Blood vessels Flashcards by Daniel Picard

What are the different types of blood vessels?

Arteries
Veins
Capillaries

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Where do arteries carry blood?

What do they branch into?

Carry blood away from the heart

Branch to form arterioles

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Where to veins carry blood?

What are the smallest veins called?

Carry blood towards the heart.

Smallest veins are called venules.

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What are capillaries?

Smallest blood vessels.

Site of exchange between blood and tissue fluid

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Provide a schematic of blood flow.

SVC/IVC/CS –> RA –> T –> RV – PSLV –> PT –> LPA, RPA –> Lungs –> 4 PV –> LA –> BV/MV –> RV –> ASLV –> Aorta, CA –> Body

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What are the three layers of blood vessels>

Tunica intima/interna
Tunica media
Tunica externa

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What is the tunica intima?

Simple squamous epithelium

Intimate contact with blood

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What is the tunica media?

Sheets of smooth muscle, elastic CT, collagen

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What layer allows for vasoconstriction/dilation? How?

Tunica media
Contract - constrict
Relax - dilate

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What is the tunica externa composed of?

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What is the lumen of the blood vessels?

Central, blood-filled space of a vessel

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What are the differences between the arteries and veins?

Arteries are more elastic - external elastic membrane

arteries have a larger smooth muscle layer
lumen of artery is circular (Even without blood)

Veins have valves

veins have a thinner tunica media (less smooth muscle)
lumen of vein is more floppy (especially without blood)

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What are the different types of arteries?

Elastic
Muscular
(Arterioles)

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What are elastic arteries?

Conducting arteries
The largest arteries - aorta and its major branches
high elastic content (dampens surge of blood pressure)
Thick tunica media, lots of elastic fibres

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What are muscular arteries?

Distributing
Lie distal to elastic arteries
Thick tunica media
Unique structures:
- internal and external elastic laminae
Can contract or relax to change the amount of blood going to certain organs

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Describe arterioles.

Smallest arteries
Larger arterioles have all three tunics
Close to capillary beds

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Describe the control of arteriole diameter.

Due to local factors in the tissues and the sympathetic nervous system

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What are capillaries?

Smallest blood vessels
Renew and refresh surrounding tissue fluid
RBCs pass in a single file

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What are the site-specific functions of capillaries at the:
lungs
SI
endocrine glands
kidneys

Lungs - oxygen enters blood, carbon dioxide leaves
SI - receives digestive nutrients
Endocrine glands - picks up hormones
Kidneys - removal of nitrogenous wastes

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What are capillary beds?

Network of capillaries running through tissues.

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What are metarterioles?

Intermediate between capillary and an arteriole

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What is a thoroughfare channel?

Intermediate between capillary and venule

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What are precapillary sphincters?

Regulate blood flow through capillaries.

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What tissues do not have a rich capillary supply?

Study These Flashcards

Tendons and ligaments - poorly vascularized
Epithelia and cartilage - avascular
Fast-Oxidative fibres

Describe the action of precapillary sphincters when running.

Precapillary sphincter to skeletal muscle opens to increase blood supply. Closes to digestive organs.

In capillaries, what are endothelial cells held together by?

Tight junctions and desmosomes.

What are intercellular clefts? | What do they allow through?

Gaps of un-joined membrane | Allow small molecules to enter and exit the capillaries

What are the four routes into and out of the capillaries? | What does each allow through?

1 - Direct diffusion - respiratory gases 2 - Through intercellular clefts - small molecules 3 - Through cytoplasmic/pinocytic vesicles - gases, nutrients, wastes 4 - Through fenestrations - water molecules

What are the three kinds of capillaries?

Continuous Fenestrated Sinusoid

What are continuous capillaries? | Where are they found?

Most common - lack pores | Brain, skeletal muscle, smooth muscle, lungs

What are fenestrated capillaries? | Where are they found?

Porous Found in sites with high rate of exchange of small molecules between blood and tissue fluid. ex: kidneys, SI, synovial membrane

What are sinusoid capillaries? | Where are they found?

Wide, leaky capillaries Fenestrated with wide open intercellular clefts. Large diameter and twisted course. Slow blood flow allowing exchange of large molecules. Incomplete basement membrane. Pericytes to control the diameter and provide structural support Bone marrow and spleen

What are pericytes?

