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Ch 18: The Cardiovascular System
Sec 18-1: Features & Functions of the
Cardiovascular System
Key Features of Cardiovascular Systems
All cardiovascular systems have 3 major parts:
1) A fluid (blood) that serves as a medium of transport
2) A system of channels (blood vessels) that channel
blood throughout the body
3) A pump (heart) that keeps blood circulating
Types of Cardiovascular Systems
Two Main Types of Cardiovascular Systems:
1) Open
- Found in invertebrates
- One or more hearts; series of blood vessels
- Hemocoel…open cavity in organism’s body where blood
collects…surrounding tissues bathed in blood
Types of Cardiovascular Systems
Two Main Types of Cardiovascular Systems:
2) Closed
- Found in all vertebrates (including humans)
- Blood is confined to the heart & series of blood vessels
travelling throughout body
- Allow more rapid blood flow
- More efficient transport of wastes & nutrients
- Provides higher blood pressure
Human Cardiovascular System
Vertebrate cardiovascular system has many functions:
1) Transport oxygen & carbon dioxide through body
2) Distribution of nutrients from digestive system
3) Transport of wastes to liver & kidneys for excretion
4) Distribution of hormones
5) Regulation of body temperature
6) Prevention of blood loss
7) Protection of body from bacteria & viruses
Ch 18: The Cardiovascular System
Sec 18-2: How the Heart Works
Location of the Heart
The Heart: Chambers
The heart consists of 4 chambers:
Two atria (atrium = singular)
- Upper chambers
- Right atrium
- Left atrium
The Heart: Chambers
The heart consists of 4 chambers:
Two ventricles
- Lower chambers
- Right ventricle
- Left ventricle
Blood Flow Through the Heart
The heart is divided into two halves…a right side &
left side.
Both sides act as separate pumps. In each pump…
- an atrium receives & briefly stores blood before
squeezing it into the ventricle immediately below
- blood from ventricles is pumped into the vessels
throughout the body
Blood Flow Through the Heart
Right Side of Heart
- deals w/ deoxygenated blood returning from body
- right atrium receives blood from two major veins
called the superior & inferior vena cava
- right atrium contracts forcing blood into right ventricle
- right ventricle contracts & sends blood to lungs via
pulmonary arteries
Blood Flow Through the Heart
Superior Vena Cava
Right Atrium
Right Ventricle
Inferior Vena Cava
Blood Flow Through the Heart
Pulmonary Arteries
To the lungs
To the lungs
Blood Flow Through the Heart
Left Side of Heart
- deals w/ oxygenated blood returning from the lungs
- oxygen-rich blood from lungs enters left atrium
through the pulmonary veins
- left atrium squeezes blood into left ventricle
- strong contractions of left ventricle send oxygenated
blood to remainder of body via the aorta
Blood Flow Through the Heart
Pulmonary Veins
From the lungs
From the lungs
Left Atrium
Left Ventricle
Blood Flow Through the Heart
Aorta
Blood Flow Through the Heart
Blood Flow Through the Heart
Blood Flow Through the Heart
Heart Valves
- Allow blood to flow in only one direction
- Valves open as blood is pumped through
- Valves close when heart muscle relaxes to
prevent back flow
Blood Flow Through the Heart
Heart Valves
- Allow blood to flow in only one direction
- Four valves:
1) Atrioventricular valves (AV)
- Between atria & ventricles
- Right AV valve = Tricuspid valve (3 flaps)
- Left AV valve = Bicuspid valve (2 flaps)
*Bicuspid (a.k.a. Mitral valve)
- Prevents blood from being pushed into atria when
the ventricles contract
- Held in place by chordae tendineae (“heart strings”)
Blood Flow Through the Heart
Blood Flow Through the Heart
Superior Surface
Blood Flow Through the Heart
Heart Valves
- Allow blood to flow in only one direction
- Four valves:
2) Semilunar valves
- Between ventricles & major arteries leaving heart
- Pulmonary semilunar
*Between right ventricle & pulmonary arteries
- Aortic semilunar
*Between left ventricle & aorta
- Prevents blood from “backwashing” into ventricles
when they relax
Blood Flow Through the Heart
Blood Flow Through the Heart
Superior Surface
Blood Flow Through the Heart
Major Blood Vessels of the Heart
The heart has several major vessels associated with it:
1) Aorta
- Exits left ventricle & “feeds” all vessels of the body
2) Pulmonary arteries (x 2)
- Exits right ventricle & sends blood to lungs
3) Superior & Inferior vena cava
- Return blood
to right atrium
from vessels of the body
LVAD
Procedure…
4) Pulmonary veins (x 4)
- Return blood from lungs to left atrium
Major Blood Vessels of the Heart
• Blood in heart chambers does NOT nourish the
heart muscle itself.
