Physiology Sem 2 Exam week 6-8 Flashcards

Question

Two important families of cytokines needed in the production of WBCs

Answer 1

Colony stimulating factors Interleukin

Answer 2

Some WBCs (particularly neutrophils and monocytes) leave the blood to enter infected or damaged tissue by the process of emigration (also called diapedesis).

Answer 3

A damaged endothelium displays adhesion ‘sticky’ molecules called selectins that stick to the carbohydrates on the surface of neutrophils. Integrins - adhesion molecules displayed by neutrophils causing them to slow down and roll along endothelial surface, then pass through endothelial cells to enter tissues

Answer 4

Phagocytosis - phagocytes migrate to tissue spaces by diapedesis Inflammation - vasodilation and permeability increases, WBC secrete substances to intensify inflammatory response, basophils leave capillaries and enter tissue to release heparin, histamine and serotonin in allergic reactions

Answer 5

transform into antibody-secreting plasma cells.

Answer 6

attack invading viruses, cancer cells, fungi and some bacteria and they are responsible for allergies, transfusion reactions and transplant rejection

Answer 7

WBC count higher than 10,000/µl of blood

Answer 8

an abnormally low level of WBC below 5000/µl of blood.

Answer 9

disc 2-4um diameter 7-10d lifespan no nucleus has mitochondria produce finger like projections when activated Production stimulated by thrombopoietin in liver contains serotonin, Ca2+, ADP and fibrinogen involved in clotting, clot retraction and clot removal

Answer 10

Darkly stained and granular α-granules: 50-80 per platelet that contain haemostatic factors proteins such as von Willebrand factor and fibrinogen Dense granules: 3-6 in each platelet, containing ADP, serotonin, histamine and calcium Lysosomal granule: contain hydrolytic enzymes important for degrading proteins

Answer 11

1. Vascular Spasm 2. Platelet plug formation 3. Blood clotting (coagulation)

Answer 12

Immediate response initiated by direct injury to smooth muscle cells, the release of serotonin by activated platelets or stimulation of pain receptors Smooth muscle in vessel walls contract, vasoconstriction, decrease blood loss for minutes-hours

Answer 13

Initiated by damage to the endothelium exposing underlying connective tissue and collagen on inner wall Attracts platelets that become sticky and adhere to site, activate and release ADP, serotonin (vasoconstrictor), thromboxane A2 forming a seal 3 Steps: 1. Platelet adhesion 2. Platelet release reaction - explained above 3. Platelet aggregation - release of ADP makes platelets sticky and adhere to make platelet plug

Answer 14

Thickens blood to protein gel consisting of serum and fibrin in which formed elements are trapped Takes 3-6 minutes to occur 3 pathways: 1. Extrinsic 2. Intrinsic 3. Common pathway

Answer 15

Triggered by external trauma to a blood vessel Within seconds this initiates the formation of an active enzyme called prothrombinase Tissue factor (TF) escapes into the blood from the surfaces of damaged cells outside blood vessels. In the presence of Ca2+, activated factor X combines with factor V to form prothrombinase

Answer 16

Triggered by internal damage to the blood vessel wall takes minutes to complete prothrombinase production Exposed collagen fibres in vessel or damaged platelets cause formation of activated factor X in presence of calcium resulting in prothrombinase production

Answer 17

Prothrombinase production by other pathways begins this process 1. prothrombinase with Ca2+ catalyses conversion of inactive prothrombin into the active enzyme thrombin 2. thrombin with Ca2+ converts soluble plasma protein fibrinogen into insoluble fibrin Production of fibrin causes - acceleration of prothrombinase production and activates platelets in intrinsic pathway to reinforce aggregation

Answer 18

Calcium molecules derived from platelets or damaged tissues Inactive enzymes made by hepatocytes Vitamin K

Answer 19

synthesis of 4 clotting factors by hepatocytes: Factor II (prothrombin), VII, IX and X Produced in LI by bacteria

Answer 20

after clot forms, retraction and pulling action of platelets on fibrin causes edges of damaged vessel to pull together allowing repair of endothelial cells

Answer 21

breaking up of clot at site of completed repair Relies on activation of plasminogen originally incorporated into clot during formation. Activated into plasmin by tissues that is proteolytic and digests fibrin and inactivates clotting factors

Answer 22

1. Inhibition of platelets -> endothelial cells + WBC produce prostacyclin that opposes thromboxane A2 on platelet adhesion and release 2. Anticoagulants -> antithrombin blocks prothrombin, heparin blocks effects of thrombin, activated protein C enhances plasminogen activators 3. Thrombolytic agents - streptokinase or tissue plasminogen activator directly or indirectly activate plasminogen

Answer 23

genetically determined antigens made of glycoproteins and glycolipids on rbc surfaces

Answer 24

blood plasma antibodies that react with antigens RBC lack eg anti-A or anti-B antibodies

Answer 25

AB do not have anti-a or anti-b antibodies in their plasma

Answer 26

agglutination clumping reaction that causes donated cells to burst, liberate haemoglobin and clog kidneys

Answer 27

People with Rh agglutinogens on the surface of red blood cells are called Rh+ (“Rh positive”) and those without are called Rh- (“Rh negative”). normal plasma does not contain anti-Rh antibodies, but develop only in Rh- people if exposed to the antigen On the next antigen exposure, anti-Rh antibodies can cause agglutination

Answer 28

A pregnant Rh- woman carrying a Rh+ baby risks foetal blood leaking across the placenta into her bloodstream. The mother’s immune system creates anti-Rh antibodies. During a subsequent pregnancy with a Rh+ baby the maternal antibodies cross the placenta and haemolytic disease of the newborn may develop causing haemolysis of the foetal red blood cells.

