Download Cardiovascular Physiology Powerpoint

The Cardiovascular System: The Heart
• Beats approximately
100,000 x/ day
• Beating
3 billion x/ 70 yr life
• Over 100,000 km of
blood vessels
• Total blood volume in
an average adult is 5L
20-1
Functions of the Cardiorespiratory System
•
•
•
•
•
Protection
Transportation
Regulation
Gas exchange
Air purifier
20-2
General Characteristics of the Heart
• Size of a closed fist
• located in thoracic
cavity between lungs mediastiniun
• 2 upper chambers atrium
• 2 lower chambers ventricles
• each set separated by
a septum
• Right side deals with
deoxygenated blood
• Left side deals with
oxygenated blood
20-3
The Heart’s Linings
• Pericardial sac filled with fluid to
reduce friction(dense irregular CT)
• Epicardium - outer lining of heart
• Myocardium is the heart muscle
• Endocardium - lines the inside of
the heart
20-4
Chambers of the Heart
• Two Atria
– Right atrium gets deoxygenated blood from the superior
and inferior vena cava
– Left atrium gets oxygenated blood from pulmonary veins
• Two Ventricles
– Left has thicker wall and pumps to the body
– Right pumps blood to lungs to get oxygenated
– Separated by interventricular septum
20-5
The Four Valves of the Heart
• Atrioventricular valves (gateway to ventricles)
– Right = tricuspid;
– Left = bicuspid/mitral
– Cusps attached to papillary
muscles by chordae tendinae
– Leaks = murmurs
• Semilunar valves
- gateway to lungs (puulmonary)
- and aorta (aortic)
20-6
Valve Function
A-V Valves
SL Valves
Atria contract, blood fills Ventricles contract, blood
ventricles through A-V pumped into aorta and
valves
pulmonary trunk through
SL valves
20-7
Internal Structures of the Heart
20-8
Blood Circulation
• Blood flow
– blue = deoxygenated (R)
– red = oxygenated (L)
20-9
Path of Blood through the Heart
• Superior and
inferior vena cava
• Right atrium
• Tricuspid valve
• Right ventricle
• Pulmonary valve
• Pulmonary trunk
• Gas exchange in
lungs
•
•
•
•
•
•
•
Pulmonary veins
Left atrium
Mitral valve
Left ventricle
Aortic valve
Aorta
Gas exchange with
working cells
20-10
The Vascular System
Venules and Veins
– Carries blood towards
the heart
– Usually carries
deoxygenated blood
except for the
pulmonary vein
– Major properties
• limited
contractibility and
elasticity
• One-way valves
(varicose veins)
Arteries and Arterioles
– Carries blood away from
the heart
– Usually carries
oxygenated blood except
for the pulmonary artery
– Thick smooth muscle
wall
– Major properties
• Contractibility
• Elasticity
20-11
The Vascular System
Capillaries
– Permit exchange of nutrients and gases; walls are one cell thick
– Capillaries connect arterioles and venules
20-12
Skeletal Muscle Pump
Bringing Blood Back to the Heart
• Three main ways:
– Thoracic pump
– Venoconstriction
– Skeletal muscle pump
• muscle contraction
• one-way valves
20-13
Coronary Circulation
• Right and left coronary arteries nourish the
myocardium (heart muscle)
• Left and right cardiac veins remove waste from the
myocardium
20-14
Conduction System of Heart
Coordinates contraction of heart muscle
20-15
Electrical Conduction of Heart
• SA node (90-100 x/ minute)
– cluster of cells in wall of Rt. Atria that fire an electrical pulse
– begins heart activity that spreads to both atria
– excitation spreads to AV node
• AV node (40-50 times x/ minute)
– in atrial septum (dividing both atria)
– transmits signal to bundle of His
– delays the impulse to allow atria to fully contract
• Bundle of His & Purkinje Fibers
– the connection between atria and ventricles (via septum)
– divides into bundle branches & purkinje fibers, large diameter
fibers that conduct signals quickly
20-16
Rhythm of Conduction System
•
•
•
•
SA node fires spontaneously 90-100 times per minute
SA node setting pace since is the fastest
AV node fires at 40-50 times per minute
If both nodes are suppressed fibers in ventricles by
themselves fire only 20-40 times per minute
• Artificial pacemaker needed if pace is too slow
• Note:
– caffeine & nicotine increase activity
20-17
Electrocardiogram---ECG or EKG
• EKG
– Action potentials of all active cells
can be detected and recorded
• P wave = Atrial Depolarization
– spreads from the SA node through
the atria
– 0.1s after the P wave begins, atria
contracts
– repolarization of atria not evident
because it is buried in the QRS complex
• P to Q interval
– conduction time from atrial to
ventricular excitation
20-18
Electrocardiogram---ECG or
EKG
• QRS complex = Ventricular Depolarization
- shortly after QRS wave begins, the ventricles contract
• T wave = Ventricular Repolarization
– ventricular repolarization
– occurs before the ventricles start to relax
– smaller & more spread out because repolarization takes
longer
20-19
Abnormal ECG/ EKG
• Large P Wave = Enlarged Atria
- problems with the bi or tricuspid valves causes a backup of blood in the
atria resulting in the expansion of the atrial walls
• Enlarged Q Wave = Myocardial Infarction (HEART ATACK!!)
• Enlarged R wave = Enlarged Ventricles
• Flatter T Wave = The Heart receiving insufficient Oxygen
• Tachycardia = a fast resting heart beat greater than 100bpm in adults
• Bradycardia=an abnormally slow/unsteady resting heart rate < 50bpm
20-20
Heart Sounds
Where to listen on chest wall for heart sounds.
