Respiratory, Cardiovascular and Genetic diseases Flashcards
(127 cards)
1
Q
Bacteria which causes tuberculosis
A
Mycobacterium tuberculosis
2
Q
Transmission of tuberculosis
A
Air-borne
3
Q
Tuberculosis Course of infection
A
1) Bacteria grows and replicates within upper regions of lungs (high oxygen conc.)
2) Phagocytic white blood cells ingest bacteria, encasing them in tubercles (nodules).
3) Bacteria replicates, damaging alveolar walls + blood capillaries.
4) Results in fibrosis + a reduction in gas exchange.
5) TB may also spread to other organs in the body.
4
Q
Symptoms of TB
A
- Persistent cough
- Breathing difficulties and chest pains
- Fatigue and loss of appetite (weight loss)
- Fever and night sweats
- Chest pain
5
Q
Prevention of TB
A
- Vaccination
- Better education about TB treatment
- Isolate TB sufferers
- Improved health facilities and treatments
- Better nutrition to strengthen immune system
- Those w/ TB are identified and treated.
- Antibiotics(rifampicin and isoniazid).
- “Directly Observed Treatment, Short-course” (DOTS)
- Surgical treatment - removal of ribs/diseased lungs
6
Q
What occurs normally when someone contracts TB?
A
Those w/ a healthy immune system, prevent TB in tubercles from developing further. Bacteria are inactive + don’t replicate.
7
Q
Asthma
A
Involves inflammation and tightening of the bronchiole walls when coming into contact w/ an irritating environmental stimuli. Results in decreased air flow to lungs and thus a decreased gas exchange rate.
8
Q
What occurs during an ‘asthma attack’?
A
1) Individual comes into contact with irritating stimuli.
2) Causes muscles around walls of bronchioles to contract and become narrower.
3) The lining becomes inflamed and begins to swell.
4) Mucus is over produced, restricting air flow.
9
Q
How does asthma differ from other lung diseases?
A
- Surface area of alveoli and elasticity of the lungs are not affected
- Fibrosis due to scarring does not occur
10
Q
Symptoms of asthma
A
- Shortness of breath
- Wheezing noise
- Tightening of the chest
- Coughing
11
Q
What causes shortness of breath associated w/ asthma?
A
Constriction of the bronchioles
12
Q
What causes the wheezing noise associated w/ asthma?
A
Air passing through the very constricted bronchioles
13
Q
In those w/ asthma, what causes tightening of the chest?
A
Not being able to ventilate the lungs properly
14
Q
Why do those w/ asthma have a persistent cough?
A
It is a reflex response to clear the narrow bronchioles of any obstructions.
15
Q
Pulmonary Fibrosis
A
Caused by scarring of lung tissue as fibrous connective tissues form as a result of damage/disease.
16
Q
What does the scarring seen in pulmonary fibrosis cause?
A
- Alveoli lining to thicken, reducing efficiency of gas exchange (longer diffusion distance)
- Loss of elasticity in lungs, affecting ability to breathe out (relies on elastic recoil of lung tissue)
17
Q
Symptoms of pulmonary fibrosis
A
- Shortness of breath
- Fatigue and weakness
- Pain and discomfort in chest
- Chronic dry cough
18
Q
What causes shortness of breath in individuals w/ pulmonary fibrosis?
A
- Thickened epithelial lining of alveoli (greater diffusion distance).
- Loss of elasticity makes ventilation difficult -maintaining a diffusion gradient across gas exchange surface is harder.
- Less O2 - reduced rate of respiration - reduced ATP production. Less ATP available for muscle contraction.
19
Q
What causes the chronic dry cough in PF sufferers?
A
Due to fibrous tissue creating an obstruction in the airways of the lungs. Typical reflex is removal by coughing. As fibrous tissue is immovable, nothing is expelled (dry).
20
Q
What causes pain and discomfort in the chest for PF sufferers?
A
Due to pressure and damage from mass of fibrous tissue in lungs and more damage from coughing.
21
Q
What causes weakness and fatigue in PF sufferers?
A
Reduced intake of oxygen into blood. Rate of respiration decreases, less energy released. Leads to tiredness.
