Resp + Cardio PST Flashcards
Describe the epicardium of the ventricle.
Outer layer of mesothelium, called visceral pericardium, then epicardial connective tissue containing:
- collagen
- fat
- nerves
- blood vessels
- lymphatics
Describe the myocardium of the ventricle.
Cardiac myocytes with blood vessels and fine connective tissue
Describe the endocardium of the ventricle.
Lined with endothelium, with endocardial connective tissue containing elastin and collagen fibres and some smooth muscle fibres underneath.
Conduction fibres are also found here but are difficult to see on slides.
What is the mitral valve leaflet made of?
Outer layer of endocardium with a dense fibrous connective tissue core, containing collagen and elastin fibres, continuous with the annulus fibrosis.
Annulus fibrosis
Fibrous rings of the heart
What is the difference between the atrial and ventricular surfaces of the mitral valve?
The atrial surface is smooth but irregular which helps the flaps to close and maintain a tight seal. The ventricular surface is a tight weave of collagen strands to prevent regurgitation.
Cells in the mitral valve leaflet
Collagen fibres Elastin fibres Cardiac muscle fibres Myofibroblasts Macrophages
The cardiac muscle of the atrium does not merge with the muscle of the ventricle. What separates the two bodies of muscle?
The fibrous skeleton
What are the chordae tendineae made of?
80% collagen, 20% elastin and endothelial cells
Where would you find purkinje fibres?
Between the endocardium and myocardium (subendocardial layer)
Running through the moderator band
What are some features that are characteristic of purkinje fibres?
Cytoplasm rich in glycogen and mitochondria
Fewer myofibrils, found at the periphery
One or two central nuclei
Where do Purkinje fibres originate?
The atrioventricular node
Which part of the myocardium do purkinje fibres supply first?
The papillary muscles, followed by the ventricular wall.
This is because the papillary muscles need to activate to contract the chordae tendineae which push the inlet valves closed so that the ventricles can go through isovolumetric contraction before ejection, which would utilise the ventricular wall.
What is the main component of the aortic valve leaflet?
Collagen
What is the difference between the ventricular and aortic surfaces of the aortic valve?
The ventricular surface consists of mainly elastin whereas the aortic surface consists of mainly collagen.
This is because the elastin needs to be able to stretch and recoil as the valve opens and closes. The collagen provides structure to the valve and prevents regurgitation.
What are the three layers of the aortic valve and what are they predominantly made of?
Lamina fibrosa - collagen
Lamina spongiosa - GAGs and interstitial cells
Lamina ventricularis - elastin
What would a muscular artery look like on a histological slide?
Very thin tunica intima with even thinner subendothelial layer and a prominent internal elastic lamina.
Thick tunica media with up to 40 layers of prominent smooth mucsle cells, intermingled with a varaible number of elastic lamellae. External elastic lamina may be present in large muscular arteries.
Thinner tunica adventitia consisting of connective tissue, lymphatic capillaries, vasa vasorum and autonomic nerves.
What is the mean blood pressure of a muscular artery in a standing adult?
85 - 95 mmHg
What colour and arrangement do the three fibres in the tunica media have?
Smooth muscle: layered, stained dark pink with very dark nuclei, concentrically arranged
Elastic fibres: sparse and squiggly. In the uni slide they’re stained black, but they often don’t pick up colour.
Collagen fibres: sparse between smooth msucle cells. Both collagen and elastin run longitudinally.
What does the internal elastic lamina look like in a muscular artery?
Prominent and squiggly, forms a border between the thin intima and the thick media. This is only applicable in death, where there is no pressure in the vessel. In life, when the pressure is high, the IEL wouldn’t be squiggly because it would be stretch out.
What is the mean blood pressure of a large vein in a standing adult?
3 mmHg (approx)
IEL in veins
It’s present, but very thin and unlikely to be seen.
How do valves originate?
They are infoldings of the tunica intima that project into the lumen to prevent backflow of blood.
What is the thickest layer in a large vein?
The tunica adventitia, although the tunica intima is also well-developed.
What would a large vein look like on a histological slide?
Well-developed tunica intima. Relatively thin tunica media, not many layers of smooth muscle but lots of connective tissue.
Thick adventitia with longitudinal bundles of smooth muscle and thick collagen fibres. Elastin fibres are also present in media and adventitia but they’re not arranged into lamella.
What are blood vessels that supply nerves called?
Vasa nervorum
What are atherosclerotic plaques made of?
Aggregated foam cells (macrophages that have eaten lipids), calcium and fibrin (which can form a cap)
Changes to a vessel wall when an atherosclerotic plaque is present
More rigid intima due to inflammation and invasion of lipoproteins
Thickened media due to scar tissue
Breakdown of IEL as plaque pushes through into the tunica media from the intima
Why is the core of an atherosclerotic lesion empty?
