Lecture 2: Cell Pathology Flashcards
Anatomy of a Cell:
- Nucleus
- Cytoplasm:
I. Mitochondria
II. Ribosomes
III. Endoplasmic Reticulum
IV. Golgi Apparatus
V. Lysosome - Plasma Membrane
Nucleus
Contains RNA and DNA arranged together called chromatin (our genetic material)
Contains other proteins
Contains a nucleolus
Where mitosis happens: duplication of these cells
Cytoplasm
The liquid interior of a cell that houses many organelles. Also contains a cytoskeleton that forms scaffolding or framework for the cell.
- Mitochondria
- Ribosomes
- Endoplasmic Reticulum
- Golgi Apparatus
- Lysosome
Cytoplasm - Mitochondria
Involved in the generation of energy by cellular respiration and the formation of adenosine triphosphate (ATP).
Liver and nerve cells require lots of energy so have lots of mitochondria
Cytoplasm - Ribosomes
Composed of small granules of RNA floating freely or attached to the rough endoplasmic reticulum. Involved in protein synthesis (structural proteins and enzymes) so very important for maintenance of basic cell functions.
Cytoplasm - Endoplasmic Reticulum
A meshwork of membranes that are continuous
with the outer plasma membrane on one side and
the nuclear membrane on the other side.
Smooth: catabolism of drugs , hormones (steroids) and other nutrients
Rough: site of protein synthesis
Cytoplasm - Golgi Apparatus
Composed of tubules and cisternae adjacent to nucleus. Proteins produced in the smooth endoplasmic reticulum (SER) pass through the golgi apparatus where they are biochemically modified and then packaged into lysosomes
Cytoplasm - Lysosome
Membrane bound digestive enzymes called acid hydrolases are packaged into this organelle. They originate in the golgi apparatus.
Cytoplasm - Cytoskeleton
Lies in between the organelles (bào quan) and in the cytoplasm (tế bào chất
Maintains cell shape and helps cell adapt to mechanical pressure.
Helpful in movement of the cell.
Composed of a network of three differing filaments:
- Microfilaments-actin and myosin
- Microtubules-tubulin, also help form mitotic spindles during cell division
- Intermediate filaments-variable
Plasma Membrane
Forms the outer surface of the cell. It is composed of proteins, lipids, carbohydrates all arranged in a complex bilayer. It is a living structure maintained constantly and requiring energy (ATP).
Normal Cell Function:
Chemical signalling occurs through interaction with other cells in the body.
- Autocrine stimulation: self stimulation
- Paracrine stimulation: from one cell to another
- Endocrine stimulation: from somewhere else in the body via the bloodstream
Homeostasis: definition
The state of balance in a cell or equilibrium “steady state”.
Balance between all things that affect the cell like pressures, nutrients, oxygen, carbon dioxide, wastes, hormones and essential minerals.
The cell functions at optimum when in equilibrium.
Cell Functions in response to injury:
If the changes in the cell are within the normal range of homeostasis the changes are reversible. If the changes are too great they are irreversible.
Cells can change in size, in number and in their form or shape.
Reversible Cell Injury
Typically mild and short lived.
Reversible cell injury causes:
- decreased energy production
- decreased protein synthesis
- increased autophagy or “self eating”.
These changes are minor so are reversible.
Irreversible Cell Injury
Typically more severe and longer lasting damage.
The damage is greater, so homeostasis can not be achieved.
Structural changes in the cell:
- Loss of cell integrity and the cell membrane ruptures and the contents of the cell is released into the extracellular fluid, the cell dies.
- Mitochondria production has fallen below the essential minimum and can not be restored, the cell dies
Causes of Cell Injury
- Hypoxia (less oxygen) & anoxia (no oxygen)
- Ischemia & deprivation thiếu thốn of essential nutrients
- Toxic injury
- Microbial pathogens Vi sinh vật gây bệnh
- Mediators of inflammatory & immune reactions (inappropriate immune response)
- Genetic & metabolic disturbances rối loạn trao đổi chất (genetic error or enzyme defects
Causes of Cell Injury:
- Causes of Cell Injury: Lack of Oxygen
Hypoxia - reduced amount of oxygen available
Anoxia - no amount of oxygen available
Most common cause of cell injury. Short term oxygen deprivation is often reversible, but long term is not. Oxygen is essential for cellular respiration, with no oxygen there is no energy production (ATP) and the cell dies.
Tissues most affected: brain, heart, kidney
Tissues least affected: connective tissues
Causes of Cell Injury:
- Ischemia & deprivation of essential nutrients thiếu thốn
This is a restriction in blood supply that causes loss of oxygen and also all other nutrients.
Causes of Cell Injury:
- Toxic injury
Direct toxic effect on cells.
eg/ heavy metals like Mercury inactivate enzymes
Indirect toxic effect on cells: it needs to be metabolized first
eg/ dry cleaning chemicals: produces free radicals and damages cell membranes
Many pharmaceutical drugs have toxic effects in large doses and may be lethal
eg/ each drug affects cells and organs differently
Causes of Cell Injury:
- Microbial pathogens
Bacteria often produce toxins that may inhibit many cell functions.
eg/ food poisoning happens when endotoxins produced by spoiled food become toxic to our gastrointestinal cells causing nausea, vomiting and diarrhea.
Viruses invade cells and kill from within, disturbing many cellular functions, if they don’t kill the cells they mark the cells as “invaded” and the immune system comes along and kills the invaded cell for the virus.
Causes of Cell Injury;
- Mediators of inflammatory & immune reactions
Cytokines sự phân bào, interferons and the complement system all may injure cells. They are produced by the body in response to infection or other immune reactions, but may go too far and kill the body’s own cells