chemical to destroy the engulfed pathogens

Question 63

B lymphocytes are components of the adaptive immunity that produce antibodies

Answer 63

True - B cells are involved in the humoral immunity as their main function is the production of Antibodies which are proteins induced against specific components of pathogens.

B cells are produced in the bone marrow and actually also mature there where they receive their training and acquire the structures required for them to recognize pathogens namely BCRs.

On activation in the lymphoid organs B cells differentiae into plasms cells, with the help of T h, and these plasma cells are responsible for the production and secretion of Abs