Arteries And Veins

Question 1

Types of arteries

Answer 1

Conducting elastic and distributing muscular

Question 2

Pulmonary circulation

Answer 2

The right side pumps the blood into the capillaries of the lung

Question 3

Systemic circulation

Answer 3

The left side pumps the blood to the rest of the body

Question 4

Exceptions of the role arteries and veins

Answer 4

Pulmonary arteries and veins
Umbilical arteries and veins

These in conditions where arteries/high o2 and veins/low o2

Question 5

Blood supply to the artery

Answer 5

Vasa vasorum

Question 6

What is the tunica interna or intima

Answer 6

Innermost layer consisting of endothelial cells that is the site of gaseous exchange in capillaries

Question 7

What is the tunica media?

Answer 7

Smooth muscle cells and elastic net layer, it is the middle layer that varies in content.

• In arteries close to the heart it is mainly elastic to allow for the expansion and relaxation of vessels
• further from the heart the tunica media of peripheral arteries and arterioles = more smooth muscle fibres

Question 8

What is the tunica externa

Answer 8

Anchors the vessels to the surrounding tissue and contains the vegetative nerves as well as the vasa vasorum

Question 9

How do capillaries structure and density vary between different tissues and organs they supply?

Answer 9

Sinusoid capillaries in liver and spleen

Question 10

Structure of venules and veins

Answer 10

The have the same 3 layers, but a larger diameter and much thinner tunica media = adaptation to much lower blood pressure

Question 11

Adaptation of veins

Answer 11

They have valves formed by the tunica interna which prevents backward blood flow
- contraction of surrounding skeletal muscle and pulsation of adjacent arteries promote venous return

Question 12

What are venous sinuses

Answer 12

These are veins with no valves or tone in liver and spleens. They can store a huge amount of blood,

Question 13

What is vasculogenesis?

Answer 13

• No bone marrow in embryos, so blood cells and endothelial cells give rise to the blood vessels
• form in blood islands of the embryonic and extra embryonic mesoderm

Question 14

What are blood islands?

Answer 14

Small cell clusters where the peripheral cells give rise to the endothelial cells and the central cells become blood cells
They extend and fuse together to make the first vascular networks

Question 15

What are the sites of vasculogenesis

Answer 15

• extraembryonic = blood islands of the extraembryonic mesoderm in the yolk sac merge to form the capillary network draining into the veins that brings nutrients and gases to embryo
• intraembryonic = forms the dorsal AOTA and posterior cardinal veins that connect to capillary networks born in mesoderm of each organ. Capillary networks or independently within the mesoderm of each organ and connect later to the vessels emerging from the newly formed aorta

Question 16

What is angiogenesis

Answer 16

• Primary capillary networks are formed and remodelled, veins and arteries are made
• Endothelial cells from existing blood vessels can be recruited to sprout new vessel or migrate to distant sites forming new vessels or capillary networks
• responsive to VEGF or hypoxia
• arteries and veins made from the same endothelial precursor cells

Question 17

Zebra fish model organism

Answer 17

Separation of arterial and venous cells occurs early
Angioblasts are born in the posterior part of the lateral plate mesoderm and migrate to the midline of the embryo where they combine to form the aorta and cardinal vein beneath it
These angioblasts are already fated to come either artery-making cells or vein making cells

Question 18

Zebra fish evidence

Answer 18

Artery and vein making cells are separate:

• ephrin b 2
• eph b4
• cell surface receptors

Question 19

What are angioblasts

Answer 19

A type of endothelial cell precursor derived from bone marrow

Question 20

Role of cell surface receptors in remodelling of blood vessels

Answer 20

• enquire connections between venous and arterial vessels in the capillary plexus
• ensure fusion fo capillaries to make larger vessels occur between between same type of vessels

Question 21

Role of vasculogenesis and angiogenesis in adult body

Answer 21

• new blood vessels after injury
• in muscles following exercise
• new vessels (collat circulation) to bypass blocked vessels

Question 22

Why is VAN in close proximity

Answer 22

• arteries form in response to VEGF > can induce angioblasts in the tissue to form adjacent nerves
• nerves secrete angiogenic factors
• arteries can secrete nerve growth factors

Question 23

What does peripheral circulation include?

Answer 23

• arteries veins and nerves often grouped together as VAN
• large vessels found superficially (cephalon vein in forelimb and saphenous vein in hind limb)
• arteries can be paired = bilateral symmetry
• almost all collateral arteries join w/other arteries (anastomose) forming a network of blood vessels (rate arteriosum)
• terminal or end arteries

Question 24

What is the regulation of peripheral circulation

Answer 24

• arteriovenous anastomoses: connection between arterioles and venules bypassing a capillary bed
• barrier arteries and sphincter veins: structures able to interrupt flow to or from capillary bed
• rete metabile: exuberant parallel branching from a blood vessel that reunite a single vessel
• sphincter veins

Question 25

What composes the portal circulation

Answer 25

• hepatic portal
• hypophyseal portal
• renal portal ( in non mammals )

Question 26

Hepatic portal circulation

Answer 26

• takes venous blood from gastrointestinal tract, spleen and pancreas to capillary bed in liver
• function: absorption and detox of metabolites before systemic circulation
• hepatic portal vein brings venous blood to the sinusoids of the liver
• hepatic veins draw venous blood from liver into caudal vena cava