Circulatory System/Heart Flashcards
What does the circulatory system consist of? 3 things
heart
blood vessels
lymphatic system
What are the three layers of large blood vessels? From innermost to outermost
Tunica Intima – innermost
Tunica Media
Tunica Adventitia – outermost
Large vessels have other small vessels called _______ branching through the adventitia and the outer part of the media.
Vasa vasorum
Which type of large blood vessels have more vasa vasorum? arteries or veins?
Veins
What are nerves within the adventitia called?
nervi vascularis
What layer of large blood vessels is comprised of the endothelium and the underlying subendothelial connective tissue?
tunica intima
In larger vessels, the tunica intima contains a band of elastic fibers called what?
Internal elastic lamina
In what blood vessel layer is the external elastic lamina found? Primarily in muscular large vessels
Tunica media
What is the tunica media primarily made of?
smooth muscle cells
What is the tunica adventitia comprised of?
Fibroelastic connective tissue
ie dense irregular CT with small amounts of elastic fibers
What do elastic (conducting) arteries do?
Conduct blood to muscular arteries
The aorta, pulmonary, brachiocephalic, common carotid, subclavian, and common iliac arteries are what kind of artery?
Elastic
What is different about the internal elastic lamina in elastic arteries vs muscular arteries?
Elastic => incomplete internal elastic lamina
Muscular => well developed internal elastic lamina
What is different about the external elastic lamina in elastic arteries vs muscular arteries?
Elastic => no distinct external elastic lamina
Muscular => thick external elastic lamina
What is the key identifying feature of elastic arteries?
A thick tunica media of 40-70 concentric elastic sheets
What are muscular arteries innervated by?
postganglionic sympathetic nerve fibers
The tunica media of muscular arteries contains up to 40 circular layers of __________ interspersed with elastic fibers
smooth muscle
What are the key identifying features you should look for in a muscular artery?
Visible internal and external elastic lamina
Tunica media contains many layers of smooth muscle
Is blood pressure higher in the artery or vein side of the circulatory system?
artery
How many layers of smooth muscle cells do arterioles usually have?
1 - 3 layers of smooth muscle cells
What should you look for when identifying an arteriole?
1- 3 layers of smooth muscle cells
What is the subendothelial connective tissue in arterioles like?
very sparse
Do capillaries have a tunica media?
no
How many layers of endothelial cells do capillaries have?
1
What are pericytes?
mesenchymal-like stem cells found in the thin sheath of reticular and collagenous fibers around a capillary
On which side of the circulatory system are pericytes primarily found?
On the post capillary side (venus)
In wound healing, pericytes may differentiate into _______ or __________
fibroblasts or smooth muscle cells
What are the three types of capillaries?
Continuous (somatic)
Fenestrated (visceral)
Discontinuous (sinusoidal)
Where are continuous (somatic) capillaries found? 5#
muscle connective tissue CNS exocrine pancreas gonads
Where are fenestrated (visceral) capillaries found? 6#
mucosa of GI tract endocrine glands renal kidney choroid plexus ciliary body
Where are discontinuous (Sinusoidal) capillaries found? 2#
liver hemopoietic organs (bone marrow, spleen)
What type of capillary has no fenestrae?
continuous (somatic)
not very leaky => not a lot of material can cross
In the CNS, _________ capillaries have a type of tight junction (occluding junction) that contributes to the blood-brain barrier?
continuous
What type of capillary has an attenuated endothelium with large fenestrae closed by thin diaphragms.
BUT STILL HAS A CONTINUOUS BASAL LAMINA
fenestrated
what type of capillary has numerous pinocytotic vesicles for transcytosis?
continuous
What is unique about the fenestrated endothelium in the glomerular capillaries compared to usual fenestrated endothelium?
They have no diaphragms
What is the difference between the basal laminae of discontinuous and fenestrated capillaries?
fenestrated (and continuous) have a continuous basal lamina
Discontinuous have and incomplete basal lamina
What type of capillary has wide gaps between cells?
discontinuous
What type of vein receives blood from capillaries?
postcapillary venules
Where does nutrient exchange primarily happen?
In the postcapillary venules
What blood vessel type is an important site for inflammatory response?
postcapillary venules
Do muscular venules have pericytes?
No
How many layers of smooth muscle do muscular venules have?
1 - 2 layers
What blood vessel layer is well developed in veins?
Tunica adventitia
What is the well developed adventitia of veins comprised of?
Multiple layers of collagenous fibers with a few smooth muscle cells and elastic fibers
Large veins have a thin media and intima but a very large ________
adventitia
What do venous valves do?
