hft - cardiovascular system
TRANSCRIPT
Cardiovascular System
Group Discussion O In small groups discuss,
O What makes up the cardiovascular system
O Functions
O Importance to exercise
The Circulatory SystemThe cardiovascular system is also known as the circulatory system. It consists of…
1. Blood 2. Blood Vessels
3. The Heart
Blood
O Components
O Functions
Blood Provides the fluid environment for cells and the medium by which many maintain are carried to and from cells:
Blood consists of:
O Plasma Red blood cells
O White blood cells
O Platelets
Functions of blood are:
● Oxygen
● Transport
● Clotting
● Fighting Infection
Oxygen Transport Exercise increases the demand for oxygen. Blood transport oxygen from the to the parts of the body that is require it. It also transports metabolic waste from cells to areas of disposal.
Clotting O Clotting is a complex process which white blood cells
form solid clots
O A damaged blood vessel wall is covered by a fibrin clot to assist repair
O Platelets form a plug at the site of the damage
O Plasma components (coagulation factors) respond to form fibrin strands which strengthen the platelet plug
Fighting Infection Blood contains antibodies and white blood cells which help defend against virus and bacteria.
The Major Blood VesselsArteries Veins
Arteries
Veins
Capillaries
Arterioles
Venules
VALVES? FUNCTION?
ArteriesArteries carry blood away from the heart and
have a thick, elastic, muscular wall.They stretch as blood is pumped in and the muscle wall contracts to force blood along.
VeinsPocket valves required to prevent backflow of
blood when muscles relaxDeoxygenated blood taken back to heart
Veins have a relatively thinner and less muscular wall than arteries. The blood is under a lower
pressure than in the arteries.
CapillariesNo valves required
Blood pressure higher than veins but not as high as arteries
Capillary walls are one cell thick. Exchange of nutrients such as oxygen occurs across
their surface.
ArteriolesJust like arteries, arterioles carry blood away
from the heart and out to the tissues of the body. In addition to this "supply train" function,
arterioles are very important in blood pressure regulation
Arterioles share many of the properties of arteries – they are strong, have a relatively thick wall for their size, and contain a high percentage
of smooth muscle.
Venules Venules are minute vessels that drains blood from capillaries and transports it to the veins
Thinner walls than arterioles, collect blood leaving capillaries and are a transport mechanism to get blood to the veins
Valves not required – high pressure at all times
Carry oxygenated blood (apart from pulmonary artery which carries
deoxygenated blood from heart to lungs
VALVES? FUNCTION?
Label Heart
Heart
How the Heart Pumps Blood
Tothe body
Tothe lungs
Fromthe lungs
Fromthe body
The left sidepumps oxygenatedblood to the rest of
the body for use.
The right sidepumps deoxygenated blood to the lungs to
pick up oxygen.
Systole / Diastole?
The Cardiac Cycle - How the Heart Beats
O Every time the heart beats it goes through a 3-part cycle:
Stage 1
O The top chambers (atria) relax and fill up with blood from the veins.
Stage 2
O The atria contract and the blood is forced into the relaxing bottom chambers (ventricles).
Stage 3
O The ventricles contract and the blood is forced out of the heart into the arteries.
How Blood is Pumped around the Body
O Blood flows around the body in a ‘figure of eight’ circuit, passing through the heart twice on each circuit.
O Blood travels away from the heart through arteries (A).
O Blood returns to the heart through veins (V).
O There are 2 separate ‘loops’ to the circuit:
O The top loop – carries blood from the heart to the lungs and back.
O The bottom loop – carries blood from the heart to all over the body and back.
Blood Flow around the Body – Top Loop
Lungs
Heart
Body
1. Blood leaves the right side of the heart via the pulmonary artery and goes to the lungs where it is oxygenated.
2. It then travels back to the left side of the heart via the pulmonary vein.
Pulmonaryartery
Pulmonaryvein
Blood Flow around the Body - Bottom Loop
Lungs
Heart
Body
3. The left side of the heart then pumps the oxygenated blood around the rest of the body for use, via the aorta.
4. Once the oxygen has been used, the blood becomes deoxygenated and returns to the right side of the heart via the vena cava.
Vena Cava
Aorta
Functions of the Circulatory System
3 main functions?