Answer 29

The right side of the heart pumps deoxygenated blood into the **pulmonary** **circulation** - The left side pumps oxygenated blood into the **systemic circulation**.

Answer 30

1. Deoxygenated blood enters right atrium from the venous circulation. 2. RA -> through right AV (tricuspid) valve -> RV 3. RV -> right semilunar (pulmonary) valve -> pulmonary trunk. 4. Deoxygenated blood carried to lungs via the pulmonary arteries. 5. In the lungs, CO2 removed, and O2 added (external respiration) 6. Oxygenated blood from the lungs -> pulmonary veins -> left atrium 7. LA -> left AV (bicuspid) valve -> LV 8. LV pumps oxygenated blood through the aortic valve into the aorta 9. The aorta branches into systemic arteries, eventually reaching tissue capillaries 10. The superior and inferior vena cava, and coronary sinus vessels all bring deoxygenated blood from the body to the right atrium.

Answer 31

Cardiac muscle fibres are connected end-to-end by thickenings of the sarcolemma called intercalated discs containing desmosomes that anchor fibres together and gap junctions permitting fast transmission of chemicals

Answer 32

Aerobic respiration ATP generated mainly by fatty acid and glucose oxidation

Answer 33

The bands and zones of a sarcomere in cardiac muscle fibres are arranged in the same way as in skeletal muscle. more and bigger Mitochondria Smaller sarcoplasmic reticulum and less intracellualr Ca storage

Answer 34

Cardiac muscle fibres connected end to end by thickenings of sarcolemma called intercalated discs

Answer 35

Just like skeletal muscle, during contraction Ca2+ binds to troponin that causes actin (in the thin filament) and myosin (in the thick filament) to slide against one another, drawing Z discs closesr and decreasing sarcomere length

Answer 36

Form cardiac conduction system - a network of specialised fibres that provide the path for electrical excitation through the heart ensuring the chambers contract in a coordinated manner in the order of excitation no stable resting membrane potential - spontaneous depolarisation is known as pacemaker potential

Answer 37

1. SA node in right atrial wall causing atria to contract at same time 2. AV node - APs slow down 3. AV bundle of his - ap conduct from atria to ventricles 4. Right and left bundle branches - extend through right and left bundle branches towards apex of heart 5. Purkinje fibres - from apex up through interventricular septum causing ventricular contraction

Answer 38

1. Rapid depolarisation (summit) - sodium in - reaches threshold, voltage-gated Na+ channels open and a rapid influx of Na+ down the electrochemical gradient. Membrane potential increases from -90mV to +20mV. 2. Depolarisation (continue) - calcium in -> depolarisation maintained (for about 0.25 s) in the plateau phase due to opening of voltage-gated Ca2+ channels. Ca2+ moves out of the sarcoplasmic reticulum and into cytosol. During this, some voltage-gated K+ channels open and K+ leaves the cells. The balance of Ca2+ in and K+ out sustains the plateau. The membrane potential is around 0mV. 3. Repolarisation (plummet - potassium out) -> additional voltage-gated K+ channels open and increased K+ outflow results in cell repolarisation. This restores the resting membrane potential. 4. refractory -> cell is refrained from further stimulation. Outlasts the contraction period which allows for the coordinated pattern of contraction and relaxation of the myocardium and prevents tetanic contractions

Answer 39

Atrial depolarisation - SA node sending AP across atria toward AV node causing atrial contraction Occurs in atrial systole

Answer 40

Ventricular depolarisation Through AV bundle, bundle of his and purkinje fibres At the same time, atrial repolarisation is occuring and atria relax (atrial diastole)

Answer 41

Ventricular systole Contraction progresses up from apex of heart As pressure in ventricle increases, AV valves shut and blood exits semilunar valves (pulmonary and aortic) into arteries out of heart

Answer 42

Ventricular repolarisation Ventricular diastole

Answer 43

Ventricular diastole - both atria and ventricles are relaxed for 0.2 seconds

Answer 44

130ml Volume of blood in a relaxed ventricle Occurs following atrial systole - where blood pushed through open AV valves into the ventricles

Answer 45

In ventricular systole, for a brief initial period when pressure rises in each ventricle, cardiac muscle fibres are contracting and exerting force however not shortening As pressure rises, the semilunar valves open and blood is pushed out of the heart. Each ventricle ejects about 70 ml of blood into its respective blood vessel- this is the stroke volume. The remaining volume after ejection is 60ml. This is called the end-systolic volume (ESV).

Answer 46

For a brief period all 4 valves are closed - isovolumetric relaxation. Relaxation of ventricles causes pressure to fall and when it is below atrial pressure the AV valves open and ventricle filling commences. They fill to about ¾ full and a new P wave commences.

Answer 47

S1 - closure of the AV valves soon after ventricular systole begins. S2 - closure of the semilunar valves (pulmonary and aortic valves) at the beginning of ventricular diastole. S3 - inaudible sound due to blood movement during ventricular filling. S4 - inaudible sound due to blood turbulence during atrial systole

Answer 48

SV x HR Resting adult male = 5.25L/min SV=70ml/beat HR = 75

Answer 49

Preload -> stretch on the ventricular muscle before it contracts - greater preload increases force of contraction and proportional to volume of blood in relaxed ventricle Contractility of heart -> greater forcefulness increases stroke volume. Positive inotropes promote influx of Ca2+ (epinephrine, glucagon, thyroid hormones) and negative ionotropes decrease force, acetylcholine or acidosis block sympathetic activation Afterload -> pressure needing to be overcome in a ventricle before blood ejection occurs through the semilunar valves. Afterload decreases, the stroke volume increases.

