Questions Flashcards
How many axon/dendritic processes does each motor neurone appear to have
0-4 depending on sample but you are only likely to see 1/10th of the whole cell body
Why are lymphocytes so much smaller than nerve cells?
Small lymphocytes are poorly differentiated and not very metabolically active. When challenged they differentiate further increasing the amount of cytoplasm and become more metabolically active. Nerve cells are fully differentiated and very metabolically active hence the larger size
Why do lymphocytes gave so little cytoplasm compared to nerve cells?
Small lymphocytes are dormant awaiting a stimulus. Once challenged they become larger with a greater amount of cytoplasm.
What shape are muscle cells, thyroid cells and cartilage cells?
Muscle cells = fusiform - long and thin with tapered ends
Thyroid cells = cuboidal and organised into spheres
Cartilage cells = globular and sit in spaces in the cartilage matrix known and lacunae
How are cells arranged in the matrix?
In clusters of 2 or 4 cells but with some singletons
Chrondocytes continue to divide after the solid matrix begins to form. Thickening of the matrix restricts the migration of daughter cells
Cells remain in clone clusters
Where in the cell is DNA located?
95% is located in the nucleus and 5% is located in the mitochondria that has their own genome - derived from the ovum / mother
What is chromatin?
Condensed DNA wound around a skeleton of basic histone proteins. In order to be transcribed it must be decondensed.
Heterochromatin = Permanently condensed DNA and is never condensed
Euchromatin = Decondensed at some point in the lifecycle
What is the significance of a prominent nucleolus in the nucleus?
Where much of the RNA of the cell is synthesised. Signifies that the cell is metabolically active and synthesises a lot of protein
Does the size or shape of cell nucleus change in the normal life cycle of a differentiated cell?
Yes
The nucleus of a cell enlarges and it’s chromatin becomes less compact as a cell moves from the dormant to a metabolically active state and vice versus
Is there a significance to an enlarged nucleus?
Apart from an increase in size associated with a shift from a dormant to metabolically active state, many cancerous cells display enlarged and atypical nuclei
What happens to the nucleus is the cell dies
It is broken down and resorbed. If this is a programmed cell death = apoptosis
Unprogrammed cell death also occurs in tissue neurosis
Approximately how much taller than wife are epithelial cells
Twice as tall as wide
What proportion of the cells in the surface epithelium are goblet cells. Give an enterocyte : goblet cell ratio
Goblet cells are relatively low.
4:1
How does staining of goblet cells differ from that of absorptive epithelial cells?
Goblet cells contain mucin that does not stain very intensely with either H+E.
They stain palely with H+E
Besides goblet cells and the brush border, what other structure stains strongly by PAS
Stains hexose sugars dark / magenta pink.
Typically the basement membrane immediately below and epithelium stains heavily as it contains glycoproteins
Where else in the human body apart from the respiratory tract can cilia be found
Female genital tract - uterine / fallopian tube
What is the name of the immediate layer of cells with blue staining granules in the cytoplasm
Granular layer / stratum granulosum
Cells contain large numbers of blue staining keratohyaline granules that are precursors of keratin that form bright orange staining superficial layers
Which layer of the epidermis have stem cells
Basal layer
That layer lost removed from the surface. From here daughter cells migrate up through the layers until they reach the surface where they are shed / desquamated
Which 2 contractile proteins are involved in ciliary movement
Tubulin
Dyneine
Which layer of the epidermis of the skin are desmosomes most prominent
Are in all living layers of skin but most prominent in prickle cell layer - a thick layer abound the basal layer
During tissue processing the cells of this layer tend to shrink.
In the shrunken state desmosomes - are spiked projections or prickles
What is the main purpose of tight junctions in the epidermal lining of the gut
To hold the cells to prevent large molecules form passing between them and gaining access to the interior of the body.
Act as a barrier and establish a gradient for the absorption of secretion of molecules from or into the gut. Only water and some selected small molecules can breach the barrier
What role do gap junctions serve in intestinal epithelia
Passage of small signal molecules to pass quickly form the interior of 1 cell to another and so synchronising the activity of the epithelium
What colour does the secretion of mucous gland cells stain with H+E
H+E does not stain mucus strongly.
Appear white / clear.
May trap and react with these dyes giving a pale pink or blue hue to the cells
Serous secreting cells contain protein rich granules that stain strongly with eosin
Are strands of collagen uniform thickness
No not normally. Type 1 collagen form strands of variable thickness
Are collagen fibres intracellular or extra cellular
Extracellular
Fibroblasts synthesise and secrete tropical lager. When this is released form the fibroblasts it forms into collagen fibres that lie outside the cell. These extracellular fibres anchor the cells
Can collagen fibres be stretched
No
Collagen is neither elastic nor contractile. It forms a basis of ligaments and tendons and in these situations is required to provide a stable but flexible attachment to bones
Why are the 3 erectile compartments within the penis each enclosed by a capsule of dense irregular tissue
Because collagen is neither elastic nor contractile and so forms an inextensive capsule or sheath
So when compartment fills with blood - during an erection - the compartment becomes rigid. It become flaccid again once the blood drains from the compartment
What structural feature sets reticulum apart from other types of collagen
It forms branched fibres whereas most forms of collagen produce only linear fibres
Which cell type produces elastic fibres and sheets
Fibroblasts
These cells produce either collagen or elastic tissue depending on the situation
What advantage does elastic tissue provide over smooth muscle in this type of blood vessel
Elasticity
As the heart contracts during systole the large vessels arising from it expand due to the elasticity
When the heart enters diastole the recoil of these stretched vessels help to drive blood around the circulation.
