Anatomy & Physiology - Cardiovascular system Flashcards
function of the vena cava?
Deoxygenated blood back to right atrium
Function of the pulmonary artery?
Deoxygenated blood from right atrium to lungs
Function of the pulmonary vein?
Oxygenated blood to left atrium
Function of the aorta?
Oxygenated blood from left ventricle to rest of body
4 types of valves?
- Bicuspid valve
- Tricuspid valve
- Semi-lunar pulmonary valve
- Semi-lunar aortic valve
Positive about the left ventricle?
Strongest chamber of heart as must pump blood the greatest distance. Walls are thicker and stronger as more force resistant
Order of blood flow?
- Right atrium
- Tricuspid valve
- Right ventricle
- Pulmonary artery
- Lungs
- Pulmonary vein
- Left atrium
- Bicuspid valve
- Left ventricle
- Aorta
Explain cardiac conduction?
- starts in the sinoatrial node (SA node) hearts pacemaker. Stimulates and contracts aorta
- Pulse travels down into atrioventricular node (AN node). Short delay (0-1 second) to allow atria to contact
- ventricles fill with blood
- impulse travels through bundle of his
- down the purkinje fibers (left + right branches of ventricle walls)
- Ventricle systole occurs / ventricle contacts
What is the heart?
Heart is myogenic - produces it’s own impulse
Neural control of the heart - sympathetic
During exercise, this system increases heart rate and cardiac output by releasing adrenaline and norepinephrine into the heart
Neural control of the heart - parasympathetic
During rest this system decreases heart rate and cardiac output, through the vagus nerve, by releasing acetylcholine into the heart
what do sympathetic nerve impulse do?
They are sent to stimulate the SAN more frequently and there is a decrease in parasympathetic nerve impulses (vagus nerves), so the heart rate increases
what are the 3 receptors?
- Chemoreceptors
- Baroreceptors
- Proprioceptors
What do chemoreceptors detect?
Detects chemical changes within the heart. 1 - Blood acidity + pH. 2 - CO2
what is the chemoreceptors reaction?
- Co2 levels increase + HR increase
- pH levels drop (more acidic), HR increase
What do baroreceptors detect?
Establish a set point for Bp. Increase or decrease is detected by these receptors
what is baroreceptor reaction?
- Decrease Bp - Increase HR
- Increase Bp - Decrease HR
What do proprioceptors detect?
Detect changes in muscle movement and contraction.
(Sensory nerve ending in muscles)
What is proprioceptors reaction?
movement detected, increase HR
Hormonal control mechanism - adrenaline
Stress hormone released by sympathetic and cardiac nerves during exercise. Also known as the fight or flight hormone.
Noradrenaline is another hormone that is released during stressful situations. Known as a fight or flight chemical
Hormonal control mechanism - Stages
- prior to exercise beginning, heart rate increases due to release of adrenaline. (Anticipatory rise)
- causes an increase in oxygen supply to muscles (fight or flight)
- increases speed and quality of impulse traveling to SAN, so more blood is pumped to the working muscles
Neural factors : INTRINSIC CONTROL
- Venous return causes change in cardiac performance. More blood retuned; more blood ejected.
- Thermo receptors detect changes in blood joint muscle temps which indicates activity.
Neural factors : NEURAL CONTORL
- Chemoreceptors: chemical changes in heart, co2 and pH
- Baroreceptors: Stretch and pressure changes in blood
- Proprioceptors: detect movement and stretch in muscles
Neural factors: HORMONAL CONTORL
- Adrenaline - increase HR
- Noradrenaline - increases transmission speed of impulses
- Acetylcholine - Decreases transmission speed
What happens to our heart rate during exercise
1) Anticipatory rise due to adrenaline. Causes the SA node to increase HR.
2) Sharp rise in HR due mainly to aerobic work.
3) HR continues to rise due to maximal workloads stressing the aerobic system.
4) Steady state as athlete meets oxygen demand with oxygen supply.
5) Rapid decline in HR as soon as the exercise stops.
6) Slower recovery as systems return to resting state. HR remains elevated to get rid of waste products produced by the body (Lactic Acid)
Effect of exercise on the heart?
Cardiac hypertrophy + Bradycardia (resting HR of below 60bpm)
Starlings law summary
- Increased venous return
- Greater diastolic filling of the heart
- Cardiac muscle stretches
- More force of contraction
- Increased ejection fraction
Mechanisms needed for venous return
- skeletal muscle pump
- gravity
- valves
- smooth muscle
- respiratory pump
What is cardiovascular drift?
Describes the drift effect of cardiovascular responses to sustained steady state exercise (despite intensity not increasing). Occurs after 10 minutes of prolonged exercise in warm conditions
Cardiovascular drift steps
- Athlete will sweat which reduces blood plasma volume
- Reduce venous return
- Due to Starling’s law - stroke volume/ ejection fraction will decrease
- HR will therefore increase
- Cardiac output is maintained as more energy is needed to cool the body
What is arterio-venous difference (A-VO2 diff)
The difference in oxygen content of arterial and venous blood leaving and returning to the heart. —> how much oxygen is extracted by the muscles
A-VO2 diff at REST
small difference due to minimal oxygen being used by muscles
A-VO2 diff durning EXERCISE
High difference as much more of the blood’s oxygen is needed by the muscles.
- more oxygen is extracted by working muscles. venous blood has less oxygen to return to the heart as has been used as energy
A-VO2 in a TRAINING ATHLETE
Will have a greater difference, allowing a greater blood supply to reach the working muscles with improved gaseous exchange. Therefore, utilizing a larger amount of oxygen from blood and remove CO2
Transport of oxygen 3 key terms
- Hemoglobin - iron containing pigment found in RBCs. Combine w/ oxygen to form oxygen-hemaglobin.
- Plasma - the fluid part of blood (mainly water). Transports blood cells.
- Myglobin - iron containing muscle pigment in slow twitch fibers. stores the oxygen in the muscles and has a higher affinity for O2 then hemoglobin
3 factors responsible for the increase in dissociation
- increase blood temp - oxygen will dissociate more readily
- Partial pressure of co2 increase - oxygen dissociates quicker
- pH - drop in pH due to more co2 lowers pH. will cause oxygen to dissociate faster. (Bohr’s shift)
what does the Oxyhaemaglobin curve help with
- Understand hoe hemoglobin in our blood carries and releases oxygen.
- The curve represents the relationship between the two
what does the Oxyhaemaglobin curve tell us
During exercise, S shaped curve shifts to the right because when muscles require more oxygen dissociation from haemaglobin in the blood capillaries to the muscle tissue occurs more steadily. The shift to the right is known as “Bohr’s shift”