Found in sinusoid capillaries, provide support and control the diameter.

What is a low permeability capillary in the body? | Why is it so?

Blood brain barrier Capillaries have complete tight junctions, no intercellular clefts Only allows vital molecules through: such as oxygen, carbon dioxide, some anesthetics. Want to be as selective as possible to prevent toxins, bacteria and such from entering the brain from the blood.

What can pass through the BBB?

oxygen, carbon dioxide, anesthetics that are fat soluble | nicotine and alcohol.

How can the BBB be opened?

During times of prolonged stress and/or extreme emotional stress, the cells of the BBB open up.

Why would we want to be able to open the BBB?

Analgesic effects Chemo to enter More localized treatment

What are the smallest veins called? Is the blood pressure in veins higher or lower than that of the arteries? ______ join to form veins. What is the thickest tunic in veins? The lumen of veins is _____ than that of arteries.

``` Venules Lower Venules Tunica externa Smaller ```

Why is the lumen bigger in veins?

Thin tunica media

What are the mechanisms to counteract low venous pressure?

Valves in some veins skeletal muscle pump breathing

Where are valves found in veins? (or where would veins with valves be located?)

in the limbs

The cusps of vein valves are made up of which layer?

Tunica intima

How does skeletal muscle pump the blood of the veins?

Muscles press against the thin-walled veins. | Veins are superficial and muscles contracting against them will push blood upwards

How does breathing counteract low venous blood pressure?

Active breathing allows more blood to get up to the heart.

Describe varicose veins. Which veins/areas are more susceptible. Who would be more susceptible? Why does it occur?

Twisted, dilated superficial veins. Valves in veins weaken and fail Veins swell with pooled blood and drainage slows. Left lower limb more susceptible. Women more susceptible than men. Occurs in individuals who are pregnant or stand for a prolonged period. Non-moving legs causes the veins to drain slowly and blood to accumulate, stretching the veins and valves.

Vascular anastomoses: Vessels interconnect to form vascular _________. Organs receive blood from more than one ______ source. Neighbouring ______ form _______ anastomoses. ______ anostomose more frequently than _______ Most commonly found: - Around _____ - In the ______ - Around the ______

``` anastomoses arterial arteries arterial veins arteries joints brain heart ```

What is an anastomoses?

Coming together of blood vessels. | Should one get blocked, there are other routes to use.

What is the vasa vasorum?

The tunica externa of large blood vessels will have tiny arteries, capillaries and veins. These are vessels of large vessels with nourish it.

Blood distribution: 60-65% of the blood volume at rest is in the _______ ______ and _______. These function as _____ ________. These include the veins of the _____ and _______ organs. Blood is diverted from this storage in times of ______. _________ causes vasoconstriction to help maintain blood pressure.

``` systemic veins venules blood reservoirs skin adbominal need hemorrhage ```

All systemic arteries branch from the _____. | All systemic veins drain into the ____, ____ or ______ ______.

aorta | SVC, IVC, CS

Why can owls turn their heads so much?

Double the cervical vertebrae | larger transverse foramen so don't impinge carotid arteries

Describe a brain freeze.

Rapid change in temperature at the back of the throat causes constriction of arteries. Pain receptors surrounding the vessels trigger nerves carrying info from face to brain Nerves normally sense facial pain, signals brain to interpret swelling coming from forehead Brain cannot feel pain Get anastomoses in the circle of willis to constrict

What does the superior mesenteric artery supply?

Pancreas, SI, ascending and part of transverse colon.

What does the inferior mesenteric artery supply?

Second half of transverse and descending and sigmoid colons, and rectum

What are pulse points?

Veins are generally more superficial than arteries but, in certain areas, have superficial arteries where the pulse can be determined. ex: side of neck - left and right common carotid arteries

What is a portal vein?

A vein that carries blood from one capillary network to another. (Artery - capillary - portal vein - capillary - vein)

Describe hepatic portal veins.

Receives blood and digested nutrients from capillaries of digestive organs and the spleen, and delivers them to the sinusoids of the liver for processing and storage.

What are the veins of the hepatic portal system?

Superior mesenteric vein Splenic vein Inferior mesenteric vein Hepatic portal vein

Draw the hepatic portal circuit.

Refer to notes.

Blood vessels Flashcards

(59 cards)