ch 22: the cardiovascular system: vessels & circulation describe the histological similarities...
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CH 22: The Cardiovascular CH 22: The Cardiovascular System:System:
Vessels & CirculationVessels & Circulation
Describe the histological similarities and Describe the histological similarities and differences of the blood vesselsdifferences of the blood vessels
Explain the pattern and names of the major arteries Explain the pattern and names of the major arteries and veins of the pulmonary & systemic circulationsand veins of the pulmonary & systemic circulations
Describe the circulatory changes that occur at Describe the circulatory changes that occur at birth, and the ones occurring with exercise.birth, and the ones occurring with exercise.
Keyconcepts:
1 aorta & 1 pulmonary trunk1 aorta & 1 pulmonary trunk
~ 2.5 cm~ 2.5 cm
10 bio capillaries (~ length 5,000 miles)10 bio capillaries (~ length 5,000 miles)
??
Histology Histology ofof Blood Blood VesselsVessels
1.1. Tunica interna or intima Tunica interna or intima (endothelium + c.t.)(endothelium + c.t.)
2.2. Tunica media Tunica media (muscle + c.t.)(muscle + c.t.)
3.3. Tunica externa or adventitia Tunica externa or adventitia (thick layer of c.t.)(thick layer of c.t.)
Distinguishing Distinguishing ArteriesArteries from from VeinsVeins::
ArteryArtery walls thicker (more muscle and elastic walls thicker (more muscle and elastic fibers)fibers)
Additional: internal & external elastic Additional: internal & external elastic membranesmembranes
Artefacts when fixing slides:Artefacts when fixing slides:
ArterialArterial walls contract; endothelium cannot walls contract; endothelium cannot contract: pleated appearancecontract: pleated appearance
VeinsVeins collapse collapse
Fig 22.1
Compare to Fig 22.1
elastic arterieselastic arteries
muscular arteriesmuscular arteries
arteriolesarterioles
capillaries
large veinlarge vein
medium-sized medium-sized veinvein
venulesvenules
Arteries – ALWAYS carry blood away from heart Veins – ALWAYS return blood to heart,
contain about 2/3 body's blood at any given time
Pulmonary trunk & aortaand their major branches
Superior & inferiorvena cava and theirtributaries
Largest, conducting arteries – lead directly from heart, subject to high pressures
External and internal carotids, brachial & femoral arteries
External and internal jugular, brachial & femoral veins
2 - 9 mm ~ 4 mm
~ 10-50 µm
~ 30 µm
Capillaries Capillaries
Intestinal mucosa Choroid plexus,endocrine glands, kidneys
Most body regions
Only endothelium
Variably permeable
somewhat permeable
Characterized by circular fenestrae or pores that penetrate the endothelium -permit exchange of larger molecules.
~ 8 µm
SinusoidsSinusoids Resemble fenestrated capillaries, yetResemble fenestrated capillaries, yet
1.1. irregular shapesirregular shapes
2.2. have longer poreshave longer pores
3.3. thinner (or no) basement membranesthinner (or no) basement membranes
Blood movement very slowBlood movement very slow
Found in the liver, heart, etc. Found in the liver, heart, etc. sometimes called sinusoidal capillary. sometimes called sinusoidal capillary.
Capillary BedCapillary Bed
= Capillary region supplying a body area= Capillary region supplying a body area
Metarteriole – Metarteriole – shunt - preferred channel through a shunt - preferred channel through a capillary bedcapillary bed
Precapillary sphincterPrecapillary sphincter - closes bed temporarily - closes bed temporarily to redistribute blood flowto redistribute blood flow
Arteriovenous anastomosis: Arteriovenous anastomosis: interconnections , alternative routes of supplyinterconnections , alternative routes of supply
Fig 22.4
Normal: From capillary bed into Normal: From capillary bed into veins and back to heartveins and back to heart
3 exceptions 3 exceptions Hypophysis Hypophysis
_________________ _________________
Liver Liver __________________________________
In kidney nephronsIn kidney nephrons
Fig 19.6
Fig 22.26
Uneven Distribution of BloodUneven Distribution of Blood
Total blood volume: ?Total blood volume: ?
