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 (<.1mm)- ex. Terminal arterioles, meta-arterioles, throroughfare, channel/preferred

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