Functions of the circulatory system
O Delivery of oxygen and nutrients
O Removal of waste products
O Thermoregulation
Functions of the circulatory system
O 3 Groups
O Research / Present
Cardiovascular Terms
HR / RHR / MHR / AH
SV / CO
Calculations?
Rest / Max Exercise
CO = 5 l/min / 30 l/min
Light Exercise
AHP - slight increase
Extensive vasodilation
Increases venous return
Increased CO
Increase BP
Heavy Exercise
OCO increases toward maximum levels
ORedirection of blood flow (Heart / Lungs / Muscles / Heart / Skin)
OBrain blood flow is unaffected
Cardiovascular and Exercise
Cardiovascular PerformanceSubject Heart (g) SV (ml) HR (bpm) CO (l/min) BP (s/d)
Nonathlete (rest)
300 60 83 ?? 120/80
Nonathlete(max)
104 192 ?? 187/75
Athlete (rest) 500 100 53 ?? 120/80
Athlete (max)
167 182 ?? 200/90
Cardiovascular PerformanceSubject Heart (g) SV (ml) HR (bpm) CO (l/min) BP (s/d)
Nonathlete (rest)
300 60 83 5.0 120/80
Nonathlete(max)
104 192 19.9 187/75
Athlete (rest) 500 100 53 5.3 120/80
Athlete (max)
167 182 30.4 200/90
How does cardiac output effect RHR?
What changes has occurred?
Cardiovascular and Exercise
Control of heart rate from brain via autonomic nervous system
Adrenaline, intensity of exercise and recovery
Oxygen debt and recovery
Control of heart rate from brain via autonomic nervous system
O The autonomic nervous system is a specialised nervous system that controls our automatic responses, for example heart rate, digestion and breathing.
O These are things we do without conscious thought.
O Heart rate is determined by a group of specialized cells in the heart itself called the sino-atrial node.
O These cells act as a pacemaker to set how fast our heart beats.
O The autonomic nervous system can alter this as necessary, so that our heart beats faster or more slowly, and the force of heart muscle contraction can change, too.
O Signals from the brain to the heart are important in exercise (both in anticipation and once the exercise starts), in response to thoughts (such as stressful situations or the pleasure of chocolate) and in the regulation of blood pressure.
Adrenaline, intensity of exercise and recovery
O Our body produces adrenaline in response to frightening, stressful or exciting situations.
O Adrenaline makes the heart beat faster and prepares the body for either flight (running away from danger) or fight (using the muscles to fight off a competitor or predator).
O More intense exercise requires a higher heart rate because the muscles need more oxygen and more food, so the heart pumps faster to deliver more blood carrying those vital components.
O We produce adrenaline in response to high intensity exercise over a long period.
O After high intensity exercise, then, the recovery period may be longer, as it will take time for the body to respond and reduce the level of adrenaline.
Oxygen debt and recovery
O Reach a point where there isn’t enough oxygen reaching the tissues to provide the energy we need.
O Shift to anaerobic respiration – releasing energy without oxygen.
O This generates lactic acid.
O When we stop exercising, our heart rate remains elevated until we have broken down the lactic acid.
O We need oxygen for this breakdown process, so producing lactic acid is sometimes called having an oxygen debt.
O So the more lactic acid you have produced, the longer it takes for your heart rate to come back to normal.
O If you are fit you release energy more efficiently; you tend to produce less lactic acid, and show a faster heart rate recovery than someone who is not fit. The size of the oxygen debt is the main factor in the length of the recovery period if there is little adrenaline circulating. Lactic acid in your muscles makes them painful.
Cardiac Adaptations
O Hypertrophy of the left ventricle
O SV increases = Increased CO at maximum levels
O RHR decreases = less beat’s needed for same CO
Vascular Adaptations
Increased muscle capillarisation
Increased haemoglobin levels (Blood plasma and red blood cells)
Decreased BP (increased capillarisation / elasticity of blood vessels / levels of HDL)
Increased a-VO2 diff (difference in o2 concentration between the arterioles and venules, a direct measurement of how much o2 muscles are using - meaning more o2 extracted by muscles
Heart Rate Monitors
Pairs
Plan an experiment to test the short term effects of exercise / recovery at different intensities