Week 4 Pt 1&2 Blood vessels & Circulation Flashcards
What is the length blood vessel in an average adult human?
60,000 miles
What are the major categories of blood vessels?
Arteries, capilaries, and veins
what are the smaller arteries called?
Arterioles
Between the blood vessels, they have 3 layers EXCEPT?
capillaries
what is the innermost layer called?
tunica interna also known as tunica intima
what is the middle layer called?
tunica media
you can find what in the tunica media?
smooth muscle
what is the outermost layer called and what is another name for it?
tunica externa (tunica adventitia)
What does the tunica interna line?
the lumen
what is structure of the tunica interna?
it has endothelium, single layer of epithelial cell, and thin layer of areolar connective tissue deep to that.
Since endothelium is an epithelial tissue, what does those cells have to sit on?
a basement membrane
what layer does the capillaries ONLY have?
tunica interna
the tunica interna of an artery looks very similar to the tunica interna of a ?
vein
Why does the tunica media vary in thickness?
depending on the type of blood vessel
what are the largest arteries called?
elastic arteries
In the elastic arteries, what structures do they have?
smooth muscle and elastic tissue in tunica media
what type of artery has the thickest wall?
muscular arteries
What layer in the arteries has the thickest wall?
the tunica media is the thickest layer of the wall
what has layers that no other type of blood vessels have?
- In the elastic arteries
- the big ones such as aorta, pulmonary trunk, pulmonary arteries, iliac or common iliac arteries,
- things that are very close to the heart and receiving blood from ventricles
-branches off arteries that do that.
what are some of the layers no other blood vessels have called?
internal elastic membrane and external elastic membrane
where is the internal elastic membrane located?
deep into the basement membrane and tunica interna
where is the external elastic membrane located?
just between the outer edge of the tunica media and the beginning of the tunica externa
what does the external elastic membrane do?
lets the elastic arteries stretch a lot
what are the benefits of the elastic arteries?
it stretches and returns to its resting size
another importance of tunica media include : if you have smooth muscle, it is gonna need 2 things which is?
oxygen and autonomic innervation
smooth muscle is an autonomic ___
effector
what happens if the blood vessels are too thick for O2 to diffuse through the tunica media?
we need blood vessels to go into the tunica media of the blood vessels to supply O2 and nutrients to the smooth muscle in the wall of the blood vessels.
what is vaso vasorum?
blood vessels of blood vessels
- blood vessels that supply O2 and nutrients to the smooth muscle in the tunica media
what are the small autonomic nerves that go into the tunica media called?
nervi vasorum
what are the nervi vasorum and what does it do?
nerves of blood vessels that control whether that smooth muscle contracts or relaxes
what is the thickest layer of an artery?
tunica media
what is the thickest layer of a vein?
tunica externa
what do arteries deal with that causes the wall to be thicker?
pressure
what are veins meant to do?
to be away to get the blood back to the heart
-not meant for high pressure which is why they don’t need a thicker wall
why don’t we do much adjusting of blood pressure in the venous side of the circulation?
the arterial pressure is what matters
there’s nothing in the body that monitors venous blood pressure. T/F
True
what do the collagen fibers that stick out from the tunica externa help with in the veins?
help anchor the veins
If you have to chase a vein in the arm with a needle, what is the reason?
they are not well anchored
why do arteries have thicker walls?
handle blood that’s under higher pressure
there are more elastic fibers in the wall of artery because?
due to the thickness of the walls
what happens when you take blood out of an artery?
because of the elastic it will stay open and the lumen will stay round bc the wall is supporting it
what happens when you take blood out of a vein?
the vein will collapse bc it was the blood that was holding it open not the wall.
elastic arteries have the most elastic fibers. T/F
True
how can you tell an artery from a vein without looking at it under a microscope?
one of them is flat and one of them has an open lumen
what is vasoconstriction?
when the smooth muscle in the tunica media of an artery CONTRACTS and the lumen of blood vessel gets SMALLER due to it being in a circle
what vasodilation?
when the smooth muscle in the tunica media RELAXES and the lumen of that artery gets BIGGER
what are elastic arteries?
biggest arteries, have the second thickest wall in the artery, and also called conducting arteries.
- blood vessels that receive blood that’s directly getting pumped from the heart or very close branches
examples of elastic arteries
aorta, pulmonary trunk, pulmonary artery, common iliac, and common carotid
what are the functions of the elastic arteries?
to stretch when stroke volume is pushed into them.