22
Q
Emphysema
A
Caused by smoking and air pollution. Leads to irreversible damage of lungs. Caused by progressive destruction alveoli walls leading to development of larger air spaces.
23
Q
What is the resulting damage of emphysema?
A
Surface area of alveoli is reduced and alveolar walls become damaged + thicken. Gas exchange becomes less efficient due to reduced SA, + increased diffusion distance. Loss of elasticity of lung tissue (loss of elastin), causes lungs to be less effective at expiration - reducing conc. gradient + rate of diffusion. Lungs less able to supply blood w/ O2, patient becomes breathless more easily. Lack of O2 to muscles reduces respiration.
24
Q
Symptoms of emphysema
A
Shortness of breath
Chronic cough
Bluish skin colouration
25
What causes shortness of breath in those w/ emphysema?
- Difficulty in exhaling (loss of lung elasticity). Lungs can't be emptied, New air can't be inhaled so breathless feeling occurs.
- Smaller alveolar SA leads to reduced levels of O2 in blood, so patient breathes more rapidly.
- Also causes barrel-shaped chest due to over-inflation from air getting trapped.
26
What causes a chronic cough in those w/ emphysema?
Lung damage + the body’s effort to remove damaged tissue + mucus (can't be removed normally), due to destruction of cilia on bronchioles.
27
What causes the bluish skin coloration seen in sufferers of emphysema?
Low levels of oxygen in the blood due to poor gas diffusion in the lungs.
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Diagnosis of emphysema
Lung function tests, chest X-rays, measurements of blood, O2 + CO2 levels and examination of sputum.
X-ray shows abnormally translucent lings w/ few normal blood vessel markings.
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Emphysema can't be cured as lung tissue cannot be regrown, however what are the possible treatments?
- Stop smoking (prevent further damage)
- Antibiotic drugs (control infection)
- Non-invasive positive-pressure ventilation (NIPPV), involves the wearing a nasal mask, supplied w/ air at slightly higher than atmospheric pressure.
- Drugs to widen bronchi (bronchodilators by inhaler)
- Steroid drugs (reduce inflammatory swelling)
- Oxygen therapy
- Alpha-1-antitrypsin replacement in individuals shown to have a deficiency in enzyme
- Exercise/training (increase physical ability)
- Surgery to remove worst affected parts
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Cardiovascular disease
Diseases of the heart and circulatory system.
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Coronary heart disease
Affects the coronary arteries (supply heart muscle w/ glucose and oxygen). Reduced flow of blood along the coronary arteries is caused by atheromas. Increased risk of myocardial infarction.
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Atheroma
Presence of fatty material (particularly cholesterol + low-density lipoproteins) within the wall of arteries under the endothelial lining of the artery.
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Atherosclerosis
Disease where plaque builds up inside the arteries. Over time, the plaque hardens and narrows the arteries.
34
Process leading to atherosclerosis
Atheromas plaques are deposited in the artery, over time they grow in size and begin to block the lumen. This causes an increase in blood pressure as the artery narrows.
As a result, macrophages in the blood get deposited under the endothelium and develop into fatty bodies (rich in cholesterol).
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What other diseases do atheromas increase the risk of?
- Thrombosis
- Aneurysm
- Peripheral vascular disease
- Cerebrovascular accident (stroke)
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Thrombosis
Formation of a blood clot caused when an atheroma breaks through the endothelium of the blood vessel, interrupting the flow of blood.
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Complications of thrombosis
- Blocks blood vessels, reducing blood supply to tissues beyond. Can cause a heart attack if in the coronary artery.
- Blood flow to heart tissue decreases causing it to die as it can not respire (lack of O2, glucose, etc)
- Can also occur with other tissue regions if they become deprived of oxygen.
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Embolus
When a thrombus is carried from its place of origin and blocks another artery
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Aneurysm
- Weakening of artery walls due atheromas.
- Weakened points swell to form a balloon-like, blood filled structure called an aneurysm. Often haemorrhage (blood loss to body part)
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How is an aneurysm treated if detected before bursting?