Answer 50

age, gender, fitness and body temperature. It is regulated by the autonomic nervous system (ANS) and chemicals.

Answer 51

Under control of a set of neurons located in the medulla oblongata in the brain- the cardiovascular centre - that receives input from higher brain centres and sensory receptors: - Proprioceptors, chemoreceptors and baroreceptors Sympathetic nerve impulses travel through cardiac accelerator nerves to increase the rate of depolarisation by the SA node (increases heart rate) and increase the contractility of cardiac muscle (increases stroke volume). Parasympathetic nerve impulses travel through the vagus nerve to decrease heart rate by ACh release and reducing spontaneous depolarisation of the SA node. Minimal contractility effects.

Answer 52

Epinephrine and norepinephrine from the adrenal medulla, thyroid hormones and calcium ions increase heart rate and contractility. Elevated blood levels of potassium and sodium ions decrease heart rate and contractility.

Answer 53

low oxygen levels (hypoxia), high acidity (acidosis) and high alkalinity (alkalosis) which all have a depressive effect on cardiac function.

Answer 54

Elevated CO and increases metabolic rate Increases venous return, more blood in left ventricle, harder muscles work. Stroke volume increases to a certain point them levels off and further increases in CO are due to heart rate increasing

Answer 55

Capillaries form a branching network of passages called a capillary bed that connect the arterial outflow (blood leaving the heart) and venous return (blood going back to the heart). Exchange materials with blood and interstital fluid Structure - lack tunica media and thin walled

Answer 56

Continuous - plasma membranes of endothelial cells form a continuous tube. Common in central nervous system, lungs, muscle and skin Fenestrated - plasma membranes of endothelial cells have many pores. Common in kidneys, small intestine, endocrine glands. Sinusoid - plasma membranes of endothelial cells have much wider fenestration. Common in liver, spleen, red bone marrow and adrenal glands.

Answer 57

the continuous movement of substances between the blood in capillaries and interstitial fluid. 1. Diffusion -> water soluble substances use fenestrations or intercelllular clefts and lipid soluble materials like O2 and Co2, steroid hormones use lipid bilayer 2. Transcytosis -> plasma proteins and blood cells become concentrated in caveolae and go endocytosis to epithelial cell lining capillary, vesciles move across cell with help of cytoskeleton, vesicles contents are released on other side into interstitial fluid by exocytosis 3. Bulk flow -> movement of large amounts of suspended material e.g. ions in fluid, in the same direction from high pressure to low pressure

Answer 58

Is generated by the pumping of the heart and is the main pressure pushing fluid out of a capillary, promoting filtration.

Answer 59

caused from remaining large proteins in capillaries that try to draw fluid back into the capillary. It is the main pressure opposing filtration and promoting reabsorption.

Answer 60

‘Pulls’ fluid out of capillaries into interstitial space where small amounts of leaked protein escaped, also promoting filtration.

Answer 61

Builds as more fluid accumulates in the interstitial spaces which pushes some (minimal) fluid back into the capillary, also promoting reabsorption.

Answer 62

Calculated by subtracting the pressures that promote reabsorption from the pressures that promote filtration. We find that more filtration occurs at the arterial end of a capillary and more reabsorption occurs at the venous end

Answer 63

An abnormal increase in interstitial fluid if filtration of fluid exceeds reabsorption. Excess filtration can be caused by: increased blood pressure and increased permeability of capillaries allowing plasma proteins to escape Inadequate reabsorption may be: decreased conc. of plasma proteins or inadequate synthesis or loss of plasma proteins from liver disease, burns, malnutrition or kidney disease

Answer 64

Blood pressure - hydrostatic pressure exerted by blood Vascular resistance - the opposition to blood flow due to friction between blood and the walls of blood vessels. It is impacted by three factors: 1. A smaller vessel lumen size increases vascular resistance 2. Increased blood viscosity increases vascular resistance 3. Increased total length of blood vessels increases vascular resistance Venous return - skeletal muscle and respiratory pump Velocity of blood flow - slowest in capillaries for exchange

Answer 65

CV centre in medulla oblongata via autonomic nervous system Sensory input -> proprioceptors, baroreceptors in aorta and neck arteries walls monitoring stretch, chemoreceptors in carotid and aortic bodies monitoring chemicals H+, CO2 and O2

Answer 66

1. Stimulus - suddenly standing drops BP 2. Receptors - BP falls and feedback from baroreceptors in carotid sinus and aortic arch decreases to CV centre 3. Control centre - The cardiovascular centre reduces parasympathetic and increases sympathetic stimulation to the heart, adrenal medulla increases epinephrine 4. Effectors - increase in HR, systemic vascular resistance and force of contraction increasing CO 5. Response - Increase BP

Answer 67

The sympathetic division continually sends impulses to smooth muscle in blood vessel walls via vasomotor nerves. The result is a moderate state of tonic contraction or vasoconstriction, called vasomotor tone

Answer 68

Epinephrine and NE increase sympathetic response and HR Systemic vascular resistance - angiotensin II from RAAS, ADH, norepinephrine and epinephrine cause vasoconstriction. ANP, Nitric oxide and epinephrine in arterioles in cardiac and skeletal muscle cause vasodilation Blood volume -> Aldosterone and ADH increase blood volume and pressure, ANP decreases them

Answer 69

released by adrenal cortex increases the reabsorption of sodium and water in the kidney, which increases blood volume and pressure.

