Lecture Outline
Adapted from Martini Human Anatomy7th ed. / Session:
Section:
Days / Time: Instructor: / FALL
52999
MW 5:00 PM – 9:20 PM
RIDDELL
Chapter 22
The Cardiovascular System: Vessels and Circulation
Introduction
There are two groups of blood vessels
Pulmonary circuit
Blood goes to and from the lungs
Systemic circuit
Blood goes to the rest of the body and back to the heart
Blood goes to both circuits at the same time with each heartbeat
Histological Organization of Blood Vessels
The walls of the vessels consist of three layers
Intima (innermost layer)
Media (middle layer)
Adventitia (outermost layer)
The layered walls give the vessels tremendous strength
Histological Organization of Blood Vessels
Intima (innermost layer)
Consists of two sublayers
Endothelial lining
Underlying layer of connective tissue
Arteries consists of a thick layer of elastic fibers giving the lining a “wavy” appearance
Histological Organization of Blood Vessels
Media (middle layer)
Consists of smooth muscle
When stimulated by sympathetic nerves, the muscles contract resulting in vasoconstriction
Relaxation of the smooth muscle results in vasodilation
Histological Organization of Blood Vessels
Adventitia (outermost layer)
Forms a connective sheath around the vessel
Composed of collagen fibers
Anchors the blood vessels in position
The walls of some vessels are too thick to obtain nutrients via diffusion so they have their own blood supply in vessels called vasa vasorum
Histological Organization of Blood Vessels
Distinguishing Arteries from Veins
Most arteries and veins run parallel to each other
Arteries carry blood away from the heart and veins carry blood toward the heart
Walls of arteries are thicker than veins
Arteries maintain their circular shape and veins
typically collapse when cut
Endothelial lining of an artery has pleated folds
Histological Organization of Blood Vessels
Arteries
As blood leaves the heart, it travels through:
Elastic arteries
Muscular arteries
Arterioles
Capillaries
Capillary beds
Histological Organization of Blood Vessels
Capillaries
Walls are thin enough to permit exchange of gases between the blood and the interstitial fluid
The diameter is about 8 microns
A red blood cell diameter is also about 8 microns
Fenestrated capillaries contain pores
Histological Organization of Blood Vessels
Capillaries (continued)
There are four mechanisms regarding the passage of material across the walls of capillaries
Material can diffuse across the endothelial lining
Material can diffuse through gaps between adjacent cells of the lining
Material can diffuse through pores
Material can move via endocytosis
Histological Organization of Blood Vessels
Capillary Beds
This is an interconnected network of capillaries
The capillary bed consists of vessels connecting arterioles with venules
There are precapillary sphincters involved in
regulating blood flow through the capillaries
Histological Organization of Blood Vessels
Capillary Beds (continued)
In areas such as the brain, heart, and stomach, a continuous, rich flow of blood is required
In these areas, more than one artery supplies a
specific area
These arteries (collateral arteries) typically fuse
forming an arterial anastomosis
If one arteriole is blocked, the other one will supply
blood to the capillary bed
Histological Organization of Blood Vessels
Capillary Beds (continued)
In areas such as the joints or visceral organs, blood flow through some vessels may be hindered due to body movement
In order to accommodate this, there must be a
direct connection between arterioles and venules
This direct connection is called an arteriovenous
anastomosis
Histological Organization of Blood Vessels
Veins
Veins collect blood from tissues and return the blood to the heart
As blood leaves the tissue and travels to the heart, it travels through the following vessels:
Capillary beds
Capillaries
Venules
Medium-sized veins
Large veins
Histological Organization of Blood Vessels
Blood in the veins returning to the heart from the lower extremities has to go against gravity
To assist in this process, many veins have valves (venous valves)
These valves compartmentalize the blood in the veins thus acting as one-way valves
If the venous valves do not close properly, varicose veins may occur
Histological Organization of Blood Vessels
The total blood volume is distributed unevenly within the vessels of the body
Arteries and capillaries contain 30–35% of the volume
Veins contain 65–70% of the volume
Veins are more distensible than arteries
Based on blood pressure, a vein can expand about 8 times as much as a parallel artery
Blood Vessel Distribution
Blood vessels can be divided into two circuits
Pulmonary circuit
Composed of arteries and veins that transport blood between the heart and the lungs
Arteries and veins travel relatively short distances
Systemic circuit
Composed of arteries and veins that transport oxygenated blood between the heart and all other tissues
Arteries and veins travel longer distances
Blood Vessel Distribution
There are functional and structural differences between the vessels in the two circuits
Blood pressure in the pulmonary circuit is lower than in the systemic circuit
Walls of the pulmonary arteries are thinner than the walls of systemic arteries