- aorta is not getting steady flow of blood from right ventricle and it has to stretch to accept 75ml SV
what happens when you stretch an elastic artery?
the elastic fibers that are getting stretched stores energy and that energy is used to help push blood forward as elastic artery returns to its resting size
-due to no constant BP
what structures are muscular arteries and what is it called?
distributing arteries
- gastric arteries
- brachial arteries
- femoral arteries
the wall of the muscular arteries are what?
the thickest walls of any artery and bc the wall is so thick, the lumen is smaller than the lumen in the elastic artery
the muscular arteries are responsible for?
delivering blood to the specific regions of the body whereas the elastic ones have the job of receiving blood that’s coming out of the heart.
what are arteriole arteries?
smallest artery that connect to capillaries.
- don’t have much tunica externa
-walls are not very thick
what are arteriole arteries responsible for?
determining where blood goes and the main spot for blood pressure control
when its cold and you don’t want to lose the heat in the surface of the body ___
we constrict the arterioles in the skin and dilate arterioles in the core making it easier to go to the core
what are the three categories of capillaries?
continuous capillaries, fenestrated capillaries, and sinusoids
why are capillaries the only blood vessels with a wall thin enough?
to allow exchange
what are continuous capillaries?
most common
- least permeable
- simple squamous epithelium
- complete basement membrane on the outside of capillary
- space between the cells called intercellular cleft
where can you find continuous capillaries?
lungs, skeletal muscle, skin, and some types of connective tissues
when something has to move from capillary from outside and into the capillaries, what are the two diff pathways?
- to diffuse through basement membrane and simple squamous epithelium
- to go in the space between the cells called intercellular cleft: small size (intercellular cleft are not very big so the things that can leave/enter capillary are also not very big)
what are fenestrated capillaries?
- intercellular clefts between the cells are bigger than the ones in continuous capillaries: medium size
- holes in the cells called fenestration’s
- complete basement membrane around capillary
- more permeable than continuous capillary
- work like strainers (if smtn wants to enter or exit, it can pass through intercellular clefts and diffuse through basement membrane and simple squamous epithelium or fenestrations)
where can you find fenestrated capillaries?
organs where we have things moving in and out
- kidneys (tend to have stuff moving out)
- small intestine (where we have stuff moving in cuz we’re absorbing it)
what are sinusoids?
- have an INCOMPLETE basement membrane
- really big intercellular clefts
- have bigger fenestrations than in fenestrated capillaries: big size
- bigger diameter than fenestrate/continuous capillaries
- very windy ( things get stuck in turns if not flexible)
Where can you find sinusoids?
liver, spleen, and bone marrow
benefits of sinusoids having really big intercellular clefts?
it makes it easier for diapedetic WBC to move in and out of the blood stream
benefits of bigger fenestrations
allow us to move things out of blood or into the blood that are bigger than what we would add in most places.
Where would plasma proteins go through and why?
sinusoids because it is made by liver and need to be put in the blood
How do you filter out the older RBC in a windy sinusoid?
When RBC get old, they lose flexibility causing them to not make sharp turns and they get stuck
what do the capillaries connect?
the arterioles to the venules
you can find capillaries in most places in something called ____
capillary bed
what structures are in a capillary bed?
short connecting structures called metarterioles
what are precapillary sphincter?
band of smooth muscle that adjusts flow into capillaries
what happens when a pre capillary sphincter is closed?
blood goes form metarteriole into venule without any blood going to the capillaries
- blood can’t go anywhere, roads are blocked
- the more that have closed, less blood that goes through capillary bed and the less oxygen and nutrients we will delivery in waste area and fewer waste product we will pick up to get out
what happens when precapillary sphincter is open?
blood can get out of arteriole and go into smaller capillary areas
what is a metarteriole?
when precapillary sphincter is open
what is it called when all precapillary sphincter is closed?
thoroughfare channel
what is the general name for thoroughfare channel?
arteriovenous anastomosis (AKA shunt)
what is an arterial venous anastomosis/shunt
you have blood going from an artery to a vein without capillaries in between.
what is an arterial anastomosis
an artery connecting to another artery without capillaries in between
what is a venous anastomosis
vein connecting to another vein without capillaries in between
which anastomosis much more common?
venous anastomosis
why is venous anastomosis more common?
