Week 2 formative quiz questions Flashcards
Liver disease and kidney disease can both cause hyperproteinaemia
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
Integral membrane proteins have an extracellular and an intracellular domain
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
It is possible for a solution to be both hyperosmotic and hypotonic
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
Activation of T and B lymphocytes and the production of immune response takes place in the thymus
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
Average circulating volume in an adult male is 5 Litres
True - It is generally slightly less in women
A glycoprotein is a molecule made up of lipid and protein
FALSE - “glyc” relates to carbohydrate (often but not always glucose) so a glycoprotein is a molecule made up of carbohydrate and protein
Glucose crosses the cell membrane by active transport
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.
The cell membrane is a lipid bilayer. The outer layers are composed of phosphate groups and the inner core is lipid
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
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
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
Antibodies have a Y shape structure and can be seen as two parts, the lower part is responsible for biding to the antigen.
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
Aquaporin channels allow ions to move between the intracellular fluid and extracellular fluid compartments in a regulated manner
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
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
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
Thf: acrptivate antibodies.
Insulin can bind to all cells of the body, but only stimulates a response in some.
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
Albumin is the most abundant of all plasma protein
True – 60% of plasma protein is albumin, 38% is globulin and the remaining 2% are clotting factors
One of the important features of adaptive immunity is that the immune response is fast and immediate
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
G proteins are an example of peripheral proteins and are involved in cell communication
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.
Components of the innate immunity include: phagocytes, mast cells, basophils, T lymphocytes.
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
There is only one type of T cell lymphocytes, namely Cytotoxic T cells, whose main function is to destroy infected cells.
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
A 2mM solution of urea has an osmolarity of 2 milliosmoles
True – as urea does not dissociate in solution, a 2mM solution of urea gives an osmolarity of 2mM
Mhc 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
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
The Na+/K+ ATPase pumps 3 sodium ions into the cell for every 2 potassium ions it pumps out
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
Membranes are always impermeable to ions
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
Anaemia, heart and lung disease will all stimulate the production of thrombopoietin
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)
Lymphocytes are the most abundant of all the white blood cells.
False – neutrophils are the most abundant white blood cells (68%), with lymphocytes coming second (25%)