Pathophysiology (cells and inflammation)

Question 1

What are the 2 main parts of the skin (the integument) and what are the accessory structures?

Answer 1

1. the epidermis- superficial thinner part, composed of epithelial tissue
2. the dermis- deeper thicker part, composed of dense irregular connective tissue

Accessory structures: hair, oil glands, sweat glands, nails, and sensory receptors

Question 2

What are the 5 layers of the skin?

Answer 2

1. stratum basale- deepest layer
2. stratum spinous- provides strength and flexibility
3. stratum granulosum- keratinocytes undergo apoptosis
4. stratum corneum- most superficial layer
5. stratum lucidem- only thick skin between granulosum and corneum

Question 3

What are the 4 main types of cells in the skin?

Answer 3

1. keratinocytes= produce protein keratin
2. melanocytes= produce pigment melanin
3. intraepidermal macrophages (langerhans cells)= involved in immune response
4. tactile epithelial cells= detect touch

Question 4

What is the healing process for an epidermal wound?

Answer 4

-basal cells at the edges of the wound become free from the basement membrane and migrate across the wound in a sheet like manner. This continues until epidermal cells meet each other (contact inhibition) and the wound is closed
-the hormone epidermal growth factor is secreted and this stimulates basal cells to divide and replace the ones that moved into the wound

Question 4

What is a deep wound?

Answer 4

One that extends to the dermis and below, meaning skin healing has to take place in all layers

Question 5

what are the phases of deep wound healing

Answer 5

1. inflammation- blood clot forms, elimination of microbes, preparing for repair
2. migration- clot becomes a scab, epithelial cells migrate to bridge the wound below the scab
3. proliferation- extensive growth of cells below the scab
4. maturation- scab sloughs off once epidermis returns to normal thickness

Question 6

What are pressure ulcers and what are the 3 main causes?

Answer 6

-wounds which involve ischaemic damage (blood flow restricted) to the skin and underlying tissue

3 main causes:
-pressure (weight of body causes capillary occlusion)
-shear (layers of skin are stretched)
-friction (caused when part of body rubs against a surface)

Question 7

What are the different pressure ulcer grades according to European Pressure Ulcer Advisory Panel

Answer 7

grade 1- non-blanching erythema of intact skin

grade 2- a lesion involving a clear blister

grade 3- a lesion involving full thickness skin loss

grade 4- a lesion in which tunnelling is present

Question 8

What is the difference between primary wound intention, secondary wound intention and tertiary wound intention?

Answer 8

Primary intention- wound is clean with little tissue loss, and edges are brought together by stitches, staples, skin glue etc e.g surgical incision

Secondary intention- edges cannot be brought together due to extent of tissue loss. takes a long time to heal and more prone to infection

Tertiary intention- wound edges could be brought together as little tissue loss, but not done immediately due to infection or contamination. Wound closed by suturing

Question 9

What is a superficial burn?

Answer 9

-involves only the epidermis
-mild pain and redness but absence of blisters
-functions of skin not impaired
-healing will take place over a few days

Question 10

What is a partial thickness burn?

Answer 10

-involves damage to the epidermis and dermis
-redness, blisters, oedema and pain
-some functions of skin will be lost
-healing will take a number of weeks and may be scarring

Question 11

What is a deep partial thickness burn?

Answer 11

-damage to the epidermis and deeper into dermis affecting structures
-slow to heal and may involve surgery

Question 12

What is a full thickness burn?

Answer 12

-damage to both the epidermis and dermis which extends to the subcutaneous layers
-loss of most functions of the skin
-always requires reconstructive surgery e.g skin graft

Question 13

What are the 4 different ways bone fractures can be classified?

Answer 13

1. position of bone ends
2. completeness of break
3. orientation of break
4. bone ends penetration of skin

Question 14

What is a compound fracture?

Answer 14

-a bone fracture that is accompanied by breaks in the skin, causing the broken ends of bone to come into contact with the outside environment

Question 15

What is a displaced fracture?

Answer 15

-pieces of bone moved so much that a gap formed around the fracture when the bone breaks

Question 16

What is a green stick fracture?

Answer 16

-a partial fracture where only the cortex and periosteum are interrupted on one side of the bone but remain uninterrupted on the other

Question 17

What is a vertical fracture?

Answer 17

-instead of a horizontal break across the bone, a linear fracture is vertical and parallel to the sides of the bone

Question 18

What is the bone fracture repair process?

Answer 18

1. Hematoma formation (death of some bone cells, pain and swelling)
2. fibrocartilaginous formation
   (granulation tissue fills gap and rejoins fracture)
3. soft callus converts to bony callus
4. bone remodelling
   (compact bone laid, osteoblastic activity occurs)

Question 19

What is a single point mutation?

Answer 19

-involves a change in a single base along the base sequence of a particular gene
-a point mutation can also be a deletion or addition, where one or more bases are deleted or added

Question 20

What are the different categories of genetic diseases and give an example of a disease of this category?

Answer 20

-autosomal dominant
e.g Huntingdon’s disease

-autosomal recessive
e.g sickle cell disease

-sex linked recessive
e.g haemophilia

Question 21

What is epigenetics?

Answer 21

-the term used to refer to factors that influence how genes are expressed within the cells in the body
-this brings about a lasting change in genetic information

Question 22

What are the 3 processes that gene activation and deactivation can occur by?

Answer 22

1. DNA methylation- methyl group is added directly to a cytosine residue that exists in a CpG sequence
2. Histone modification- acetyl and methyl groups are added directly onto histone tails which changes how genes are expressed
3. RNA changes

Question 23

What are the 2 groups of proteins responsible for the progress of cells through various checkpoints of the cell cycle?

Answer 23

Cyclins and Cyclin-dependent kinases (Cdks)

Question 24

What are proto-oncogenes and what do they do? Give some examples

Answer 24

-Normal genes which affect normal cell growth and proliferation but also have the potential to contribute to cancer development if their expression is altered

-they turn the cell on to divide (car accelerator)

-growth factors, receptors, signalling enzymes, transcription factors

Question 25

What are tumour suppressor genes and what do they do? Give some examples

Answer 25

-a family of normal genes that instruct cells to produce proteins that restrain cell growth and division

-They turn cell division off- loss of these proteins allow a cell to grow in an uncontrolled fashion

-like a break pedal that doesn’t work

Question 26

What are DNA repair genes and what do they do?

Answer 26

-code for proteins whose normal function is to correct errors that arise when cells duplicate their DNA prior to cell division

-mutations in DNA repair genes can lead to a failure in repair, which in turn allows subsequent mutations to accumulate

Question 27

What is gene amplification and what effect does it have/ cancers that is causes?

Answer 27

-where a single gene is amplified so there are more copies then there should be in a chromosome
-this means the protein is over expressed and changes the behaviour of the cell
-can be the cause of breast and stomach cancer

Question 28

What is the result of gene mutations if they make too much protein, makes a different protein, or doesn’t make any protein?

Answer 28

-too much protein= alters cell structure
-different protein= alters cell function
-no protein= alters cell behaviour

Question 29

What is chromothripsis?

Answer 29

-one massive genomic rearrangement during a single catastrophic event in the cells history

Question 30

In what ways can genetic mutations can cause alterations in cell division?

Answer 30

-Altering the instructions for cell growth

-Turning off tumor suppressor genes

-Turning on oncogenes

-Altering DNA repair genes

-Causing aneuploidy (a genetic change when chromosomes aren’t separated properly during cell division, resulting in cells with too many or too few chromosomes)

Question 31

What is silencing?

Answer 31

A type of epigenetic modification that regulates gene expression in a cell to prevent the expression of a specific gene