blood moves more slowly in venous side of circulation
and the venous anastomosis gives you more opportunity to bypass any clots that develop
what does slow moving blood promote?
clotting
what is an angiogenesis?
growing new blood vessels
what triggers angiogenesis?
hypoxia
- not enough O2, make more blood vessels to get more O2 delivered
what helps blood move through the capillaries?
vasomotion
what is vasomotion
acts like a pump
- rhythmic contraction & dilation of small blood vessels
autoregulatory controllers
how is vasomotion controlled?
oxygen level in tissue where O2 is headed
- pH
- CO2
what are the categories of veins?
venules, medium veins, and large veins
What is the smallest vein called?
Venules
Structure of a venule
- thin walls
- very little smooth muscle (less than arteriole)
Where do venules carry blood to?
Medium size veins
What is the difference between veins and arteries?
Veins have a bigger diameter and thinner wall bc there’s much more smooth muscle
- tunica media in the wall of an artery is thicker than the tunica media in the wall of a vein
Where do the medium sized veins empty into?
The large veins
examples of large veins
- Common Iliac veins
- jugular veins
- IVC and SVC
What are central veins?
Veins in the head, neck, torso, and abdomen
What are peripheral veins?
Veins in arms, legs, feet, hands, fingers, and toes
What’s the difference between central and peripheral veins?
Peripheral veins have valves and central veins do NOT.
Percentages of how much blood is distributed at rest
- heart 7%
- systemic arterial system 13%
- systemic capillary system 6%
- arterial side of circulation: under 30%
- venous side of circulation: over 70%
What is the venous side of circulation called?
Capacitance side
When talking about veins, we’re talking about what type of vessels
Capacitance vessels
What does capacitance mean?
There’s room in the vein to store blood.
Capacitance information about veins
Thin layer of smooth muscle, they’re able to expand more than most of arteries except elastic arteries
Bc blood in venous side of circulation is at lower pressure than arterial side of circulation, and bc the walls are thinner, I can put more blood im venous side than arterial side.
If you need some blood back and put more in arterial, I can tract little bit of smooth muscle in veins and that raised the pressure and pushes more blood towards the heart.
What happens if you constrict the veins a little bit?
It makes the pressure gradient between the vein and the heart bigger cause more blood to go back to the heart and to the arterial side of the circulation.
If you don’t get blood into the heart what happens,
Can’t get blood out of heart causing death
If you can’t get blood to the lungs what happens?
No point in pumping blood due to not delivering oxygen bc you have not oxygenated the blood
If you don’t get blood to the brain what happens?
Control system is not working well and you are brain dead
What is blood pressure?
Monitors arterial blood pressure unless said otherwise
After the aortic valve, what is the average BP
100mm Hg
What is the average BP in the areolar end of the capillary
35mm Hg
What is a hydrostatic pressure?
How we describe pressure being put on a container by fluid.
-if fluid is blood and container is an artery, the arterial BP is the hydrostatic pressure
What is the BP in a capillary called?
Capillary hydrostatic pressure (CHP)
In a normal healthy person at rest, the pressure in the beginning of capillary is?
35mm Hg
By the time you get to the end of a capillary and enter venule what is the BP?
18mm Hg
By the time you get back to the RA, what is the pressure..
0
The pressure in the RA is the highest or lowest BP in the circulation?
Lowest
If you want to get the blood from the venule end, end of capillary, to go back up and into RA, what happens to the pressure?
Pressure has to keep getting lower to keep the blood moving
What is circulatory pressure ?
The change in BP from beginning of circulation to end of circulation
What forms the basilar artery?
2 vertebral arteries
Basilar artery is gonna branch into ?
Posterior cerebral arteries and posterior communicating arteries
Where we have branching what would we get in the brain?
Cerebral artery and communicating artery
Posterior communicating artery joins up with another artery where _____
Where the internal carotid connects
How is it possible for you to get blood in the middle cerebral artery by going around the circle?
If internal carotid is blocked and blood is not going through it, blood coming out of basilar artery going into posterior communicating artery has nowhere to go, pressure increases. Eventually, pressure getting higher in one area than another and blood starts flowing around the circle in the opposite direction
The circle in the brain is set up due to?
If there is a blockage, we have a way to get blood to other parts of the circle
We can use pressure gradient to move blood around the circle to?
So we can get deliver pass a blockage
The two common iliac arteries lead to what?
