Pathophysiology (cells and inflammation) Flashcards
What are the 2 main parts of the skin (the integument) and what are the accessory structures?
- the epidermis- superficial thinner part, composed of epithelial tissue
- the dermis- deeper thicker part, composed of dense irregular connective tissue
Accessory structures: hair, oil glands, sweat glands, nails, and sensory receptors
What are the 5 layers of the skin?
- stratum basale- deepest layer
- stratum spinous- provides strength and flexibility
- stratum granulosum- keratinocytes undergo apoptosis
- stratum corneum- most superficial layer
- stratum lucidem- only thick skin between granulosum and corneum
What are the 4 main types of cells in the skin?
- keratinocytes= produce protein keratin
- melanocytes= produce pigment melanin
- intraepidermal macrophages (langerhans cells)= involved in immune response
- tactile epithelial cells= detect touch
What is the healing process for an epidermal wound?
-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
What is a deep wound?
One that extends to the dermis and below, meaning skin healing has to take place in all layers
what are the phases of deep wound healing
- inflammation- blood clot forms, elimination of microbes, preparing for repair
- migration- clot becomes a scab, epithelial cells migrate to bridge the wound below the scab
- proliferation- extensive growth of cells below the scab
- maturation- scab sloughs off once epidermis returns to normal thickness
What are pressure ulcers and what are the 3 main causes?
-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)
What are the different pressure ulcer grades according to European Pressure Ulcer Advisory Panel
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
What is the difference between primary wound intention, secondary wound intention and tertiary wound intention?
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
What is a superficial burn?
-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
What is a partial thickness burn?
-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
What is a deep partial thickness burn?
-damage to the epidermis and deeper into dermis affecting structures
-slow to heal and may involve surgery
What is a full thickness burn?
-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
What are the 4 different ways bone fractures can be classified?
- position of bone ends
- completeness of break
- orientation of break
- bone ends penetration of skin
What is a compound fracture?
-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
What is a displaced fracture?
-pieces of bone moved so much that a gap formed around the fracture when the bone breaks
What is a green stick fracture?
-a partial fracture where only the cortex and periosteum are interrupted on one side of the bone but remain uninterrupted on the other
What is a vertical fracture?
-instead of a horizontal break across the bone, a linear fracture is vertical and parallel to the sides of the bone
What is the bone fracture repair process?
- Hematoma formation (death of some bone cells, pain and swelling)
- fibrocartilaginous formation
(granulation tissue fills gap and rejoins fracture) - soft callus converts to bony callus
- bone remodelling
(compact bone laid, osteoblastic activity occurs)
What is a single point mutation?
-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
What are the different categories of genetic diseases and give an example of a disease of this category?
-autosomal dominant
e.g Huntingdon’s disease
-autosomal recessive
e.g sickle cell disease
-sex linked recessive
e.g haemophilia
What is epigenetics?
-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
What are the 3 processes that gene activation and deactivation can occur by?
- DNA methylation- methyl group is added directly to a cytosine residue that exists in a CpG sequence
- Histone modification- acetyl and methyl groups are added directly onto histone tails which changes how genes are expressed
- RNA changes
What are the 2 groups of proteins responsible for the progress of cells through various checkpoints of the cell cycle?
Cyclins and Cyclin-dependent kinases (Cdks)
What are proto-oncogenes and what do they do? Give some examples
-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
What are tumour suppressor genes and what do they do? Give some examples
-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
What are DNA repair genes and what do they do?
-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
What is gene amplification and what effect does it have/ cancers that is causes?
-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
What is the result of gene mutations if they make too much protein, makes a different protein, or doesn’t make any protein?
-too much protein= alters cell structure
-different protein= alters cell function
-no protein= alters cell behaviour
What is chromothripsis?
-one massive genomic rearrangement during a single catastrophic event in the cells history
In what ways can genetic mutations can cause alterations in cell division?
-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)
What is silencing?
A type of epigenetic modification that regulates gene expression in a cell to prevent the expression of a specific gene