The plaque has a necrotic core because it cuts off blood supply to cells in it, which die and cause more inflammation. There are no longer living cells in the centre of this lesion.
Three ways plaques can cause a stroke
1) Thrombus forms on top of plaque, causing sudden occlusion of artery and ischaemia in the area.
2) Thrombus forms on top of plaque then embolises and lodges in a smaller vessel.
3) IEL and media are weakened causing arterial wall rupture. This can cause subarachnoid haemorrhage.
How does blood pressure vary in a healthy elastic artery?
120 - 80 mmHg
Diameter of aorta
About 22 mm (ascending) and 16 mm (descending)
Proportion of tunica intima in the aorta
20%
How is elastin arranged in the aorta?
Intima: one layer - the internal elastic lamina
Media: both elastic fibres and fenestrated elastic lamellae, concentrically arranged. Also external elastic lamina.
Adventitia: some elastin fibres but relatively underdeveloped
What do fenestrated sheets of elastin (lamellae) and elastic fibres look like on a histological slide?
Fenestrated sheets of elastin look like squiggly lines in longitudinal section and small broken up lines in transverse.
Elastic fibres look like long squiggly or curved lines in longitudinal section and small dots in transverse.
What vessels could be in the coronary sulcus of the heart?
Coronary sinus
Coronary veins
Coronary arteries
What features are characteristic of a lymphatic vessel?
Very thin wall of endothelial cells
Variable in diameter
Will contain proteins and other stain-loving material
Lack a clear cut separation between tunics
Don’t contain red blood cells
What is the epithelium of the anterior laryngeal pharynx?
Pseudostratified ciliated columnar epithelium with mucus glands
What is the epithelium of the posterior laryngeal pharynx?
Stratified squamous epithelium with fat and connective tissue underneath
Why does the epithelium differ between the posterior and anterior aspects of the laryngeal pharynx?
They come into contact with different things.
The anterior aspect leads to the larynx and the trachea, so comes into contact with air, therefore it can afford to only have one layer and needs to moisten that layer for the air.
The posterior aspect leads to the oesophagus, so comes into contact with abrasive food, therefore needs multiple sacrificial layers of cells.
What is the epithelium on the epiglottis?
Anterior (upper) and tip is stratified squamous because it comes into contact with abrasive substances. The posterior (lower) surface is pseudostratified ciliated columnar epithelium.
What structures are in the lamina propria?
Mucus glands Blood vessels Lymphatics Nerves Connective tissue
Why is the C shaped cartilage of the trachea interrupted in some slides?
The further down you get, the more discontinuous it becomes. Also, sectioning error can cause discontinuous look.
What tissue is between the C shaped cartilage rings?
Loose connective tissue
What type of muscle is the trachealis muscle and when would it contract?
Smooth muscle
Could contract during coughing to push foreign materials up and out
What are the two sources of mucus in the trachea?
Goblet cells and seromucus glands
What are some examples of conditions where goblet cell number might increase?
Bronchitis
Smoking
Chronic sinusitis
What type of epithelium lines ducts in the lamina propria?
Simple cuboidal epithelium
What type of cartilage is in the trachea?
Hyaline
What type of epithelium is present in the bronchus?
Pseudostratified ciliated columnar epithelium with goblet cells
What type of epithelium is present in the bronchiole?
Simple ciliated cuboidal epitherlium
Where are mucus glands located in the conducting airways?
Below epithelium in bronchus
Which airways contain cartilage and how is it arranged?
Trachea - C shaped
Bronchi - hyaline cartilage plates
What type of muscle is present in the conducting airways and how is it arranged?
Smooth muscle in longitudinal spirals
How are elastic fibres arranged in the conducting airways?
Between epithelium and smooth muscle. Arranged longitudinally.
3 major differences between a bronchus and a bronchiole
1) Cartilage in bronchus, not in bronchiole
2) Distinctive goblet cells in bronchus vs indistinctive club cells in bronchiole
3) Pseudostratified columnar epithelium in bronchus, simple cuboidal in bronchiole
Where are the pulmonary arteries located in the lung and how is their wall organised?
Pulmonary arteries run with airways, have thin walls with very large, filled lumens and they carry oxygen poor blood.
Where are the bronchial arteries located in the lung and how is their wall organised?
Bronchial arteries run in airway walls under smooth muscle, have thick walls with a small lumen and carry oxygen rich blood.
Where are the pulmonary veins located in the lung and how is their wall organised?
Pulmonary veins are found in the spongy area of the lung or in the middle of alveoli, away from pulmonary arteries. They have very thin walls and are generally small due to the low pressure. They carry oxygen rich blood.