Lead to the main arterial blood supply in both legs
What is the first major branch we are concerns about when we come form the thoracic cavity into the abdominal cavity?
Celiac trunk
What are the three branches of the celiac trunk?
Left gastric artery, splenic artery, and common hepatic artery
From the celiac trunk, where do we get blood to?
Liver, spleen, and stomach
What is below the celiac trunk?
Superior mesenteric artery and inferior mesenteric artery
What do the superior mesenteric artery and inferior mesenteric artery supply?
Main arterial blood supply to the intestinal tract
What is another thing branching off the abdominal aorta?
R and L renal arteries
What are specific arteries of the gonadal arteries ?
Testicular or ovarian artery
Where do the common iliac arteries branch into a large branch called?
External iliac which goes out of the pelvic cavity and into leg
What is the smaller branch that common iliac branches to?
Internal iliac
Internal iliac supplied blood to?
Pelvic organs
- urinary bladder
- ovaries and testis
What wraps around each femur?
Lateral circumflex artery
Behind the knee, the femoral artery turns to?
Popliteal artery
The popliteal artery branches into three arteries called?
Posterior tibial (medial)
Anterior tibial (middle)
Fibulae artery (lateral)
What can you get from the dorsalis pedis artery
To check pedal pulse to see circulation into the foot
Just like palmar arches in the arterial circulation fed by radial and ulnar arteries, what do we have on the foot?
Plantar arches in the foot fed by anterior, fibular, and posterior arteries
What comes off the arches on the foot?
2 digital arteries going into each toe
How are arteries and veins different
- Arteries are meant to distribute blood and venous system is meant to collect it
- More variability in the Venous side of circulation than arterial side.
- some people don’t have certain veins due to genetic
Many veins are named as___
Their corresponding artery
In the venous side of circulation, the superficial veins are gonna have different names due to what?
They don’t travel with the corresponding arteries
Everything below the heart will empty into the ?
IVC
What gets drained into the SVC?
The head, neck, thoracic cavity, and arm except lungs
Inside cranial cavity, what DONT we have? And what do we have instead?
Veins. There is dura sinuses that act like veins
What are dura sinuses?
Spaces that we find in the dura where we find reflections of dura, etc. where they attache to main part of the dura where they make triangle spaces and blood travels through those to empty into jugular veins
How do you get to the arterial side of the circulation to the venous side of the circulation?
ONLY through Capillaries
SVC is formed by?
2 brachial cephalic veins coming together
How many cephalic arteries and cephalic veins do you have?
2 cephalic veins and 1 cephalic artery
Where does the internal jugular vein bring blood back from?
The brain
What is the beginning of the brachial cephalic vein?
Where the internal jugular connect the right subclavian cephalic vein
What functions like veins?
Superior and inferior sagittal sinus , transverse sinus, and straight sinus
Don’t have the wall structure like veins but carry blood towards the heart
Where is the cephalic vein and where does it empty into?
Goes from the base of thumb and all the way up and empties into the axillary vein
How do you get blood from your right finger into the SVC?
You can use the deep veins or superficial veins unless she specifies
On medial side of arm, what doe we have?
Basilic vein which meets w brachial at bottom of axillary
Each finger has how many veins?
2 digital veins which empty into palmar venous arches
Where do the palmar venous arches empty into?
Basilic vein, ulnar vein, radial vein, and cephalic vein
What is the major abdominal vein?
IVC
What empties in the IVC?
R and L renal veins where we have variations away from bilateral symmetry
On the left side, the gonadal vein empties into?
The renal vein where the blood is taken into the IVC
IVC is formed by?
The joining of the two common iliac veins
Each common iliac vein is made by?
Internal iliac and external iliac veins coming together
The external iliac is the main vein that receives blood from?
Coming out of the leg
If we start at foot, name the veins
- We have 2 digital veins in each toe,
- plantar venous arches that received blood from digital veins,
- deep veins (posterior tibial, anterior tibial, fibular)
- popliteal vein
- femoral vein
- external iliac vein
What is the most lateral in all the vein in lower leg
Small saphenous vein which empties into popliteal vein
How is the small saphenous vein beneficial in cardiac bypass surgery?
You harvest small saphenous vein to bypass blockage
They sew it around blockage
What is the most medial vein in leg
Great saphenous vein
- from plantar venous arch which goes all the way up to external iliac
Where is the internal iliac vein receiving blood back from?
