Cell 1 Flashcards
List three cellular constituents
organelles
inclusions
cytosol
Define cytoplasm
Part of the cell external to the nucleus. Also suspends organelles and inclusions
Define cytosol (cytoplasmic matrix)
portion of the cytoplasm without organelles and inclusions
What are inclusions?
nonliving entities found in the cytoplasm and nucleus.
What are some examples of inclusions?
stored food, pigments, crystalline in composition
Are proteins stored in the cytoplasm as inclusions?
no
What are the stored foods in the cytoplasm?
Glycogen and Fat droplets
What cells contain an abundant of glycogen?
liver and striated muscle cells (skeletal and cardiac)
Glycogen can be seen with which stain?
PAS reaction
What is McArdle disease?
myophosphorylase deficiency - glycogen storage disease due to genetic defect in muscle phosphorylase and is specific to skeletal muscle.
Where do you see the accumulations of glycogen in McArdle disease?
sarcolemma (plasma membrane of muscle)
A patient presents to the clinic complaining of cramping during strenuous exercise leading to exercise intolerance. Myoglobin is found to be elevated with exercise, creatine kinase is also elevated, and venous lactate level does not increase with exercise. What is the most likely diagnosis?
McArdle disease
What are examples of fat droplets as stored foods?
adipocytes, hepatocytes, muscle, and steroid-secreting cells
Where do you see lipids accumulation in lipid storage disease?
fatty liver (alcoholic and non-alcoholic)
How do lipids show up in stains usually?
empty light areas (washed out during tissue processing)
Hepatocytes in fatty liver will have what kind of appearance?
signet ring due to fat displacing the nucleus to the cell’s periphery
What are two types of pigments?
exogenous and endogenous
What is responsible for yellow-orange color of white fat?
carotene
What is carotene?
exogenous pigment that is fat soluble. gives an orange colored pigment
What is carotenemia? And is it reversible?
Benign condition that causes yellow pigmentation of the skin. It is reversible.
What is inhaled dust?
exogenous pigment that gets phagocytized by macrophages in the lungs. aka carbon particle
What is anthracosis?
accumulation of carbon particles in lungs and regional lymph nodes. condition is harmless.
Why do tattoos stay on the skin?
Tattoos are exogenous pigments that are stored by macrophages of the dermis
What endogenous pigments can be found in the body?
hemoglobin, hemosiderin, bilirubin, melanin, and lipofuscin
Where are hemoglobin and myoglobin found?
hemoglobin - RBCs
myoglobin - striated muscle fibers
What is cyanosis?
blue pigmented skin
What is hemosiderin?
iron containing pigment
Where are hemosiderin found?
macrophages of the spleen and liver
What is the color of hemosiderin in a H&E stain?
brown
What stain can be used specifically for hemosiderin?
Prussian blue
What is hemosiderosis?
increased deposition of hemosiderin in tissues and organs
Under what conditions do you see hemosiderosis?
- increased absorption of iron in diet
- impaired use of iron by the body
- hemolytic anemias
- transfusions
What is hemochromatosis?
more severe accumulation of iron due to a genetic defect resulting in excessive iron absorption or transfusion
When hemosiderin is found in cardiac cells, what could it be indicative of?
- heart failure cells (macrophages)
- congestive heart failure
What color does bilirubin produce?
yellow-brown pigment
In what conditions do you see elevated levels of bilirubin?
liver and biliary disease, for example
- causes jaundice (yellowing of skin and sclera)
What is another term for jaundice?
icterus
What are the three types of melanin?
eumelanin, neuromelanine, phaeomelanin
What color pigment does eumelanin produce?
brown-black
Where is eumelanin normally found?
membrane-limited granules in the epidermis and pigment layer of retina
Where will you find the nucleus of eumelanin?
supranuclear location - the nucleus is located above the melanin as a protection mechanism for DNA
What two conditions will you see increased production of eumelanin?
in response to UV radiation and in Addison’s disease in response to elevated ACTH
Eumelanin is absent in albinos, why?
absence of tyrosinase
What color pigment does neuromelanin have?
black-brown pigment
Where is neuromelanin found?
neurons
Where is neuromelanin found most abundant at?
most pigmented areas in the brain are the substantia nigra (black substance) and locus coeruleus
What function does neuromelanin have?
putative neuroprotective
Where are the granules limited to in neuromelanin?
membrane-limited granules
What is observed in the nerve cells of Parkinson’s disease?
Depigmentation of dopaminergic cells in nerve cells located in the substantia nigra
Which type of melanin is responsible for red color hair?
phaeomelanin
What is the downside to having red hair?
not protective against UV radiation
What color pigment does lipofuscin have?
brownish-yellow pigment
Where does lipofuscin accumulate?
long-lived cells such as neurons and cardiac and skeletal muscle cells
Accumulation of lipofuscin is a measure of what?
cellular stress
Accumulation of lipofuscin is observed in what type of conditions?
severe malnutrition and cachexia
Inclusions can also be found in organelles where their presence is a feature of disease. Give an example of such condition.
Nuclear inclusions seen with cytomegalovirus infections
What is lipofuscin?
polymer of lipids and phospholipids complexed with proteins
In a H&E stain, a structure is observed to be dark blue and is surrounded by a clear halo, what might this structure be?
intranuclear inclusion body (cytomegalovirus)
Where are crystalline inclusions found?
- Leydig cells (crystal of Reinke)
- Sertoli cells of the testis (inclusion of Charcot-Bottcher)
What organelle separates the cell’s internal environment from its external environment?
Plasmalemma (plasma membrane)
It is an organelle!!
Plasmalemma represents what fraction of the total membrane of a cell?
2-5%
What imaging tool can be used to see plasmalemma?
electron microscopy (it’s only 7.5 to 10nm thick!)
What are the three types of lipids in the lipid bilayer? Which is the most abundant?
Phospholipids (most abundant)
Glycolipids
Cholesterol
What is the function of cholesterol in the lipid bilayer?
strengthens the lipid bilayer and makes it less deformable, thus less permeable to small, water-soluble molecules
What are the two types of proteins found in the lipid bilayer?
peripheral and integral
What are lipid rafts?
small areas of membranes where sphingolipids and cholesterol are chiefly concentrated.
What is the function of lipid rafts?
signaling platform where certain specific signaling proteins aggregate and serve as signals
Some cancer cell types have greater concentrations of cholesterol, this correlates with what?
More lipid rafts
What drug has been shown to reduce raft formation? And what is its mechanism?
Simvastatin, cholesterol inhibitor, induces apoptosis by reducing raft formation
What is down regulated in lipid raft reduction?
cell survival signaling molecule, Akt receptor (protein kinase)
What is the most abundant organelle in hepatocytes?
mitochondria
What part of the cell can flex between soluble and gelatinous in some regions?
cytoplasm (gel/sol phase)