• The heart has its own nourishing circulatory
system…
1) Coronary arteries
- Feed heart muscle oxygenated blood
2) Cardiac veins
- Remove deoxygenated blood from heart muscle
Major Blood Vessels of the Heart
The Heart’s Conduction System
The heart is controlled by an intrinsic conduction
system:
- Cardiac muscle cells contract w/o nerve impulses in
regular, continuous pattern
- Individual cells communicate w/ each other by way
of intercalated discs
The Heart’s Conduction System
The heart is controlled by an intrinsic conduction
system:
- System of nodes set the pacing of the contractions
1) Sinoatrial node (SA)
- natural pacemaker
- sets number of contractions/min
- causes atria to contract
2) Atrioventricular node (AV)
- takes signal from SA node & triggers ventricles to
contract
The Heart’s Conduction System
The Heart’s Conduction System
Cardiac Cycle
Cardiac Cycle – Facts
- the alternating between the contracting & relaxing of
the heart chambers
- happens around 100,000 times a day
- at rest, 1 cycle lasts just under 1 second
Cardiac Cycle
Cardiac Cycle – Features
- begins with both atria contracting simultaneously pushing
blood into ventricles
- a fraction of a second after atria relax, ventricles contract
pushing blood either to lungs or rest of body
- ventricles relax & heart rests momentarily
Cardiac Cycle
Cardiac Cycle & Heart Sounds
- Ventricular systole
*When ventricles contract they force the atrioventricular valves
to close
“lub”
Cardiac Cycle
Cardiac Cycle & Heart Sounds
- Ventricular diastole
*When ventricles relax, the semilunar valves close
“dup”
Blood Pressure
Systolic pressure
- force exerted by heart when ventricles contract
Diastolic pressure
- force being exerted by heart when ventricles are relaxed
Blood pressure is measured as the systolic pressure over
the diastolic pressure
Ex. 110/ 64
Blood Pressure
Blood pressure generally decreases as the distance
away from the heart increases
Radial Pulse
Stethoscope
Stethoscope
Measuring Blood Pressure
Measuring Blood Pressure
Systolic Pressure
Measuring Blood Pressure
Diastolic Pressure
Variations in Blood Pressure
“Normal” blood pressure ranges
- Systolic = 110-140 mm HG
- Diastolic = 60-80 mm HG
Hypotension (abnormally low blood pressure)
- Systolic = less than 110 mm HG
- Usually associated w/ sickness
Hypertension (abnormally high blood pressure)
- Systolic = greater than 140 mm HG
- Can be dangerous if chronic
Variations in Blood Pressure
Condition
Systolic
Diastolic
(Top Number)
What to Do
(Bottom Number)
Optimal*
Less than
120
and
Less than 80
Recheck in 2 years
Normal
Less than
130
and
Less than 85
Recheck in 2 years
High-normal**
130-139
or
85-89
Recheck in 1 year
Hypertension***
Stage 1
140-159
or
90-99
Confirm within 2
months
Stage 2
160-179
or
100-109
See doctor within 1
month
Stage 3
180 or
higher
or
110 or higher
See doctor
immediately or within 1
week
Ch 18: The Cardiovascular System
Sec 18-3: What is Blood?