Answer 70

released by the posterior pituitary in response to dehydration or reduced blood volume. Causes vasoconstriction and increased water reabsorption in the kidney which increases blood volume.

Answer 71

Ability of a tissue to automatically adjust its _own_ blood flow to match its metabolic demand for supply of O2 and nutrients and removal of wastes. 1. Temperature changes - warmth promotes vasodilation 2. Myogenic response - reflex response of smooth muscle in arteriole walls. Increased BP -> smooth muscle stretch -> vessel responds by constricting and vice versa 3. Vasodilators and contrictors -> histamine, K+, H+ and lactic acid dilates whilst serotonin from platelets, thromboxane A2 cause constriction 4. Change in O2 -> systemic vessels dilate with low O2, pulmonary vessels constrict with low O2 allowing blood flow to better ventilated areas of lungs

Answer 72

Excess filtered fluid unable to be returned to the blood flows into lymphatic capillaries to become lymph contains components of blood plasma such as excess fluid, plasma proteins, fats and fat-soluble vitamins (e.g. A, D, E and K).

Answer 73

wide diameter, overlapping endothelial cells and anchoring filaments higher colloid osmotic pressure creating a ‘pull’, closed end and greater permeability than blood capillaries The increased fluid pressure causes anchoring filaments to pull on endothelial cells to create larger openings between the cells, and pushes their overlapping ends open

Answer 74

Lymph in capillaries -> larger lymphatic vessels -> through lymph nodes for filtration -> enters one of the 5 lymphatic trunks that drain lymph from a region in the body -> Valves in lymphatic vessels and the skeletal muscle and respiratory pumps move lymph towards the heart -> From the trunks, lymph empties into one of the lymphatic ducts: 1. The thoracic duct (left lymphatic duct) receives lymph from left side of the head, neck, chest, the left upper extremity, and the entire body below the ribs. It drains lymph into venous blood at the junction of the left internal jugular vein and the left subclavian vein. 2. The right lymphatic duct receives from upper right side of the body + drains lymph into venous blood at the junction of the right internal jugular vein and right subclavian vein.

Answer 75

Red bone marrow - Found in the epiphysis of long bones or interior of flat bones Thymus - bilobed organ located between the aorta and sternum B and T lymphocytes form here

Answer 76

Red bone marrow Require immunocompetence - ability to mount specific immune response

Answer 77

Immature pre-T cells leave the bone marrow and migrate to the thymus and gain immunocompetence.

Answer 78

lymph nodes, spleen and lymphatic nodules (follicles) like the tonsils, appendix and Peyer’s patches in the intestine

Answer 79

Leave primary lymphatic sites via blood and colonise parts of secondary lymphatic tissues to respond to threats

Answer 80

Lymph flows through nodes in one direction (afferent vessels > sinuses > efferent vessels), slowing down the flow and trapping foreign substances such as bacteria and tumour cells.

Answer 81

antibodies secreted by plasma cells and activated T cells.

Answer 82

cortex and medulla

Answer 83

Aggregates of B cells in lymphatic nodules Presence of an antigen causes the dendritic cells to ‘present’ the antigen to the B cells; the B cells differentiate into antibody-secreting plasma cells and memory B cells. This is the third line of defence. The plasma cells migrate to the medulla and make their way to the efferent vessel

Answer 84

T cells which upon antigen presentation by dendritic cells stimulates their proliferation. This is also the third line of defence. T cells migrate from the lymph node to sites of antigen in the body.

Answer 85

macrophages and lymphocytes (B and T cells) arranged close to the central arteries.

Answer 86

blood-filled venous sinuses and splenic cords containing RBCs, macrophages, lymphocytes, plasma cells and granulocytes

Answer 87

Macrophages remove worn-out RBCs and platelets (found in the blood). Storing platelets (1/3 of the body’s supply) Providing a blood reservoir (particularly important during haemorrhage to maintain blood volume) In the foetus the spleen also is the site of haematopoesis

Answer 88

Lymphatic nodules are egg-shaped masses of lymphatic tissue that are not surrounded by a connective tissue capsule. Nodules are scattered throughout the connective tissue of mucous membranes e.g. Peyer’s patches in small intestine

Answer 89

first and second lines of defence First line -> skin, MMs, secretions of skin and MMs, physical and chemical barriers provided by the skin, coughing, vomiting Second line -> antimicrobial substances, phagocytes, natural killer cells, inflammation, and fever. Takes place when pathogens breach first line. Mechanism are also non-specific

Answer 90

lymphatic capillaries in the SI lymph draining the small intestine appears milky white in appearance and is referred to as chyle

Answer 91

a small part of antigen that triggers the immune response

Answer 92

In processing the antigen is broken down into fragments in a cell and then associated with one type of MHC molecule (either class I or II). In antigen presentation, the antigen-MHC complex is then inserted into the cell plasma membrane

Answer 93

These foreign antigens are present in fluids outside of body cells e.g. bacteria and parasitic worms. They are phagocytosed by an antigen-presenting cell (APC) first and then processed with MHC-II molecules. The antigen-MHC-II complex is presented on the cell’s surface. APCs migrate to lymphatic tissue to present the antigen to T cells