65 -70% in veins65 -70% in veins (= blood reservoir) (= blood reservoir) lumen is larger than in corresponding arteries
30-35% in heart, arteries and 30-35% in heart, arteries and capillariescapillaries
Table 22.7
Why are valves found in veins but not in
arteries?
Do all veins have valves?
Venous Venous valve valve pathology ?pathology ?
Blood Vessel PathologiesBlood Vessel Pathologies
1.1. AneurysmsAneurysms
2.2. Atherosclerosis Atherosclerosis = type of = type of Arteriosclerosis)Arteriosclerosis) thickening and toughening of arterial walls
Pathogenesis covered in Physiology
Gross Anatomy Gross Anatomy of of
Circulatory SystemCirculatory System
Pulmonary & Pulmonary & Systemic CirculationsSystemic Circulations
Fig 22.9
Right ventricle into pulmonary trunk to pulmonary arteries to lungs
Return by way of 4 pulmonary veins to left atrium
Pulmonary Circuit
Brachiocephalictrunk1
Left commoncarotid
Left subclavian3
2
Aortic ArchAortic Arch
Systemic Circuit
Circle of Willis = Circle of Willis = Cerebral Arterial CircleCerebral Arterial Circle
= Ring of vessels = Ring of vessels surrounding pituitary surrounding pituitary gland - supplies cerebrum gland - supplies cerebrum and cerebellumand cerebellum
Brain can receive blood Brain can receive blood from carotids or from carotids or vertebrals vertebrals (significance?)(significance?)
v
ic
Fig 22.13
Circle of Willis
Descending aorta• thoracic aorta• abdominal aorta
Abdominal aorta
Common iliac
External iliac
Femoral
Descending Aorta Descending Aorta - Thoracic Area- Thoracic Area
Bronchial arteries - supply Bronchial arteries - supply bronchi and lungsbronchi and lungs
Pericardial arteries - supply Pericardial arteries - supply pericardiumpericardium
Mediastinal arteries - supply Mediastinal arteries - supply mediatinal structuresmediatinal structures
Esophageal arteries - supply Esophageal arteries - supply esophagusesophagus
Paired intercostal arteries- Paired intercostal arteries- thoracic wallthoracic wall
Superior phrenic arteries - Superior phrenic arteries - supply diaphragmsupply diaphragm Fig 22.17
Descending Aorta Descending Aorta - Abdominal Area- Abdominal Area
Celiac trunc - 3 branches – to liver, Celiac trunc - 3 branches – to liver, gallbladder, esophagus, stomach, gallbladder, esophagus, stomach, duodenum, pancreas, and spleenduodenum, pancreas, and spleen
Superior mesenteric– to pancreas Superior mesenteric– to pancreas and duodenum, small intestine and duodenum, small intestine and colonand colon
Paired suprarenal - to adrenal glandsPaired suprarenal - to adrenal glands
Paired renal – to kidneysPaired renal – to kidneys
Paired gonadal – to testes or ovariesPaired gonadal – to testes or ovaries
Inferior mesenteric – to terminal Inferior mesenteric – to terminal colon and rectumcolon and rectum
Paired lumbar – to body wallPaired lumbar – to body wall
Fig 22.17
Circulation Circulation Changes at BirthChanges at Birth
No blood coming from placentaNo blood coming from placenta
Ductus venosus becomes Ductus venosus becomes ligamentum venosusligamentum venosus (=ligamentum teres)(=ligamentum teres)
Foramen ovale closes & becomes Foramen ovale closes & becomes fossa ovalefossa ovale
Ductus arteriosus closes and Ductus arteriosus closes and becomes becomes ligamentum arteriosumligamentum arteriosum
Umbilical vein and arteries degenerateUmbilical vein and arteries degenerate
Patent foramen ovale
For more congenital circulatory problems see p. 606
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