EXAM PREP [EXTENDED RESPONSE] Flashcards
Name and briefly describe the function of any four formed elements within the blood.
1) Neutrophils participate in phagocytosis. They engulf bacteria and release lysosomes to digest them.
2) Red blood cells - oxygen-carrying protein that takes oxygen from the lungs and delivers it throughout the body. Also transports waste.
3) Platelets - help stop blood loss through platelet plug formation.
4) Natural killer cells - lymphocytes that directly attack foreign invaders and diseased cells like cancer cells.
Name the three general mechanisms by which blood loss is prevented in a damaged blood vessel. For
each mechanism, include any two events that take place.
Vascular spasm
- smooth muscle lining a blood vessel contracts
- collagen is exposed to blood components
Platelet plug formation
- platelets stick to exposed collagen
- release chemicals (e.g. serotonin) that attract more platelets to the area
Blood clotting
- prothrombinase and Ca2+ convert prothrombin into thrombin
- thrombin converts fibrinogen into insoluble fibrin threads
Describe the pathway of a drop of blood through the heart, from entry into the heart as deoxygenated blood to its final departure as oxygenated blood. Include all relevant blood vessels, chambers and valves.
Deoxygenated blood enters the right atrium of the heart through the superior vena cava, inferior vena cava and coronary sinus. It flows through the tricuspid valve into the right ventricle and then through the pulmonary valve to the pulmonary artery to be delivered to the lungs for gas exchange to lose CO2 and gain O2.
Oxygenated blood returns to the heart through the pulmonary veins to the left atrium and travels through the bicuspid value to the left ventricle. It leaves through the aortic valve to be distributed throughout the body (systemic circulation).
Define the term ‘vascular resistance’ and describe how three (3) different factors contribute to it. For each factor listed include the relationship to vascular resistance.
Vascular resistance = friction that prevents or slow blood flow through a vessel
- Size of blood vessel lumen - the smaller the diameter, the greater the vascular resistance
- Blood viscosity - increased viscosity = increased vascular resistance
- Total blood vessel length - the longer the vessel, the greater the resistance
Describe the formation of lymph and outline the sequence of lymph flow through the body to re-enter the blood circulation.
- Excess fluid filtered out of blood capillaries drains into lymphatic vessels and becomes lymph
- Lymph flows through lymphatic capillaries then lymphatic vessels then nodes to be filtered.
- Lymphatic vessels carry it out of nodes to five principal trunks which then pass it on to ducts.
- The right lymphatic duct drains lymph from the upper right side of the body into venous blood via the right subclavian vein.
- The thoracic duct is the main collecting duct which drains lymph from the rest of the body into venous blood via the left subclavian vein.
Name any four (4) antibody types (immunoglobulins) and for each describe a (i) location and (ii) function in the body.
(GAME)
IgG - found in blood; crosses the placenta from mother to foetus conferring immune protection in newborns
IgA - found in breast milk; provides protection of mucous membranes against bacteria and viruses
IgM - blood; causes lysis of microbes
IgE - blood; provides protection against parasitic worms
Discuss any four (4) factors that affect the affinity of haemoglobin for oxygen. For each factor discuss how it affects the binding to haemoglobin.
Acidity
> An increase in H+ in the blood (increased acidity) causes O2 to dissociate more readily from haemoglobin.
Carbon dioxide partial pressure
> Much of the CO2 in the blood is converted to carbonic acid which partly dissociates into hydrogen ions. As H+ concentration increases, it becomes more acidic which helps O2 release from haemoglobin.
Oxygen partial pressure
> The greater the PO2, the more oxygen will combine with haemoglobin until all molecules are saturated.
BPG levels
> Increased BPG levels mean fewer molecules for oxygen to bind to, decreasing the affinity of haemoglobin for oxygen.
List any four (4) stimuli that affect the rate and depth of breathing. For each stimulus explain how it changes
breathing pattern.
1) increase in body temperature - increases breathing rate and depth
2) prolonged pain - increases
3) decrease in blood pressure - increases
4) stretching of anal sphincter - increases
Discuss the chemical digestion of carbohydrates. In your answer describe the (i) enzymes involved, (ii) sites, and (iii) all end-products of carbohydrate digestion.
In the mouth, salivary amylase starts breaking down polysaccharides into smaller chain carbohydrates; HCl in the stomach ends its activity.
In the small intestine, pancreatic amylase breaks down the remaining polysaccharides and brush-border enzymes digest disaccharides into monosaccharides (glucose, fructose and galactose) which the digestive system can absorb.
Discuss the chemical digestion of proteins. In your answer describe the (i) enzymes involved, (ii) sites, and (iii) end-products of protein digestion.
In the stomach, proteins are fragmented into peptides by pepsin.
[pepsin is produced by chief cells and activated by HCl]
Enzymes in pancreatic juice - trypsin, chymotrypsin, carboxypeptidase and elastase - continue to break down protein into peptides. Each split peptide bonds between different amino acids.
In the small intestine, digestion is completed by two peptidases in the brush border to create single amino acids.
Name one (1) hormone that regulates glomerular filtration rate (GFR). In your answer discuss its (i) stimulus, (ii) site of action, (iii) mode of action and (iv) whether it increases or decreases GFR.
Angiotensin II
Stimulus - decrease in blood volume or pressure
Site and mode of action - constriction of afferent and efferent arterioles
Decreases GFR
Discuss any four (4) abnormal urinary components and, for each, indicate a possible cause.
1) Glucose - glucose is usually fully reabsorbed in the proximal convoluted tubule. Presence usually indicates diabetes mellitus
2) Red blood cells - pathological conditions such as tumours
3) Ketone bodies - high levels in urine may indicate diabetes mellitus because diabetics don’t make enough insulin or the body doesn’t respond well to it, so they can’t use sugar in the blood for energy.
4) Urobilinogen - normal urine contains some urobilinogen but too much may indicate liver disease such as hepatitis because your liver can’t recycle it into bile.
Name any two (2) male accessory sex glands that contribute to the formation of semen. Next, describe the function of any three (3) substances within seminal fluid.
1) Seminal vesicles
2) Prostate
- Fructose secreted by seminal vesicles is used by sperm for ATP production
- Prostaglandins contribute to sperm motility and viability, and may stimulate smooth muscle contraction within the female reproductive tract
- Clotting protein semenogelin helps semen coagulate after ejaculation
Name in the correct order the four (4) phases of the female reproductive cycle. Discuss how the uterus lining changes in any two (2) of these phases.
- Menstruation
- Preovulatory phase
- Ovulation
- Postovulatory phase
Menstruation - prostaglandins cause the uterine spiral arterioles to constrict. Glandular tissue dies and the stratum functionalis layer is shed. The endometrium becomes very thin.
Preovulatory phase - Oestrogens stimulate repair of the endometrium. Cells of the stratum basalis undergo mitosis and produce a new stratum functionalis. Thickness of endometrium doubles.