Important in driving blood around the coronary circulation that occurs during diastole as a result of elastic recoil
If the vessels become hardened or elastic is has severe repercussions
Are fat cells large, average or small in size
Fat cells vary in size depending on the amount of fat stored within them
Normally large cells but starvation or dieting will reduce the size of the fat stores and of the cells.
Number of fat cells in the body is determined in the first 6 months of life. Starvation will not reduce the number of cells just the size of the stores
What type of lipid is normally contained in the fat droplets
Triglyceride
Do chrondocytes appear singly or in clumps within the matrix
Clumps
Can elastic cartilage be fractured
Yes.
But it is the most difficult of the 3 main types to fracture.
What term describes the tough outer casing of an intervertebral disc and it’s more fluid core
Intervertebral discs can likened to a flattened tennis ball but with a fluid filled core
Outer casing is known as annulus fibrosis while the semi liquid core is the nucleus pulposus.
If the outer casing becomes weakened or torn the inner core oozes out and solidifies pressing in adjacent structures l- this is a slipped disc
What type of collagen in found in fibrous cartilage
Type 2 collagen
This is different from collagen in the bone that is mainly type 1 collagen
Do the nuclei of the smooth muscle cells lie in the middle of the fibre or to 1 side
Middle
Smooth muscle is made from entire unfused cells. Each cell has its own nucleus that sits in the centre of the cell
Can you see striations across the muscle fibres
No
Striations are a gesture of skeletal and cardiac muscle but not smooth muscle. The contractile fibres - actin and myosin - of smooth muscle is not organised into sarcomeres
How long is a tropocollagen molecule
300 nanometers
Collagen fibres are formed of overlapping assemblies of tropocollagen units. This overlapping gives rise to characteristic banding of collagen fibres. The banding is very fine and can only be seen with an electron microscope
Do all collagen fibrils assemble themselves into fibres visible with a light microscope
No
Some forms of collagen are not fibrillary
Do all collagen fibres contract
No
Nor do they stretch
Do elastic fibres contract
Strictly no
They can be stretched but shortening is due to elastic recoil. They cannot shorten from their base length
What happens to the fat droplets when lipids are withdrawn from fat cells to be used as a source of energy
It gets smaller but is very rarely entirely used up
Where in the body is brown fat most likely to be found
Chest - between the shoulder blades
How does articulate cartilage differ form hyaline cartilage at other sites in the body
Most cartilage is surrounded by a fibrous perichondrium which is a rich source of chrondoblasts for the synthesis and repair of cartilage
Articulat cartilage does not have a perichondrium on its articular surface and so is slow to repair
How does hyaline cartilage receive its nutrients and oxygen
By diffusion of the surrounding tissues
At many sites in the body cartilage does not have a direct blood supply although large masses of cartilage often do
Do smooth muscle cells contract faster or slower than skeletal muscle fibres
Slower
Most smooth muscle cells do not have their own separate nerve supply but rely son a stimulus arriving via the gap junction between cells
All skeletal muscle fibres have their own direct nerve supply but rely
Are smooth muscle cells individually innervated
No
Many depend on contact with adjacent smooth muscle cells for their stimulus. Blocks of smooth muscle are described as being elastically coupled via the gap junction that links cells together
Approximately how many times thicker is the wall of the artery compared to that of the vein
3 times the thickness
Does the accompanying vein have the same 3 layers of tissue in its wall as the artery does
Yes but thinner
The medial layer often contains collagen as well as smooth muscle
How much bigger is the diameter of the venule compared to the arteriolar
Venule diameter is 1.5 - 2 times the arterioles.
The area of the lumen of the venule is 3 times the arterioles
What are the lymphatic valves made from
The same material that venous valves are made from
They are covered on both surfaces by an endothelium that lines all the blood vessels and lymphatics. Inside are some strands of collagen
What is myelin mainly composed of
It is membranous in nature and consists of a phospholipid bilayer with proteins inserted into it and spanning between the layers.
Sphingomyelin is the most predominant phospholipid. There are unique proteins and lipoproteins including proteolipid protein - myelin basic protein, PO protein and peripheral myelin protein whose abnormal expression results in several recognisable diseases and conditions
What is a mesaxon
Point where 2 limbs of the Schwann cell (PNS) or oligodendrite (CNS) that engulf the axon fuse
It is the focal point where the myelin is inserted into the myelin sheath
What is the fundamental physiological difference between myelinated and unmyelinated axons
Speed of conduction along a myelinated axon is FASTER than in an unmyelinated one
What term is used to describe connective tissue that binds together axons together to form a nerve fibre
Perineurium
Endoneurium = connective tissue between individual axons
Epineurium = that which binds nerve fibres together to form a nerve
Are all myelinated axons of the same diameter
No
Axon diameters vary with the sub type of the nerve
What conduction speeds are typical of unmyelinated and myelinated neurons
Depends on diameter if axon and whether or not it is myelinated
Unmyelinated axons = 1 - 20 m/s
Myelinated axons = 10 - 100 m/s
Myelinated axons have faster conduction velocities than unmyelinated axons 100x their diameter
List 2 neurotransmitter substances contained within the neurosecretory vesicles which when released depolarise the post synaptic cell
Cholinergic and Adrenergic
Release acetylcholine and noradrenaline respectively
What term is used to describe a nerve cell that it’s more than 2 processes arising from its cell body
Multi polar
Unipolar = 1 process
Pseudo-unipolar = apparently 1 process
Bipolar = 2 processes
What types of cytoskeletal fibres are contained in neurones
Microtubules and neurofilaments
What specific functions do the cytoskeletal filaments of neurones serve
Microtubules consisting of assemblies if tubulin and dynein are closely associated with the process of axonal transport - transport of vesicles from the Golgi apparatus in the neuron cell body to the end of the axon and back again - anterograde and retrograde respectively
Neurofilaments are a class of intermediate filament unique to neurones. Play a part of the cytoskeleton of nerve cells and seem to play a major part in the determination of axon diameter
What types of products are synthesised on the Nissl substance
It is RER common to most cell types
Site of synthesis of proteins destined for export from the cell or for the inclusion into its membranes. It is well developed in neurones because they have a large surface area and large numbers of vesicles whose contents are discharged from cells
Does all of the blood pass through a capillary bed on its way around the body
Not necessarily
They are lots of arterio-venous shunts in the body that allows some of the blood some of the time to pass directly from the arteries to veins or arterioles to venule a without passing through a capillary bed
Most organs are able to control their perfusion
Some cells leave the blood stream via venule or capillaries. How?