Blood
Blood has two major components
1) A fluid called plasma (55-60%)
2) Various cellular components (40-45%)
- Red blood cells
- White blood cells
- Platelets
Other facts about blood
1) The average human has 5-6 liters of blood
2) It accounts for about 8% of total body weight
3) About 90% of plasma is water
Red Blood Cells
Red blood cells (RBCs)
- called erythrocytes & make up 99% of all blood cells
- red color caused by the pigment hemoglobin
*Hemoglobin carries O2…more O2 = more red
- formed in the bone marrow
- each cell only lives about 4 months
- approx. 2 million die & are replaced every second
Red Blood Cells
Red blood cells (RBCs)
- Blood type determined by special proteins on red
blood cell membranes
- 4 possible blood types (A, B, AB, & O)
- “Rh factor” is another protein associated w/ RBCs
*If present, you are Rh+; if absent, you are Rh-
White Blood Cells & Platelets
White blood cells (WBCs)
- help defend the body against disease
Platelets
- cell fragments that aid the blood in clotting
Ch 18: The Cardiovascular System
Sec 18-4: Structure & Function of
Blood Vessels
Blood Vessels
Blood vessels
- the “plumbing” of the circulatory system
- function is to transport blood (along w/ dissolved
nutrients, O2, & wastes) throughout the body
- made up of the following:
arteries, arterioles, capillaries, venules, & veins
Blood Vessels
Arteries
- Thick-walled vessels that carry blood AWAY from heart
- Walls have thin layer of smooth muscle that help
pressurize & push blood through them
Arterioles
- Very similar to arteries, only smaller
- Branch off main arteries & travel all over body
Major Arteries of the Body
Blood Vessels
Veins
- Thin-walled vessels that return blood to heart
- Much larger in diameter than arteries making pressure
much lower
- Valves help keep blood from back-flowing
- Skeletal muscle helps “milk” blood back to heart
Venules
- Smaller versions of veins that pour deoxygenated
blood from tissues back into larger veins
Major Veins of the Body
Blood Vessels
Artery
Vein
Blood Vessels
Capillaries
- Walls only 1 cell thick…easy
nutrient/gas exchange between
blood & tissue
- Vascular shunt
*Prevents flow of blood to
extremities in crisis situation
Blood Vessels
Blood Vessels of the Brain
Ch 18: The Cardiovascular System
Sec 18-5: Structure & Function of the
Lymphatic System
Lymphatic System
Lymphatic system
- Works very closely with circulatory system
- Consists of a network of lymph capillaries & larger
vessels that empty into circulatory system
- Includes numerous lymph nodes
- Also includes the thymus & the spleen
Lymphatic System
Functions of Lymphatic System
1) Returns excess fluids that leak from capillaries back to
bloodstream
2) Transports fats from small intestine into bloodstream
3) Defends body by exposing bacteria & viruses to WBCs
Ch 18: The Cardiovascular System
Homeostatic Imbalances of the
Cardiovascular System
Homeostatic Imbalances
1) Heart Block
-
Damage to AV node w/ loss of control of SA node
Affects hearts ability to coordinate contractions
2) Fibrillation
-
Rapid, uncoordinated “shuddering” of heart muscle
3) Tachycardia
-
Rapid heart rate (>100 bpm)
Can lead to fibrillation
Homeostatic Imbalances
4) Bradycardia
-
Low heart rate (<60 bpm)
5) Ischemia
-
Lack of blood supply to an area…in this case, the
heart
6) Heart murmur
-
“Swishing” sound after closing of valves due to
leakage
Homeostatic Imbalances
7) Congestive heart failure
-
As blood flow OUT of the heart slows, blood
returning to heart through the veins backs up
-
Causes swelling of the tissues
-
Can cause Pulmonary edema (fluid build-up in lungs
due to left side of heart not pumping effectively)
Homeostatic Imbalances
Congestive Heart Failure
Blood Flow Through the Heart
Pulmonary Edema
Blood Flow Through the Heart
8) Varicose veins
-
Pooling of blood in feet/legs causing veins in legs to
become
& dilated
Varicosetwisted
Veins
Blood Flow Through the Heart
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9) Thrombophlebitis
-
Inflammation of a vein that results in a clot
-
If clot breaks away, it can travel toward heart, lungs,
or brain & cause a blockage…death
Blood Flow Through the Heart
10)Atherosclerosis
-
“Hardening” or filling of the arteries w/ plaque
(fatty, calcified deposits)
Coronary Artery
For Fun… 
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m1/s7/trm1s7_3.htm