Non-communicable diseases Flashcards
NCDs overview
long duration, slow onset, not transmissible from person to person
eg. cardiovascular diseases, cancer, diabetes etc
risk factor definition
anything that increases the likelihood of developing a particular disease
Risk groups
- Medical condition that inc risk
- Behaviour eg smoking drinking
- hereditary. eg family history
what are the
- preexisting conditions
- behavioural/lifestyle choices
- hereditary/genetic factors
associated with strokes
conditions:
- hypertension
- high cholesterol
behaviour:
- excessive salt
- excess alcohol activity
hereditary
- sickle cell disease
what are the
- preexisting conditions
- behavioural/lifestyle choices
- hereditary/genetic factors
associated with lung cancer?
conditions:
- chronic lung diseases
behaviour:
- smoking
- asbestos exposure
- radiation exposure
hereditary:
- 1st degree family member with lung cancer
- gender
what are the
- preexisting conditions
- behavioural/lifestyle choices
- hereditary/genetic factors
associated with asthma?
conditions:
- another allergic condition
behaviour:
- exposure to allergens
- smoking
hereditary:
- blood relative with asthma
what are the
- preexisting conditions
- behavioural/lifestyle choices
- hereditary/genetic factors
associated with type 2 diabetes?
conditions:
- aged 45+
- gestational diabetes
behaviour:
- physical activity < 3 times a week
- being overweight
hereditary:
- blood relative with diabetes
- certain ethnicities
tumour def
a lump or growth of abnormal cells that undergo uncontrolled cell division
what is the definition of cancer?
a disease caused by usually caused by a mutation that causes uncontrolled cell division and leads to the formation of a tumour
4 typed of cancer
- Carcinoma (external & internal body surfaces)
- Sarcomas (supporting tissue)
- Lymphomas (lymph nodes and tissue of IS)
- Leukaemias (blood cells)
Benign tumour
- Uncontrolled division
- Slow growing, located within one specific tissue, cells do not break off & spread
- not normally life threatening but can apply pressure
Malignant tumour
- tumours grow rapidly
- cells can and do break off & spread to other tissues
- one metastic = cancer
- primary tumour (original), secondary tumour
Control of cell division
proto-concogenes & tumour supressor genes
Proto-oncogenes
- Controls normal cell growth
- Stimulates cell division after stimulation from growth factor
- If a mutation occurs, forms oncogene
- ∴ DNA replication is triggered without the extra-cellular growth factor, causing abnormally high production of GF
Tumour supressor gene
- TSG codes for production of protein that stops cell division & causes apoptosis
- If mutation occurs, stops production of protein
- Leads to continual division
outline the role of the c-Myc gene and explain [how its mutated form can cause cancer]
regulator gene on chromosome 8 responsible for regulating 15% of gene expression
[Myc constantly expressed –> unregulated expression of genes –> cell proliferation and cancer formation]
p53
- codes for transcription factor
- also has several anti-cancer effects
- damaged dna is repaired by proteins activated by p53
- Can stop cycle at g1 to repair damage
Mutagen
- physical, biological or chemical agent that mutates DNA causing frequency of mutations to increase
eg. UV radiation, alcohol, virus
Carcinogen
a mutagen that specifically leads to cancer as a result of uncontrolled cell division
outline the role of the Ras gene and explain [how its mutated form can cause cancer]
- division stimulated by extra-cellular messengers
- [division stimulated by Ray gene without hormone, cell cycle inhibition removed]
Explain how smoking contributes to lung cancer [6]
- tar is a known carcinogen which enters lung cells
- destroyed cilia prevent removal of tar, hence have more time in contact with epithelial cells
- enters nucleus
- Proto-oncogene mutates to form oncogene
- uncontrolled cell division
- formation of tumour cells
why does chance of cancer increase with age
- more mutations
- weaker immune system
- more exposure to carcinogens
how do viruses cause cancer
- their DNA enters nucleus
- causes mutation that affects protooncogenes
- leads to uncontrolled cell vision
X-rays
- high energy radiation
- x rays passes through soft tissue, film turns black
- bones absorb x rays, film turns white
-quick and easy, cannot distinguish without further tests
Mammography
- low energy X rays
- can detect small tumours in breast tissue
- breast places between two plates which press firmly together
- mammogram examined to identify any areas of calcification
-quick, non invasive, cannot distinguish without further tests
CT scan
- X rays passing through the body at different angles
- Gives detailed image (tomogram) of the internal structure of the body
- Patient lies down continuously moved through a rotating x-ray beam
- on the opposite side of the body x rays are detected
- Gives more detail than standard x-ray (3D image)
-non invasive, costly, can’t distinguish without further tests
MRI
- Magnetic resonance imaging
- single scan can give multiple pictures from many angles
- Patient has to lie very still, no metal
- Magnet creates magnetic field that lines up the protons in hydrogen atoms
- beam of radio waves spin protons and signal emitted is converted into detailed 3D image
+ non-invasive; good for soft tissues
- costly; can’t distinguish without further tests
PET scan
- produces 3d images of functional processes in the Boyd
- uses tracer (fluorodeoxyglucose most common)
