Download Cardiovascular system

CARDIOVASCULAR SYSTEM
Physiology Topic #3
THE HEART
LEARNING GOALS
• I will be able to identify the structure and function of the heart.
• I will be able to explain how the heart contracts.
• I will be able to find my target heart rate.
CARDIOVASCULAR ANATOMY
• the heart is a muscle (MYOCARDIUM)
• characteristics:
• involuntary contractions
• capable of speeding up
• fatigue resistant (approx. 3 billion
contractions/lifetime)
HEART ANATOMY
• the heart is considered a “double pump” and is divided
into R and L sides
• R heart - pumps deoxygenated blood from the veins to
the lungs (for PULMONARY CIRCULATION)
• L heart - pumps oxygenated blood from the lungs to
the body (for SYSTEMIC CIRCULATION)
• each side consists of 2 chambers
CHAMBERS OF THE HEART
THE ATRIA
• receive the blood from the body (right atrium) and lungs
(left atrium) before pumping it into ventricles
• act as ‘reservoirs’ for blood while ventricles are pumping
THE VENTRICLES
• these larger pumps receive blood from atria and
pump it to the lungs (RIGHT VENTRICLE) or to
the body (LEFT VENTRICLE)
• NOTE: the right pumps de-oxygenated blood,
the left pumps oxygenated blood
ADDITIONAL STRUCTURES
STRUCTURE
tricuspid valve
bicuspid (mitral) valve
pulmonary artery (1/lung)
pulmonary veins (2/lung)
vena cava (inf. & sup.)
aorta (& descending
aorta)
pulmonary semilunar
valve
aortic semilunar valve
FUNCTION
STRUCTURE
FUNCTION
tricuspid valve
separates R atrium from the R ventricle
bicuspid (mitral) valve
separates L atrium from the L ventricle
pulmonary artery (1/lung)
carries blood from the R ventricle to the lungs
pulmonary veins (2/lung)
return blood from the lungs to the L atrium
vena cava (inf. & sup.)
return blood to the heart from the upper body (superior)
& from the lower body (inferior)
aorta (& descending
aorta)
carries blood from the heart out to the upper body
(aorta) & to lower body (descending aorta)
pulmonary semilunar
valve
prevents blood from flowing back from the pulmonary
artery into the R ventricle again
aortic semilunar valve
prevents blood from flowing back from the aorta into the
L ventricle again
FOR YOUR VIEWING PLEASURE
• internal structure
• mechanics
• anatomy
MECHANICS OF THE
ATRIO-VENTRICULAR VALVES
• muscular extensions of the ventricle walls,
PAPILLARY MUSCLES, attach to the valves
via CHORDAE TENDINAE & prevent them
from opening up into the atria
• Ensures unidirectional flow of blood in heart
ELECTRICAL CONDUCTION
ELECTRICAL CONDUCTION
OF THE HEART
• heart can speed up according to the oxygen demands of
the muscles
• the speed at which the heart contracts is governed by a
collection of nerve cells in the R atrium called the SINUS
NODE
• the SINUS NODE stimulates contraction independent of
the brain
• The heart’s pacemaker
• Chew on this!
ELECTRICAL CONDUCTION
1. SINUS (SA) NODE gives signal to contract
2. signal is passed from the R atrium to the L
atrium by the INTERNODAL PATHWAY
3. signal moves to the bottom of the atria and is
passed to the INTERVENTRICULAR SEPTUM
by the ATRIOVENTRICULAR (AV) NODE
4. nervous tissue in the septum called the
BUNDLE OF HIS, splits into R and L branches
5. the R and L BUNDLE BRANCHES pass the
signal on to the PURKINJE FIBRES at the
bottom of each ventricle
BLOOD PRESSURE
• During one CARDIAC CYCLE, there are 2 “main events”:
1.DIASTOLE - phase of relaxation when heart is filling
with blood (therefore, low pressure in blood vessels)
2.SYSTOLE - phase of contraction where heart ejects
blood (therefore, high pressure in blood vessels)
MEASURING HEART RATE
WHAT’S YOUR RESTING HEART RATE?
• to get a true measure of RHR, you need to take it FIRST
thing in the morning
• from an athletic perspective, a low RHR is a good thing
b/c then you should be able to work a little harder before
reaching your maximum heart rate (MHR)
• TRY IT...count for 10 s
• RHR = _____ beats X 6 = _____ bpm
WHAT’S YOUR MAX HEART RATE?
• to find out the max # of times your heart
should be able to beat in 1 minute...
• MHR = 220 - your age = _____ bpm
• MHR = 226 - your age = _____ bpm
WHAT’S YOUR TARGET HEART RATE?
• to get any cardiovascular benefit from exercise, you
need to work your heart enough, but not too much
(or you’ll tire out too quickly)
• the general rule of thumb is that you should work
out at 50-85% of your MHR (depending on your
existing level of fitness)
LEARNING GOALS
• I will be able to identify the structure and function of the heart.
• I will be able to explain how the heart contracts.
• I will be able to find my target heart rate.
REVIEW QUESTIONS
CARDIO REVIEW Q’S
1. Describe the role of each of the 4 valves in the heart.
2. All of the valves have the same basic function...what is it?
3. Which valves are responsible for the ‘sounds’ of the heart?
4. Why is the L ventricle larger than the R?
5. What is the function of the interventricular septum?
6. What part of the ventricle receives the message to
contract first? Why?
7. Describe what happens to the (a) heart (b) blood pressure during
DIASTOLE.
8. Describe what happens to the (a) heart (b) blood pressure during
SYSTOLE.
9. If you want to gain an aerobic benefit from exercise, why shouldn’t you
exercise (a) above 85% (b) below 50%