There are no holes in the venule or capillaries for them to pass through
They attach to the lining endothelium and then temporarily break open the junctions between adjacent endothelial cells in order to insinuate between them
What happens if the endothelial lining of a blood vessel is damaged or lost
This exposes collagen of the underlying connective tissue
The collagen reacts with platelets circulating in the blood inducing them to release clotting factors - a clot is formed
Can severed fibres regenerate
Yes if the cell body survives
If a peripheral nerve is cut the part proximal to the cut survives although the part distal to the cut dies leaving only some Schwann cells intact. If a surgical repair is undertaken the proximal stump can be encouraged to grow out and repopulate the distal stump growing out 1-2cm per week until it reached it target organ
What is the role of satellite cells
These surround nerve cell bodies and play a supportive role, plying the nerves with nutrients, growth factors etc.
What is an axon hillock and where is it found
Can be seen in histological preparations as a pale zone in the perikaryon (cytoplasm surrounding the nucleus) at the entry to the axon
It contains vesicles derived from the Golgi apparatus and it is the site of origin of the nerve stimulus
What natural brown pigment granules are found in the cell bodies of some neurones
Lipofuscin granules / neuromelanin
The latter can be found in large quantities in neurones of the substantia nigra, a region of the brain that contains dopamine
Cel bodies within the sympathetic ganglia contain lipofuscin granules. These are breakdown products that are not fully digested and accumulate within the perikaryon of these cells
Cardiac and voluntary (skeletal) muscles appear similar in many respects but how do they differ structurally, physiologically
Skeletal muscles are multinucleated syncytia - cardiac muscle cells are single cells with central rather than peripheral nuclei linked by intercalated discs. Cardiac muscle cells are a specialised type of skeletal muscle
Unlike skeletal muscle cells, cardiac myocytes must be able to contract and relax without rest and they secrete hormones (ANP). Cardiac myocytes have a shorter refractory period than skeletal muscles cells
An important feature of intercalated discs are desmosomes. What is their function?
Desmosomes serve to anchor 1 cardiac muscle cell to the next, by connecting their intermediate cytoskeletal filaments
An important component of intercalated discs are gap junctions. What is the function of them?
Gap junctions allow ions to flow between cardiac smooth muscle cells connecting the cells electrochemically
There is a delay between the contraction of the atria and the ventricles. What feature causes this delay?
Cardiac impulse must pass from the atria to the ventricles via there AVN which delayed the signal slightly
There are rings of fibrous connective tissue between the atria and the ventricles which prevent them from being directly electrically couples other than via the AVN
What is the function of the chordae tendinae
They are strands of fibrous connective tissue which ANCHOR THR PAPILLARY MUSCLES of the myocardium to the valve leaflets of the mitral and tricuspid valves
They allow papillary muscles to open the valves and prevent the valves from everting during systole
What conditions may cause physical damage to the heart valves
- Advanced age is associated with calcification of the aortic valve
- Rheumatic fever can damage any cardiac valves but most commonly affects the aortic and mitral valves
- Infective endocarditis destroys cardiac calves (occurs with Staph cocc infections)
Myocardial infarction can be complicated by rupture of papillary muscles resulting in sudden valvular incompetence
Why would a defective heart valve lead to heart failure
Incompetent valves cause blood to enter the preceding chamber while stenoic valves increase the after load
Myocardium has to work harder to meet the metabolic demands of the tissues. This causes cardiac hypertrophy and eventually the heart will not be able to adapt sufficiently to maintain the circulation - resulting in heart failure
Where in the myocardium are the bundle branches located
Run from the AVN down through the septal myocardium beneath the endocardium towards the apex of the heart and here they branch and then run back up the free walls of the L + R ventricles
What type of tissue covers the outside surface of the heart
Outermost layer is the pericardium. It is composed of a single layer of mesothelial cells, resting on a basement membrane supported by a basement membrane and a thin layer of loose fibrous and elastic connective tissue. This is the visceral pericardium and extends over the inner surface of the pericardial sac - parietal pericardium
What is the endocardium and what is to composed of
The endocardium is the innermost layer of the heart
Compose is a single layer of vascular endothelial cells supported by a basement membrane and a thin layer of loose fibrous and elastic connective tissue
Why might the number of reticulocytes increase in the circulating blood
Severe blood loss (several pints)
There are 3 types of granules within neutrophils. List the role of each
Type 1 = LYSOSOMES involved in digestion of foreign material phagocytosed by the cell - the most numerous type of granule not unique to neutrophils
Type 2 = unique to neutrophils. Contents secreted from the cell and involved in the regulation of the INFLAMMATORY RESPONSE
Type 3 = CONTAINS ENZYMES which when secreted by the cell facilitate the insertion of proteins into the membrane of the cell surface
What is the characteristic feature of eosinophil granules
At the light microscope level it is their intense pink staining with Romanowsky type stains.
