Ch. 19 B.V. Flashcards
Angiogenesis
The growth of new blood vessels from pre-existing vessels.
Science of blood vessels
Angiology = “angio” vessels
Sequence of B.V.
Arteries –> arterioles –> capillaries –> Venules –> Veins
Layers of B.V.
All B.V. have 3 layers except capillaries.
1) Tunica intima
2) Tunica media
3) Tunica externa
Capillaries have:
- 1) Endothelium
- 2) Basement membrane or basal lamina
Types of arteries
1) Elastic 2) Muscular
Elastic Arteries
1) Are closest to the heart. High in elastin
2) Expand during systole acting as pressure reservoir. Very stretchy
3) Recoil during diastole to keep the blood moving
Vascular anastomoses
- “communicating opening” is a connection between two blood vessels.
- Anastomoses serve the same volume of tissue. When one B.V. is damaged the other one suplies blood to the tissue.
- Blood vessels form special interconnections called vascular anastomoses. Most organs receive blood from more than one arterial branch, and arteries supplying the same territory often merge forming arterial anastomoses = alternate pathway called **collateral channels. **
Muscular Arteries
1) Carry blood to specific organs
2) Tunica media is thick (more smooth muscle)
3) Less stretchy than elastic arteries and more active in vasoconstriction and vasodilation.
Artherosclerosis
degenerative vascular disease that decreases the elasticity of arteries.
1) endothelium is injured
2) lipids accumulate and oxidize
3) smooth muscles cells proliferate and a fibrous cap forms (fibrous lesions with core of dead cells = plaque)
4) plaque enlarges and Ca2+ deposites –> rupture.
Types of capillaries
1) continuous capillaries
2) Fenestrated capillaries
3) Sinusoid capillaries
continuous capillary
- Ordinary capillaries without fenestrations
- For the diffusion of water and solutes.
- With tight junctions called intercellular clefts.
- found in muscle, skin, lung, central nervous system, and other tissues,
fenestrated capillary
- Have fenestrations.
- Primarily the glomerular capillaries in the nephrons of the kidney.
- “fenestra, for “window” have pores in the endothelial cells that allow small molecules with the exception of medium and large proteins to pass.
Sinusoidal capillaries (sinusoids)
- have large gaps between endothelial cells that permit the passage of blood cells.
- These capillaries are found in the bone marrow, spleen, and liver.
- Larger irregular shape lumens and fenestrated. Fewer tight junctions and larger intracellular clefts.
Types of blood circulation(5)
- Systemic
- Pulmonary
- Coronary
- Hepatic
- Fetal
Systemic circulation
- Oxygenated blood travels from the left side of the heart to the various areas of the body.
- Gas, nutrient, and waste exchange occurs across the capillary walls into the interstitial fluids outside the capillaries and then into the surrounding cells.
- The deoxygenated blood returns to the right side of the heart.
Hepatic circulation
Aorta –> celiac artery (splenic, hepatic, left gastric) –> Hepatic artery –> LIVER <– Hepatic portal veins
LIVER –> inferior vena cava
Hepatic portal veins:
- Superior mesenteric vein: drains the small intestine and stomach.
- Splenic vein: drains spleen, part of stomach and pnacreas
- Inferior mesenteric vein: drains large intestine and rectum
Fetal circulation
- Oxygenated blood from the placenta enters the fetus through the UMBILICAL VEIN
- Most of the newly oxygenated blood bypasses the liver via the DUCTUS VENOSUS and combines with deoxygenated blood in the inferior vena cava
- Blood then joins deoxygenated blood from the superior vena cava and empties into the right atrium
- Since pressure in the right atrium is larger than pressure in the left atrium most blood will be shunted through the FORAMEN OVALE
- Some blood does travel from the right atrium to the right ventricle through the pulmonary trunk but most blood bypasses the pulmonary artery and moves directly to the aorta via de DUCTUS ARTERIOSUS.
- Deoxygenated blood returns to the placenta via the UMBILICAL ARTERIES originating from the internal iliacs near the bladder.