Answer 94

Present within the body cells. Antigens are digested in the cytoplasm and their fragments combine with MHC-I molecules. The antigen-MHC-I complex is presented on the body cell (not an APC) membrane

Answer 95

third line of defence refers to the elimination of intruders using helper T cells and cytotoxic T cells Effective against foreign antigens that are bound to our own cells (e.g. viral proteins), some intracellular pathogens (e.g. viruses), transplanted cells and cancer cells

Answer 96

1. Activation - Activation through (1) antigen recognition and (2) costimulation. An activated T cell can then undergo clonal selection. 2. Proliferation - During clonal selection activated helper or cytotoxic T cells undergo cell division to form a clone of identical cells that recognise the same antigen 3. Differentiation - These new clones are either the effector cell which carry out the immediate immune response or long-lived memory cell

Answer 97

by releasing granzymes, protein-digesting enzymes that trigger apoptosis of the infected body cells. The released microbes are then phagocytosed. Also directly kill cells by releasing perforin and granulysin which add channels or holes into the target cell membrane

Answer 98

secrete cytokines including interleukin-2 which is a trigger for T cell proliferation. Interleukin-2 also serves as a co-stimulator for cytotoxic T cells and B cells in their activation.

Answer 99

destruction of antigens by antibodies. Antibodies are produced and secreted by plasma cells. This form of immunity works mainly against antigens dissolved in body fluids (humors) and extracellular pathogens. B cells populate lymph nodes, spleen and mucosa-associated lymphatic tissue.

Answer 100

1. Activation: The B cell receptor binds to an antigen which is either unprocessed (naïve - antigen alone) or processed (antigen taken up by B cell and associated with the MHC-II complex). Processed antigens are recognised by helper T cells which releases costimulators e.g. interleukin-2 that activate B cells more intensively. 2. Proliferation: Activated B cells next undergo clonal selection to increase in numbers, forming memory B cells and plasma cells. 3. Differentiation: Effector cells called plasma cells and memory B cells form.

Answer 101

blood and lymph Secreted after initial exposure to an antigen; bind to ABO antigens and activate complement system

Answer 102

Sweat, tears, saliva, mucous, breast milk, and gastrointestinal secretions Protect mucous membranes against bacteria and viruses

Answer 103

On B cell surfaces Act as antigen receptors; involved in the activation of B cells

Answer 104

Blood, lymph and intestines Enhances phagocytosis, neutralises toxins and activates the complement system. Only class of antibody to cross placenta

Answer 105

On mast cells and basophils Protection against parasitic worms; Involved in allergic and hypersensitivity reactions

Answer 106

1. Neutralising antigens - bind to sites on bacteria or viruses to prevent attachment to body cells 2. Immobilising bacteria - attack cilia or flagella 3. Agglutinating and precipitating antigens - antibody-antigen complexes cross link to form lattices that clump to be phagocytosed 4. Complement activation - classical pathway 5. Enhancing phagocytosis - complement, precipitation, opsonisation

Answer 107

After the first encounter with an antigen the first class of antibody to be produced is IgM, followed by IgG days later. This is followed by a gradual decline in antibody titre. On second encounter with the same antigen, rapid proliferation of memory cells results in a far greater antibody titre (mainly of IgG) than during a primary response

Answer 108

T cells - need both. Self-recognition develops via positive selection in the thymus- meaning if pre-T cells possess the correct T cell receptor they will survive. Self-tolerance develops via negative selection- meaning the pre-T cells that react to own body peptides are eliminated by apoptosis.

Answer 109

B cells - because B cells mainly respond to extracellular threats as they do not use the ‘cell-cell’ response as used by T cells.

Answer 110

1. Interferons - trigger synthesis of antiviral proteins 2. Complement - consists of a group of normally inactive proteins in the blood plasma, that can be activated through various mechanisms during infection. Causes cytolysis, phagocytosis and inflammation 3. Iron binding proteins - inhibit growth of certain bacteria by reducing the amount of freely available iron. transferrin, lactoferrin, haemoglobin, ferritin 4. Antimicrobial proteins - chemotaxic and attract mast cells. Dermicidin from sweat glands, defensins from neutrophils, thrombocidin from platelets

Answer 111

1. Chemotaxis 2. Adherence - of phagocyte to microbe 3. Ingestion - of microbe via pseudopods on phagocyte to form phagosome 4. Digestion - via lysosomes 5. Killing - chemical digestion by enzymes

Answer 112

Redness, heat, swelling, pain, and loss of function.

Answer 113

1. Vascular phase -> vasodilation and increased capillary permeability allowing defence factors to enter tissues 2. Cellular phase -> phagocytes migrate into tissue spaces through diapedesis (neutrophils first to arrive then monocytes) that remove damaged tissue and invading microbes 3. Tissue repair ->Fibroblasts lay down collagen fibres and ECM, blood vessels restored and epithlial cells multiply to fill wound with new tissue. First intention healing produces minimal scarring and second intention produces more

Answer 114

Edges of skin dermis are close together and wound free of pathogens - close wound edges allow clot to form fast Tissue repair is rapid Minimal scarring

Answer 115

Occurs if wound edges further apart or wound infected Phagocytes have to clear infection before repair commences - tissue repair is longer Scabs form - healing begins from deeper layers, scab keeps fluid in so immune cells move freely. Fibroblasts lay down collagen fibres forming scar tissue

Answer 116

a systemic innate immune response of abnormally high temperature triggered by pyrogens Regulated by hypothalamus Intensifies effect of interferons, inhibits bacterial growth and speeds up tissue repair

Answer 117

specificity to antigen Memory of previously encountered antigens

Answer 118

Immunogenicity - ability to provoke immune response Reactivity - ability to react to cells or antibodies it provoked

Answer 119

Smaller than an epitope and has reactivity but lacks immmunogenicity. Stimulates an immune repsonse when bound to a carrier molecule.

