Ch. 48 Cardiovascular System

Introduction

• The cardiovascular system is the transportation system of the body
• It is comprised of blood, heart, and blood vessels
• The system supplies nutrients to and removes waste products from various tissues of the body
• The conveying media is liquid in form of blood which flows in a closed tubular system

Function of the Cardiovascular System

• Transport nutrients, hormones
• Remove waste products
• Gaseous exchange
• Immunity
• Blood vessels transport blood
  • Carries oxygen and carbon dioxide
  • Also carries nutrients and wastes
• Heart pumps blood through blood vessels

Components of the Cardiovascular System

1. Blood
2. Heart
3. Blood vessels

Blood

• Made up of blood cells and plasma
• Blood cells:
  • Erythrocytes (red blood cells)
  • Leukocytes
  • Thrombocytes (platelets)
• Plasma is the fluid portion

Heart

• The heart is a four chambered, hollow, muscular organ approximately the size of your fist
• Location:
  • Superior surface of diaphragm
  • Left of the midline
  • Anterior to the vertebral column, posterior to the sternum

Functions of the Heart

• Generating blood pressure
• Routing blood
  • Heart separates pulmonary and systemic circulations
• Heart valves ensure one-way blood flow
• Regulating blood supply
  • Changes in contraction rate and force match blood delivery to changing metabolic needs

Blood Vessels

• A closed network of tubes
• This includes:
  • Arteries
  • Capillaries
  • Veins
• Arteries (Distributing Channels)
  • Thick walled tubes
  • Elastic fibers
  • Circular smooth muscle
• Capillaries (Miscroscopic Vessels)
  • One cell thick
  • Serves the Respiratory System
• Veins (Draining Channel)
• General Structure:
  • Tunica intima
  • Tunica media
  • Tunica adventitia

Classification of Blood Vessels

• Conducting Vessels
• Distributing Vessels
• Resistance Vessels
• Exchange Vessels
• Capacitance/Reservoir Vessels

Arteries

• Blood vessels that carry blood away from the heart are called arteries
• They are the thickest blood vessels and they carry blood high in oxygen known as oxygenated blood
• Lumen is small
• No valves
• Repeated branching

Classification of Arteries

• Elastic- ex. Aorta and its major branches
• Muscular- ex. Renal, Testicular, Radial, Tibial
• Arterioles (

Capillaries (5-8 micron)

• The smallest blood vessels are capillaries and they connect the arteries and veins
• This is where the exchange of nutrients and gases occurs
• Two kinds of Capillaries:
  • Continuous- skin, lung, smooth muscle, connective tissues
  • Fenestrated- pancreas, endocrine glands, small intestine, choroid plexus, cilliary process etc

Sinusoids

• Sinusoids- large irregular vascular space (30-40 micron) ex. liver, spleen, bone marrow, suprarental, parathroid

Veins

• Blood vessels that carry blood back to the heart are called veins
• They have one-way valves which prevent blood from flowing backwards
• They carry blood that is high in carbon dioxide known as deoxygenated blood (low oxygen blood)
• Thin walled
• Large irregular lumen
• Have valves
• Dead space around
• Types:
  • Small
  • Medium
  • Large
• Some veins don’t have valves
• Some veins don’t have muscular tissue
• Factors responsible for venous return:
  • Muscle contraction
  • Negative intrathoracic pressure
  • Pulsation of arteries
  • Gravity
  • Valves

Circulation

• Coronary Circulation- the circulation of blood within the heart
• Pulmonary Circulation- the flow of blood between the heart and lungs
• Systemic Circulation- the flow of blood between the heart and the cells of the body
• Fetal Circulation
• Portal Circulation- the flow of blood between two sets of capillaries before draining in systemic veins

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