At the electron microscope level they appear oval in shape and have dense crystalline cores
In what conditions are the numbers of eosinophils likely to increase
After a parasitic infection
In what ways do basophils interact with eosinophils in their physiological function
Mast cells secrete histamine that is a potent vasodilator that can result in INFLAMMATION
Eosinophils act to neutralise the action of histamine
What is the diameter of a lymphocyte? How does it compare with that of a RBC and a granulocyte
- RBCs have a diameter of 7.8 micrometers
- Neutrophils have a diameter of 12 micrometers
- Small lymphocytes are approx. 10 micrometers in diameter
Lymphocytes grown in size as they mature
List 2 organs that have fixed macrophages derived from circulating monocytes
Liver
Spleen
What do the 3 types of platelet granules contain and what are their functions
- Alpha granules contain CLOTTING FACTORS
- Delta granules contain SEROTONIN that is absorbed into them from the plasma following the discharge of clotting factors
- Perioxisomes contain CATALASE and enzymes used in the elimination of oxygen radicals
Inspired air is filtered, warmed and humidified as it is drawn through the nose and layer parts of the bronchial tree. This conditioning helps to prevent damage to the alveoli. What structural features of a respiratory epithelium can be associated with these 3 roles
This is a non keratinised relatively thin epithelium which therefore allows the escape of water (humidification) and heat (warming).
It bears CILIA and a layer of mucus on the surface which traps particulates
What are the names of the nasal sinuses, where are they placated and where do they enter (connect with) the nasal cavity
Maxillary Ethmoid Sphenoid Frontal located in the bones of the skull of the same names
Ethmoid and maxillary sinuses open it it he nasal cavity below the upper and middle turbinates respectively
Frontal sinus drains into the roof of the nasal cavity anterior to the olfactory epithelium.
Sphenoid sinuses drain into the roof of the nasal cavity posteriorly
What colour do goblet cells stain
Have optically clear cytoplasm which does not stain
Wine glass shape
What is the difference between a lymph nodule (MALT) and a lymph node
They are very similar
A lymph node is a discrete encapsulated collection of lymphoid tissue. MALT is less discrete, lacks a capsule and is present in a mucosa, often related to the epithelium
Are all of the cells lining this bronchiole ciliated
Yes
Lined with ciliated columnar ciliated epithelium
What is the likely fate of particulate carrying alveolar macrophages
They enter the respiratory and terminal bronchioles and are expelled from the lungs via the muco ciliary escalator
What is the likely fate of particulate carrying fixed (septal) macrophages
They remain in the interstitium of the lungs or enter the lymphatics
What occurs if the particulate matter is indigestible or larger than a macrophage
It causes macrophages to fuse together to form giant cells
It may induce granuloma formation
What are the pulmonary vessels from largest to smallest
Largest = pulmonary artery
Medium = pulmonary arteriole
Smallest = pulmonary venule
Essential components of the larynx include true and false folds and the vestibule of the larynx. Where are these located and what type of epithelium covers these areas
Below the epiglottis in the larynx the mucosa is thrown into 2 sets of folds
Uppermost = False cords lined by RESPIRATORY EPITHELIUM (though may be islands of stratified squamous epithelium)
Lowermost = true vocal cords lined by STRATIFIED SQUAMOUS EPITHELIUM
Vestibule lies between these 2 sets of folds and is covered by respiratory type epithelium
A prominent feature of bronchioles is the ring of smooth muscle that underlies the epithelium. What function does this muscle serve. What stimuli might cause it to contract. What would be the consequence of its contraction
It allows the diameter of the bronchioles to be regulated, controlling the flow of air to the perfused parts of the lungs. Contraction reduces the liminal diameter of the bronchiole and so increases resistance to airflow
Muscle are innervated by the autonomic nervous system. Parasympathetic stimulation causes the muscles to CONTRACT while sympathetic stimulation (beta 2 adrenoreceptors) causes it to relax.
Reduced airflow. Widespread contraction as seen in anaphylaxis and asthma will cause breathlessness and wheeze
What particular function does the elastic tissue in the walls of the alveoli serve?
It allows alveoli to stretch to accommodate the inhaled air and then allows the air to be expelled by recoiling. It also serves as a spring tethering bronchiolar walls open, preventing bronchiolar and alveolar collapse during expiration.
There are 7 barriers through which O2 must pass / diffuse to exchange between the air and the blood. List them in order starting from the air sac
- Air sac
- Type 1 pneumocyte cell membrane
- Type 1 pneumocyte cytoplasm
- Type 1 pneumocyte cell membrane
- Basement membrane
- Endothelial cell membrane
- Endothelial cell cytoplasm
- Endothelial cell membrane
Premature babies often experience a deficiency of surfactant in their lungs because the cells that produce it develops late during gestation. What name is given to this condition and what effects does it have
The he absence of surfactant causes infantile respiratory distress syndrome
Surfactant is needed to reduce surface tension, making it easier to inflate the alveolar airspace. In infantile respiratory distress syndrome there is widespread alveolar collapse
Describe the histology of the lip
The lip contains muscle fibres, part of the ring muscle that surrounds the mouth (orbicularis oris muscle) - a muscle is facial expression
What is the parotid duct lined by
Stratified cuboidal epithelium
What is the major constituent of the secretion of the parotid gland
It is a MUCUS SECRETING GLAND and the major constituent is a high molecular weight mucopolysaccharide. These can absorb large amounts of water and are very good lubricants, both of the mouth and tongue and bolus of food
What are serous demi lunes
Half mooned shaped clusters of serous cells that lie at the closed ends of the branched mucus secreting tubules that make up part of this gland
Describe preparation of fat cells for microscopy
Clear staining areas
During preparation of the tissue for microscopy the triglyceride is extracted form the fat cells leaving clear spaces
Submandibular gland is infiltrated with fat
What is the epiglottis covered by
Stratified squamous epithelium
Where are mixed sero-mucous glands found
In the back of the tongue
Pale staining mucous tubules and darker staining serous elements
What are mucous glands characterised by
Pale blue staining cytoplasmic contents (mucus) and flattened cell nuclei
Which end of the oesophagus is voluntary / striated muscle found
At the proximal end
The muscularis mucosa lies deep to the gastric glands. It consists of 2 layers of smooth muscle. What is the additional material
Elastic tissue that is frequently present and serves to cause the collapse of the stomach in emptying
Wells developed in carnivores and prevents the perforation of the stomach wall by sharp fragments of bone
What is the normal pH of gastric juice
2
For which tissue constituent (foodstuff) does pepsin have an affinity and what benefit does this confer of the process of digestion
It digests proteins but has an affinity for collagen.