Answer 120

Antigen recognition - binding of foreign antigen to t cell receptor. CD4 and CD8 proteins on surface of t cell act as coreceptors to enhance binding of antigen Costimulation - secondary signal in the form of cytokine (interleukin-2) or molecules on PM of another cell

Answer 121

Use their TCR to bind to an exogenous antigen fragment To aid this interaction, the CD4 receptor on the helper T cell, binds to MHC-II molecules on the surface of APCs that are associated with the antigen fragment. The APC provides costimulation and activates the helper T cell.

Answer 122

also use a TCR to bind to an endogenous antigen fragment The CD8 receptor on the T cell binds to antigens associated with MHC-I molecules on infected body cells, tumour cells and transplanted tissue cells.

Answer 123

four polypeptide chains (two heavy and two light chains) linked by disulfide bonds at the hinge region The variable regions of the heavy and light chains combine to form the antigen-binding site The constant regions for the stem of an antibody that serves common functions in all antibodies

Answer 124

The thoracic cage expands because of two muscle actions: the diaphragm contracts and the external intercostal muscles lift the ribs. The lungs attached to the thorax also expand. Contraction of the inhalation muscles causes alveolar pressure to fall below atmospheric (758 mmHg) creating a pressure gradient that brings air into the lungs.   Active process

Answer 125

At rest is a passive process with no muscular contraction involved. When the diaphragm and external intercostal muscles relaxes, the elastic recoil of the chest wall and lungs pulls the thoracic cage down/in, decreasing the space (volume) Decreased space = increased pressure in lungs (alveolar pressure) = air flows out

Answer 126

the sternocleidomastoid muscles, scalene muscles and pectoralis minor muscles contract (active process) to elevate the sternum and first 5 ribs. Occurs during exercise, stress or some respiratory conditions

Answer 127

Alveolar surface tension - inwardly directed force exerted by the alveolar fluid that coats the inside of alveoli. This force accounts for 2/3rd of elastic recoil during exhalation. Surfactant from type II alveolar cells decreases this. To inhale, muscle force expanding lungs has to overcome this. Lung compliance -> effort to stretch lungs and chest wall. High compliance = lungs expand easily. Low compliance caused by scar tissue or fibrosis Airway resistance -> Resistance increases during exhalation as bronchioles grow smaller. Constriction of bronchioles in asthma causes more resistance

Answer 128

External respiration refers to the exchange of respiratory gases across the respiratory membrane between alveoli and red blood cells in pulmonary capillaries. Internal respiration refers to the exchange of gases between the tissue cells and red blood cells in systemic capillaries.

Answer 129

resp. rate x tidal volume

Answer 130

The volume of air that reaches the respiratory zone each minute Respiratory rate x (tidal volume - dead space)

Answer 131

Gas partial pressure, surface area for gas exchange, diffusion distance and the molecular weight and solubility of gases

Answer 132

The volume (depth) of each breath, about 500ml is tidal volume.

Answer 133

Refers to the amount of additional air that can be forcibly inhaled or exhaled respectively.

Answer 134

The total volume of air that can be displaced from the lungs by maximal exhalation after a maximal inhalation is the vital capacity.

Answer 135

A portion of non-measurable air that remains in the lungs after maximal exhalation is the residual volume.

Answer 136

(6,000 ml) is the maximum amount of air your lungs hold (vital capacity + residual volume).

Answer 137

About 70% of carbon dioxide forms bicarbonate ions in plasma, the remaining 23% is bound to haemoglobin as carbaminohaemoglobin and some 7% dissolved in plasma.

Answer 138

(98.5%) is bound the haemoglobin in red blood cells. - Only the remaining 1.5% dissolved in plasma can escape capillaries and enter tissue cells.

Answer 139

Partial pressure of oxygen - greater the PO2, more oxygen combines with haemoglobin until all saturated. PO2 high in pulmonary capilaries, lower in tissue capillaries so it unloads oxygen into tissues Acidity - increases, then affinity of haemoglobin for O2 decreases and dissociates. Haemoglobin can buffer H+ and bind to it when acidity is high, decreasing its affinity for O2 (Bohr effect) CO2 partial pressure - greater PCO2 = haemoglobin releases O2 and blood pH lowers also releasing O2 Temperature -> warmer, haemoglobin releases O2 more

Answer 140

Higher affinity for O2 as it binds 2,3-biphosphoglycerate (BPG) less strongly and carries more oxygen to offset low oxygen saturation in maternal blood

Answer 141

2,3-biphosphoglycerate - produce produced in RBC during glycolysis Greater BPG = more O2 released from haemoglobin

Answer 142

CO competes with O2 for the same binding sites on haemoglobin and has 200 times more affinity to Hb than O2.

Answer 143

When oxyhaemoglobin is lower, more CO2 is transported in blood.

Answer 144

1. Bicarbonate - 70% 2. Haemoglobin - 23% bound to globin portion 3. Plasma - 7%

Answer 145

CO2 diffuses out of tissue cell and enters the RBC in a capillary - some binds to Hb causing oxygen displacement Some binds to water = makes carbonic acid = dissociated to bicarbonate and H+ Some bicarbonate moves out of rbc down conc. gradient, some H+ binds Hb in bufferring effect and O2 is released out of rbc

Answer 146

As deoxygenated blood passes through pulmonary capillaries CO2 dissociates from Hb and along with dissolved CO2 in plasma, the gas diffuses into the alveolar air and out of the body.

