Session 7 Lecture Notes Flashcards
What genes regulate normal cell proliferation?
Proto-oncogenes
What 4 effects can a chemical signal have on a cell?
- Survive
- Divide - enter the cell cycle
- Differentiate
- Apoptosis
What part of the cell cycle can you see under a light microscope?
Mitosis and cytokinesis (NOT interphase)
Can cells with damaged DNA normally replicate and why?
NO
Because there are checkpoints during the cell cycle that check for mutations etc
2 important checkpoints are end of G1 and end of G2
The most important checkpoint is the R checkpoint
What is the most commonly altered checkpoint in cancer cells?
The R checkpoint (when cells make it past this they are able to replicate - the point of no return)
If a faulty cell activates a checkpoint what protein moves it into apoptosis?
p53
What enzymes and proteins are responsible for regulating the cell cycle?
Cyclin - dependent kinases (enzymes) are activated when bound by certain cyclins (proteins)
What action does CDK do when bound by its correct cyclin?
It phosphorylates its target protein (substrate) by adding a phosphate from ATP to stretches of AAs
How many times can a cell divide if telomerase doesn’t exist?
61.3 times (the telomere shortens each time the cell divides)
What is hyperplasia?
Cells increase in NUMBER which leads to an increase in tissue or organ size
What is hypertrophy?
Cells increase in SIZE which leads to an increase in tissue or organ size
What is atrophy?
Cells becomes SMALLER which leads to the organ or tissue shrinking in size
What is metaplasia?
Cells are replaced by a different cell type
This is because STEM CELLS that produced one line of cells switch to another line (the cell itself DOES NOT switch)
What 2 types of tissue can hyperplasia occur in?
Labile and stabile tissue
Give 2 examples of pathological hyperplasia
- Eczema
2. Goitre (due to iodine deficiency)
In which type of tissue can hypertrophy occur?
Labile, stabile and especially permanent
Give 2 examples of physiological hypertrophy
- Skeletal muscle
2. Pregnant uterus
What is compensatory hypertrophy?
Damage to either:
- one of a pair of organs (eg a kidney)
- damage to part of a single organ
Which causes the remainder to enlarge to compensate
There are many examples of pathological atrophy - name some
- Reduced functional demand/workload (atrophy of disuse)
- Loss of innervation (denervation atrophy)
- Inadequate blood supply
- Inadequate nutrition
- Loss of endocrine stimuli
- Persistent injury eg polymyositis (inflammation of muscle)
- Aging (senile atrophy)
- Pressure eg tissue around an enlarging brain
Give an example of atrophy of extracellular matrix
Osteoporosis (lack of bone substance i.e. losing the bone matrix)
In which cells types does metaplasia usually occur?
Labile or stabile tissue
Does metaplasia predispose to cancer?
Yes it can in some cases
It can be a prelude to dysplasia and cancer
What is aplasia?
Complete failure of an organ or tissue to develop (it is an embryonic developmental disorder)
It can also be used to describe an organ whose cells have ceased to proliferate
What is hypoplasia?
Underdevelopment or incomplete development of tissue or organ at embryonic stage (inadequate cell number)
What is involution?
Normal programmed shrinkage of an organ (overlaps in some way with atrophy where cells cease to proliferate)
What is reconstitution?
Can this occur in humans?
Replacement of a lost part of the body
The only time this has been seen is when a child under the age of 4.5 years loses part of the finger - it can grow back
What is atresia?
An imperforation of an opening (eg closed anus)
What is dysplasia?
Abnormal maturation of cells within a tissue (often a pre-cancerous condition)
Name some complications of a head injury
Raised intracranial pressure
Infection (in a fracture or penetrating wound)
Neurological defects
What is a pnuemothorax? What injury could cause this?
Air in the pleural cavity
Could be caused by a rib fracture
What is a haemothorax?
What injury could cause this?
Blood in the pleural cavity
Often caused by a rib fracture (where intercostal arteries are particularly susceptible)
What is a tension pneumothorax?
Air gets into the pleural cavity
Every time the lung expands more air gets into the pleural cavity
Gradually the pressure builds up and pushes the mediastinum over
What organs could be affected in abdominal injuries?
- spleen
- liver
- pancreas
- small intestines
How are burns calculated?
Rule of 9s Every section of the body is 9% Head Chest Abdomen Upper back Lower back Front left leg Back left leg Front right leg Back right leg Left arm (4.5% for front and back) Right arm (4.5% for front and back Genitals - 1%
What systemic effects are seen following burns at 30% surface area?
- Release of inflammatory mediators such as cytokines
- Increased vascular permeability = loss of fluid and proteins
- Myocardial contractility decreased leading to hypotension and end organ hypoperfusion
- Respiratory changes
- Metabolic changes (metabolic rate hugely increases)
- Down regulation of immune system
What is systemic inflammatory response syndrome?
SIRS must have 2 of the following:
- high or low temp
- heart rate over 90 BPM
- high respiratory rate
- high or low WBC count
How is sepsis different to SIRS?
In sepsis there needs to be a site of infection
