Cardio Flashcards
Two circuits of cardio system
Pulmonary: right heart -> lungs -> left heart
Systemic: left heart -> body -> right heart
Arteries carry blood AWAY from heart except which one?
Veins carry blood TO heart except which one?
Pulmonary artery
Umbilical vein
Artery order going away from heart
Elastic arteries
Muscular arteries
Arterioles
What are the function of pericytes
Regulate the blood flow of capillaries
3 layers of vasculature
Inner: tunica intima
Middle: tunica media
Outer: tunica adventitia
Tunica intima characteristics
Inner: sim squamous ET
Middle: subendothelial layer
Outer: internal elastic lamina
Subendothelial layer made of
Loose CT
Aka lamina propria
Tunica media made of
Smooth muscle in circular layer
Produces ECM
NOOOO fibroblasts
External elastic lamina
Tunica adventitia made of
Loose CT made of fibroblasts unlike tunica media
Contains: vasa vasorum, Nervi vasorum, and lymph vessels
Vasa vasorum
Blood vessels of the tunica adventitia
Feeds and takes away ox/deox blood from the blood vessel itself
Nervi vasorum
Nerve endings in blood vessel to stimulate
Regulates constriction and dilation
Artery vs Vein
Arteries have very prominent layers
Veins have thinner layers and valves
Large veins may have muscle in tunica adventitia, usually larger than artery
Only some veins have an internal elastic lamina
Vasculogenesis
What is it, when does it occur
De novo, NEW blood vessels formed
Embryogenesis
VEGF is secreted by mesenchymal cells which tells angioblasts to line up and form a tube to make INTIMA
Angiopoeitins recruit smooth muscle to cover intima which makes the MEDIA layer
Angiogenesis
What is it, when does it occur
Existing blood vessels sprout new branches
Embryogenesis and adulthood
Basal lamina breaks down and VEGF recruits angioblasts to line up in tube and angiopoeitin recruits smooth muscle to make media
When does angiogenesis begin
When heart starts pumping blood
This creates a hydrodynamic force that begins and mediates the development of new blood vessels
Normal vs portal system
Normal: artery -> capillary -> vein
Portal 2 types:
Arterial portal: afferent arteiole -> cap -> efferent arteriole -> cap (deox) -> vein , Blood remains oxygenated for second cap
Venous: arteriole -> cap -> vein-> cap -> vein
blood remains deoxygenated for second cap
POINT: allows short, direct transfer of material through the blood between two organs without having to traverse the heart/systemic circuits
Arterial and venous portal locations
Arterial: KIDNEY
Venous: Hypothalamus
What is a direct connection between an artery and a vein with NO caps in between
Where is this seen?
Arteriovenous anastomosis
SHUNT
Seen in the skin
What maintains the integrity of the blood vessels
Blood pressure
What is the systolic measurement?
Diastolic measurement?
Vessel pressure during heart pumping HIGHER
Vessel pressure during heart filling LOWER
Blood pressure is highest in the ____ and lowest in the ____
Aorta
Vena cava
Largest arteries are the
Elastic arteries
Closest to heart
Elastic artery characteristics
Thin tunica intima, falls apart during x section bc so small, hard to see
Very muscular with 80 layers of SM in media layer
Produce own ECM and ELASTIN network that stores potential energy and controls BP
Thin adventitia
Two things that control blood pressure
- Elastic lamina in media layer, stores potential energy when stretched and snaps back to keep blood flowing
- Precapillary sphincters in arterioles, small ring of smooth muscle that controls blood flow into organs
Muscular artery characteristics
Medium sized
Do most of systemic work
Tunica media has 20 layers of SM that produce COLLAGEN, not elastin
VERY prominent internal and external elastic lamina
VERY thick adventitia
Arteriole characteristics
AKA?
Resistance arteries
Smallest artery
Has precap sphincters
Thin tunica media of about 2-3 layers
What arteries are Innervated by autonomic nerves and respond to hormones
Arterioles
The last artery before capillaries is known as the
MET arteriole
What blood vessel is known as the “resistance vessel” and is the primary vessel that regulates BP?