Section of artery replaced with a synthetic tube
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Peripheral vascular disease
Narrowing of the arteries in lower extremities, leads to an increased risk of thrombosis. Leads to circulatory problems with inadequate oxygen being supplied to the legs, feet etc. increasing the risk of infection
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Symptoms of cerebrovascular accident
- 10% of strokes are caused by bleeding from arteries in the brain, directly damaging the brain’s tissues and causing loss of blood supply.
- Symptoms depend on region of brain affected.
- Slurred speech, confusion, difficulty in walking, arm and leg weakness and numbness along one side
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Cerebrovascular accident/Ischaemic stroke
- Obstruction of the cerebral artery (supplies blood to brain).
- Atheroma cause blockage, increasing risk of blood clot blocking artery.
- Clots often arise from carotid arteries in neck, and travel to the brain blocking the arteries supplying the cerebellum.
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Risk factors associated with cardiovascular disease
```
Age
Smoking
Gender
Stress
Diet
High blood pressure
Genetic predisposition - overproduction of cholesterol by liver
Exercise
Diabetes
```
45
Why does risk of cardiovascular disease increase w/ age?
Fat is deposited in the walls of the arteries throughout life.
46
Why does smoking increase the risk of cardiovascular disease?
Chemicals in smoke diffuse into the blood and affect properties of endothelial cells of arteries, increasing their uptake of fat. Nicotine increases heart rate and blood pressure, making CHD more likely. Nicotine can also cause higher cholesterol levels.
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How does gender affect the risk of cardiovascular disease?
Hormones like progesterone and estrogen use more fat in their synthesis, so less fat is available in the blood of females, making them less likely to develop atheromas.
48
How does stress increase the risk of cardiovascular disease?
Causing an increase in blood pressure and also affects hormone levels, leading to increased fat deposition in arteries.
49
How does diet affect the risk of cardiovascular disease?
Intake of animal fat containing a higher proportion of saturated fats/cholesterol increases blood cholesterol and low-density lipoproteins in the blood increasing the risk of atheroma and associated diseases.
50
What is the role of high density lipoproteins (HDLs)?
Remove cholesterol from tissues and transport it to the liver for excretion protecting the arteries against heart disease.
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What is the role of low density lipoproteins (LDLs)?
Transport cholesterol from the liver to the tissues, including the artery walls, which they infiltrate leading to development of atheroma and heart disease.
52
Cholesterol
Essential part of plasma membranes, and is transported in blood plasma as tiny lipoprotein spheres (either HDLs or LDLs).
53
How does exercise decrease the risk of developing cardiovascular disease?
Decreases lipid levels in the blood as they are used in respiration. An increase in the rate of blood flow during exercise reduces the build up of fat deposits and the formation of clots.
54
How does diabetes increase the risk of developing cardiovascular disease?
Metabolism of both glucose and lipid is affected by a lack of insulin. Insulin injections may lead to an imbalance in the amount of lipid in the blood and consequently an increased risk of an atheroma developing.
55
Correlation
Where a change in one of two variables is reflected by a change in the other variable. Some factors may show a correlation with a disease but there may be no actual evidence to prove it is the cause of the disease.
56
Cause
A factor which is directly a cause of a disease. Can only be established when scientists have produced compelling experimental evidence to show a particular factor is causing a disease.
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Relative risk
Risk is measured by comparing the likelihood of harm occurring in those exposed to a hazard with those who are not exposed to it.
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Effects of tumours
- Abnormal cell growth damages organs affecting function
- Cause new capillary networks to form diverting blood away from tissues (angiogenesis)
- May cause blockages/obstructions in blood vessels, lymphatic vessels & ducts
- Exert pressure on other organs causing problems
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Angiogenesis
When new capillary networks form around tumours, diverting blood away from tissues.
60
Two main gene sets which control rate of cell division
Proto-oncogenes – stimulate cell division
| Tumour suppressor genes – slow cell division
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Risk factors of cancer
Chemical carcinogens
Ionising radiation
Diet
Genetic predisposition
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Cancer treatments
```
Surgery
Radiotherapy
Chemotherapy
Immunotherapy
Monoclonal antibodies
Hormonal therapy
```
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How does radiotherapy treat cancer?
Ionizing radiation induces DNA damage which triggers cell death. Radiation doses are divided to allow for recovery of normal tissue and thus reduce side effects
64
How does chemotherapy treat cancer?
