Extras Flashcards
Define an X-ray.
An electromagnetic packet of energy (photons) with extremely short wave-length between 0.1 and 10 nanometers.
What does the X-ray tube contain?
vacuum, anode, cathode, tungsten target, rotor, oil
What are the three types of interactions between X-rays and matter?
- Scatter
- Transmission (e.g air)
- Absorption (e.g tooth)
Define attenuation.
Process by which radiation loses power as it travels through matter, increases with density and thickness and increases with atomic number.
Relate colour of tissue with attenuation factor.
Whiter tissue = higher attenuation factor.
What is a digital radiography?
Digital acquisition of images onto a network of images.
What is ultrasound?
Transmit high frequency sound pulses.
Describe how ultrasound works.
Sound waves travel into body and hit a boundary between tissues, some waves reflect back to the probe while some travel further to another boundary. Reflected waves are picked up by the probe and relayed to machine which calculates distances using speed of sound in tissue and time of echo’s return to form 2D image.
What are the advantages of using ultrasound?
Cheap, portable, no radiation, great for soft tissue.
What are barium studies?
A radio-opaque contrast agent is used to outline GI tract. The high atomic number of barium absorbs more X-ray photons than surrounding tissues.
What re complications of barium studies?
Bowel disturbances and colonic perforation.
Describe CT.
Rotating X-ray tube with multipole beams and a single six of rotation.
often used with iodinates contrast.
What is a disadvantage of using CT?
Ionising radiation which can lead to disruption of chemical bonds within living tissue.
What measurement is used to describe the absorption of radiation by the human body?
Sievert
Describe transformation of cells from ionising radiation.
Leads to altered cell metabolism and function and to cancer development (i.e worse than cell death).
How can healthcare professionals minimise exposure to ionising radiation?
Use shield, minimise time exposed, distance.
Discuss distance in relation to ionising radiation.
As distance from source doubles, exposure rate decrease by a factor of four.
What are the main functions of the lymphatic system?
- tissue drainage
- return of plasma proteins
- absorbed fat transport in gut
- tissue fluid has osmotic pressure
- immunity
- drains escaped cell-free plasma from the extracellular spaces back to the venous system.
Discuss the route of the lymphatic system.
One-way from periphery back to centre (due to valves).
What is the lymphatic vessels permeable to?
Fluid, lymphocytes, fats (in small intestine) and small proteins only.
Where in the body is there no lymphatic drainage?
Epidermis, cartilage, bone, CNS.
What controls flow of lymph?
Muscle contraction, valves, pressure changes and gravity
What causes tissue drainage in lymphatic system?
Increased hydrostatic pressure forcing plasma proteins out of blood of tissues.
What is the function of lymph nodes?
- Acquired immunity
- Reabsorption of lymph (about 8L/day)
What is the function of the germinal centres (secondary lymphoid follicles) in lymph nodes?
Maturation, isolation, localisation and activity sites of B and T cells.
Where are deep lymph nodes found?
Accumulate at base of limb and within trunk.
What causes enlargement of superficial lymph nodes?
Infection (e.g TB and glandular fever), inflammatory hyperplasia and tumour growth (primary tumour = Hodgkin’s lymphoma and secondary as a result of metastasis)
What are the drainage routes of lymph?
- Initial drainage = symmetrical from limbs, head, neck and trunk.
- Deep lymphatic drainage follows routes of arterial blood supply
- Ultimately all congregate into 2 large ducts
what are the two main lymphatic ducts?
- Thoracic duct
2. Right lymphatic duct
How does a global health perspective enhance patient care?
Goes back to root cause of poor health and disparities e.g social, political, cultural etc.
What are the benefits of global health?
- achieves equity in health
- population-based prevention and individual care
What has happened to non-communicable diseases in recent years?
Non-commincable diseases (cardiovascular, cancer, chronic diseases and diabetes) have increased
Compare health and illness in relation to social gradient.
The lower the socio-economic position, the worse the health.
What are the social determinants of health?
- income related to life expectancy
- socioeconomic class and environment
- unsafe water and sanitation
- malnutrition
What are disease related to and give examples.
- Waterborne (e.g cholera, typhoid and dysentery)
- Water-washed (e.g scabies. lice, tick-borne)
- Water-based (e.g schistosomiasis and other helminth infections)
- Water-related (e.g dengue, yellow fever, malaria)
What are the three main types of diarrhoea disease?
Bloody, watery, epidemic
What interventions can improve global health?
- improved water supply
- water quality interventions
- personal hygiene
- sanitation
Name an example of a global health burden.
Access to surgery
Name a global health issue.
Maternal mortality.