Prevent retrograde blood flow
Where are venous valves primarily found?
lower limbs
Do venous valves have any muscle in them?
no
valves are paried semilunar folds of the ________ covered with endothelium
tunica intima
What is a mesh of connections between arterioles and venules called?
arteriovenous anastomoses
At an anastomosis, there is a specialized tunica media with a ________
sphincter
When the sphincter shunt of an anastomoses is closed, where does blood flow?
Arterial blood flows into the capillary bed
When the sphincter shunt of an anastomoses is open, where does blood flow?
Blood bypasses the capillary bed and flows into a vein
Some microvascular beds have a __________ sphincter which controls the amount of blood flowing into the capillaries
precapillary
Where is fluid scavenged by the lymphatic system recycled back into the body?
At the base of the neck
Do lymph nodes have a basal lamina?
No
How does lymph move through lymphatic vessels?
By other nearby muscles contracting
What are lacteals in the intestine important for?
fat absorption
Lymphatic vessels originate in CT as what?
Closed-end anastomosing capillaries
When looking at slides what is the distinguishing feature of lymphatic capillaries?
no basal lamina
What are the two key areas of the body that have no lymphatic system?
CNS and bone marrow
What are the two parts of the lymphatic system that are structurally similar to veins with contractile smooth muscle present?
thoracic duct and right lymphatic duct
Skeletal muscle has lymphatics only in __________?
perimysium
What prevents the backflow of lymph?
paired cusp valves
What blood vessels are primarily involved in blood pressure regulation?
arterioles
What blood vessel’s elastic recoil maintains flow in diastole?
elastic
What type of blood vessel contains capillary sphincters?
Precapillary arterioles
What type of blood vessel is very permeable – blood tissue exchange – inflammation?
Postcapillary venules
What is it called when fatty deposits in intima block vessels?
atheroscleosis
What is smooth muscle cell proliferation that follows angioplasty procedures. May occlude vessel
Restenosis
What is an aneurysm?
Ballooning out of artery due to weakness in the arterial wall
What condition is caused by a decrease in muscle tone and failure of venous valves?
Varicose veins
What cholesterol related molecule gets below the tunica intima in blood vessels, and can cause an inflammatory response potentially leading to the formation of an atheroma?
LDL
What do endothelial cells produce? 3#
Prostacyclin from arachidonic acid (omega - 6)
Nitirc oxide
endothelin-1
What does prostacyclin do?
Inhibit platelet adhesion and clot formation
What does nitric oxide do?
Causes smooth muscle in the tunica media to relax VASODILATION
What does endothelin-1 do?
Stimulates vasoconstriction
If you see a lot of lipid and fat you are in what layer of the heart?
epicardium
What are the three layers of the heart from innermost to outermost?
endocardium
myocardium
epicardium
What is everything in the heart lined by?
endothelium
What part of the heart’s impulse conducting system can be found within the subendocardial CT?
Purkinje fibers
What is the myocardium comprised of?
cardiac muscle tissue
In the ventricles, the myocardium is arranged into what two layers?
deep and superficial
The fibers of which myocardium ventricular layer have a spiral course around the ventricle?
superficial
The fibers of which myocardium ventricular layer have a circular course around the ventricle?
deep fibers
The outermost coat of the epicardium is formed by _______ cells.
mesothelial
The epicardial mesothelium is = ___________
the visceral layer of the serous pericardium
Underneath the mesothelium is a subepicardial layer of loose CT and adipose tissue that contains what?
Coronary blood vessels and nerves
What type of tissue is the cardiac skeleton comprised of?
Dense irregular CT
What is the fibrous portion of the interventricular septum called?
Septum membranaceum
What are fibrous rings around the origins of the pulmonary artery, aorta, and atrioventricular canals called?
Annuli fibrosi
What is the fibrous tissue between the arterial foramina and the atrioventricular canals called?
trigona fibrosa
Make sure you can identify cardiac skeleton!!!
Okay okay jeeezzzz
Valves have both _______ and _______ CT layers surrounded by __________
dense and loose
endothelium
Purkinje fibers are modified _________ cells, and are filled with __________
They perform a neural function
muscle
glycogen
What is the AV bundle of His formed by?
purkinje fibers
What type of nerves slow the heart down?
They are branches off what major nerve?
parasympathetic
Vagus
What type of nerves accelerate heartbeat
sympathetic
What is atrial natriuretic peptide released by?
modified atrial muscle cells
What promotest the release of atrial natriuretic peptide in the heart?
high blood pressure
What is the primary effect of atrial natriuretic peptide?
To increase sodium and water secretion from the kidney
