Histology of Cardiovascular System Flashcards
What are the functional components of the cardiovascular system?
Blood vascular system and
Lymphatic vascular system
Circulation from heart to lungs
Pulmonary circulation
Circulation from heart to rest of the body
Systemic circulation
What happens to the blood as it goes to smaller types of blood vessels?
It slows down
From 33 cm/s in the aorta and pulmonary artery to about 0.3 cm/s at the level of arterioles and capillaries
The lymphatic vascular system merges with the _________ and eventually joins venous circulation.
Thoracic Duct
What causes lymph movement?
Lymph movement is due to contraction of surrounding skeletal muscles, returning excess lymph to the blood circulatory system.
The endothelium is has what kind of epithelial tissue type?
Simple squamous
What are the vasoactive factors produced by the endothelium?
Nitric oxide - vasodilator
Endothelins - vasoconstrictor
The endothelium converts ___________ to ____________ in order to increase blood pressure.
Angiotensin I to Angiotensin II
What are the functions of the endothelium?
- Nutrient Exchange
- Vasoactive factor secretion
- Angiotensin conversion
- Lipolysis of lipoproteins
- Receptors for leukocyte binding
- Anti-thrombogenic functions
Main component of tunica media
Smooth muscles
True or false. Smooth muscles in the endothelium have their own basal lamina.
True
Arrangement of smooth muscles in endothelium:
Circumferential
Connective tissues have: __________ and __________
Collagen and elastic fibers
Connective tissues are arranged:
Longitudinally
3 layers of the blood vessels arranged from closest to lumen to periphery
Tunica intima
- endothelium
- basement membrane
- internal elastic lamina
Tunica media
- smooth muscle
- external elastic lamina
Tunica externa
Epithelial type of tunica intima
Simple squamous endothelial cells
The internal elastic lamina is a fenestrated sheet of collagen. True or false?
False, it’s a fenestrated sheet of elastin
The internal elastic lamina is prominent in _________
Muscular arteries
It consists of arranged smooth muscle cells arranged circumferentially around the lumen
Tunica media
Increase in pressure leads to the ___________ of the tunica media
thickening
Which has thicker tunica media? Heart or brain blood vessels?
Heart, because they experience greater pressure
Tunica Externa/Adventitia is a _____________ composed of _______________, arranged ____________.
connective tissue composed of type I collagen and elastic fibers arranged longitudinally
Microvasculature attached to the walls of thicker blood vessels to provide nutrients which cannot penetrate their thick walls:
Vasa vasorum
Location of vasa vasorum:
Tunica externa/advantitia and outer half of tunica media
Vasa vasorum supply these layer/s:
Tunica externa/adventitia and tunic media
Vasa vasorum more frequently seen in ________.
Veins (compared to arteries)
Histologically, how do you differentiate vasa vasorum from arterioles, venules, and capillaries?
Vasa vasorum are attached beside another bigger blood vessel
Nerves arising from the medullar oblongata, innervating blood vessels
Nervi vasorum
Nervi vasorum arise from ____________
Medulla oblungata (reticular center)
Nervi vasorum are found in bundles in the ___________.
Tunica adventitia
They are responsible for maintaining vasomotor tone
Nervi vasorum
Contraction of the ventricles forces blood into the arteries, making them expand. What do you call this?
Ventricular systole
Relaxation of the ventricles, blood continues to flow due to recoil from the elastic tissues of arteries. What do you call this?
Ventricular diastole
Three main types of arteries:
- Elastic Arteries
- Muscular Arteries
- Arterioles
Largest type of artery:
Elastic arteries
Medium-sized artery:
Muscular arteries
Smallest type of artery:
Arterioles
This layer is broadest in arteries:
Tunica media
They are called conducting arteries and are considered as auxiliary pumps:
Elastic arteries
Responsible for ensuring the continuous flow of blood
Elastic arteries
Elastic fibers have a high amount of _______ in ________.
they have a high amount of elastin in tunica media
Examples of elastic arteries:
- Aorta and its primary branches
- right brachiocephalic trunk
- left common carotid artery
- left subclavian artery - Pulmonary artery and its branches
Responsible for storage and secretion of von Willebrand factor, a glycoprotein responsible for platelet aggregation (clotting)
Weibel-Palade bodies
Weibel-Palade bodies are located in which layer?
