Physiology Knowledge

Question 1

Why don’t blood vessels burst?

Answer 1

Fluid exerts forces on blood vessel walls perpendicularly, blood vessels exert forces back at an equal and opposite direction

Question 2

How do levers in the human body provide mechanical advantage?

Answer 2

Muscles only contract small distances but allow limbs/joints to move further and fast. A small force moved through a large distance is changed to a large force moved through a small distance

Question 3

How do biomaterials take advantage of extension and strain?

Answer 3

Most of our tissues are composites for instance collagen and elastin. Collagen stretch easily until their max length, where the force increases rapidly. Elastin force is proportional to extension. A combination allows for extension with modest force.

Question 4

What is the sequence of events allowing inspiration?

Answer 4

1. Diaphragm descends and the rib cage rises
2. Thoracic cavity vol. increases
3. Lungs are stretched, intrapulmonary volume increases
4. Intrapulmonary pressure drops
5. Air flows down pressure gradient until pressure is 0 and equal to atmospheric pressure

Question 5

Explain the response of the body in the heat and cold?

Answer 5

At a high temperature, the skin heats up. Blood vessels open up and increase the possibility of heat loss. At a low temperature the skin is lower temperature, heat is restricted to essential organs and flow to the periphery is restricted

Question 6

What are some effects of increasing metabolic rate?

Answer 6

Demand for extra energy i.e. food. Higher O2 consumption. Higher CV activity. Rise in temperature of surface and limbs. Higher rate of body cooling i.e. conduction, convection and radiation

Question 7

What is the basic structure of the CV system?

Answer 7

Lungs with deO blood into right side of heart, pumped into lungs, into pulmonary veins, into left side, pumped into systemic arteries, to capillaries, to organs, to systemic veins, to pulmonary arteries, to pulmonary capillaries, to lungs.

Question 8

Explain stressed and unstressed volume.

Answer 8

Unstressed volume is where volume added to the container has no effect on the pressure within the container, then at V0 the volume creates a pressure difference and this increases as it is now within the stressing or excess volume.

Question 9

How does high and low compliance affect stressing volume?

Answer 9

High compliance vessels are less effected by volumes, they change volume easily, and pressure increases more slowly. Low compliance vessels are more effected by volumes, and do not change easily and pressure increases quickly.

Question 10

Right atrial pressure is always equal to…

Answer 10

Cardiac output

Question 11

Vao is…

Answer 11

unstressed volume in arteries

Question 12

Va is…

Answer 12

Volume in the arteries

Question 13

Stressing volume vae is…

Answer 13

va-vao

Question 14

Pressure in the arteries is…

Answer 14

stressing volume/compliance which is vae/ca

Question 15

How is a simple model of a pump with arteries, capillaries, veins and a right atrium a spherical cow?

Answer 15

There are no blood cells, no turbulent flow, resistances and compliances are linear, no pulse flow, less bits

Question 16

How does ultrasound work?

Answer 16

When ultrasound meets a boundary between one medium and another they are partially reflected and partially transmitted, these reflections and their intensities are detected and used to develop an image.

Question 17

Why is it hard to see detail in cells?

Answer 17

It is hard to view cells when they are alive because they may be moving and performing processes
There is low contrast
Narrow focal plane, blurry, need thin sections
Post-mortem cells, autolysis occurs, fixation causes shrinkage and histological processing can cause chemical damage

Question 18

Describe how stains can selectively alter the wavelength of light to discriminate between cell components with different chemical properties.

Answer 18

Depending on the chemical properties of components the stain will bind to different structures and change the colour, causing a contrast between different structures

Question 19

How does specimen processing alter physical and chemical properties of tissues?

Answer 19

Formaldehyde fixation:
Hardens tissue
Cross links nitrogen on proteins
Can perfuse arteries or veins

Question 20

How is fluorescence used to make low contrast structures visible?

Answer 20

A fluorphore replaces a stain and can be bound to a cell component or antibody, some are autofluorescent tissue. By using a fluorescent microscope these structures can then be viewed, a beam splitting mirror allows in only the appropriate wavelengths

Question 21

How are antibodies used to visualised specific components of cells and tissues?

Answer 21

Antibodies bind to specific biomolecules and then by visualising the antibodies we can see those structures. We can see intensity of stain or abundance by visualising atnibody response

Question 22

Explain how confocal microscopy works.

Answer 22

Draw diagram label

Question 23

How are radionucleide sources administered to the patient?

Answer 23

They are combined with pharmaceuticals or other compounds to ensure they are taken up and localised in the relevant organs of the patient.

Question 24

How do radionucleides emit radiation?

Answer 24

Isotropically, which makes localising the source of radiation difficult and inefficient.

Question 25

What are types of nuclear medical applications?

Answer 25

Scintigraphy and gamma cameras using technetium 99m to label metastases
Myocardial perfusion test
Thyroid probe using I-127
SPECT using a gamma camera and many views over 180 or 360 degrees to construct a cross sectional view
PET using beta emitters, detects annihilation events

Question 26

What is radiation therapy and some examples?

Answer 26

Uses ionizing radiation to treat disease. Tumour cells are more susceptible to radiation damage than normal cells It can be delivered via high energy Xray beams, gamma rays from radioactive sources, proton beams, linear accelerators, brachytherapy, hadron therapy