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General - Histology 🔬 > L1: Membranous cellular organelles > Flashcards

L1: Membranous cellular organelles Flashcards

1
Q

What are the parts of the cell?

A

1) Cell membrane

2) Cytoplasm - cytosol - cytoplasmic matrix

3) Cell organelles

4) Cell inclusion

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2
Q

What is cell membrane?

A

It is a membrane that surrounds cell and controls the passage of substances in and out of the cell.

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3
Q

How is the cell membrane seen under microscopes?

A

-It can’t be seen under light microscope but seen under electron microscope as tri laminar structure with two electron dense layers surrounding a electron lucent layer. (They are called unit membranes)

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4
Q

What is cell membrane composed of chemically?

A

Proteins-lipids-Carbs.

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5
Q

What is the role of lipids in the cell membrane?

A

-It forms a double layer of phospholipids which consist of hydrophilic polar head and hydrophobic non-polar tail which act as passage for lipid soluble substances

-Cholesterol which is found in the cytoplasmic side of the bilayer.

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6
Q

What is the role of proteins in cell membrane?

A

Integral protein: which play a role in the passage of water soluble substances.

Peripheral proteins

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7
Q

What is the role of carbohydrates in cell membrane?

A

It forms glycocalyx which is glycolipids and glycoproteins.

And it is well developed and thick in small intestine.

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8
Q

What is the func. Of cell membrane?

A

Keep the composition of the cell.

Bulk transport (Exocytosis) (Endocytosis)
(Pino=Liquid) (Phago=Solid).

Cell coat (Attachment to other cells - Cell recognition - Immunity- Receptors )

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9
Q

What is the mitochondria?

A

-It is the powerhouse of the cell as it produces ATP and it may reach 1000 in number like in liver cells

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10
Q

How is the mitochondria seen under Light microscope?

A

-It isn’t seen by LM except by using iron H which gives dark blue color or by using janus green B which gives green color or histochemically by using succinic dehydrogenase activity.

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11
Q

How is the mitochondria seen under EM?

A
  • it can be seen by EM and it appears as double membrane vesicle in which the outer membrane is smooth and allows the passage of small molecules and ions where the inner membrane is folded into the matrix, these folds are called cristae or shelves.

The inner membrane contains electron transport and respiratory enzyme and by negative stain it shows elementary particles which are sites for phosphorylation enzymes.

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12
Q

What is the matrix?

A

-It is the substance enclosed by the inner membrane and it is more electron dense than the cytoplasm where it contains matrix granuales that are rich in Ca and Mg cations and are electron dense, these granuales contain citric acid cycle(krebs) enzymes and mitochondrial DNA and RNA

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13
Q

What is the func. Of mitochondria?

A

-Production of ATP for cell use.
-Has DNA and RNA to inc. in No. when needed.
-plays an imp. Role in B-Ox. Of short chain fatty acids.

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14
Q

What is the endoplasmic reticulum?

A

-It is a system of flattened membrane bounded, anastomosing and inter-communicating narrow tubules and cisternae.

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15
Q

What is the site of rEM?

A

In protein secreting cells like plasma cells and pancreas

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16
Q

How is rEM seen under LM and EM?

A

LM:basophilic due to ribosomes.

EM: parallel flattened membranous cisternae and the cytoplasmic surface is rough due to ribosomes.

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17
Q

How is sEM seen under EM and LM?

A

LM: can’t be seen
EM: smooth communicating narrow tubules with no ribosome

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18
Q

What is the site of sEM?

A

-It is found in lipid forming cells like liver cells.

19
Q

What is the func of rEM?

A

It is responsible for glycosylation of proteins, segregation and packaging and transferring to golgi body as transfer vesicles.

20
Q

What is the func of sEM?

A

-Synthesis of lipids.
-Play a role in muscle contraction.(store ca in skeletal muscles)
-Breaking of glycogen.
-Detoxification of certain drugs and hormones in the liver.

21
Q

what is the Golgi apparatus?

A

It is a membranous organelle. Plays an important role in the secretory system of the cells.

22
Q

how is Golgi apparatus seen under LM?

A

the area occupied by the Golgi apparatus appears unstained. It is called a Negative Golgi image. demonstrated by (silver) stain &appears as a brown network.