Facilitates breakdown meat by attacking the connective tissue between the muscle fibres
Where is a lymph nodule located
Within the lamina propria of the mucosa of the pyloric region of the stomach
Where do part of the Brunner’s gland lie
In the submucosa of the duodenum
It’s a useful distinguishing feature of this part of the small intestine being absent from both the jejunum and the ileum
Where is a parasympathetic ganglion located
Between the 2 layers of smooth muscle that make up the muscularis externa. It is part of Auerbach’s plexus of nerves that regulate the contraction of the muscle coat
Which of the 2 layers of smooth muscle that make up the muscularis externa is thicker - the inner circular layer or the outer longitudinal layer
The inner circular layer is 4 or 5 times thicker than the outer longitudinal layer
What is smooth muscle
It is part of the muscularis mucosa that is severely interrupted by the lymphoid tissue that forms Peyer’s Patches which lie partly in the lamina propria but mainly in the submucosa below
Which epithelium is on the outer surface of the gut
Simple squamous
They make up the mesentery or serosa of this region of the gut
What type of muscle is part of the external sphincter of the rectum / anal canal
Voluntary (striated muscle)
Where are the blood vessels in the rectum
In the submucosa
The distal end of the gut is renowned for large blood vessels ( branches of the IMA) l. Veins of which may become varicose and form haemorrhoids
What type of tissue is present in the anal gland
Glandular tissue present in humans but more abundant in some animals
Taste buds detect acid, bitter, sweet and salty sensations. How are these distributed across the tongue
Sweet = detected by buds at the tip of the tongue
Salty = either sides towards the front of the tongue
Sour = tastes further back
Bitter = tastes are detected across the whole back of the tongue
Parotid saliva contains immunoglobulins. Where are they produced and what is their function
Plasma cells resident in the gland produce immunoglobulin A (IgA). These IgA are discharged into the saliva where they combine with proteinaceous “secretory pieces” also produced by the glands. These complexes are protected from digestion which allows the IgAs to reach the intestine unmodified
A part of the duct of the parotid gland is known as a striated duct. What gives rise to these striations and with what function can they be associated
Striations are a result of deep invaginations of the basal plasmalemma of the cells and large elongated mitochondria that lie perpendicularly between them
A similar arrangement of organelles is seen in some of the cells of kidney tubules. This pattern is indicative of resorption of water and the transfer of ions across the cells
The striated tubules of salivary glands are capable of the secretion and resorption of water and ions from the saliva
What is dental plaque
Calcified deposit rich in dead or dying oral bacteria and food debris
Do the enzymes produced by salivary glands and swallowed continue to function in the stomach
Salivary enzymes have neutral pH optima and work rapidly in the mouth but they become inactivated by the acid environment of the stomach
However the enzymes continue to act in the stomach within the holidays of food where they are shielded from the gastric juices, until such time as the bolus is dispersed
The glands of the pyloric region of the stomach secrete gastrin. What is its functions and what other cells of the stomach does it influence
Gastrin is produced by ENDOCRINE SECRETING CELLS IN THR PYLORIC REGION of the stomach and in the duodenum promotes the secretion of HCl by the parietal cells of the body and fundus of the stomach
How and by what route are triglyceride mainly absorbed from the gut
Some triglyceride are absorbed into the capillaries of the intestine most are broken down into monoglycerides and fatty acids before being absorbed by the enterocytes
Once taken up they are reconstituted and combined with proteins before being secreted through their baso-lateral membranes as macromolecular chylomicrons. These are taken up by lacteals and transported to the bloodstream via lymphatics - finding their way to the live by a somewhat circuitous route
The gut has an intrinsic innervation consisting of a network of interconnecting nerves and ganglion cells. There are 2 main parts to this network. Where are they located in the wall of the gut and what names are given to these 2 main parts
There are 2 main subdivisions to the enteric nervous system. A plexus of nerves within the submucosa of the gut known as Meissber’s plexus regulates the mucosa and the processes of absorption and secretion while a second interconnected plexus between the layers of muscle that make up the muscularis externa - Auerbach’s plexus regulates much of the contractile activity of the gut
Soon after birth a baby acquires immunity through the acquisition of Igs provided by the mother’s milk. What structural features of the gut allow the uptake of these macromolecules and to what extent are the Igs digested by the enzymes of the gut
Enterocytes of the gut have specific receptor complexes that allow the uptake (undigested) of certain Igs they subsequently form part of the system of passive immunity. This system is at its most active in the neonate in response to Igs in the mothers first milk (colostrum) but declines in significance within a few months
What are bile canaliculi and how do they relate to the bile ducts
Bile canaliculi are extra cellular channels between hepatocytes into which the hepatocytes secrete bile. These channels coalesce at the edges of the liver lobules and drain the bile into bile ductile that form part of the portal triad
Do liver cells divide / replicate
Yes
Bi-nucleate liver cells (in the process of division) constitute 2% to 3% of the liver mass. Unlike most other tissues of the body the liver is capable of substantial regeneration
What are Ito cells and what is their pathological significance
Lie in the sinusoids of within the liver.
