Flashcards in WEEK 2 Deck (58):
The use of radiation (such as x-rays) or other imaging techniques (ultrasound and MRI) to diagnose or treat disease.It provides images of almost any organ, system or body part in a noninvasive way so that diagnoses can be made.
Describe the medical imaging technique of an X-ray, what does it involve? List its advantages & disadvantages.
High energy part of the EM spectrum which allows x-rays to pass through the body and reach a film (unlike light)
ADV: Good for showing trauma, joint disease, chest pathology & bowel obstructions (among other things)
DIS: High energy waves absorbed by body tissues & energy generates free radicals which can interact with genetic material causing damage
Causes an increased risk of cancer.
Describe the medical imaging technique of an CT (computer tomography), what does it involve? List its advantages & disadvantages.
How it works: D = detectors
T = x-ray tube
X = x-rays
R = direction of rotation
ADV: Lets you look in any plane.
Used to stage tumours, for trauma, cerebrovascular disease, surgical emergencies etc
DIS: V.v. expensive to buy AND run
High radiation dose ( a CT of the abdomen/pelvis is equivalent to 400 chest x-rays)
Describe the medical imaging technique of an PET (Positron Emission Tomography), what does it involve? List its advantages & disadvantages.
HOW it works:
Principle 1 = unstable compound decays by emitting positron (animatter). Positron then hits an electron, mutual annihilation, 180 deg pulse gamma radiation
Principle 2 = Most cancers have a high rate of metabolism (main metabolic agent = glucose) Therefore, if an usntable compound is joined to a glucose molecule, it will accumulate at sites of high metabolic activity
ADV: used for staging of tumours & for detecting recurence AFTER treatment
DIS: cyclotron(mini particle accelerator), short half life, expensive £££, high dosage of radiation
Describe the medical imaging technique of an Ultrasound, what are its advantages & disadvantages?
ADV: safe, used for soft tissue detail, mainly on heart, pelvis, abdominal solid organs & obstetrics
DIS: cannot penetrate bone, the waves are scattered by air & so cannot view bowel, also solid organs may be obscured by gaseous bowel
Describe the medical imaging technique of an MRI (Magnetic Resonance Imaging), what does it involve? List its advantages & disadvantages.
A magnetic field is applied & short burst radiowaves applied at resonant frequency. Protons give up energy & this is detected to make the picture
ADV: non-ionising radiaiton, few known side-effects, wonderful soft tissue visualisation & characterisation, able to do functional studies
DIS: expensive, dangerous (metal in room or patients), noisy, pts must lie for long periods of time, claustrophobic
What are the 4 types of body tissues?
2. Connective tissues
4. Neural tissues
Describe the characteristics of epithelia.
Functions in: secretion, absorption, transport, as a barrier & for strength/support
Covers surfaces but have varied shape & arrangement (flat, cube, columned, multilayered)
Are bound to each other by specialised junctions & adhesion molecules
Sit of the BM - which contains proteins that link to the surface of epithelial cells, they also contain filament proteins which provide strength
What is the function of (i) Microvilli (ii) Cilia
(i) Contain actin, for absorption/sensing
(ii) contains microtubules for movement/lateral transport
What are the 4 main types of junctions? What are their functions?
1. Tight junctions = sealing
2. Desmosomes = strengthen cell links
3. Gap junctions = connect cytosols of adjacent cells for v.small molecules
4. Adherens junctions = spots of actin (connection linking movement protein)
Describe the characteristics of nervous tissue. (i) What is a neuron (ii) What is the function of an axon (iii) What is the function of dendrites?
(i) Separate cells that communicate by releasing chemicals by secretion at the ends of cell processes
(ii) Direct stimulus AWAY from the cell
(iii) Direct stimulus TOWARDS the cell
What are the 4 types of glial cells of the CNS? Describe their function.
1. Oligodendrocytes - myelination, one cell builds a number of internodes
2. Astocytes "star cells" - metabolic & mechanical support. Contribute to scar formation
3. Microglia - come from blood, essentially macrophages
4. Ependyma - lining cells of CNS cavities
What are the 2 types of glial cells of the PNS?
1. Schwann cells - myelination
2. Satellite cells - support cells in ganglia
What are the 3 types of muscle cells? What do cardiac cells contain for strength?
Cardiac cells contain ionic coupling (i.e. gap junctions) for strength
What is connective tissue?
A mix of different cells & ECM (which contains fibrous proteins, structural carbohydrates & proteins mineral deposit
What is the function of (a) Fibroblasts (b) Macrophages (c) Mast cells (d) Plasma cells?
(a) synthesise fibrous proteins
(b) Phagocytose foreign bodies/organisms. Present antigens to stimulate immune cells
(c) synthesise histamine & other inflammatory mediators
(d) Synthesise antibodies (mature B cells)
Describe the role of (i) White fat (ii) Brown fat.
