Histology Flashcards
What is euchromatin?
DNA actively undergoing transcription
What is heterochromatin?
DNA that is condensed and not undergoing transcription
What is the rough ER coated with?
Ribosomes
What happens at the smooth ER?
Site of lipid synthesis
What are inclusions?
Components which are synthesised by a cell e.g. pigments or lipid droplets
What are microfilaments composed of?
Actin
What is the role of a cellular junction?
To link individual cells together to form a functional unit
What do occluding (tight) junctions do?
Link cells to form a diffusion barrier
What are the two types of anchoring junctions?
Adhering and desmosomes
What do adherent junctions do?
Link submembrane actin bundles of adjacent cells
What do desmosomes do?
Link submembrane intermediate filaments
Where are desmosomes common?
Skin
What do communicating (gap) junctions do?
Allow movement of molecules through adjacent cells
What is the combination of dyes most commonly used?`
Haematoxylin and eosin
What type of dye is haematoxylin and what does this have affinity for?
Basic dye- has affinity for acid molecules and stains them blue/purple
What type of dye is eosin and what does this have affinity for?
Acidic dye- has affinity for basic molecules and stains them pink
What are the 4 main tissue types?
Epithelium, connective, muscle and nervous
Where is epithelia found and what can it form?
Surface of body and lining hollow organs- forms glands
What does muscle tissue do?
Generates force by contracting
What does nervous tissue allow?
Rapid communication between body parts
What do all epithelial cells have at their basal surface?
Basal lamina to which other cells are attached
Are epithelial cells vascularised?
No
How do nutrients enter epithelial cells?
Diffusion through basal lamina
Are epithelial cells polarised or not?
Yes
What are the 3 different shapes of epithelial cells?
Squamous (flattened), cuboidal and columnar
What do simple, stratified and pseudostratified epithelia mean?
Simple- 1 layer
Stratified- 2+ layers
Pseudostratified- looks like more layers but all are in contact with basal lamina
What is prominent microvilli on epithelial cells known as?
Brush border
What are cell surface specialisations on epithelia?
Microvilli, cilia, keratin
What are goblet cells?
Single cell mucus glands
What does glandular epithelia produce?
Secretory hormones
Where are substances secreted out of endocrine glands?
Basal end through the vascular system
What is a name for endocrine glands?
Ductless glands
Where are substances secreted out of exocrine glands?
Towards the apical end into a lumen, duct or body surface
What is a name for exocrine glands?
Ducted glands
What are the different types of connective tissue?
Hard, soft and blood/lymph
Where is soft connective tissue found?
Tendons, ligaments, mesentery, dermis
Where is hard connective tissue found?
Bone and cartilage
What are the two types of soft connective tissue?
Loose or dense
What are the types of dense connective tissue?
Aligned (tendon)
Irregular (dermis)
Regarding collagen
How does cartilage receive nutrients since it is avascular?
Adjacent tissues through diffusion
What are the 3 types of hard connective tissue?
Hyaline, elastic and fibrocartilage
What is the most common type of hard connective tissue and where is it found?
Hyaline- tracheal rings, costal cartilage and epiphyseal growth plates
What type of bone is the outer shell and what does this make up?
Cortical bone, makes up the shaft (diaphysis)
What does the cancellous or trabecular bone make up?
Ends of bone (epiphysis)
What are the 3 major types of muscle?
Skeletal, smooth and cardiac
Where is smooth muscle predominantly sound?
Organs
How would you describe skeletal muscle?
giant, striated, multi-nucleated, cylindrical cell
Where is the nucleus located in skeletal muscle?
Peripheries
What is the sarcolemma?
Cell membrane of muscle cells
Does cardiac muscle have striations?
Yes but not as prominent
Is cardiac muscle multi-nucleated?
No
What does nervous tissue consist of?
Neurones and glia
What are glia?
Support cells
What is nervous tissue surrounded by?
A coat of connective tissue
What are astrocytes?
Glia which support and aid ion transport
What are oligodendrocytes?
Glia which produce myelin
What are microglia?
Glia which provide immune surveillance
Which types of secreting cells of salivary glands stain intensely and which stain a little amount?
Serous secreting- stain intensely
Mucous secreting- little stain
What type of ducts are found in salivary glands, and what do these contain lots of?
Straited ducts with lots of mitochondria
Where in the GI tract is non-keratinised stratified squamous epithelium found and what is the function of this?
Oral cavity, pharynx, oesophagus and anal canal- this is protective
What type of epithelium is found in the stomach?
Simple columnar epithelium with extensive tubular glands- secretory
What type of epithelium is found in the small intestine?
Simple columnar epithelium with villi and tubular glands- absorptive
What type of epithelium is found in the large intestine?
Simple columnar epithelium with tubular glands- protective and absorptive
In the large intestine, the longitudinal smooth muscle is not continuous. How would it be described?
Found in 3 muscular strips known as teniae coli
Where do most of the neurones of the GI tract exist?
Between the two muscle layers which make up the muscularis externa
What two parts produce the mucus which traps particles and takes them out of the airway?
Epithelial goblet cells and submucosal glands
What type of cartilage does bronchi have in their walls?
Hyaline
Do bronchioles have cartilage?
No
What happens to the columnar cells of the epithelium as you move further down the respiratory tract?
They get shorter
Can gas exchange occur across columnar epithelium?
No
What are alveoli lined by?
Simple squamous epithelium
Where do central veins of liver lobules drain to?
hepatic vein
What is the space for blood flow between hepatocytes known as?
Sinusoids
What are erythrocytes and what do they lack?
Red blood cells (99% of blood cells)- they lack a nucleus
What are the 5 principle types of leukocytes which make up around 1% of blood cells?
Neutrophils, eosinophils, basophils, monocytes and lymphocytes
What type of blood cells are collectively called granulocytes?
Neutrophils, eosinophils and basophils
How do you distinguish a neutrophil?
Multi-lobed nucleus
What are the 3 layers of a muscular artery?
Tunica intima, tunica media and tunica adventitia
What separates the tunica media and tunica adventitia?
External elastic membrane
What type of epithelium do blood vessels have and what is this known as?
Simple squamous epithelium- known as endothelium
What are the very largest arteries often termed?
Elastic arteries
What are venous valves extensions of?
Tunica intima
What is significant about the nucleus of neutrophils?
Multi-lobed
Granules in the cytoplasm of eosinophils have a high affinity for what?
Eosin
What is significant about the nucleus of eosinophils?
Bi-lobed
What do granules in basophils have a high affinity for?
Basic dye
What are monocytes?
Precursors of macrophages
What shape is the nucleus of monocyte?
Kidney bean shaped
Do platelets have a nucleus?
No