Answer 147

A cluster of neurons dispersed bilaterally in the brain stem Medullary respiration centre -> in medulla oblongata controls basic rhythm of respiration and contains dorsal and ventral respiratory groups - inspiratory and expiratory area respectively Pontine respiratory group -> in pons, modifies basic rhythm. Neurons active in inhalation and exhalation and transmit impulses to DRG in medulla to modify rhythm

Answer 148

Dorsal respiratory group neurons generate impulse to diaphragm and external intercostals for inhalation for 2 seconds cuasing contraction Exhalation - DRG inactivates and diaphragm and external intercostals relax for 3 seconds for passive recoil of lungs

Answer 149

Inhalation - neurons in VRG generate impulse to diaphragm, external intercostals and accessory muscles (sternocleidomastoid, scalenes, and pectoral minor). This results in their contraction. Exhalation - Another set of neurons in the VRG generates impulses to the accessory muscles of exhalation (internal intercostals and abdominal muscles) to contract

Answer 150

Cortical regulation allows conscious control Voluntary breath-holding is limited by increased H+ and CO2. If the breath is held to cause fainting, breathing resumes when consciousness is lost.

Answer 151

Detects lung expansion with stretch receptors (baroreceptors) and limits inflation depending on ventilatory need and prevents damage. This is an important protective mechanism that comes into play during severe exercise.

Answer 152

Stimulus - disrupts homeostasis by altered chemical composition of blood (Co2, O2 or H+) Controlled condition - increase in PCO2 over 40mmHg is hypercapnia. A drop below 40mmHg is hypocapnia. Receptors -> 1. central chemorecepors in medulla oblongata respond to CO2 and H+ in CSF. If PO2 falls below 50 mmHg, the central chemoreceptor become depressed and the DRG fails to be stimulated -> fewer nerve impulses being sent to the breathing muscles -> possible fatal result. 2. The peripheral receptors in aortic arch and carotid artery respond to PO2, PCO2 and H+ in blood. If levels of arterial blood PO2 drop below 100 mmHg, (but still above 50 mmHg), only the peripheral chemoreceptors are activated. This negative feedback cycle results in hyperventilation (as when PCO2 is high). Control centre -> DRG recieve stimulatory signals and fire more impulses Effectors -> increased nerve stimulation of breathing muscles causing hyperventilation Response -> Increased volume of the thoracic capacity increases PO2 in inhalation and decreases PCO2 (and H+) in exhalation. This returns arterial blood levels of CO2 to normal relieving excess stimulation of the chemoreceptors.

Answer 153

PCO2 over 40 PO2 falling from 100 to 50 Increased activity of proprioceptors Increase body temp Decrease BP Stretching of anal sphincter Prolonged pain

Answer 154

Severe pain PCO2 below 40 Decreased activity of proprioceptors Decreased body temp Increased BP

Answer 155

Peristaltic movements pass over the stomach every 15 to 25 seconds to macerate food, mix it with secretions of the gastric glands and reduce it to chyme. Intense waves near the pylorus, vigorous waves in body of stomach and gentle waves in fundus. Peristaltic waves move gastric contents forward by propulsion. However, as particles are initially too big to pass through the pyloric sphincter, they are forced back up in retropulsion. The cycle continues until the food particles are small enough to pass through the pyloric sphinter.

Answer 156

Starts in mouth - salivary amylase continues to break down polysaccharides like starch into trisaccharides, disaccharides and short chain glucose polymers. After an hour, the amylase enzyme is inactivated by the acidity of the gastric juice.

Answer 157

Starts in the stomach Lingual lipase (originally secreted by the tongue) is activated. Gastric lipase, secreted by the stomach chief cell, breaks down triglycerides into fatty acids and diglycerides. This enzyme has limited activity in adults.

Answer 158

Starts in the stomach. Pepsinogen is activated into pepsin which breakdowns proteins into peptides.

Answer 159

Absorption is limited due to the impermeability of stomach epithelial cells. Mucous cells absorb water, ions, short-chain fatty acids and certain drugs (e.g. alcohol and aspirin).

Answer 160

Producing bile salts used in bile for emulsification and absorption of lipids. Excretion of bilirubin into bile for metabolism in small intestine by bacteria and elimination in faeces from large intestine.

Answer 161

The liver has many enzymes to process toxins (e.g. alcohol) and has two detoxification processes.

Answer 162

Activating vitamin D precursor produced by the skin

Answer 163

Processing drugs and hormone (oestrogen_

Answer 164

Excreting bilirubin

Answer 165

Storing glycogen, some vitamins and minerals for later use

Answer 166

Metabolism of lipids (storage of triglycerides), plasma protein synthesis, breakdown of glycogen

Answer 167

Stores bile between meals from liver Releases bile during meals

Answer 168

Parasympathetic impulses and vagus nerves. Cholecystokinin (CCK): causes gallbladder to contract and release stored bile into the duodenum. Secretin: causes liver to increase its output of bile.

Answer 169

Pancreatic juice clear, colourless containing water, salts, sodium bicarbonate and digestive enzymes Acini cells produce the digestive enzymes that contribute to chemical digestion of starch (via pancreatic amylase), proteins (via pancreatic proteases), fats (via pancreatic lipase) and nucleic acids (via ribonuclease and deoxyribonuclease).

