Cardiovascular system Flashcards
What are the two circuits that blood flows?
- pulmonary circuit and systemic circuit
What does the pulmonary circuit do?
carries deoxygenated blood to the lungs and oxygenated blood back to the heart
What does the systemic circuit do?
carried oxygenated blood to the body and deoxygenated blood back to the heart
Where is the heart positioned?
behind sternum and ribs for protection
Explain the left side of the cardiac muscle?
has thicker muscular wall which can contract with more force to circulate oxygenated blood from the lungs through the large systemic circuit to the muscles and organs
Explain the right side of the cardiac muscle?
contracts to circulate deoxygenated blood from the body through the pulmonary circuit to the lungs
What lies between the atria and ventricles?
atrio-ventricular valves
What lies between the ventricles and exiting blood vessels ?
lemi- lunar valves
Explain the path of blood through the left side of heart?
- blood is oxygenated at the lungs
- through pulmonary vein
- into left atria
- oxygenated blood through left bicuspid AV valve
- into left ventricle
- forced out of left side into aorta
- then to muscles and organs
Explain path of blood through right side of heart?
- deoxygenated blood from muscles and organs arrives through right atria through vena cava
- right atria to right AV valve (tricuspid) to right ventricle
- forced out right side of heart into pulmonary artery
- carries deoxygenated blood to lungs
What is the cardiac muscle?
myogenic
WHat does myogenic mean?
- has capacity to generate its own electrical impulses that through muscular walls forcing contraction
What is the conduction system?
set of five structures which pass the electrical impulse through the cardiac muscle in a coordianted fashion?
What are the five parts of the conduction system?
- sino- atrial node
- atrio- ventricular node
- bundle of His
- Bundle branches
- Purkyne Fibres
What is the sino atrial node?
- located on right atrial wall
- SA node generates the electrical impulse that fires through the atria walls causing them to contract
What is the atrioventricular node?
- collects impulses and delays it for 0.1 seconds to allow atria to finish contracting
- releases to bundle of His
What is the bundle of His?
- located in the Septum of heart
- splits impulses in two ready to be disturbed through each seperate ventricle
What are the bundle branches?
carry the impulse to base of each ventricle
What are the purkyne fibres?
- distribute the impulse through ventricle walls, causing them to contract
What happens when the electrical imoulses journey is complete?
atria and ventricles relax and heart refills with blood
What is the cardiac cycle?
refers to process of cardiac muscle contraction and movement of blood through its chambers
What are the two phases of the cardiac cycle?
- cardiac diastole and cardiac systole
What is cardiac diastole?
relaxation of the cardiac muscle, firstly of the atria then the ventricles
What is cardiac systole?
contraction of the cardiac muscle, firstly atria then ventricles
Explain diastole?
- atria and then ventricles relax, expanding drawing blood in atria
- pressure in atria increase opening AV valve
- blood passively enters ventricles
- SL valves are closed to prevent blood from leaving heart
Explain atrial systole?
- atria contract, forcing remaining blood into ventricles
Explain ventricular systole?
- ventricles contract, increasing pressure closing Av valves to prevent backflow in atria
- SL valves are forced open as blood is ejected from the ventricles into aorta and pulmonary artery
What is heart rate?
the number of times the heart beats per minute
WHat is stroke volume?
the volume of blood ejected from the left ventricle per beat
What is cardiac output?
the volume of blood ejected from the left ventricle per minute
What is bradycardia?
a resting heart rate below 60 bpm
Cardiac output formula?
heart rate x stroke volume
What is venous return?
the return of blood to the right atria through the veins
What are the two types of exercise?
- sub maximal
- maximal
What is sub- maximal?
exercise is at a low- to moderate intensity within a performers aerobic capacity or below the anaerobic threshold
What is maximal exercise?
exercise is a t a high intensity above a performers aerobic capacity, which will take performer to exhaustion
What is the vascular system?
dense network of blood vessels and the blood which they carry in one direction around every corner of the human body. ensures oxygen and nutrients are delivered to all respiring cells
What does the blood function to do?
- transport nutrients such as oxygen and glucose
- protect and fight disease
- maintain the internal stability of the body
What are the three types of blood vessels?
- arteries
- veins
- capillaries
What do arteries and arterials do?
transport oxygenated blood from the heart to muscles and organs
Explain characteristics of arteries?
- large layer of smooth muscle
- elastic tissue to cushion and smooth blood
- small lumen
Explain arteriols?
- large layer of smooth muscle allow blood vessels to vasodilate and vasoconstrict to regulate blood flow and control blood pressure
What are pre capillary sphincters?
