IMMS Flashcards
What colour do nerve cells stain?
Shades of brown
What cells are in the spinal cord?
Within the spinal cord are some motor neurons. These are some of the largest cells in the body (see image below).
What do motor neurones show?
Motor neurons in the ventral horn of the spinal cord showing axons or dendrites arising from them. These are described as multipolar cells because when seen whole they have more than two processes.
What are lymphocytes like?
- among the smallest nucleated cells in the body
- circulate in the blood and are found in large numbers in organs such as in lymph nodes, the tonsils and the thymus gland
- Many tissues also have lymph nodules full of lymphocytes within their fabric.
What can the lymph node be stained with?
Part of a lymph node stained with H&E showing many small lymphocytes.
What does the nucleus of lymph nodes stain?
The nuclei of these cells stain dark blue but their cytoplasm is very scanty
Which dyes are used to stain?
two dyes, haematoxylin and eosin. This is often referred to as H&E staining.
What colour does H&E stain?
Haematoxylin stains cell nuclei blue and eosin stains cell cytoplasm and many extracellular fibres pink.
What does the dark blue stain of a cell nucleus show?
The cell nucleus that stains dark blue with haematoxylin can tell you a lot about the metabolic activity of a cell.
What does the size of the cell nucleus show?
A large cell nucleus often denotes a highly active cell whereas a thin or small nucleus in which it is difficult to see any of the infrastructure often denotes a relatively dormant cell.
What is thyroid histological image like?
Image shows:
• roughly circular structures (in 2D – spheres in 3D)
•Each lined by a single layer of cuboidal/columnar epithelial cells
•Centre of each structure is acellular, filled with a homogenous eosinophilic material
What are tissue slices size?
Thinner than a cell
What is the most common dye?
Haematoxylin and Eosin (H&E).
Many extra cellular fibres e.g. collagen,elastic stain pink
What does not stain?
Watery extra-cellular jelly does not stain at all
What are the other stain?
PAS - sugars
Van Gieson - elastic
Trichromatic - 3 types of cell
Alcian blue - mucins
What are the size of lymphocytes?
Small cells – lymphocytes about 10 micrometres in diameter, with very little cytoplasm
What are the size of motor neurones?
Large cells – motor neurons 100 micrometres wide with axons up to 1 meter in length
What are the shapes of cells?
Rounded
Polygonal
Fusiform
Squamous (flattened)
Cuboidal
Columnar
How does metabolic activity relate to size of cell?
Inactive/dormant cells are smaller
Metabolically active cells often have nucleoli
What cells last days, months, years?
Days: lining of the gut
Months: lots of tissues –
blood
skin
connective tissues
Years: bone and tendons
Nearly whole life: (limited regeneration) skeletal muscle
Whole life: nerves and brain
cardiac (heart) muscle
germ cells
What does the nucleus contain?
Euchromatin
Heterochromatin
Nucleolus
Double nuclear membrane
DNA
What occurs at the nucleolus?
1-3 microns in diameter
Site of ribosomal RNA formation
What is the mitochondria like?
Powerhouses of the cell
Site of oxidative phosphorylation
Have their own DNA
Double membrane – inner membrane is
What occurs at the outer and inner membrane of the mitochondria?
Outer:Lipid synthesis
FA metabolism
Inner: Respiratory chain
ATP production
What occurs in the matrix and intramembranous space of the mitochondria?
Matrix - TCA (Krebs’) cycle
Intermembranous space - Nucleotide phosphorylation (ADP to ATP)
What occurs in the matrix and intramembranous space of the mitochondria?
Matrix - TCA (Krebs’) cycle
Intermembranous space - Nucleotide phosphorylation (ADP to ATP)
What occurs at the RER?
Site of protein synthesis
Highly folded flattened membrane sheets
What occurs at the SER?
Site of membrane lipid synthesis
Processes synthesised proteins
Highly folded flattened membrane sheets
What occurs at the Golgi apparatus?