Pelvic organs
What is the portal system?
Arteries to capillaries, to veins, to capillaries, to veins
What are the three veins that are significant in the portal system?
Superior mesenteric vein
Splenic vein
Inferior mesenteric vein
Where are the three veins in the portal system receiving blood from?
All digestive organs that absorb nutrients
The splenic, inferior, and superior mesenteric veins come together to form what?
The hepatic portal vein
Because the hepatic portal vein is collecting all the blood coming from organs in digestive tract that absorb food, what happens to everything you ate n absorbed that’s not a lipid?
before if goes through the general circulation, it goes through the liver.
There are two organs in charge of regulating composition of blood, kidneys and liver, and if you send everything we absorbed through the liver before we let it out into general circulation, what happens?
We can store excesses
What if you ate sugar, and you don’t store that excess glucose before it goes into the general circulation, what happens?
Blood glucose and insulin glucose will go all over the place
We can also take stuff out that is harmful before it can get into the general circulation. T/F
True
If something causes the BP in the hepatic portal vein or venous circulation in liver to go up, what happens?
It gets harder to get blood out of digestive organs and they can be damaged by high venous pressure
Having smtn that makes it harder to get through the liver, what happens?
It can jeopardizes the digestive organs
What are the advantages to the portal system?
- Liver can examine blood and take stuff out that’s harmful or excess
(Can protect ourselves from things that aren’t good for you) - higher levels of something, we can remove excess and store it
Differences between fetal circulation and circulation at birth?
- There’s a placenta (place where gas, nutrients, and waste exchange happens)
- no mixing of fetal blood and maternal blood in placenta - We have two umbilical arteries
- branches of internal iliac arteries - one umbilical vein bringing blood from placenta back to fetal body
- when it comes into the liver, it branches into two pieces. Smaller branch provides nutrients and blood to developing liver so it can keep developing. Larger branch goes through the liver but doesn’t supply anything , just a passageway surround by liver) - Ductus venosus
- take most of blood that’s come in through umbilical vein, through the liver and put it directly to the IVC - Foramen ovale (hole in interatrial septum)
- it lets us bypass the lungs - Ductus arteriosus (direct connection between pulm trunk and aorta)
- due to pressure being higher in the right side of heart, the blood will move through passageway from Pulm trunk and into aorta and now we bypass the lungs either through the foramen ovale or ductus arteriosus
Why do we bypass liver in fetal?
Most of livers functions are being performed by the placenta so we don’t need all the blood to go through the liver
How can we bypass the lungs in a fetus?
The lungs haven’t been expanded yet so there’s a lot more resistance to blood flow meaning in a fetal heart, the pressure in the right side of the heart is higher than pressure on the left side of heart. Blood will move through that hole, into RA, into LA that lets you skip the RV and lungs.
Lungs don’t need much blood going to them, like the liver, we’re gna send little blood there so it can keep developing but we don’t need to do gas exchange in lungs due to the placenta
Umbilical arteries are not good anymore because?
We are not sending blood to the placenta and will eventually become scar tissue
Why do we cut the umbilical arteries at birth?
We cut them so they don’t carry blood
What else do we cut when we cut the cord?
Umbilical vein
What’s another difference at birth?
Placenta gets delivered
If you cut the umbilical vein, what happens to the ductus venosus?
The blood that it carries comes from the umbilical vein, so when we cut it, there is no more blood going to the ductus venosus which you have taken its blood supply at birth
When the baby takes its first breath and expands the lungs, what happens to the blood flow?
The resistance to blood flow in lungs drops and so does the pressure in right side of heart
- pressure in left side of heart is higher than right side.
When blood tries to go from high to low pressure now that baby has taken a breath, pressure is higher in left side of heart, what happens when it tries to go through the foramen ovale?
It pushes the flap of tissue and the pressure holds it over the hole and will eventually become part of a wall and seal off the foramen ovale
What happens to ductus arteriosus at birth?
Once baby has taken a couple of breaths and oxygen levels go up in blood, it makes the ductus arteriosus contract separating the pulmonary circulation completely from systemic circulation.
- It has smooth muscle in the wall and instead of it being circular, it’s spiral, and sensitive to oxygen. High oxygen levels make it contract (spiral shape makes a wring type action)
- it will take months for this to close permanently and it can also open up again