Type I cell histology
Flat, long, thin
Found in the alveolar wall
Type II cell histology
Rounded/cuboidal
Found in the alveolar wall
Macrophages histology (lungs)
Can be fixed in the alveolar wall or floating in alveolar air space
What cell type lines alveolar capillaries?
Squamous epithelium
Where is connective tissue located in the lungs?
Interalveolar septum
Provides support for capillaries
Contains collagen, elastin and fibroblasts
How would alveolar size differ in emphysema?
Large air space with decreased surface area for gas exchange
How would macrophages differ in congestive heart failure?
Presence of red blood cells in macrophages indicates backflow of blood from heart to lungs due to high BP
What do carbon particles in the lungs suggest?
Pollution, smoke inhalation
What would thicker blood vessel walls in the lungs indicate?
Congestive heart failure, especially if the thickened walls are in the pulmonary veins.
Indicates backflow of blood from heart to lungs due to increased blood pressure, causing extra stress on these vessels and them to change to more rigid structures to handle the pressure.
Where would you find the transverse pericardial sinus?
Top recess in the posterior serous pericardium
Separates the great arteries and veins
Posterior to PT and ascending aorta, superior to LA, anterior to SVC
Useful for coronary bypass
Where would you find the oblique pericardial sinus?
Small recess in pericardial cavity situated behind base of heart
Underneath transverse pericardial sinus
Formed by cardiac looping tissue reflecting back onto pulmonary veins
Where would you find the coronary ostia?
Behind the aortic valve
Musculi pectinati
Parallel ridges in the walls of the atria of the heart
More and larger in the right atrium
Only in the auricle of the left atrium
Fossa ovalis
Remnant depression of foramen ovale between left and right atria
Crista terminalis
Smooth surfaced, thick portion of heart muscle
Divides musculi pectinati and auricle from smooth surface of right atrium
Chordae tendineae
Fibrous cords of connective tissue that connect the papillary muscles to the AV valves in the ventricles
Papillary muscles
Muscles located in the ventricles that attach to the AV valve cusps via chordae tendineae
Trabeculae carnae
Rounded or irregular muscular columns which project from the inner surface of the right ventricle of the heart
Interventricular septum
Wall separating ventricles from each other
Moderator band
Muscular band of heart tissue in the right atrium only
Also known as septomarginal trabecula
Coronary sinus
Collection of veins joined together to form a large vessel that collects blood from the myocardium and takes it back to right atrium
3 indentations seen in the oesophagus
1) where it’s compressed by the left atrium
2) where it’s crossed by the arch of the aorta
3) where it’s compressed by the left main bronchus
Where does the azygos vein come from?
It’s formed by the union of the ascending lumbar vein with the right subcostal vein and ascends upwards, sprouting right intercostal veins on the way
Where do the hemiazygos and accessory hemiazygos veins come from?
Branch from the azygos vein around T8/9 level and cross to the left hand side of the thorax
The accessory hemiazgos vein ascends and sprouts 5 left intercostal veins
The hemiazygos vein descends and sprouts 3 left intercostal veins and the left subcostal vein
Where would you find the arch of the azygos vein?
At the level of the transthoracic plane
The ‘arch’ is where the vein curves over the right main bronchus to join up with the SVC
Where would you find the thoracic duct?
Between the azygos vein and descending thoracic aorta
The inferior end is the cisterna chylii
It exits between the left carotid artery and internal jugular vein
Right vagus nerve pathway
Comes down over right subclavian artery
Branches off into right recurrent laryngeal nerve which loops around right subclavian artery and ascends
Vagus continues down posterior to SVC and right main bronchus
Left vagus nerve pathway
Comes down to the left of aorta
Branches off into left recurrent laryngeal nerve which comes around aorta and ascends
Vagus continues down anterior to thoracic descending aorta
Muscles of the thoracic cage
External intercostal Internal intercostal Innermost intercostal Transversus thoracis (same plane as innermost intercostals) Subcostal muscles (same plane as innermost intercostals and transversus thoracis)
Where do the intercostal nerves come from?
Anterior rami
12th one is called the subcostal nerve
Where do anterior intercostal arteries 1 - 6 come from?
Direct from the internal thoracic artery
Where do anterior intercostal arteries 7 - 9 come from?
Musculophrenic artery
Where do posterior intercostal arteries 1 and 2 come from?
Supreme intercostal artery
Where do posterior intercostal arteries 3 - 11 come from?
Thoracic aorta
Anterior intercostal veins drain into:
Internal thoracic vein
Posterior intercostal veins drain into:
Azygos/hemiazygos venous system
Where would you find the lingula?
Between the upper and lower lobes of the left lung, because it doesn’t have a middle lobe