Arteriole
Bc they have precap sphincters that are a ring of SM around the arteriole to control blood flow into the capillaries
Endothelial cell function in a blood vessel
Keep the blood vessel lined and healthy
Act as a barrier with a junctional complex, so no foreign materials can pass through
Endothelial cells in BV functions
- Convert angio 1 into angio 2 IN LUNG ONLY
- Inactivate bradykinin and serotonin
- Lipolysis of lipoproteins
- Prevent blood coagulation bc they run in the direction of blood flow, keeps blood flow non turbulent
- Nuclei bulge into lumen
- Secrete nitric oxide and endothelial 1
Smooth muscle Relaxer vs Contractor
What are they secreted by?
Vaso relax: Nitric Oxide, dilates BV
*NO relaxing
Vaso constrict: Endothelin 1 and Angiotensin 2
Secreted by endothelial lining in blood vessels
Capillary characteristics
Endothelium and basement mem ONLY
Facilitates gas exchange
Diameter only allows one RBC at a time
Blood moves SLOWLY to allow greater diffusion
Have pericytes
Pericyte function
Adult cap stem cells that are normally QUIESCENT, but are activated upon damage and function to repair the damage
Attach to outside of capillary and LAMINA PODIA act like fingers that wrap around cap
3 types of caps
Continuous
Fenestrated
Discontinuous
Continuous caps
TIGHT JUNCTIONS, strict transport
Only found in areas where strict transport is necessary
BBB of CNS, muscles, BAB (blood air barrier) of lungs
Continuous BM
Use vesicular transport
Vesicular transport
Aka transcytosis
Used in continuous capillaries to transport material with vesicles
Fenestrated caps
Looser junctions to allow medium transport
Found in endocrine glands, GIT, gallbladder
Have areas where endothelial cells thin out, these are called “fenestrations” to make material exchange easier
Fenestrations may have a diaphragm
Continuous BM
Fenestration diaphragms
Fenestrations Make material exchange easier in fenestrated caps
Diaphragms hold the fenestrations together, some fen caps do not have these
Discontinuous caps
Aka
Sinusoidal caps in LIVER, microville on hepatocytes project through these gaps directly into the lumen of the endothelial cell
For EASY transport of materials
Found in bone marrow, liver, spleen
Large gaps “fenestrae” between endothelial cells
Can have a discontinuous or ABSENT BM
Aortic aneurysm
Where does it occur?
Tunica media
Neutrophils invade the tunica media and secrete ELASTASE which causes inflammation, and destroys the tunica media, creates scar tissue
Must be surgically fixed
Endothelial cells turn ____ into ____ to regulate BP. How is the blood pressure regulation accomplished?
Angio 1 into angio 2
Angio 2 is a vasoconstrictor to increase blood pressure
- It does this by constricting the JUXTA CELLS in kidney thus lowering the GFR (glomerular filtration rate) to increase the blood in the rest of the vasculature
- Stim adrenal cortex to release ALDOSTERONE which increases water and Na+ resorption into blood, this increases the blood pressure
How to endothelial cells regulate lipolysis?
When cholesterol gets into lumen of of vasculature, macrophages digest the lipid
If lipids accumulate, over time the macrophages will lose and lipid will form plaque in the tunica intima, which may eventually break through into the lumen
What is it called when endothelial cells prevent blood coagulation in vasculature
Antithrombogenic activity
2 types of vascular occlusion
Atherosclerosis
Restenosis
Atherosclerosis
Plaque build up in tunica media due to high cholesterol/lipids
Restenosis
When the SM in the tunica media crosses the IEL and forms layers in tunica intima which can bust out into the lumen
Can occur after stent placement
What occurs when vascular occlusion occurs in the heart vasculature
Heart INFARCTION
The heart has decreased oxygen
causes cardiac myocytes to die
fibroblasts proliferate in these areas to make scar tissue FIBROSIS
New cardiomyocytes cannot be made in adult hearts!