- Damages DNA of cancer cells, causing cell death.
- Damages cellular spindle apparatus, preventing cell division
- Inhibits DNA synthesis
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Interleukin 2
Form of immunotherapy, which induces a small remission rate in some forms of cancer
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How do monoclonal antibodies treat cancer?
Antibodies produced recognize cancer cells, and mark them for destruction by the immune system. Radioactive atoms and chemo-drugs can be attached to the antibodies.
67
How does hormonal therapy treat cancer?
Some tumours respond well to inhibition of certain hormones. E.g. Tamoxifen is associated w/ breast cancer.
68
Risk factors of breast cancer
- Reproductive and hormonal factors (exposure to oestrogen)
- Genetic predisposition
- Chest irradiation and specific types of previous benign breast disease are also risk factors.
- Obesity, alcohol and physical activity
69
Which genes make people more predisposed to developing cancer?
BRCA-1
BRCA-2
p53
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What factors affects the likelihood of an individual developing breast cancer?
- First menstrual cycle at an early age increases risk
- Late menopause increases risk
- Child bearing at a younger age decreases risk
- Breast feeding decreases risk
- Use of HRT increases risk (also depends on BMI)
71
Symptoms of breast cancer
- Lump or area of thickened tissue in breast
- Change in size or shape of breasts
- Discharge from nipples
- Lump or swelling in armpit
- Dimpling on skin of breasts, rash around nipple.
- Change in appearance of nipple (inversion)
- Pain in breasts or armpits (not menstruation)
72
Detection of breast cancer
- Routine self-examinationof breasts for lumps
- Screening programs
- Fine needle aspiration (removes a sample of tissue)
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Treatment for breast cancer
- Removal of tumour by surgery
- Mastectomy (whole breast & lymph nodes)
- Radiotherapy
- Chemotherapy
- Endocrine (hormonal therapy)
- Monoclonal antibodies
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Cervical cancer
Cancer of the ring of smooth muscle at the neck of the womb (cervix). Causes 1000 deaths per year.
75
Risk factors of cervical cancer
```
Age
Human papilloma virus
Sexual activity
Oral contraceptive use
Immunosuppresion
Smoking
Genetic predisposition
```
76
How does age affect development of cervical cancer?
Women aged 30-34 are more like to develop it due to a peak in sexual activity during the 20s (contraction of HPV more likely). Women aged 80-84 are more likely as incidence increases with age.
77
How does smoking increase the risk of developing cervical cancer?
Linked to inaction of tumour suppressor genes in cervical tissue. Also associated with decreased immune response in the cervix epithelium.
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Symptoms of cervical cancer
Often symptoms don't appear until the advanced stages, symptoms are also difficult to notice.
- Vaginal symptoms (bleeding between periods, after intercourse or after menopause)
- unpleasant smelling vaginal discharge
- persistent lower back pain
- discomfort during intercourse
79
Methods of detection for cervical cancer
Cervical screening (smear test)
Biopsy
Colcoscopy
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Biopsy when identifying cervical cancer
Tissue sample of cervix taken to search for cancerous cells.
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Colcoscopy when identifying cervical cancer
Follows screening if abnormalities are found, involves looking at a magnified image of the cervix.
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Cervical screening procedure
Involves taking a sample of cells from the cervix w/ a small brush, these are tested in a lab for abnormalities.
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Treatment for early cervical cancer
Surgery to remove some/all of the womb.
| Radiotherapy
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Treatment for advanced cervical cancer
Radiotherapy
Chemotherapy
Surgery
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Treatment for potentially cancerous cells found during cervical screenings
- Large loop excision of the transformation zone (LLETZ)
- Abnormal cells cut away using a fine wire and an electrical current
- Cone biopsy
- Area of abnormal tissue is removed during surgery
- Laser therapy, burns away abnormal cells
86
Risk factors of prostate cancer
```
Age
Ethnicity
Genetic predisposition
Diet
Exercise
```
87
How does ethnicity affect incidence of prostate cancer?
African-Caribbean and African men are more likely to develop prostate cancer than men of Asian and South/Central American descent.
