Histology Flashcards
what is the maximum amount of shortening of a sarcomere?
30%
how does skeletal muscle appear when cut transversely?
as a number of polygonal pink fibres arranged in clumps (fascicles). each pink staining block is a separate muscle fibre, on the periphery of each fibre are blue staining cell nuclei
the banding of skeletal muscle is often difficult to see in H&E stained specimen, what stain can we used for better resolve?
staining with iron haematoxylin produces better contrast and make int possible to resolve all of the bands within a sarcomere.
how are muscle attached to bones?
via tendons or mysium that surrounds the muscle fibres wither in the form of numerous small collagen bundles.
discuss sharpey’s fibes
The collagen bundles of Sharpey’s fibres merge with the fibrous periosteum of the bone and merge with the collagenous matrix of the bone itself. This form of attachment spreads the force of the muscle over a wide area. Good examples are the origins of the rotator cuff muscles on the blade of the scapula
describe the histology of seminiferous tubules
they are lined by stratified epithelium. they contain sertoli cells and spermatozoa. sertoli cells tightly joined to form the blood testis barrier . Each semniferous tubule is enclosed by a thin fibrous.
what cells line the rete testis?
cuboidal epithelium
what cells line the epididymis?
tall pseudo-stratified columnar epithelium, small rounded basal cell support ball columnar cells with very long microvilli (sterocilli). The tube is surrounded by a thin layer of smooth muscle, this becomes thicker and multilayered as it appraoches the vas deferens
what cells line the vas deferens?
layers of smooth muscle. not as tall pseudo-stratified columnar epithelium and shorter microvilli
which structures appear most prevalent in the renal cortex?
proximal convoluted tubules. the PCT are longer and becuase they are convoluted the same tubule appear many times in thesame section. Thus, the structure is most commonly found.
what cells line the glomerular capillaries
The inside of the glomerular capillaries is lined by fenestrated vascular endothelial cells, and podocytes line the outside.
What types of epithelium lines the renal pelvis?
urothelium
what hormone does the Juxtaglomerular apparatus secrete?
renin
what parts of the kidney are most sensitive to aldersterone?
cells of the distal tubule and collecting ducts are the most sensitive to aldosterone. this is where the hormone promotes the reabsoprtion of sodium ions and water, thereby concentrating the urine and conserves body fluid.
what are lacis cells?
they are light staining pericytes in the kidney found outside the glomerulus, near the vascular pole. They resemble smooth muscle cells and play role in blood flow and pressure (RAS) regulation.
does the ureter have a muscularis mucosa?
No, It is lined by urothelium beneath which is a lamina propria. Beneath this is a well developed muscularis propria.
does the Bladder have a muscularis mucosa?
Yes, the bladder contains a poorly formed muscularis mucosa and a prominent muscularis propria, both are smooth muscle. Muscularis propria has three layers of muscle only apparent at the bladder neck. the lamina propria, muscularis mucosa and submucosa separates the muscularis propria from the urothelium.
what does the macular densa do?
It may monitor sodium levels and may influence the initial filitration process of the glomerulus.
Describe the histology of the Proximal convoluted tubule
Cuboidal epithelium, Round central/basal nuclei. brush border of microvilli at apical end. many mitochondria (for active transport) so appears eosinophillic
what does bacterial enzyme hydrolysis in the gut produce, which is then excreted in faeces
stercobilinogen
what structure is situated within the duodenal loop
pancreas
which compound is returned to the liver by the enterohepatic circulation?
urobilinogen
what structure is in the middle of the hepatic lobule?
Central vein
What is the cause of physiological Jaundice of the newborn?
Excess breakdown of foetal haemoglobin
obstructive jaundice is commonly caused by the gall stone within what structure?
the common bile duct
what do Stellate cells store?
vitamin A
what do Kupffer cells do?
they are macrophages that break down haeme to bilirubin using an enzyme
What are the three main components of bile?
bile salts 70%
phospholipids
bilirubin
Describe a classic lobule
Area drained by one central hepatic venule. Some hepatocytes are more richly oxygenated than others. Hepatocytes near central vein are more deprived.
Describe hepatocytes
Polyhedral epithelial cells. Abundant mitochondria, which cannot be seen easily. Large central spherical nuclei. There is a prominent nuclei, few are binucleate. Numerous peroxisomes.
What are the three important surfaces of hepatocytes.
.
Most (70%) are in contact with permits exchange of material with blood space of Disse. 15% canalicular permits excretion of bile. 15% of intercellular
What are contained in space of disse?
Reticulin fibres and stem cells
What are sinusoid
Are highly specialised blood vessels. Thin discontinuous fenestrated endothelium. No basement membrane between vascular endothelial cells and hepatocytes. Contains scattered Kupffer cells.
What cells line the intrahepatic biliary tree? What cells line extrahepatic bile ducts
Lined by simple cuboidal to columnar epithelium, or simple columnar epithelium.
Describe the histology of the gallbladder
The gallbladder concentrates and store bile, expels bile via the common bile duct into the duodenum. Lined by simple columnar epithelium, specialised mucosa and loose fibrous connective tissue. It does not have a muscularis mucosa, has a thick layer of smooth muscle muscularis propria and a layer of loose fibrous connective tissue
What cells line the mouth?
Stratified squamous non keratinising epithelium
what protects the outlet of the oropharynx?
A ring of lymphoid tissue
what are the three pairs of saliva re glands that secrete into the oral cavity?
Parotid, sublingual, and submandibular
Describe the Histology of the tone.
The tongue is covered by a stratified squamous epithelium come out non carrot and eyes on its ventral surface but heavily character dies on its dorsal surface due to constant abrasion on this surface.
Describe the Histology of parotid salivary glands.
They are secretory cells, which are pyramidal in shape. The basal Cytoplasm is filled with rough endoplasmic reticulum and the apex of the cell contains prominent secretion granules.
Discuss the structure of the epiglottis.
The epiglottis lies posterior to the tongue and it is directly attached to it. Most of its surface is covered by stratified squamous epithelium although the lower part of its posterior surface has a pseudostratified columnar ciliated epithelium. Internally it contains a plate of elastic cartilage and its submucosal often contains lymph nodules and Salivary glands.
What’s roughens the surface of the tongue?
Filiform papilliae
Where are the circumvallate papillae?
between the anterior 2/3 and posterior third of the tongue
What feature confirms the site of origin of the oesophagus?
Squamous lined ducts. Oesophageal mucosa is lined by a nonkeratinizing stratified squamous epithelium also found in the mouth. The ducts are unique to the oesophagus.
What do parietal cells secrete?
Gastric parietal cells secrete hydrochloric acid and intrinsic factor. Intrinsic factor plays a role in the absorption of vitamin B12. Vitamin B12 is absorbed in the terminal ileum.
In the duodenum what is the purpose of Brunner’s glands?
They secrete an alkaline mucus that helps neutralise gastric acid.
Which autonomic nerve plexus innervates the gastrointestinal tract?
Meissner’s plexus lies in them submit mucosa, Auchbahs plexus lies between the layers of the muscularis propria.
Do you find lymphoid aggregates in the jejunum?
No, prominent lymphoid aggregates also known as Peyer’s patches are found in the ileum but they are not present in the judging him or duodenum.
What Artery supplies the colon ?
The superior mesenteric artery and the inferior mesenteric artery.