Parallel stacks of membrane
Processes macromolecules synthesised in the ER
Particularly prominent in Plasma cells – seen as a perinuclear ‘hoff’
What are the faces of the Golgi apparatus?
Cis face
- nuclear-facing receives transport vesicles from SER phosphorylates some proteins
Trans Golgi network
Proteolysis
Sorts macromolecules into vesicles which bud from the surface
Medial Golgi
Central part
Forms complex oligosaccharides by adding sugars to lipid and peptides
What are vesicles?
Very small spherical membrane-bound organelles used for transport, storage and exchanging cell membrane between compartments
What are the types of vesicles?
Several types:
Cell-surface derived pinocytotic and phagocytotic vesicles
Golgi-derived transport vesicles
ER-derived transport vesicles
Lysosomes
Peroxisomes
What are lysosomes like?
Derived from Golgi apparatus
H+-ATPase on membrane creates low internal pH (pH 5)
Contain acid hydrolases that degrade proteins
Initial hydrolase vesicles fuse with endosomes with the correct membrane proteins to produce endolysosomes
What are perioxosomes like?
Small (0.5-1.0 microns) membrane-bound organelles containing enzymes which oxidise long-chain fatty acids
What is the cytoskeleton composed of?
Plasma membrane
Microfilaments
Mitochondrion
Intermediate filaments
Endoplasmic reticulum
Microtubule
Vesicle
What are the microfilaments like in the cytoskeleton?
Microfilaments - 5nm diameter ACTIN
Globular G-actin polymerises into filamentous F-actin
Forms a bracing mesh (cell cortex) on the inner surface of the cell membrane
What are the micro tubules in the cytoskeleton like?
Microtubules - 25nm diameter TUBULIN proteins
All cells except erythrocytes
Made of α- and β-tubulin which arrange in groups of 13 to form hollow tubes
What are the micro tubules in the cytoskeleton like?
Microtubules - 25nm diameter TUBULIN proteins
All cells except erythrocytes
Made of α- and β-tubulin which arrange in groups of 13 to form hollow tubes
What is the intermediate filaments in the cytoskeleton like?
Intermediate filaments - 10nm diameter - 6 types of protein
- Anchored to transmembrane proteins
- Spread tensile forces through tissues
- Specific functions generally not known
- Useful to tell one cell type from another
What are the localisation of intermediate filaments in the cytoskeleton?
Cytokeratins - Epithelial cells
Desmin - Myocytes
Glial fibrillary acidic protein - Astrocytic glial cells
Neurofilament protein - Neurons
Nuclear laminin - Nuclei of all cells
Vimentin - Mesodermal cells
What are the localisation of intermediate filaments in the cytoskeleton?
Cytokeratins - Epithelial cells
Desmin - Myocytes
Glial fibrillary acidic protein - Astrocytic glial cells
Neurofilament protein - Neurons
Nuclear laminin - Nuclei of all cells
Vimentin - Mesodermal cells
What are lipofuscin?
Lipofuscin
Membrane-bound orange-brown pigment
Peroxidation of lipids in older cells
Common in heart and liver
What are lipids and glycogen like?
Lipid
Non-membrane-bound vacuoles
Appear as empty space as dissolve in processing
Adipocytes and liver
Glycogen
CHO polymer in cytoplasm
Normally only seen on electron microscopy
Accumulates in some cells & diseases
What is the composition of tissues?
Cells
Interstitial fluid
water
salts in solution
peptides and proteins (e.g. plasma proteins, hormones, etc.)
Extracellular material
Fibrillary proteins – e.g. tendons
Glycosaminoglycan jelly
inorganic salts as solids
What are the types of tissue?
Epithelia - protection, absorption, secretion
Muscle - smooth, skeletal, heart
Supporting tissues - cartilage, bone, tendons, blood
Nerves - brain, peripheral, visceral
Germ cells - ova, sperm
What are epithelia?
Epithelia comprise a cohesive sheet of cells, with one or more layers, resting on a basement membrane.