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How does diet affect incidence of prostate cancer?
- A diet rich in calcium increases the risk.
| - Men who eat foods rich in nutrients like lycopene (red fruit), and selenium (Brazil nuts)
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Symptoms of prostate cancer
Symptoms don't usually occur until the tumour is large enough to put pressure on the urethra.
- Need to urinate more frequently
- Difficulty in starting to urinate
- Straining or taking a long time while urinating
- Weak flow
- Feeling that your bladder has not emptied fully
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Methods of detecting prostate cancer
No single definitive test
- Urine test to check for and rule out infection.
- Blood test to test the level of prostate specific antigen - Physical (digital rectal) examination to detect prostate enlargement.
- Biopsy of prostate gland
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Treatment for prostate cancer
- Prostatectomy
- Hormone therapy –reduce testosterone levels
- Radiotherapy
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Stages of gene therapy
1) Identifying the gene causing disease.
2) Obtaining and cloning healthy copies of gene.
3) Transferring healthy genes into patient e.g. by vector.
4) Ensuring genes reach target cells + function normally
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Cystic Fibrosis
Inherited disorder disease caused by defective recessive gene. It codes for a channel protein regulator protein. CFTR controls movement of Cl- in cells.
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Down Syndrome
Results from non-dysjunction of chromosome 21 during meiosis, causing 24 chromosomes rather than 23.
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Characteristics of individuals with down syndrome
- Facial features: upwards slanting eyelids, small mouth with protruding tongue, flat and rounded face.
- Learning difficulties (different for each individual)
- Short stature, small skull (poor skeletal development)
- Coarse, straight hair
- Squat hands with a characteristic crease
96
Turner's syndrome (XO female)
Incompletely developed females, no obvious external differences to other females. Symptoms:
- Small uterus, absent ovaries, infertility.
- Shortness of stature, averaging 1.5 m
- Puffy fingers w/ deep set finger nails, lower hair line
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Klinefelter's syndrome (XXY male)
Feminized males.
- Smaller testes, infertility due to no sperm
- Taller than average and obese torso
- Little facial hair
- High voice pitch
- Some breast development
- Educational difficulties + behavioural problems
98
What is a common cause of human chromosome abnormalities?
Failure of replicated chromosomes to segregate during Anaphase II, this is known as non-disjunction.
99
What occurs in cystic fibrosis?
- Results in a missing amino acid (phenylalanine) in the CFTR protein. Make channel protein defective.
- Cl- remain in cell, so Na+ enters to balance -ve.
- Due to high ion conc. in the cell, water enters the cell from mucus lining the cell.
- Leads to secretion of large amounts of thick + sticky mucus by epithelial cells, mostly in lungs + pancreas
100
Implications of cystic fibrosis on the lungs
- Accumulation of thick mucus in lungs, narrowing air passages, restricting air flow causing breathing difficulties.
- Increased diffusion distance and reduced surface area for gaseous exchange in alveoli. Less O2 in blood
- Traps microorganisms as cilia cannot move mucus, results in repeated lung infections.
101
Treatments for cystic fibrosis
Physiotherapy, enzyme supplements and gene therapy.
102
Use of liposomes as vectors
- Membrane of molecule contains sugars allowing recognisation by receptor proteins on target cells.
- Fuse with cell membrane allowing specific gene to enter cell (endocytosis).
- DNA enters nucleus.
- Must attach to cell’s DNA and integrate into host cells DNA.
- If gene is expressed it may code normally
103
Phenylketonuria (PKU)
Disease caused by inability to convert phenylalanine into tyrosine.
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Cause of PKU
- Enzyme PAH is faulty in the liver.
- Gene for enzyme on chromosome 12. Causes phenylalanine to build up in body.
- Excess is converted to toxins which affect mental development
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Symptoms of PKU
- hyperactive and irritable behaviour in children
- awkward posture and walk
- lighter skin pigmentation and fair hair
- eczema
- repetitive movements of fingers, hands or body
- convulsions due to abnormal brain activity
106
Why do suffers of PKU have no symptoms at birth?
Whilst in the uterus, excess phenylalanine moves across the placenta + is removed by the mother’s liver.