They are fat storing cels that play a pivotal role in FATTY DEGENERATION and FIBROSIS of the liver in such conditions as cirrhosis of the liver
From what circulating blood type are Kupffer cells derived? give an example too of another differentiated cell type that originates from the same cell line?
Kupffer cells are macrophages that like tissue histiocytes (tissue macrophages) are derived from circulating monocytes.
Osteoclasts in bone are also derived from the same source
What is in the gallbladder
Thin walled venule in the wall of the gallbladder. The gallbladder concentrates bile by resorbing some of it water
The fluid is passed into the venules and veins in the wall of the sac
Which hormone causes the gallbladder to contract and where in particular is this hormone produced
Cholecystokinin (CCK)
Produced by ENDOCRINE CELLS IN THE WALL OF THE DUODENUM and released in response to fat arriving in the duodenum from the stomach
Where are the hormones synthesised that cause the exocrine pancreas to secrete?
Mainly in the wall of the duodenum.
The pancreas also receives secretor-motor fibres from the vagus (cranial X) nerve
The pancreas secretes a wide range of proteolytic enzymes. What mechanism exists to prevent these enzymes digesting in the pancreas itself?
They are secreted in an inactive form as ZYMOGENS and are normally only activated when they are reach the lumen of the duodenum. In some forms of pancreatitis however the gland does break down autolytically
What is a Pacinian Corpuscle
They are pressure sensors found in the dermis of the skin although they are a regular feature of the pancreas. Their role here is not well understood
What is a small nerve ganglion
Embedded in the exocrine part of the pancreas
Almost certainly a parasympathetic ganglion associated with the Vagus nerve
What is the Islets of Langerhans
Contains endocrine cells including beta cells that produce insulin
Some of the blood entering the liver has come directly from the spleen via the splenic branch of the hepatic portal vein. What products in particular is this branch carrying to the liver
It carries, among other molecules the products of red cell breakdown, most notably IRON CARRYING FERRATIN
How are the products transported from the spleen to the liver
Ferratin - a protein with an iron core is discharged by the spleen and is poked up by the Kupffer cells in the liver
Describe simple columnar epithelia
- Oval / spheroidal nucleus whose longer axis is perpendicular to the base of the cell
- TALLER THAN THEY ARE WIDE
- Either have microvilli or cilia
- microvilli = gut enterocytes
- cilia = respiratory tract
Describe the PCT
PCT leads into the loop of Henle. PCT is in the cortex of the kidney (surrounded by glomeruli) but some straight portions project into the medulla
List 2 important proteins that normally pass from the blood into the primary folate ate but are then recovered/ reabsorbed by the PCT
Almost any small negatively charged protein can enter the glomerular filtrate but will be reabsorbed.
Proteins such as albumin and Hb are too large to enter the filtrate
Briefly, what is the fundamental difference in the permeability to water of the thin descending and ascending limbs of the loop of Henle and what is the consequence of this difference
The thin descending limb has LOW PERMEABILITY to ions and urea, while being HIGHLY PERMEABLE to water
The thin ascending limb is NOT PERMEABLE to water, but it is permeable to ions.
This creates a conc. gradient within the renal medulla
Within the cortex of the kidney, which is the more numerous type of tubule, PCT or DCT
Both the PCT and DCT are mainly contained within the cortex of the kidney.
The PCT is normally longer and more tightly coiled than the DCT.
Hence sections of the PCT appear more numerous than those of the DCT
Where in the body is angiotensin 2 produced
Renin secreted by modified muscle cells in the walls of the AFFERENT arterioles of the glomerulus catalyses the conversion of angiotensinogen that is produced by the liver into angiotensin 1. This is converted to angiotensin 2 mainly in the lungs.
This goes on to stimulate the release of aldosterone by glomerular cells in the cortex of the suprarenal gland. This in turn promotes the reabsorption of sodium and water from the glomerular filtrate mainly by the cells of the DCT and CDs
Which cells of the kidney are particularly responsive to aldosterone
Cells of the DCT and CD, where this hormone promotes the reabsorption of sodium and water and thereby concentrates the urine and conserves body fluid
What is the average number of layers of cell to the urothelium? How would you predict this would change if the bladder were full rather than empty
Where the urothelium is cut obliquely it appears to have more layers of cell than where it is sectioned perpendicularly. Not withstanding this the apparent number of layers of cells in the urothelium is between about 4 to 6. In fact this layering layering is an artefact as all the cells maintain contact with the basement membrane and layering is due to the “squashing up” of the cells when the bladder is empty
It is a stratified epithelium with a pseudo stratified component. As the bladder fills with urine the epithelium is stretched and the apparent number of layers of cells decrease. In its most stretched state it appears as a single layer of cells covered by urine proof umbrella cells
In which layer of the wall of the ureter is it located
This is one of the many thin-walled venules that lie in the lamina propria underneath the urothelium of the ureter
Describe smooth muscle
Part of 1 of the 2 spiral layers of muscle of which the wall of the ureter is composed
What is an umbrella cell
On the surface of the urothelium. These cells are adapted to be urine proof and protect the underlying cells of the urothelium
What system could a small nerve be part of
This is a small nerve which is almost certainly part of the autonomic nerve supply to the wall of the bladder. It is not possible to decide whether it is a sensory nerve providing information as to the degree of distension of a bladder or a motor nerve that could cause contraction of the muscle during micturiton. It is most likely to be a parasympathetic nerve fibre from the sacral outflow
Sympathetic nerves mainly supply the blood vessels to the bladder
What kind of tissue lies underneath the prostatic urothelium
Dense fibrous connective tissue which will restrict the distension of the urothelium at this point