Tunica intima
True or False. Only elastic arteries can store von Willebrand factor.
True
P-selectins are found in which layer?
Tunica intima
Fenestrated, concentrically-arranged sheets of elastin, interspersed between collagen fibers and smooth muscle cells
Tunica media
Elastin fibers appear black in _______ stain. Meanwhile, it appears pink in ________ stain.
Elastin fibers: Black in orcein stain while pink in H&E
Highly collagenous layer but may also have elastin
Tunica externa/adventitia
Nervi vasorum is located in which layer/s?
Tunica externa/adventitia
Vasa vasorum is located in which layer/s?
Tunica adventitia and tunica media
True or false. Elastic laminae are prominent in elastic arteries?
False, because they are continuous with the elastic fibers of the tunica media.
These are also known as distributing arteries
Muscular arteries
Type of artery responsible for the distribution of blood to the different parts of the body
Muscular arteries / Distributing arteries
Elastic arteries have much elastin in their tunica media. Meanwhile, muscular arteries have much _________ in their tunica media.
Smooth muscle
Examples of muscular arteries:
Brachial, Radial, Ulnar, Femoral, Popliteal arteries
Cerebral and Coronary arteries
The tunica intima of muscular arteries have a more prominent ___________.
Internal elastic lamina
Contains fibroblasts, elastic, and collagen fibers arranged longitudinally.
Tunica adventitia
Bundles of unmyelinated axons terminate at this layer
External elastic membrane of tunica adventitia
Principal component of peripheral resistance to blood flow pressure:
Arterioles
Anti-hypertensive drugs act on which blood vessels?
Arterioles
Transition from large arteries to arterioles is evidenced by:
- _______________
- _______________
- Reduction of internal elastic lamina
2. Reduction of smooth muscle in tunica media
These are transitional vessels from terminal arterioles to capillaries
Metarterioles
Metarterioles have a ________ layer of smooth muscles, spaced a short distance apart, completely encircle the tube of the epithelium.
Discontinuous
Smooth muscle cells continuous with the capillaries:
Precapillary sphincter
These are sensitive to the changes in chemical concentration of the blood (pH, CO2 and O2 levels)
Chemoreceptors like carotid body and aortic body
Chemoreceptors transmit signals to the _____________.
Respiratory system
Carotid body is located where?
Bifurcation of common carotid and internal carotid artery
Type of carotid body that secrete neurotransmitters:
Glomus (Type I)
Neurotransmitters secreted by glomus (type I):
Serotonin and Dopamine
Surrounds a cluster of 2-6 glomus cells:
Sheath (Type II)
Blood supply of carotid body:
Mayer’s ligament
Innervation of carotid body:
CN IX (Hering’s Nerve)
Chemoreceptor found between left common carotid and left subclavian:
Aortic body
Responsive to changes in blood pressure
Baroreceptors
Baroreceptor located at the wall of the internal carotid artery
Carotid sinus
Done to decrease blood pressure among hypertensive patients
Carotid massage
Innervation of carotid sinus
Hering’s Nerve (CN IX)
Old people have higher blood pressure because ____________.
The elasticity of their blood vessels has significantly reduced
What tissue migrates into the tunica intima as one ages (leading to accumulation of fat)?