Blood Vessel Distribution Vessel Distribution
Functional patterns of the pulmonary and systemic circuits
The distribution of arteries and veins is the same on the left side of the body as it is on the right side of the body except for the venae cavae and the aorta
A single vessel will have different names according to specific anatomical boundaries
Arteries and veins often anastomose
Blood Vessel Distribution
The Pulmonary Circuit
Blood leaves the heart by passing through the pulmonary valve
Blood enters the pulmonary trunk
Blood enters the left and right pulmonary arteries
Blood arrives at the lungs to drop off carbon dioxide and pick up oxygen
Blood returns to the heart via the pulmonary veins
Blood enters the left atrium of the heart
Blood Vessel Distribution
The Systemic Circuit
Blood leaves the heart by passing through the aortic valve
Blood enters the ascending aorta and then the aortic arch and then it branches into:
Brachiocephalic trunk (then the right common carotid and right subclavian arteries)
Left common carotid artery
Left subclavian artery
Descending aorta
Coronary arteries
Blood Vessel Distribution
The Systemic Circuit (continued)
Ascending aorta
Begins at the aortic valve
Left and right coronary arteries branch off the base of the ascending aorta
Aortic arch
Forms an arch going toward the left and posterior side of the heart
Branching off the aortic arch are three elastic arteries
Blood Vessel Distribution
The Systemic Circuit (continued)
Branches of the aortic arch
Brachiocephalic trunk gives rise to the right
common carotid artery (supplies blood to the right side of the head and brain) and to the right subclavian artery (supplies blood to the right arm)
Left common carotid artery (supplies blood to the left side of the head and brain)
Left subclavian artery (supplies blood to the left arm)
Blood Vessel Distribution
The Systemic Circuit (continued)
The subclavian arteries
Give rise to the vertebral arteries
Give rise to the axillary arteries
Prior to forming the axillary arteries, the subclavians form three branches:
Thyrocervical trunk (supplies muscles of the neck, head, and upper back)
Internal thoracic artery (supplies the pericardium and anterior wall of the chest)
Vertebral artery (supplies the brain and spinal cord)
Blood Vessel Distribution
The flow of blood from the subclavians
Axillary artery
Branches to form the humeral circumflex artery
Brachial artery
Branches to form the deep brachial artery
Divides to form the radial and ulnar arteries
Arteries anastomose at the wrist forming the superficial palmar arch and deep palmar arch
Blood Vessel Distribution
The Carotid Arteries
The common carotids ascend the neck
Divide to form the internal carotids and external carotids
The carotid sinus is at the base of the internal carotid artery consisting of baroreceptors and chemoreceptors
Blood Vessel Distribution
The internal and external carotid arteries
External carotids supply the neck and outside of the skull
Internal carotids enter the skull to deliver blood to the brain
Internal carotid branches to form:
Ophthalmic artery (supplies the eyes)
Anterior cerebral artery (supplies frontal and parietal lobes of the brain)
Middle cerebral artery (supplies the midbrain and lateral surfaces of the brain)
Blood Vessel Distribution
Blood supply to the brain
Blood in the vertebral arteries go to the brain via:
Left and right vertebral arteries fuse to form the basilar artery
Basilar artery branches many times in the area of the pons
Basilar artery eventually forms the vessels of the cerebral arterial circle (circle of Willis)
Blood in the internal carotid arteries goes to the brain via:
Anastomosing with the cerebral arterial circle
Blood Vessel Distribution
The Descending Aorta
A continuation of the aortic arch
Divided into thoracic aorta and abdominal aorta
Blood Vessel Distribution
The Thoracic Aorta
Branches to form the following vessels:
Bronchial arteries
Pericardial arteries
Mediastinal arteries
Esophageal arteries
Intercostal arteries
Superior phrenic arteries
Blood Vessel Distribution
The Abdominal Aorta
Branches to form the following vessels:
Celiac trunk
Superior mesenteric artery
Inferior mesenteric artery
Inferior phrenic arteries
Suprarenal arteries
Renal arteries
Gonadal arteries
Lumbar arteries
Right and left common iliacarteries
Blood Vessel Distribution
The Celiac Trunk
Branches to form the left gastric artery
Supplies the stomach
Branches to form the splenic artery
Branches to form the left gastroepiploic artery to supply the stomach
Branches to form the pancreatic arteries to supply the pancreas
Blood Vessel Distribution
The Celiac Trunk (continued)
Branches to form the common hepatic artery
The common hepatic artery branches to form:
Hepatic artery proper to supply the liver
Right gastric artery to supply the stomach
Cystic artery to supply the gallbladder
Gastroduodenal artery to supply the duodenum
Blood Vessel Distribution
Inferior Mesenteric Artery
Branches to form the left colic and sigmoid arteries
Supply the terminal portions of the large intestine
Branches to form the rectal arteries
Supply the rectum
Blood Vessel Distribution
Arteries of the Pelvis
The common iliac arteries
Branch to form the internal iliac artery