How does the human kidney differ histologically from that of a smaller mammal such as a mouse or rat
It is a compound kidney rather than a simple kidney which is the case with small mammals. A simple kidney has a single medulla with a single surrounding cortex. A compound kidney is, in effect, many simple kidneys in the same bag, with multiple medullary zones each surrounded by cortex. The human kidney consists of between 15 and 20 simple kidneys fused together with primary and secondary calyxes draining into a single renal pelvis
Briefly, how is blood flow through the glomerulus regulated
Regulated by constriction of the afferent and efferent arterioles
Which do you think is more tightly coiled, the PCT or the DCT
Apart from the straight portions of the tubules, the PCT is more tightly coiled than the DCT. This results in more transverse and fewer oblique sections through the PCT than through the DCT
Why do the loops of Henle differ in length from 1 nephron to another
This depends on the point of origin of the nephron. Nephrons whose glomeruli originate close to the surface of the kidney (outer cortex) have short loops of Henle that project only as far as the outer reaches of the medulla whereas those nephrons whose glomeruli arise close to the medulla have long loops that project deep into the medulla
Why is the wall of the ureter composed mainly of smooth muscle rather than of fibrous connective tissue
The muscular wall or the ureter undergoes peristaltic contraction that helps to conduct the urine to the bladder
Which nerve tract supplies the muscle in the wall of the urinary bladder and causes it to contract during micturition
Micturition occurs once the external sphincter of the ladder is relaxed (sympathetic stimulation) and the muscle wall of the bladder (detrusor muscle) contracts (parasympathetic stimulation)
What glands drain into the prostatic and penile urethra
Many of the genital glands drain into the proststic urethra including the prostate itself, the seminal vesicles and the deferent duct (sperm)
The bulbs-urethral glands and other smaller mucous glands drain into the membranous and penile urethra
What type of epithelium lines the distal end of both the male and female urethra
Both lined by STRATIFIED SQUAMOUS epithelium
What would be the consequence of failure of the blood-testis barrier
It is likely that the individual would recognise his sperm as “non-self” and raise antibodies against them. These would then destroy the sperm rendering him infertile
Identify the 4 cell types from left to right
Spermatagonia - Sertoli cell - germ cell - spermatid
What type of cell is contained and what does it synthesis
Cluster of Leydig cells that synthesise and SECRETE TESTOSTERONE
At what stage of development of sperm does the reduction division take place
The 1st meiotic division during which the developing sperm go from being 2n (number of chromosomes) to 1n occurs when the primary spermatocytes become secondary spermatocytes
Where in the relation to the blood-testis barrier does this reduction division take place
On the luminal side of the of the blood testis barrier where the developing spermatids are not in direct contact with the blood stream and they are therefore not detected by the individual creating them.
This prevent the production of auto antibodies that may well destroy the developing sperm
What do thin stereo cilia do
Long and thin that project from the surface of the epithelium of the epididymis.
They can help provide nutrients to the sperm stored in the epididymis. Unlike true cilia they are not motile nor do they have a core of microtubules as true cilia do
Talk about other structures in addition to the vas deferens
Transverse section through the spermatic cord. It is encircled by the internal spermatic fascia which encloses not only the vas deferens but also the testicular artery, nerves, lymphatics and veins all of which are present
At vasectomy, how would you differentiate between the vas deferens and other vessels running in the cord (a) by gross appearance and (b) histologically
The thick muscular wall of the vas deferens provided more resistance to the touch (feels cord-like) and unlike the testicular artery is difficult to compress and has no pulse
Histologically the 2 tubes can be differentiated by the thickness of the smooth muscle wall, which is much thicker in the vas deferens and composed of 2 distinct layers and by the nature of the epithelial lining which is pseudo stratified one in the vas deferens but a SIMPLE SQUAMOUS endothelium in the artery
What does smooth muscle do in the penis
When smooth muscle contracts (during ejaculation) it squeezes the secretions out of the gland
Describe a type of gland
Spiral tubular gland from the submucous zone of the prostate gland
Describe the skeletal muscle (11a)
Skeletal muscle it is in close contact with the underside of the prostate gland and is almost certainly part of the pelvic diaphragm that includes the LEVATOR ANI MUSCLE
What does the small mucous gland do
Small mucous glands that discharges its secretion into the penile urethra
Extreme resistance may be felt when trying to insert a catheter trans-urethrally into the bladder of a man. What histological structures may be the cause of this resistance
Sometimes the tip of the catheter can be diverted into the blind ended bulbo-urethral glands that discharge into the membranous part of the male urethra. The shorter and straighter female urethra does not normally pose the same problem
Where is the small arteriole (11a)
Small arteriole is within the erectile compartment of 1 of the corpora cavernosa
What surrounds the shaft of the penis
A small UNMYELINATED nerve in the loose connective tissue of the skin surrounding the shaft of the penis
In what way does the epithelium inside of the prepuce (foreskin) differ from that of the rest of the penis and what consequence does this have for disease processes
The epithelium on the inside of the prepuce is STRATIFIED SQUAMOUS KERATINISED epithelium. It is very thin and very lightly keratinised. It is prone to the ingress of invading organisms
Prime site for the uptake of HIV and circumcision greatly decreases the entry of this virus mainly bc the remaining and exposed epithelium becomes much more heavily keratinised
Erection and ejaculation are separate but interlinked processes. How are these processes controlled neuronally and which anatomical nerves are involved?
