Tissues of the body L1.1 Flashcards
Define histology
Study of tissues
State the 4 fundamental tissue types
- Epithelial tissue
- Muscle tissue
- Nervous tissue
- Connective (support) tissue
Define tissue
Functional arrangement of cells
State a function of membranes
Allow compartementalisation
State the most prominent cell structure
- Nucleus
State function of nucleus
Stores genomic DNA
Site of mRNA trasncrption
Contains NUCLEOLOS - site of RNA synthesis + initial assembly of ribosomes
State functions of nucleolus
- RNA synthesis
- Initial assembly of ribosomes
Describe the structure of the nucleus
- Nucleolus
- Stores genomic DNA
- Surrounded by nuclear envelope (double membrane) continuous with RER
- Supported by network of intermediate filaments
Which cells have an abundance of RER?
Biosynthetic cells (pancreatic, acinar)
Basophilic RER stains are vert strong with basic dyes (e.g. haematoxylin)
Describe the structure of the RER
Continuous with nuclear envolope
Histology of pancreatic acinar cell clusters
Describe the composition of ribosomes
rRNA
75 distinct proteins
Describe the function of ribosomes
Catalyse protein synthesis
(large (60s) + small (40s) subunits associate when bound to mRNA in order to catalyse protein synthesis
State the function of free polyribosomes (polysomes)
Synthesis of structural, nuclear, peroxisomal, mitochondrial proteins which stay within the cell
State the function of membrane-bound ribosomes
Syntyhesis of membrane lyososomal proteins
Synthesis of proteins to be secreted
Describe the structure of SER
Smooth Endoplasmic Reticulum
Not associated with ribosomes
Where is SER abundant ?
Liver (lipid biosynthesis)
Mammary gland (in lipid biosynthesis)
Ovary
Testis
Adrenal glands (steroidogenesis)
Muscle (storages Ca2+)
Histology of pancreatic acinar cell
State 3 functional parts of golgi apparatus
- Cis face - nuclear facing
- Medial golgi: central
- Trans golgi network
State the role of the specific coat protein within golgi apparatus
Tagged on golgi apparatus
Targets vesicles to correct compartment
Histology of Golgi Apparatus
Histology of Golgi Apparatus
State main types of cell vesicles
- (Cell surface-derived) endocytotic vesicles (e,g, phagocytotic)
2.( Golgi derived) transport + secretory vesicls
3.( ER derived) transport vesicles
- lysosomes
- Peroxisomes
Where are lysosomes derived from?
Golgi Appartus
How is the membrane of the lysosome not dissolved by H+ actively pumped from cytosol into lysosome?
Highly glycosylated membrane proteins
Protect membrane from the action of hydrolytic enzyme - vacuolar ATPase
This enzyme actively pumps H+ across membrane to maintain acidic pH for the acidic hydrolases (nuclease, proteases etc)
State the role of membrane proteins in the membrane of the lysosome
Highly glycosylated membrane proteins
Protect membrane from the action of hydrolytic enzyme - vacuolar ATPase
This enzyme actively pumps H+ across membrane to maintain acidic pH for the acidic hydrolases (nuclease, proteases etc)
What is Autophagy ?
Self-Eating
- Lysosomal breakdown of non-functioning organelles / cellular components
- (Homeostatic process) to prevent accumulation of damaged components in cell
- The digested products are recycled
Describe the process of autophagy
- Organelle engulfed by region of SER to form autophagosome, which fuses with lysosome
Describe how tumour cells use autophagy
To recycle substrates
Therefore, inhibition of autophagy can prevent cancer (inhibts the recycling of substrates)
Histology of phagolyososome
Give an example of a substance that cannot be reused after the autophagy process
Residual bodies
- Remnants of phagolysosomes containing indigestible material (can form lipofuscin granules)
as we age, increased amount of residual bodies in our body