Answer 170

Two types of movements: segmentation and migrating motility complex (MMC). Segmentation -> localised mixing contractions that occur in portions of the intestine distended by a large volume of chyme. They occur 12 times per minute to bring food particles in contact with the mucosa for absorption. There’s no propulsion. MCC -> the type of peristalsis that occurs in the small intestine when distension of the small intestinal wall lessens (after segmentation). Each wave migrates progressively along the small intestine, reaching the end in about 90-120 minutes.

Answer 171

Intestinal juice contains water, mucous, brush-border enzymes, and lysozyme. Absorptive cells lining the mucosa secrete several brush border enzymes to complete the chemical digestion of carbohydrates, proteins, fats, and nucleic acids.

Answer 172

In the mouth, salivary amylase In the small intestine - pancreatic amylase break down starch and dissacharides into oligosaccharides and disaccharides - lactose, maltose and sucrose Brush border enzymes in SI (lactase, maltase, sucrase) break disaccharides into galactose, glucose and fructose

Answer 173

Pepsin in stomach in presence of HCl breaks protein into large polypeptides Pancreatic enzymes in SI (trypsin, chymotrpysin and carboxypeptidase) break large polypeptides into small polypeptides Brush border enzymes in SI (aminopeptidase, carboxypeptidase and dipeptidase) break small polypeptides into amino acids

Answer 174

Unemulsified fats are emulsified by detergent action of bile salts from the liver in the small intestine Pancreatic lipase in the small intestine breaks emulsified fats into monoglycerides and fatty acids, and glycerol and fatty acids

Answer 175

All carbohydrates are absorbed as monosaccharides. The indigestible cellulose and fibres are eventuially excreted in faeces from the large intestine. GLucose and galactose -> secondary active transport with Na+ Fructose -> facilitated diffusion

Answer 176

Majority of proteins are absorbed as amino acids (with some dipeptides and tripeptides), that occurs in the duodenum and jejunum. Amino acids - active or secondary active transport with Na+ across brush border Dipeptides and tripeptides - secondary active transport with H+

Answer 177

Triglycerides are digested into monoglycerides and fatty acids, which are either short-chain (under 10-12 carbon atoms) or long-chain fatty acids. Short fatty acids -> water-soluble and dissolve in the intestinal chyme, absorbed into a capillary Larger fatty acids and monoglycerides -> absorbed into lacteals. From here, the chylomicrons enter lymphatic system -> pass into the cardiovascular system -> reaching the liver or adipose tissue

Answer 178

Haustral churning after the relaxed haustra fill and stretch. Eventually, they contract and squeeze, shifting contents to the next haustra. Mass peristalsis is a strong wave that drives contents into the rectum ~4 times daily. The defecation reflex is a spinal reflex that causes the walls of the sigmoid colon and rectum to contract and the anal sphincters to relax. With the next mass movement, the reflex is stimulated again.

Answer 179

Resident bacteria ferment the remaining carbohydrates, releasing hydrogen, carbon dioxide and methane gases. Undigested proteins are converted to amino acids and broken down into aromatic compounds and fatty acids. Excess bilirubin turns into simpler pigments (such as stercobilin), giving faeces the brown colour

Answer 180

Small amounts of water, ions, and vitamins (B and K) are absorbed.

Answer 181

Cephalic phase - activated by smell, sight, thought, or initial taste of food. The neural centres in the cerebral cortex, hypothalamus, and brain stem send a message to the facial and glossopharyngeal nerves to stimulate the salivary glands to secrete saliva. Saliva then triggers the vagus nerve, which stimulates the gastric glands to secrete gastric juice. The gastric phase commences once food reaches the stomach. It is regulated by the nervous and endocrine systems (gastrin released from g cells in response to distention and high pH, inhibited with pH below 2). Gastrin stimulates gasgtric juice secretion, contracts lower oesophageal sphincter and increase gastric motility The intestinal phase begins when food enters the small intestine. It is responsible for promoting digestion of food in the small intestine and slowing the exit of chyme from the stomach. Governed by neural (enterogastric reflex) and hormonal control (secretin and CKK)

Answer 182

gastrin secretion - stimulate parietal cells to secrete H and Cl- ions into stomach lumen to form HCl Stimulates chief cells to secrete pepsinogen, contracts lower oesophageal sphincter, increases stomach motility, relaxes pyloric sphincter

Answer 183

intrinsic factor secreted by parietal cells

Answer 184

Long-chain fatty acids and monoglycerides recombine inside absorptive cells in gut to form triglycerides. Triglycerides join with cholesterol and phospholipids to form chylomicrons that exit absorptive cells by exocytosis and enter the lacteal of villus - then to thoracic duct Short-chain fatty acids exit absorptive cells by diffusion.

Answer 185

Neural control of the intestinal phase of digestion Arises from the distention of the duodenum by the presence of chyme. Nerve impulses are sent to the medulla oblongata causing the inhibition of parasympathetic nerves and stimulation of sympathetic nerves to the stomach. This stops gastric motility and increases contraction of the pyloric sphincter to decrease gastric emptying

Answer 186

acidic chyme Stimulates pancreatic juice rich in bicarbonate that buffers acidic chyme in duodenum and slows production of stomach acid

Answer 187

Amino and fatty acids Increases bile and pancreatic juice in duodenum, decreases stomach emptying and produces satiety

Physiology Sem 2 Exam week 6-8 Flashcards

(214 cards)