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What occurs if PKU is not treated from birth?
- Severe mental retardation can occur.
- Untreated patients have IQs of less than 20.
- Before treatment was available, more than 1% of those in mental hospitals had PKU.
- Untreated sufferers rarely live beyond the age of 30.
108
Identification of PKU
- Important to test in newborns as irreversible damage occurs after 6 months.
- A very sensitive blood test detects higher than normal levels of free phenylalanine in the blood of sufferers. Levels are commonly 30—50 times higher than normal. - The test is now carried out on all babies four days after birth by pricking the heel for a blood sample.
109
Treatment of PKU
- Condition is managed by reducing amount of phenylalanine in the diet to minimum required.
- Blood levels are monitored for the first few years of life to check the correct balance is being maintained. -
- Excess phenylalanine in adulthood is not damaging, presumably because brain development has ceased, so a normal diet can then be adopted.
110
Sickle cell anaemia
Disease in which red blood cells change shape in low oxygen environments. About 1 in 1600 black African people suffer from this disease
111
Cause of sickle cell anaemia
Substitution mutation on chromosome 11, where amino acid glutamic acid is replaced by valine in the β chains of haemoglobin.
Valine makes the haemoglobin of sickle cell sufferers less soluble after dissociating from O2
Haemoglobin will come out of solution and crystallise into rigid, rod like fibres. This changes the shape of the red blood cells from a circular flat disc to a sickle shape
112
Symptoms of sickle cell anaemia
Anaemia and changing shape of red blood cells at low O2 conc.
The blood cells block capillaries and small blood vessels preventing normal blood flow, resulting in painful arms, legs, back and stomach.
Other secondary symptoms include enlarging of heart, kidney damage, poor growth + development.
Sufferers tend to be more prone to infection.
113
What are the symptoms of heterozygous sufferers of sickle cell anaemia?
Have usual symptoms but only at very low O2 concs. Due to codominance of alleles.
114
Treatment of sickle cell anaemia and thalassaemia
Regular blood transfusions to restore normal proceedings.
115
Thalassaemia symptoms
Severity of symptoms depends on no. of globin genes deleted. Anaemia occurs, and gall stones develop and problems with the spleen arise.
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α Thalassaemia
Absence of one or both of the α globin genes resulting in haemoglobin lacking one or both of the α polypeptides.
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β Thalassaemia
Absence of one or both of the β globin genes resulting in haemoglobin lacking one or both of the β polypeptides.
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Cholesterol
Fatty substance found in the plasma membrane to help control membrane fluidity. Transported in blood plasma as lipoproteins.
119
Metastatsis
Breaking away and moving of cancerous cells to other areas of the body, via the blood and lymphatic systems.
120
Problems with gene therapy
- Vector may not reach target cell
- Normal gene may not enter nucleus
- Normal gene may not fuse w/ host DNA
- Normal gene may not be switched on
- Cell may die before gene expression
121
Effects of mutation on CTFR protein
- Causes Cl- to remain in the cell, causing Na+ to enter.
- This causes water to enter the cell from the cell's mucus lining.
- Leads to secretion of lots of thick, sticky mucus from epithelial cells. Especially in the pancreas and lungs.
122
Implications of cystic fibrosis on digestion
- Mucus blocks the pancreatic duct and intestine resulting in reduced quantities of enzymes, slowing digestion.
- Mucus layer increases diffusion distance for absorption of digested food so more lost in faeces.
123
Implications of cystic fibrosis on fertility
Males are infertile, females usually are due to mucus blocking ducts in reproductive system.
124
How does physiotherapy help those with cystic fibrosis?
Help move mucus from the lungs, aiding breathing, and reducing risk of infections.
125
How does enzyme supplements help those with cystic fibrosis?
Makes up for enzymes blocked from entering the stomach, and allows faster digestion.
126
Virus as a vector in gene therapy
Specific cell type is used to target a specific cell.
- Desired gene inserted into 'harmless' virus
- Virus binds to target cells, enter and releases gene
- Gene attaches to host DNA and incorporates itself
- Gene is expressed and virus may reproduce
127
Disadvantage of using a virus as a vector
May infect cells and cause disease or be attacked by the host's immune system