23
Q

How is golgi body seen under EM?

A

4-10 saccules (flattened membranous cisternae) piled one above the other forming a stack. Each saccule is narrow at its central part and wide at its periphery. Each stack has a concave surface called mature face or trans face

convex surface called immature face, cis face, or forming face.

Micro-vesicles (transfer vesicles): They are tiny vesicles present at the immature
face. They originate by budding from the rER.
Macro-vesicles (secretory vesicles): large in size pinched out from the mature face
of Golgi stack, migrate to the cell membrane, fuse with it and discharge their
content by exocytosis or Remain in the cell as lysosomes

24
Q

What is the function of the Golgi apparatus?

A
  1. Concentrates & modifies proteins by adding (carbohydrate or sulfates).
  2. It involves in storage, modification, and packaging of excretory products.
  3. It makes lysosomes.
  4. recycling re-usable membrane and maintaining the cell membrane and cell coat in a good condition
25
Q

what are the lysosomes?

A

membranous organelles contain a large variety of acid hydrolases for intra-cytoplasmic digestion.

26
Q

what are the types of lysosomes?

A

primary and secondary.

27
Q

what are primary lysosomes?

A

They are spherical flattened membrane-bounded vesicles filled with hydrolytic enzymes, they have moderate electron-dense granular core and they are smaller, homogenous, and not yer engaged in intra-cytoplasmic digestion.

28
Q

what are secondary lysosomes?

A

They are spherical flattened membrane-bounded vesicles with hydrolytic enzymes, they have heterogenous electron-dense core and they are larger and engaged in intra-cytoplasmic digestion.

29
Q

what is the result of fusion of primary lysosome with phagosome?

A

heterolysosome

30
Q

what is the result of the fusion of primary lysosome with dead organelles?

A

autophagic vacoule

31
Q

what is the result of the fusion of the primary lysosome with pinocytotic vesicles?

A

multi-vesicular body

32
Q

what happens after the turning of primary lysosome into secondary one?

A

it digests these bodies with enzymes then the remaining undigested part is called the residual body.

33
Q

what is the fate of heterolysosome?

A

It will be expelled to the outside by exocytosis.

34
Q

what is the fate of autophagic cells?

A

accumulate in the cells of: liver, heart and nerve cells as lipofuscin pigment (wear and tear pigment)

35
Q

what is the fate of multi-vesicular vesicles?

A

Unknown

36
Q

what happens after death concerning lysosomes?

A

After death, anoxia increases the lysosomal permeability. The hydrolytic enzymes leak to the cytoplasm and digest it (Post mortem degeneration and autolysis).

37
Q

what are the functions of lysosomes?

A
  1. Digestion of nutrients within the cell
  2. Defensive
  3. Removal of old organelles
  4. Change of inactive hormones to active ones
  5. Help sperm to penetrate the ovum
38
Q

what happens in case of congenital abnormal function or deficiency in one of the lysosomal enzymes?

A

Impair the function of the cell as a result of the accumulation of certain materials.

39
Q

what are lysosomal storage diseases?

A
  1. Tay Sach’s syndrome.
  2. Gaucher disease.
  3. Gout.
40
Q

what are peroxisomes and microbodies?

A

they are tiny spherical membrane-bounded vesicles.

41
Q

what do peroxisomes contain?

A

Contains:
Hydroxy acid oxidase.
D-amino acid oxidase
Uricase (in rodents only)
catalase enzyme converts H2O2 → H2O + O2

42
Q

how are peroxisomes seen under LM?

A

LM: H&E Cannot be identified.
Histochemical: for catalase enzyme.

43
Q

How are peroxisomes seen under EM?

A

EM:
a-In human: membrane-bounded vesicles containing a homogenous electron-dense granular material.

b- In rodents: possess an electron-dense semicrystalline (nucloid) core rich in uricase
enzyme.

44
Q

what is the function of peroxisomes?

A

1-Segregate the developing H2O2 and protect the cell from its damaging effect.
2. Important for the formation of bile acids.
3. B-oxidation of long-chain fatty acids.
4. Play role in the metabolism of alcohol.

General - Histology 🔬 (8 decks)

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