- FGS injected to the patient prior to scan. Uptake is a marker for uptake of glucose. cancerous cells metabolise faster than normal, so absorb more FGS
- Pet scan detects radiation given off by tracer
+ accurate; fine detail; 3D coloured images
- can’t distinguish without further tests
Biopsies
- Removal of a sample of tissue
- send to lab to be analysed and to distinguish between cancerous and non-cancerous
- Bone marrow biopsies- diagnose blood cancers, detected cancers that start somewhere & spread to BM
- Endoscopic biopsies- smear test
- Needle biopsies- used when tumour felt through skin
+ can distinguish
- invasive
Blood tests
- Diagnostic and monitoring purposes
- CAA125- high levels may mean ovarian cancer
- P (prostate-specific antigen)- detect prostrate cancer
+ effective diagnostic tool
- invasive
Ultrasound
- high-frequency sound waves
- handheld transducer moved over skin which delivers sound waves which reflect off organs and are detected
+ very safe, cheap, portable
- can’t distinguish without further tests
what is screening
testing people who are known to be at risk of a certain condition before symptoms start
Aim= enable better outcome for individual
eg. breast, prostrate. cervical, bowel
Reliability
not 100% reliable or accurate
However, potentially reduce the risk of developing the condition if individual acts on advice given & make appropriate lifestyle changes
False negative may be due to
- cancer doesn’t show up x-ray, may be too small, human error
False positives may be due to
increased number of screening, human error
Suggest how isoflavone may affect action of oestrogen
- has similar shape to oestrogen
- hence complementary to receptor
- prevents oestrogen from binding
sensitive vs specific test
sensitive- may pick it up early on
specific- only picks it up when cancer is present
biological marker examples
protein, glycoprotein, glycolipid
features of cam that allow growth factors to bind
proteins & glycoproteins act as receptors, complementary
Breast cancer genetics test
- BRCA1 & BRCA2
- 40-90% of women carrying mutations in BRCA genes will develop cancer
- Risk increases with age
BRCA1 & BRCA2
- These genes produce tumour suppressor proteins
- Proteins repair dna
- mutations= failure to repair dna
- other genes eg TP53 + PTEN
Who can have genetic screening for breast cancer
- Strong family history
- Mutation research carried out on living relative with cancer to determine faulty gene
- then, a faulty gene is identified in an individual ie predictive testing
- This process is expensive for NHS
Bowel Cancer
- Hereditary non-polyposis colorectal cancer= type of bowel cancer caused by a mutated gene
- Mutation in genes which repair DNA
Benefits & negatives of genetics testing
\+ relief from uncertainty can make informed decisions about future lifestyle changes inform individual to make appropriate treatment decisions
-
anger, anxiety, depression
-which treatment to have
-absence from work etc
Treating cancer- surgery
Breast:
Lumpectomy- removal of tissue and surrounding tissue
Masectomy- removal of entire breast. Lymph nodes may also be removed
Colon:
Colectomy- removal of part of colon containing tumour
Ends of colon are joined back together by anastomosis. May need temporary stoma
Treating cancer- Chemo
- can be used prior to surgery to shrink the tumour. Or after surgery to ensure all cells are removed. Or to treat cancer which has spread
- Uses chemicals that are toxic to dividing cells
- Cancer cells divide more rapidly than normal cells, so it has more effect on them
- But can affect whole body rather than just cancer cells eg. bone marrow cells, hair follicles etc as these divide faster and more regularly
symptoms: hair loss, fatigue, loss of appetite, nausea and vomiting
Treating cancer- Radiotherapy
- uses ionising radiation to destroy cancer cells
- Destroys actively growing cell more than others
- causes damage to dna. especially if going through SMR
- can be targeted accurately to tumour
- can be used before or after chemotherapy
Treating cancer- Immunotherapy
- anticancer drugs can be attached to monoclonal antibodies which bind specifically to cancer cells
- Or can be tagged with enzyme that converts inactive form of cytoxic drug into active form
- ONLY attach to specific cancer cells, so can be administered at high dose
- ADEPT= antibody directed enzyme prodrug therapy
- eg. Herceptin- user for breast cancer. Has complementary binding sites for a specific protein receptor on cam of breast cancer cells. Binds to it and stops cells dividing rapidly
Treating cancer- Complementary therapies
- Focuses on making person feel better during other treatments
- Reduces side effects
- eg, reiki, meditation, acupuncture, hypnotherapy
- Positive mental attitude can have positive impact on improving effectiveness of immune system
Treating cancer- Hormone related therapies
-Tamoxifen- used to treat breast cancer
-Oestrogen stimulates gene transcription:
Diffuses through csm, binds to a specific receptor, allostery, receptor complex binds to coregulator, diffuses to nucleus, binds with chromatin, transcription occurs, increases growth and division of breast cancer cells
-Tomoxifen binds to oestrogen receptor. Complex still forms
-But, It does not undergo allostery, so blocks binding of coregulator, no transcription occurs
-Effective for some types of breast cancer in short term. After 2-3 years, woman can develop resistance. So different drug needs to be prescribed to reduce oestrogen levels