(i) stores energy BUT is extremely dynamic. Produces adipokines which send signals to regulate nutritional balance. E.g. leptin sends signals to the brain that the body has "had enough to eat"
(ii) Makes heat by uncoupling oxidative phosphorylation in mitochondria. Conters hypothermia in babies & is located in the upper trunk region.
What is the function of epithelial tissue?
It covers all external & internal body surfaces & forms boundaries between body compartments
What separates epithelial cells from the underlying connective tissue? Describe it.
- thin sheet composed of collagen & glycoprotein. Produced partly by epithelial cells & partly by underlying connective tissue cells
For simple squamous epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 1 Layer
(ii) Flattened, plate like
(iii) Lining of body cavities, lining of capillaries & BVs
For simple cuboidal epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 1 Layer
(ii) Approx same height & width
(iii) Secretion & absorption in the liver & kidneys
For simple columnar epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 1 Layer
(ii) Approx twice as tall as wide
(iii) Secretion & absorption in the GI tract
For pseudostratified epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 1 Layer
(ii) Appears like 2 layers as some cells are short & others tall
(iii) Respiratory epithelium lines conducting part of the airway
For stratified squamous epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 2 or more layers
(ii) Apical layer is flattened
(iii) Protective function in oesophagus & epidermis
For stratified cuboidal epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 2 or more layers
(ii) Apical layer is cuboidal
(iii) Secretion in salivary glands & sweat glands
For stratified columnar epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 2 or more layers
(ii) Apical layer in columnar
(iii) Male urethra
For transitional epithelium, (i) How many layers is it made up of (ii) What is the shape of the cells (iii) Give examples.
(i) 2 or more layers
(ii) Apical layer is cuboidal
(iii) Lining of bladder i.e. urothelium (as is distensible)
What is the function of (i) Goblet cells (ii) Cilia ?
(i) Production & secretion of mucus
(ii) Movement of molecules & substances away from a certain area/part of the body
For tight junctions, describe their function & what they are composed of.
They connect the membrane of 2 neighbouring cells tightly together in a series of studs appearing as ridges with no extracellular space.
They prevent movement of membrane components between the proteins & lipids
Also prevent passage of molecules across the sheet of cells through the paracellular pathway.
Made up of claudins & occludins
For adhering junctions, what is their function?
They completely encircle each cell providing some stability & binds the cells of a tissue together so that the cytoskeletons of each neighbouring cell meet and join, thus the cells effectively become a functional unit
For desmosomes, what is their function & what are they composed of?
Formed from plaques just below the plasma membrane, bound to cytoskeletal elements.
The plaque is attached to the plaque of another cell, or to the ECM, by proteins which span the intracellular space
V.similar to adhering junctions but they are MORE dense.
Integrins & cadherins are involved
For gap junctions, what are they composed of & what is their function?
Formed from integral membrane proteins called connexons. 6 connexons form a channel between 2 adjacent cells through which water, small molecules, signalling molecules & ions can pass.
When sheets of cells are joined by gap junctions, they can respond to stimuli as a unit rather than individually
What are the 3 main types of carbohydrates?
Describe monosaccharides; What are they composed of? What are the two types? What are the 2 ways they can be detected/tested for?
Typically 3-6 carbons. A carbonyl group & several hydroxyl groups.
Can be aliphatic (straight) or aromatic (cyclic)
Are all reducing sugars so can be tested for using Fehling's reagent. BUT in a clinical setting a glucose oxidase test is used as it is quicker, easier & the colour change is proportional to glucose levels
How are carbohydrates displayed? Explain this mapping. Also name & describe the 2 types of isomers which come along with this method.
Using a Fischer Projection - places the most oxidised group at the TOP (carbonyl group) & chiral carbons at intersection of vertical & horizontal lines.
- the -OH group on the chiral carbon furthest from the top determines whether it is a:
L isomer = -OH on the LEFT side
D isomer = -OH on the RIGHT side
What carbohydrate can the body NOT digest? What is done to overcome this problem?
- it is converted to glucose before being digested
What is Galactosemia? What can it result in?
Lack of the enzyme required for galactose metabolism
Resulting in an accumulation of galactose intermediates & has toxic effects in the liver, brain, kidneys & eyes.
How is a disaccharide formed? Name 3 important disaccharides & state from what they are formed.
By a condensation reaction of 2 monosaccharides, forming a glycosidic bond. This is reversible.
Glucose + Glucose = Maltose
Glucose + Galactose = Lactose
Glucose + Fructose = Sucrose
What are 5 important D type isomers? State WHY they are significant.
D - glyceraldehyde = simplest sugar
D - glucose = most important in diet
D - fructose = sweetest sugar
D - galactose = part of milk sugar
D - ribose = used in RNA
Describe the make-up of lactose. What is a lactose intolerance? Where is this intolerance common?