Erection = Parasympathetic NS whose nerve fibres travel in the pelvic outflow (pelvic splanchnic nerves)
Ejaculation = SYMPATHETIC autonomic event whose nerve fibres mostly derive form the hypogastric plexus (terminal part of the sympathetic chain
REMEMBER POINT AND SHOOT
Which erectile compartments are the least rigid during ejaculation
2 corpus cavernosa usually becomes more rigid than the corpus spongiosum
The penile urethra passes through this compartment and therefore is less liable to be compressed than if it were to pass through the rigid compartments, thus ensuring the passage of seminal fluid during ejaculation
How do you know if a specimen was taken from a child, woman of child bearing age or form an old woman
The THICKNESS OF THE STRATIFIED SQUAMOUS EPITHELIUM lining the vagina and outside surface of the cervix
Describe some cel types on smears
Darker staining orange coloured cells that are derived from the deeper layers of the vaginal wall.
Paler grey staining cells tend to predominate in the first half of the menstrual cycle
Describe the type of epithelium on the cervix
STRATIFIED SQUAMOUS = outside of the cervix
SIMPLE COLUMNAR = cervical canal
Is the lining epithelium of the cervix shed at menstruation
No
Although the epithelium lining the cervix undergoes cyclical changes during the menstrual cycle. Most of the time the mucus it secretes is thick and forms a weak plug to the cervical canal but this breaks down and the secretions become more fluid following ovulation in order to encourage the entry of the spermatazoa
During the pregnancy the uterus increases enormously in size and regresses afterwards. How is this achieved
As the placenta begins to develop there is a burst of mitotic division within the myometrium that increases the number of smooth muscle cells.
However this is of short duration and is not the major mechanism by which the uterus grows. Most of the enlargement of the uterus is due to hypertrophic y of the muscle cells. After delivery the muscle cells lose mass and the uterus returns more or less to its original size
Where are the dividing cells
Dividing cells in the glands of this proliferating endothelium
how do you know if a specimen was taken from the early or late secretory phase
Spiral arteries are well developed and that there is blood in the stroma is indicative of later secretory phase.
Anoxia due to the temporary closure of the spiral arteries and leakage of blood into the stroma causes the functional layers of the endometrium to detach from the basal layers
Where does fertilisation of an ovum normally occur
Fertilisation of an ovum normally occurs in the ampulla although it can occur anywhere in the uterine tube or in the body of the uterus
Where do ectopic pregnancies often implant
Occur in the uterine tube where they are life threatening to the mother.
They can occur in the peritoneal cavity.
Describe the ellipses in the female reproductive tract
The largest ellipse = Graafian follicle
Working anti-clockwise —> secondary follicle, primary follicle, primordial follicle.
Only a few primordial follicles that start this sequence of development reach maturity (Graafian follicle) and in some cases it takes more than 1 menstrual cycle for the follicle to develop fully.
Many of the developing follicles are reserved as atretic follicles before completion
Describe a Graafian follicle
Divided into 2 layers
Outer spindle shaped cells = THECA EXTERNAL
Inner rounded cells = THECA INTERNA
Thecal cell layers persist as the corpus outrun following eruption of the follicle at ovulation
Describe surroundings of developing ovum
Dark pink staining zona pellucida that surround the developing ovum
Cumulus oophorus - part of the theca interna that’s surrounds the ovum
Describe how the cells of the corpus vary
Theca externa = small stellate in shape and pale staining
Theca interna = larger globular in shape and strongly pink staining
Is there any barrier to the cervical canal
Normally filled with sticky mucus that helps to prevent in ingress of bacteria and other infections into the body of the uterus
It is replaced by a more fluid secretion following ovulation which allows the passage of sperm into the female genital tract
What are the names given to the major 2 regions of the endometrium, the part shed at menstruation and the part that remains
The portion closest to the myometrium that remains after menstruation = STRATUM BASALE while the thicker more superficial portion that is shed at menses = functionalis (functional layer) or the decidua
What vestigial structure is often present in the mesovarium and what is the origin
Oophoron which is the homologue of the part of the male genital tract
Through which part of the ovary does eruption of the Graafian follicle normally occur
Through the germinal epithelium on the antimesenteric border of the ovary
SIMPLE CUBOIDAL EPITHELIUM that is continuous with the SQUAMOUS epithelium of the peritoneum
Describe the granular layer
Contains KERATOHYALINE granules (precursors of keratin)
MOST SUPERFICIAL OF LIVING LAYERS OF THE EPIDERMIS
What is the dermal papillae
Dermal papillae caused by the irregular (wavy) basal layer of the epidermis
Describe the dividing cells in the basal lateral of the epidermis
Recognised by the pale staining of their cytoplasm and the very compact nature of their nuclear chromatin
Where is the Langerhans cell in the epidermis
Within the SPINOUS (prickle cell layer) of the epidermis
Describe the parts of a hair follicle
Sebaceous glands = discharges into the hair sheath
Erector pilli muscle = SMOOTH MUSCLE that causes the hair to stand on end
Describe the Pacinian Corpuscle
A pressure sensor
Most of these are encountered in the dermis of the skin but occasionally they occur in other organs, notably the PANCREAS
Where is a Meissner’s corpuscle located
Dermal papillae
Describe the structure of the eyelid
Large Meibomian gland (a modified and enlarged sebaceous gland)
Hair bulbs of 2 eye lashes
Striated muscle fibres part of the orbicularis oculi muscle (that allows you to screw up your eyes)
What type of epithelium lines the lactiferous duct
STRATIFIED CUBOIDAL EPITHELIUM
Here it shows the surface later as being almost columnar but elsewhere it is often low cuboidal
IF THE NUCLEUS IS ROUGHLY CIRCULAR ~ EPITHELIUM IS CUBOIDAL