20-21
Systole and Diastole
• Cardiac cycle
– Systole when ventricles contract
(heart empties)
– Diastole when ventricles relax
(heart fills)
• Heart sounds heard through a
stethoscope
Lub - a “long/low” sound
- closing of the a-v valves (tri/bi)
Dub - A “sort/sharp” sound
closing of the s-v (aorta/ pulmonary)
20-22
Cardiac Cycle
20-23
Cardiac Output
• Amount of blood pushed into aorta or
pulmonary trunk by ventricle
• Determined by stroke volume and heart rate
• CO = SV x HR
– at 70ml stroke volume & 75 beat/min----5.25 L/min
– entire blood supply passes through circulatory
system every minute
• Cardiac reserve is maximum output/output at
rest
– average is 4-5 L/ min while athlete is 7-8 L/ min
20-24
Cardiac Output Calulations
Example: HR = 70 bpm SV = 70 mL
(Q) CO = HR x SV
= 70 beats/ min x 70 mL of blood/ beat
= 5040 mL/ min
= 5.04 L/ min
20-25
Factors Affecting Heart Rate
1) Age – child’s HR much faster than adult
2) Emotional State of the Individual
- Parasympathetic Nervous System HR
- Sympathetic Nervous System HR
3) The physical state & efficiency of the heart
- Athletic heart has larger SV & lower RHR
- Couch Potato has a faster RHR
20-26
Regulation of Heart Rate
• Nervous control from the cardiovascular
center in the medulla
– Sympathetic impulses ↑ heart rate & contraction
– parasympathetic impulses ↓ heart rate.
– Baroreceptors (pressure receptors) detect
change in BP and send info to the cardiovascular
center
20-27
Regulation of Heart Rate
• Heart rate is also affected by hormones
– epinephrine, norepinephrine, thyroid
hormones
– ions (Na+, K+, Ca2+)
– age, gender, physical fitness, and
temperature
20-28
Influences on Stroke Volume
• Preload (affect of stretching)
– Frank-Starling Law of Heart
– more muscle is stretched,greater contraction force
– more blood more force of contraction results
• Contractility
– autonomic nerves (stress), hormones
a)  Contractility = Parasympathetic Stimulation
•
b)  Contractility = Sympathetic Stimulation
• Afterload
– amount of pressure created by the blood in the way
– high blood pressure creates high afterload
20-29
CV Systems’ Adaptation to Exercise
• With improved CV fitness
- SV will increase (increased mass & contractibility)
- therefore, RHR will decrease
- Also the Max CO will increase
(VO2 Max will also increase due to this)
- RBP will become more constant (120/80)
- Rick of CV diseases will decrease
- Increased # of capillaries around the heart
20-30
CV Systems’ Adaptation to Exercise
1) Increased Myoglobin (02 binding pigment)
- acts as an 02 store aiding in the diffusion of 02
2) Increased oxidation of carbohydrates
- training increases the muscles capacity to break
down glycogen in the presence of 02
3) Increased oxidation of fats
- training increases the muscles capacity to break
down fatty acids in the presence of 02
20-31
VO2 Max
VO2 Max
Definition: the max amount of O2 that can be
consumed per minute during max exercise
(measured in mL/ kg)
- also known as aerobic power
- this is an individuals max aerobic capacity, or
ability to consume O2 at the cellular level
20-33
VO2 Max
• 93% of VO2 Max is under genetic influence,
although it can be improved through
training, there is a genetic ceiling
• Max VO2 doesn’t differ between boys &
girls before puberty, after puberty females
are 25 – 230% less than values
20-34
VO2 Max
- Capacity depends on the amount of O2 that can be
delivered to the muscles compared to the amount of
O2 used by the muscle
- O2 consumption is important to prolonged exercise.
(Endurance activities such as marathons, triathletes)
20-35
Blood Pressure
Blood pressure refers to the force exerted by
circulating blood on the walls of blood vessels
• Systolic - The force your blood exerts
when the heart is contracting
• Diastolic - The force your blood exerts when
the heat is relaxing
• Measured using a sphygmanometer
20-36
Blood Pressure
• Factors affecting blood pressure
– Cardiac output
– Peripheral resistance
– Blood volume
• Blood pressure
– Normal = 120/80mmHg
– Hypertensive = 140/90mmHg
20-37
Hypertension
- persistently elevated blood pressure
- a major cause of heart failure, kidney failure, &
stroke
Risk Factors:
- 1)
Sex – male
- 2) Race – Black
- 3) Lifestyle – smoker, diet, drinker
4) Genetics – hypercholesterolemia, glucose
intolerance (diabetic)
20-38
Hypertension (mm Hg)
Normal Mild HT Moderate Severe
HT
HT
Very
Severe
HT
Systolic
120
140-160
160-180 180-200
200+
Diastolic
80
90-100
100-110 120-130
130+
20-39
Myocardial Infarctions/
Attacks
• Blockage of a coronary artery (due to
plaque & fat) depriving the heart of O2
• Tissue in the affected area suffers
permanent injury & signals its distress by a
very sharp pain (angina)
• If the damage to the heart muscle is too
extensive, the individual will not survive
20-40
Myocardial Infarctions/
Attacks
• Signs: pressure in the chest that lasts more than a
few minutes, or goes away comes back
• Spreading pain – shoulders, neck, left arm
• Lightheaded, sweating, nausea
20-41
Angina Pectoris
1. Chest pain due to CHD
2. Ischemia (insufficient blood supply)
3. Occurs when blood flow to the heart
doesn’t meet increased demands
Rx: take nitroglyerin
- relaxes the veins ( amount of venous
return, work of the heart)
- relaxes the coronary arteries
( the amount of blood supplied to the heart)
20-42