Necrotic/fibrous heart tissue does NOT STAIN in images
Large vein characteristics
Larger lumen than arteries
Very irregular lumen shape
Thin tunica media that produces COLLAGEN, not elastin like a large artery
Minimal or ABSENT elastic lamina
SM found in the ADVENTITIA, longitudinally arranged unlike artery
Medium veins characteristics
Similar to large veins
Thinner tunica intima than large veins
What is the KEY feature of veins
VALVES
What are valves made of and how do they function
Core: elastic CT
Outer layer: endothelial cells
Contraction of surrounding skeletal muscle constricts veins pushing the blood up past the valves
The valves immediately close to prevent back flow
Varicose veins
Damage to vein valves
Caused by sedentary lifestyle
Blood pools in veins bc valves no longer work to prevent back flow
Commonly seen in legs where there is increased blood flow
Thrombosis
Hemorrhoids
Diseases involving veins
Thrombosis: When a blood clot becomes dislodged and travels to the lungs
Hemorrhoids: When blood vessels dilate in the anal canal, can cause bleeding during defecation
Lymphatic system vasculature
System of blind ending caps that permeate through CT of the body
Carry lymph to the large vessels that drain into veins
Absorb excess interstitial fluid around caps
How is an edema formed
When excess interstitial fluid does not drain into the lymph system
Fluid accumulates and causes swelling
Why does fluid leak out of arteries and where does it go?
There is a higher hydrostatic pressure in arteries than veins bc of their distance from the heart, arteries have higher BP
There is a high osmotic pressure in veins than in arteries bc of ALBUMIN
So there is a tendency for fluid to leak out into surrounding CT which is then absorbed by lymph caps
Lymph capillary characteristics
Have valves
Contains leukocytes in lumen that ARE NUCLEATED (seen in images compared to RBC in caps w no nucleus)
Sim squamous ET and BM
Evident in SMALL INTESTINE MV
Lacteal location and function
Blind ending lymph cap that projects into a microvilli in small intestine
Lined by sim squamous ET
Absorbs LIPIDS
Where are carbs and proteins absorbed?
Where are lipids absorbed?
Blood capillaries
Lacteal
*Lipids and Lacteal
Layers of the heart wall
Inside- Endocardium
Myocardium
Outside- Epicardium
Endocardium
Heart inner layer
- Endothelial lining
- SM and CT
- Autonomic nerves
- Purkinje fibers
Purkinje fibers. AKA
Location
Characteristics
Located in the sub endocardium
Conduction of lower part of ventricles
Aka
Specialized cardiac myofibers
Large uni or binucleated cells
Structure: similar to skeletal muscle, DIAD, intercalated discs, nuclei centrally located
Myocardium
Heart middle layer
Bulk of the heart
1. Cardiac myocytes
2. Firbroblasts
Myoendocrine cells
What is atrial natriuretic factor and what is it produced by
Acts on the kidney and causes excretion of Na+ and H2O, pee becomes less concentrated
Produced by the myoendocrine cells in the myocardium
Epicardium
Outer layer of the heart
Made of parietal and visceral layers
Epicardium= parietal pericardium= fibrous CT outside of heart for protection
Pericardial space between layers filled with fluid
Holds the vasa vasorum which supplies blood to the heart itself
Holds nerves and adipose tissue and apex to cushion
Parietal vs Visceral pericardium
Parietal= epicardium and is made of fibrous CT, outermost layer of heart Visceral= mesothelial lining closest to myocardium
Conduction of the heart
- SA node in RA
- AV node in RA
- Bundle branches
- Purkinje fibers in Lower ventricles (located in the sub endocardium layer)
All conduction tissue is ____
Specialized cardio myocytes
3 junctions of intercalated discs
Fascia adherens- along z line
anchors w ACTIN
Gap junctions- 6 connexins make 1 connexon, perpendicular to z line
Ionic coupling
Macula adherens- spot desmosome, present throughout
All myocytes are _____
Electrochemically coupled
Orientation of myocytes in the myocardium
Muscle cells in the myocardium
Fibers TWIST for better TORQUE and contraction to support blood expulsion
Closer to Epi- fibers superior to inferior
Middle- fibers run anterior to posterior
Closer to endo- fibers run superior to inferior
Adult cardiac myocytes do NOT undergo
Hyperplasia (Proliferate! ) They are unable to create more cells
ONLY done by smooth muscle
They do however undergo hypertrophy in response to overload
Hypertrophy definition
And describe what occurs in hypertrophy of cardiac muscle
Increase in tissue size due to enlargement of cells
Can be done by all muscles
When the heart is being overworked due to a clogged BV, heart pumps harder to make up for it
Which can lead to increased genes, protein synth, and changes to ECM
This interferes with intercalated discs
PATHOLOGIC