Disaccharides of beta-D-galactose & either alpha OR beta -D-glucose. Contains a Beta-1,4-glycosidic bond. Is found in MILK.
Lack of lactase enzyme in the SI => lactose passes into the colon & bacteria starts to ferment lactose.
Common in Japan & China as a hereditary condition. Can also arise from injury to the SI.
Describe polysaccharides; What is the most common? What they are typically composed of?
GLYCOGEN - the storage form of glucose. Found mainly in liver & muscle.
Made from multiple glucose units linked by alpha-1,4 & alpha-1,6-glycosidic bonds
What is (i) Starch (ii) Amylose (iii) Amylopectin (iv) Alpha-amylase?
(i) The plant form of the carbohydrate ingested by humans
(ii) The unbranched starch comprised of glucose units (alpha-1,4-linkage)
(iii) The branched form with alpha-1,4-linkage to the alpha-1,6-lilnkage
(iv) secreted by salivary glands
What hydrolyses amylose & amylopectin?
What are the 4 domains of the duties of a doctor?
1. Knowledge, skills & performance
- make the care of your pt the first concern
2. Safety & quality
3. Communication, partnership & teamwork
4. Maintaining trust
Describe fibrous joints, giving examples of where they are found on the body.
Bones separated by fibrous tissue => allowing NO movement
E.g. skull, teeth, IO membrane btween radius & ulna
Describe primary & secondary cartilaginous joints, giving examples of where they are found on the body.
PRIMARY (synchondrosis) = strong fixed joints where bones are separated by hyaline cartilage
E.g. permanent junction btween ribs & costal cartilage
SECONDARY ( symphyses) = strong joint that allows for some LIMITED movement, bones are permanently joined by a fibro-cartilagenous disc that's useful for shock absorption
E.g. intervertebral discs, pubic symphysis
Describe synovial joints, listing the major features. (HINT: there's 6 major features).
The most common type of joint, allowing for free movement. Major Features:
1. Articular Cartilage
- hyaline, low friction, surface with high tensile strength, poor blood supply
2. Fibrous Capsule
- collagen fibres, thickened along lines of stress to form ligaments. May be intrinsic or extrinsic
3. Synovial Membrane
- collagenous tissue that lines the fibrous capsule. Secretes synovial fluid
4. Articular disc (meniscus)
- fibrocartilage. Found in joints w.rotatory movements
- closed sacs lined with synovial membrane & lubricated w.fluid. Found where friction occurs
6. Synovial Sheaths
- specialised bursae that surround tendons where they are subjected to pressure (e.g. hand & foot)
What are the 6 types of synovial joint? List what movements they do & give examples.
- sliding/gliding. Numerous & nearly always small.
- acromioclavicular joint, vertebrae
- Flexion & extension. Uniaxial
- Elbow, ankle
- Abduct, adduct, flex, extend - circumduction also possible. Biaxial.
- CMC at base of 1st digit
- Flex, extend, abduct, adduct. Less circumduction than saddle. Biaxial
- Metacarpophalangeal joints
BALL & SOCKET
- Flex, extend, abduct, adduct, lat&med rotation, circumduction. Multiaxial
- Shoulder, hip
- rotation. Uniaxial
What are the 3 factors which influence joint stability?
1. Shape of the bones
2. Strength & position of the ligaments
3. Tone of the surrounding muscles
What is (i) Depp Fascia (ii) Superficial Fascia?
(i) Divides limbs into compartments. A dense fibrous connective tissue. Surrounds muscles, bone, nerves & BVs.
(ii) thin layer of loose fatty connective tissue underlying the skin, binding it to the parts beneath
What is Antagonist muscle action?
A muscle that opposes the action of another
e.g. biceps & triceps
What is a (i) Ligament (ii) Tendon?
(i) Inelastic BUT flexible. BOTH strengthens joint & limits its movements to certain directions
(ii) Attaches muscle to bone
What is the theory of consequentialism? What is its downfalls?
An action is right if, and only if, it promotes the best consequences.
- the greatest good for the greatest number.
- some actions that lead to the best consequences seem wrong in themselves & can promote certain individuals to be treated unjustly
- also problem of actual.vs.intended consequences
What is the theory of deontology? What is its downfalls?
An action is right if, and only if, it is in accord with a moral rule or principle.
- consequences DO matter
- the decision to decide on which duties to follow & HOW they are ranked (hierarchy) is unclear
What is the theory of virtue ethics? What is its downfalls?
An action is right if, and only if, it is what a virtuous agent would do in the circumstances.
- this may be very culturally specific
- doesn't state HOW virtues are decided upon
What are 3 other common types of ethics?
What are the 4 principles of medical ethics?
1. Respect for autonomy