the cardio: vessels and circulation

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