Smooth muscle from tunica media
Physiological response of blood vessels to aging
Arteriosclerosis
Accumulation of plaques secondary to the deposition of muscles in the tunica intima
Atherosclerosis
Occlusion in the coronary vessels
Myocardial infarction
Occlusion in a blood vessel in the brain
Cerebrovascular accident/ Stroke
Thinning and swelling of blood vessel wall
Aneurysm
Smallest diameter among blood vessels
Capillaries
Capillaries consists of:
a single layer of endothelial cells and their basal lamina
Capillaries don’t have:
Tunica media and tunica adventitia
Special cells attached outside the endothelium that accompany capillaries
Pericytes
Pericyte process that is longitudinal
Primary process
Pericyte process that is circumferential
Secondary process
Function of pericytes
Capillary repair during injury
True or False. Pericytes have actin, myosin, and troponin.
True
Transport system of capillaries
Transcytosis
Vesicles derived from Golgi apparatus used by capillaries for transport
Caveolae
Type of capillaries found in internal organs (viscera) where high rate of nutrient exchange occurs
Fenestrated capillaries / Visceral capillaries
Continuous layer of endothelium around the lumen of the capillary without fenestrae
Continuous Capillaries / Somatic / Smooth capillaries
Type of capillary in muscles, connective tissues, nervous tissues, and lungs:
Continuous capillaries
Type of capillaries that have irregular outlines and varying shapes
Sinusoidal capillaries / Discontinuous capillaries
Capillaries found in the liver, spleen and bone marrow
Sinusoidal capillaries
Blood vessel with thin walls, lumen collapsed, and boundaries less distinct:
Veins
Smallest vein
Venule
Veins that branch immediately from the capillary and a site for exchange of nutrients and cell migration besides capillaries. They also serve as exit doors for WBCs (preferential site for migration of leukocytes).
Postcapillary venules
Extensions or semilunar folds of the intima that project into the lumen of the vein
Valves of veins
Vein with all three layer distinguishable:
Large veins - inferior vena cava, portal vein, splenic vein
Alternative microvascular pathway in which blood flows through two successive capillary beds separated by a portal vessel allowing effective delivery of nutrients.
Portal system
3 portal systems:
- Hepatic portal system (Liver)
- hepatic portal vein - Renal portal system (Kidneys)
- efferent arteriole - Hypophyseal Portal System (Brain; Hypothalamus to Pituitary)
- hypophyseal portal vein
Portal system with the only atrial portal vessel
Renal portal system (efferent arteriole)
3 layers of cardiac wall
Endocardium, Myocardium, Epicardium
Epicardium type of epithelium:
Simple squamous endothelial cells with fibroelastic tissue
Continuous with the tunica adventitia of blood vessels
Epicardium
Thickest layer or the heart consisting mostly of cardiac muscle. It is continuous with the tunica media of blood vessels.
Myocardium
Continuous with the tunica intima of blood vessels. It is a single layer of squamous endothelial cells resting on a subendocardial layer.
Endocardium
3 layers of the endocardium and their contents
- Inner layer: endothelium and connective tissue
- Middle myoelastic layer: smooth muscle fibers and connective tissue
- Deep layer/subendocardial layer: contains connective tissue, blood vessels, nerves, merges with the myocardium and contain Purkinje fibers
Pale-staining fibers due to high glycogen content with sparse peripheral myofibrils
Purkinje fibers
Pacemaker of the heart located near the junction of the superior vena cava and the right atrium
Sinoatrial Node
Located beneath the endocardium of the interatrial septum
Atrioventricular Node
Flow of polarization from the SA node
SA node -> AV node -> Bundle of His -> Bundle branches -> Purkinje fibers
Four fibrous rings surrounding the valve orifices
Annuli fibrosis
Atrial cardiac fibers attach to:
Annuli fibrosis of pulmonary artery and aorta
Ventricular cardiac fibers attach to:
Annuli fibrosis of atrioventricular valves
Structure that connects the rings of annuli fibrosis
Trigona Fibrosis (Fibrous trigone)
Single layer of endothelium with no fenestrations and no basal lamina
Lymphatic capillaries
Do lymphatic vessels have valves?
Yes, they come from the tunica intima