- ring of smooth muscle surrounding the entry of capillary bed.
- they dilate and constrict to control blood flow through capillary bed
What are capillaries?
brign blood slowly into close contact with the muscles and organ cells for gaseous exchange
Explain characteristics of capillaries?
- walls have a single layer, thin enough to allow gas, nutrient and waste exchange
What do veins and venuoles do?
transport deoxygenated blood from the muscles and organs back to the heart.
What is the main vein?
vena cava
Characteristics of veins and venuls?
- small layer of smooth muscle allowing them to venodilate and venoconstrict to maintain the slow flow of blood towards the heart
What is venous return?
return of blood to the heart through the venules and veins back to the right atrium, largely against gravity
Why is a greater venous return needed during excersise?
there is a greater demand for oxygen so more oxygenated blood requires greater venous return so that stroke volume and cardiac output can increase.
What are the five mechanisms that aid venous return?
- pocket valves
- smooth muscle
- gravity
- muscle pump
- respiratory pump
How do pocket valves aid venous return?
- valves prevent backflow of blood
How does smooth muscle aid venous return?
- layer of smooth muscle in vein wall venoconstricts to create venomotor tone which aids movement of blood
How does gravity aid venous return?
blood from upper body, above heart, helped to return by gravity
How is muscle pump an aid in venous return?
during exercise, skeletel muscle contract compressing veins located between them, squeezing blood back to heart
How does the respiratory pump aid venous return?
- during inspiration and expiration, pressure differnace between thoracic and abdominal cavity is created, squeezing blood back to heart
How does a cool down help recovary?
- low intensity exercise maintains muscle and respiratory pump to aid the return of blood to the heart
what happens to heart rate during submaximal exercise?
- heart rate can plateau as we reach confortable steady state
Explain heartrate response to increasing exercise intensity?
- initial rise in HR, due to release of adrenaline hormone
- rapid increase in HR at start of exercise due to increased blood flow and oxygen delivery
- steady HR sustained during intensity as oxygen meets demand
- initial rapid decrease in HR as recovery is entered and action of muscle pump reduces
- more gradual decrease in HR to rest
How is stroke volume able to increase during exercise ?
- increased venous return
- Frank Sterling mechanism
What is frank sterling mechanism?
- increased venous return leads to an increased stroke volume, due to increased stretch of of the ventricle walls and therefore force of contraction
Why does stroke volume reach a plateau during sub- maximal exercise?
- increased heart rate towards maximal intensities does not allow enough time for the ventricles to completely fill with blood in the diastole phases
WHat system involuntarily regulates heart rate ?
autonomic nervous system
The higher the firing rate of the SA node, the higher the …
heart rate
What is the cardiac control centre?
a control centre in the medulla oblongata responsible for HR regulation
What is the main role of the CCC?
receives information from the sensory nerved and sends direction through motor nerves to change HR
What are the three control mechanisms of the CCC?
- neural control
- intrinsic control
- hormonal control
What controls the involuntary heart rate ?
automatic nervous system
What is cardiac output at rest?
approximately 5 l/min
What does the ANS control?
heart rate and firing rate of SA node.
Explain how changes to the heart rate happens?
- medulla oblongata in the brain, cardiac control center recieves information from the sensory nerves and sends direction through motor nerves to change HR
What three main sources of information detrrmine the action of the CC
- neural control
- intrinsic control
- hormonal control
what is neural control?
- chemoreceptors in muscles, aorta and carotid arteries inform the CCC of chemcial changes in the blood stream, eg CO2 and lactic acid
- proprioceptors in muscles, tendons and joints inform the CCC or motor activity
- baroreceptors located in blood vessel walls inform CCC of increased blood pressure
What is intrinsic control?
- temperature changes will effect viscosity of blood and speed of nerve impulse transmission
- venous return changes will effect stretch in ventricle walls, force of ventricular contraction and therefore stroke volume
what is hormonal control?
adrenaline and noradrenaline are released from adrenal gland increasing force of ventricular contraction, increasing spread of electrical activity through the heart
What will happen if there is an increase in HR required?
sympathetic nervous system is actioned, releasing adrenaline, noradrenaline and sending stimulation to the SA node via the accelorater nerve.
What will happen if there is a decrease in HR required?
the parasympathetic nervous system is actioned to inhibit these effects via the vagus nerve, lowering heart rate
What are chemoreceptors? (general)
detect change in chemicals
What do baroreceptors detect?
blood pressure
What do proprioceptors detect?
-muscle movement
DONE UP TO PAGE 40
done up to page 48 (or 40)
What does the vasomotor control center do?
in the brain and controls the vascular shunt mechanism