Supplies the urinary bladder, walls of the pelvis, external genitalia, and the medial side of the thigh
Branches to form the external iliac artery
Supplies blood to the legs
Blood Vessel Distribution
Arteries of the Leg
External iliac arteries form the:
Femoral artery
The femoral artery continues to form the popliteal artery, and then splits to form the anterior tibial artery and posterior tibial artery
Deep femoral artery
Blood Vessel Distribution
Arteries of the Foot
The anterior tibial artery forms the dorsalis pedis artery
The posterior tibial artery forms the medial and
lateral plantar arteries
Blood Vessel Distribution
Systemic Veins
Veins collect blood from the body tissues and return it to the heart
Blood returns to the heart from the lower extremities via the inferior vena cava to the right atrium
Blood returns to the heart from the upper extremities via the superior vena cava to the right atrium
Blood returns to the heart from the lungs via the pulmonary veins to the left atrium
Blood Vessel Distribution
Venous Return from the Cranium
The superficial cerebral veins drain into:
Superior and inferior sagittal sinuses
Petrosal sinuses
Occipital sinus
Left and right transverse sinuses
Straight sinus
All of the venous sinuses drain into the internal jugular vein
The internal jugular drains into the brachiocephalic veins
Blood Vessel Distribution
Venous Return from the Cranium (continued)
The vertebral veins drain into the brachiocephalic veins
Blood Vessel Distribution
Venous Return from the Head
Veins from the head converge to form the:
Temporal vein
Facial vein
Maxillary veins
The temporal and maxillary veins drain into the
external jugular vein
The facial vein drains into the internal jugular vein
Blood Vessel Distribution
Venous Return from the Neck
Vessels in the neck drain into the external jugular vein
The external jugular vein drains into the subclavian vein
Blood Vessel Distribution
Venous Return from the Upper Limb
Blood returns to the heart from the hands in the
following sequence:
Digital veins
Superficial and deep palmar veins
The superficial palmar veins drain into the cephalic vein
Subclavian vein
Brachiocephalic vein
Superior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Upper Limb
Blood can also return to the heart from the hands in the following sequence:
The superficial palmar veins drain into the cephalic vein
Median cubital vein
Basilic vein
Axillary vein
Subclavian vein
Brachiocephalic vein
Superior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Upper Limb
Blood can also return to the heart from the hands in the following sequence:
The superficial palmar veins drain into the basilic vein
Axillary vein
Subclavian vein
Brachiocephalic vein
Superior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Upper Limb
Blood can also return to the heart from the hands in the following sequence:
The deep palmar veins drain into the radial and ulnar vein
Those veins will unite to form the brachial vein
Axillary vein
Subclavian vein
Brachiocephalic vein
Superior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Abdominal Area
The following veins drain into the inferior vena cava or the superior vena cava, which drains into the right atrium
Lumbar veins go superior and drain into the superior vena cava
Gonadal veins: the right gonadal vein drains into the inferior vena cava, the left gonadal vein drains into the left renal vein and then into the inferior vena cava
Hepatic veins drain into the inferior vena cava
Blood Vessel Distribution
Venous Return from the Lower Limb
Blood leaves the foot and returns to the heart via the following veins
Plantar veins
Drain into the anterior tibial, posterior tibial, and fibular veins
Popliteal vein
Femoral vein
Common iliac vein
Inferior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Lower Limb
Blood also leaves the foot and returns to the heart via the following veins
Dorsal venous arch
Great saphenous vein
Femoral vein
External iliac vein
Common iliac vein
Inferior vena cava
Right atrium
Blood Vessel Distribution
Venous Return from the Hepatic Portal System
Blood in the inferior mesenteric, splenic, and superior mesenteric veins drains into the hepatic portal system
Liver sinusoids
Hepatic veins
Inferior vena cava
Right atrium
Cardiovascular Changes at Birth
The fetal cardiovascular system differs from the adult cardiovascular system
The fetal lungs are nonfunctional
The fetal digestive system is nonfunctional
All fetal nutritional and respiratory needs are provided by diffusion across the placenta
Blood in the fetal internal iliacs enters the umbilical arteries
Enters the umbilical cord
Enters the placenta
Cardiovascular Changes at Birth
All fetal nutritional and respiratory needs are provided by diffusion across the placenta (continued)
Blood leaves the placenta
Enters the umbilical vein
Enters the ductus venosus
Enters the fetal liver
Enters the inferior vena cava
Enters the fetal right atrium
Cardiovascular Changes at Birth
All fetal nutritional and respiratory needs are provided by diffusion across the placenta (continued)
Blood in the right atrium can pass through the
heart via the following methods:
Through the tricuspid valve to the right ventricle
Through the foramen ovale to the left atrium