CARDIOVASCULAR SYSTEM Blood Vessels
GENERAL 3 Types of Blood Vessels: Typical Blood flow: Arteries Veins Capillaries Typical Blood flow: Heart Arteries Arterioles Capillaries Venules Veins Heart
STRUCTURE OF BLOOD VESSELS 3 Tunics (Coats): Tunica Intima (Interna) Innermost, Thin Endothelium (Simple Squamous E.T.) + C.T. Tunica Media Middle, Thickest
STRUCTURE OF BLOOD VESSELS continued Smooth Muscle Fibers, Arranged Circularly C.T. (Elastic & Collagen) Tunica Externa (Adventitia) Fibrous C.T. Sheath
The Vascular System Slide 11.24 Figure 11.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ARTERIES Carry Blood Away From the Heart Under Highest Pressure Thickest Walled (Tunica Media) Arteries usually carry oxygenated blood Pulmonary Arteries Carry O2 Poor Blood Systemic Arteries Carry O2 Rich Blood
ARTERIES continued 2 Types of Arteries: Elastic Largest (Aorta, Pulmonary Trunk) Thickest Tunica Media with Increased Elastic Tissue Can Stretch & Recoil (Elastic Rebound) Reduces Pressure Differences Between Systole & Diastole
ARTERIES continued Muscular (Distribution) Tunica Media: Smooth Muscle Fibers > Elastic Fibers Can Change Diameter Can Influence Blood Flow & Blood Pressure Capable of Growth & Establishing Collateral Circ. Contract when Injured
Tunics of Elastic and Muscular Arteries Figure 11.8b Slide 11.24 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ARTERIES continued Arterioles Smallest arteries Deliver Blood to Capillaries Regulate Capillary Blood Flow
VEINS Return Blood to the Heart Thinner-walled Wider Lumen, Greater Diameter Tend to be more Superficially Located
The Vascular System Slide 11.24 Figure 11.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
VEINS continued Under Lowest Pressure Valves In Veins Carrying Blood Against Gravity Venules Smallest Veins Receive Blood from Capillaries
The Anatomy of Veins Slide 11.24 Figure 11.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
VEINS continued Venous Return Assisted By: Muscular Compression Skeletal Muscle Contractions Aids Venous Return Respiratory Pump Pressure Drops in Thoracic Cavity During Inhalation, Pulling Blood into Venae Cavae
Movement of Blood Through Vessels Arterial blood is pumped by the heart Veins use the milking action of muscles to help move blood Figure 11.9 Slide 11.27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
CAPILLARIES Thinnest Walls (tunica intima) Site of Exchange via Diffusion Some capillaries form Capillary Beds Precapillary Sphincters (& smooth muscle in arterioles) regulate blood flow into capillaries
Figure 11.10 Slide 11.28b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Hepatic Portal System Carries Venous Blood From Capillaries in Digestive Organs to Capillaries in Liver Contains Substances Absorbed from Digestive Tract (Nutrients, Wastes, Toxins) Liver Stores, Converts, Detoxifies Liver also Receives Arterial Blood from Hepatic Artery
Special Circuits: Hepatic Portal System Figure 11.14 Slide 11.33 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
FETAL CIRCULATION - General Differs from Adult “Non-functional” Lungs & Digestive Tract Primary Functions Carried out by Mom’s Systems Exchange Between Fetal Blood & Maternal Blood Occurs at Placenta
FETAL CIRCULATION – Fetal Vessels Placental or Umbilical Vein Returns O2 Rich Blood from Placenta to Fetus Branches Below Liver; 1st Branch Joins Portal Vein Ductus Venosus Branch of Umbilical Vein (O2 Rich) Bypasses Liver; Empties into Inferior Vena Cava
Special Circuits: Fetal Circulation Figure 11.15 Slide 11.34 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
FETAL CIRCULATION – Fetal Vessels continued Foramen Ovale Interatrial Opening Bypasses Pulmonary Circ. Ductus Arteriosus Connects Pulmonary Trunk & Aorta
Special Circuits: Fetal Circulation Figure 11.15 Slide 11.34 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
FETAL CIRCULATION – Fetal Vessels continued Placental or Umbilical Arteries (2) Branch off Internal Iliac Arteries Carry Blood towards Placenta
Special Circuits: Fetal Circulation Figure 11.15 Slide 11.34 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
FETAL CIRCULATION – Fate of Fetal Vessels Umbilical Vein Round Ligament of Liver Ductus Venosus Ligamentum Venosum Foramen Ovale Fossa Ovalis Ductus Arteriosus Ligamentum Arteriosum Umbilical Arteries Umbilical Ligaments
Coronary Circuit Part of Systemic circuit Coronary Arteries are 1st vessels to branch from aorta (ascending aorta) Supply myocardium of heart with oxygen Drain into right atrium via coronary sinus