Topic 10 Flashcards
Define Neoplasia
This is the process of cell growth, in the case for a tumour it happens autonomously and lakes regulatory control over cell growth and division
Cell cycle
Interphase
This phase can take many years and it is the longest in the cell cycle
G1- cell growth, make sure organelles are healthy and functioning well, to prepare for DNA replication
G1 checkpoint- determines if the cells DNA is damaged if it is, it can either enter a non-dividing state, called the G0 phase, where the DNA repair mechanisms try to fix the problem, or the cell can self-destruct in a process called apoptosis
Now, if the cell does get the go-ahead at the G1 checkpoint, it enters the S phase. S stands for “synthesis”, because during this phase, DNA is replicated, so that each daughter cell receives identical copies of the genetic material.
So for each chromosome from G1, an identical copy is created.
The cell enters G2 this is the stage whereby the celll duplicates its organelles so there is enough for two
Steps for mitosis
mnemonic
Please Make Another Two Cells
Prophase- The membrane around the nucleus disintegrates, and the chromosomes condense and become visible under a microscope. Two organelles called centrosomes migrates to opposite poles of thee cell
Metaphase- The chromosomes moves to the centre of the cell, whereby each centrosomes sends spindle fibers and attaches it to the centromere of each chromosome
Anaphase- The spindle fibers are pulled so the two chromatids are seperated
Telophase- This is when a nuclear membrane surrounds the each chromatids, then cytokineses takes place
What proteins are their to control the movement of the different stages
Cyclins are groups of proteins that control the entry and progression of cells through cell cycle.
The Cyclins bind to cyclin-dependent kinases (CDKs)
Define what a Benign tumour
Benign tumours- are composed of well-differentiated cells that resemble the cells of the tissues of origin and are characterized by a slow, progressive rate of growth that may come to a standstill or regress. They are not dangerous however only if they compress or disturb the functions of adjacent structures then they can be dangerous or lead to death
Define what a Malignant tumour is
Malignant neoplasms, which invade and destroy nearby tissue and spread to other parts of the body, tend to grow rapidly and spread widely and have the potential to cause death. Because of their rapid rate of growth, malignant tumors may compress blood vessels and outgrow their blood supply, causing ischemia and tissue injury. Some malignancies secrete hormones or cytokines, enzymes and toxins they can also induce inflammatory response this will effect the healthy and also the malignant tissue
What are the two types of malignant neoplasm
Solid- this are initially confined to a certain organ or tissue.As the growth of the primary solid tumor progresses, cells detach from the original tumor mass, invade the surrounding tissue, and enter the blood and lymph systems to spread to distant sites, a process termed metastasis
Hematologic cancers- These are when the tumour is originally found in the blood
What does loss of differentiation mean
they do not exhibit normal features and properties of differentiated cells and hence are more simi- lar to embryonic cells.
What does Aneuploidy
The cells of undifferentiated tumours have abnormal number of chromosomes
What is the name for the etiological factors for malignant tumours
Cancerogens and they are divided into physical, chemical and biological
What are the Physical factor to cancer
Radiation such as ionising radiation. i.e x-rays, ultrasounds, MRI, CT ultraviolet
What are the chemical cancerogens
Compounds of
Carbon
Nitrgen
PAH products due to incomplete burning.
Polycyclic aromatic hydrocarbons have a local effect when applied to skin
Arsenic, Cobalt nickel
What are the biological cancerogens
Viruses- oncoviruses
What are Endogenous Cancerogens
These are
Steroid hormones bilic acid cholesterol free radicals peroxides derivatives of amino acids tryptophan
What are the stages of neoplasia
Neoplastic transformation/Initiation
describes the exposure of cells to a carcinogenic agent that causes them to be vulnerable to cancer transformation. The carcinogenic agents can be chemical, physical, or biologic al and produce irreversible changes in the genome of a previously normal cell.
Neoplastic promotion
Promotion is the second step that allows for prolific growth of cells triggered by multiple growth factors and chemicals.2 Promotion is reversible if the promoter substance is removed. Cells that have been irreversibly initiated may be promoted even after long latency periods. The latency period varies with the type of agent, the dosage, and the characteris- tics of the target cells. Many chemical carcinogens are called complete carcinogens because they can initiate and promote neoplastic transformation.
Neoplastic Progression
Progression is the last step of the process that manifests when tumor cells acquire malignant phenotypic changes that promote invasiveness, metastatic competence, autonomous growth tendencies, and increased karyotypic instability.
Define Epigenetic Mechanism
changes in the patterns of gene expression without a change in the DNA. Epigenetic mechanisms may “silence” genes, such as tumor suppressor genes, so that even though the gene is present, it is not expressed and a cancer-suppressing protein is not made. One such mechanism of epigenetic silencing is by methylation of the promoter region of the gene, a change that prevents transcription and causes gene inactivity.
Define Anaplasia
This is due to the cells not being able to differentiate and increased multiplication. The morphology of Anaplasia is increased mitosis, loss or partial loss of maturity, presence of a nuleus, the cell shape is round.
Cells such as the mitrochondria becomes smaller and the golgi apparatus changes structure.
What type of energy does anaplasia cells require
due to anaplasia cells constant growth they require energy. They form energy by glycolysis the final result is lactate acid. This is due to the lack of mitochondria and the oxidative enzyme thus increasing the lactic acid build up. This type of energy consumption is similar to embryonic cells
They have more enzymes which are for cellular division.
Protein synthesis for mitosis increases
anaplasia cells have increased water
potassium increases
calcium reduces
electrical conductivity increases
Antigens on anaplasia surface is changed.
In terms of function for malignant cells they tend to ose the normal cellular functions such as secreting gastric juice such as that of stomach cancer. In addition to that they also reduce in the secretion of hormones i.e thyroxin, ADH…
Immunity and cancer
Those who are immunocompromised have a higher chance of obtaining cancer compared to those who are healthy. This is because the immune system is able to fight off the pathogen.
In regard to those who are immunocompromised
the cancer are able to camouflage their own antigens so that the body does not recognise them, have an appearance as a fetal antigen, and they are simplified
