Chapter 13 Blood Vessels and Circulation (copy)

Blood vessels outside the heart are divided into two classes:

Blood vessels outside the heart are divided into two classes:

Pulmonary

Systemic

Pulmonary vessel

which transport blood from the right ventricle of the heart through the lungs and back to the left atrium

systemic vessels

which transport blood from the left ventricle of the heart through all parts of the body and back to the right atrium

Blood Vessel Functions

1.Carry blood

2.Exchange nutrients, waste products, gases within tissues

3.Transport substances

4.Regulate blood pressure

5.Direct blood flow to tissues

Vessel Structures

Arteries

Veins

Capillaries

Arteries:

•carry blood away from heart

•thick with a lot of elastic tissue

Veins:

•carry blood toward heart

•thick with less elastic tissue

Capillaries:

exchange occurs between blood and tissue fluids

Blood Flow

•Blood flows from arteries into arterioles

•Arterioles into capillaries

•Capillaries into venules

•Venules to small veins

•Veins return to heart

Blood Vessel Walls

Tunica intima:

Tunica media:

Tunica adventitia:

Tunica intima:

•innermost layer

•simple squamous

Tunica media:

•middle layer

•smooth muscle with elastin and collagen fibers

Tunica adventitia:

- outermost layer

•connective tissue

Types of Arteries

Elastic arteries:

Muscular arteries:

Elastic arteries:

•largest in diameter

•thickest walls

•Example - aorta and pulmonary trunk

Muscular arteries:

•medium to small size

•thick in diameter

•contain smooth muscle cells

•can control blood flow to body regions

Capillaries

•Blood flows from arterioles into capillaries

•Capillaries branch to form networks

•Blood flow is regulated by smooth muscle cells, precapillary sphincters

Capillaries

Walls consist of only a simple endothelium surrounded by delicate loose connective tissue.

Types of Veins

Blood flows from capillaries into venules

Blood flows from venules into small veins

All 3 tunics are present in small veins

Medium sized veins:

•collect blood from small veins and deliver to large veins

Large veins:

•contain valves

Pulmonary Circulation Vessels

Pulmonary circulation

Pulmonary  trunk

Pulmonary veins

Pulmonary circulation:

•blood vessels that carry blood from right ventricle to lungs and back from left atrium of heart

Pulmonary  trunk:

•Carries blood from right ventricle towards lung

Pulmonary veins:

•exit lungs and carry O2 rich blood to left atrium

Systemic Circulation Vessels

•The systemic circulation carries blood from the left ventricle to the tissues of the body and back to the right atrium.

•Oxygenated blood from the pulmonary veins passes from the left atrium into the left ventricle and from the left ventricle into the aorta.

•Arteries distribute blood from the aorta to all portions of the body

Parts of the Aorta

Ascending

Aortic arch

Descending

Thoracic

Abdominal

Ascending:

•passes superiorly from left ventricle

Aortic arch:

•Contains 3 major arteries which carry blood from aorta to head and upper limbs

Descending:

•extends through thorax and abdomen to pelvis

Thoracic:

•part of descending aorta that extends through thorax to diaphragm

Abdominal:

•descending aorta that extends from diaphragm where it divides at the common iliac arteries

Arteries of the Head and Neck

Branches of aortic arch

Brachiocephalic artery

Left common carotid artery

Left subclavian artery

Right common carotid artery

Right subclavian artery

Branches of aortic arch:

•brachiocephalic artery

•left common carotid artery

•left subclavian

Brachiocephalic artery:

•first branch off aortic arch

•supplies blood to right side of head and neck

Left common carotid artery:

•2nd branch off aortic arch

•supplies blood to the left side of head and neck

Left subclavian artery:

•3rd branch off aortic arch

•supplies blood to left upper limbs

Right common carotid artery:

•branches off brachiocephalic artery

•supplies blood to right side of head and neck

Right subclavian artery:

•branches off brachiocephalic artery

•supplies blood to right upper limbs

Arteries of the Upper Limbs

Axillary arteries:

Brachial arteries:

Ulnar arteries:

Radial arteries:

Celiac trunk arteries:

Superior mesenteric arteries:

Inferior mesenteric arteries:

Renal arteries:

Hepatic arteries:

Testicular arteries:

Ovarian arteries:

Inferior phrenic arteries:

Lumbar arteries:

Axillary arteries:

•continuation of subclavian in the axilla (armpits)

Brachial arteries:

•continuation of axillary artery that extends into the arm

•where blood pressure measurements are taken

Ulnar arteries:

•branch of brachial artery

•near elbow

Radial arteries:

•branch of brachial artery

•supply blood to forearm and hand

•pulse taken here

Celiac trunk arteries:

•supply blood to stomach, pancreas, spleen, liver, upper duodenum

Superior mesenteric arteries:

•supply blood to small intestines and upper portion of colon

Inferior mesenteric arteries:

•supply blood to colon

Renal arteries:

•supply blood to kidneys

Hepatic arteries:

•supply blood to liver

Testicular arteries:

•supply blood to testes

Ovarian arteries:

•supply blood to ovaries

Inferior phrenic arteries:

•supply blood to diaphragm

Lumbar arteries:

•supply blood to lumbar vertebra and back muscles

Arteries of Pelvis

Common iliac arteries:

External iliac arteries:

Internal iliac arteries:

Common iliac arteries:

•branches from abdominal aorta

•divides into external and internal iliac arteries

External iliac arteries:

•division of common iliac artery

•supply blood to lower limbs

Internal iliac arteries:

•division of common iliac

•supply blood to pelvic area

Arteries of the Lower Limbs

Femoral arteries:

Popliteal arteries:

Anterior and posterior arteries:

Fibular arteries:

Femoral arteries:

•supply blood to thigh

Popliteal arteries:

•supply blood to knee

Anterior and posterior arteries:

•supply blood to leg and foot

Fibular arteries:

•supply blood to lateral leg and foot

Veins

•Veins return blood to the heart.

•In the systemic circulation, the blood returning to the heart is deoxygenated.

•In the pulmonary circulation, the blood returning to the heart in the pulmonary veins is oxygenated.

Superior vena cava:

•returns blood from head, neck, thorax, and right upper limbs

•empties into right atrium of heart

Inferior vena cava:

•returns blood from abdomen, pelvis, lower limbs

•empties into right atrium of heart

Veins of the Head and Neck

External jugular vein:

Internal jugular vein:

Subclavian veins

Brachiocephalic veins:

External jugular vein

•drain blood from head and neck

•empties into subclavian veins

Internal jugular vein:

•drain blood from brain, face, neck

•empty into subclavian veins

Subclavian veins:

•forms brachiocephalic veins

Brachiocephalic veins:

•join to form superior vena cava

Veins of the Upper Limbs

Brachial veins

Cephalic veins:

Median cubital veins:

Brachial veins:

•empty into axillary vein

Cephalic veins:

•empty into axillary vein and basilic vein

Median cubital veins:

•connects to cephalic vein

•near elbow

Veins of the Thorax

Right and left brachiocephalic veins:

Azygos veins:

Internal thoracic veins:

Posterior intercostal veins:

Hemiazygos vein:

Right and left brachiocephalic veins:

•drain blood from thorax into superior vena cava

Azygos veins:

•drain blood from thorax into superior vena cava

Internal thoracic veins:

•empty into brachiocephalic veins

Posterior intercostal veins:

•drain blood from posterior thoracic wall

•drains into azygos vein on right side

Hemiazygos vein:

•receives blood from azygos vein of left side

Veins of the Abdomen and Pelvis

Common iliac vein

External iliac vein

Internal iliac vein

Renal vein

Common iliac vein:

•formed from external and internal iliacs

•empty into inferior vena cava

External iliac vein:

•drains blood from lower limbs

•empty into common iliac vein

Internal iliac vein:

drains blood from pelvic region

•empties into common iliac vein

Renal vein:

•drains blood from kidneys

Hepatic Portal System

Liver is a major processing center for substances absorbed by intestinal tract.

Portal system:

•vascular system that begins with capillaries in viscera and ends with capillaries in liver

•uses splenic vein and superior mesenteric vein

Veins of the Lower Limbs

Femoral veins

Great saphenous veins

Popliteal veins

Femoral veins

•drain blood from thigh and empty into external iliac vein

Great saphenous veins:

•drain from foot and empty into femoral vein

Popliteal veins

•drain blood from knee and empty into femoral vein

Blood Pressure

•is the measure of force blood exerts against blood vessel walls.

•Systolic pressure: contraction of heart

•Diastolic pressure: relaxation of heart

•Average Blood Pressure: 120/80

Pulse Pressure

is the difference between systolic and diastolic blood pressures.

•Example - 120 for systolic / 80 for diastolic; pulse pressure is 40 mm Hg

•- points can be felt near large arteries

Capillary Exchange

•Most exchange across capillary wall’s occurs by diffusion.

•Blood pressure, capillary permeability and osmosis affect movement of fluids across capillary walls.

•Net movement of fluid from blood into tissues

•Fluid gained in tissues is removed by lymphatic system

Local Control of Blood Flow

•Local control achieved by relaxation and contraction of precapillary sphincters

•Sphincters relax blood flow increases

•Precapillary sphincters controlled by metabolic needs of tissues

•Concentration of nutrients also control blood flow

•Blood flow increases when oxygen levels decrease

Nervous Control of Blood Flow

Vasomotor center

Vasomotor tone

Vasomotor center

•In pons and medulla oblongata

•sympathetic division

•controls blood vessel diameter

Vasomotor tone

•state of partial constriction of blood vessels

•increase causes blood vessels to constrict and blood pressure to go up