The Cardiovascular system Flashcards
What’s the order of blood flow ?
1) Deoxygenated blood is in the RIGHT ATRIUM
2) Deoxygenated blood enters the RIGHT VENTRICLE
3) Deoxygenated blood is pumped to the lungs via the PULMONARY ARTERY
4) At the lungs gas exchange occurs and the blood becomes oxygenated
5) Then the oxygenated blood travel back to the LEFT ATRIUM via the PULMONARY VEIN
6) Oxygenated blood travels to the LEFT VENTRICLE
7) Oxygenated blood then gets pumped around the body by the AORTA
What are the step of the hearts conduction system?
- the cardiac impulse is initiated by the SA node - this is the hearts pacemaker
- The impulse is passed through the right and left atrium walk to the AV node
- AV node passes the impulse through the “bundle of his” which is in the septum
- The impulse goes from the “bundle of his” to the “bundle branches”
- the Impulse then travels to the ventricles via the “Purkinje fibres” - where both ventricles contract
What 3 nerves are in the NEURAL CONTROL?
• CHEMORECEPTORS = located in the aorta and carotid arteries they inform the CCC of chemical changes e.g. O2/ CO2 levels and changes in the blood pH level
• PROPRIOCEPTORS = located in the muscles, tendons and joints and they inform the CCC of motor activity
• BARORECEPTORS = located in the blood vessel walls and inform the CCC of an increase in blood pressure
What in the HORMONAL CONTROL?
• ADRENALINE and NORADRENALINE are released in the adrenal glands which increase the force of contraction and the spread of activity through the heart
What is in the INTRINSIC CONTROL ?
• THERMAL DETECTORS they detect any temperature change that will affect the viscosity of blood.
• VENOUS RETURN changes will affect the stretch of ventricle walls, force of contractions and also stroke volume
What 2 ways can the CCC respond ?
• If an increase in HR is needed then the Sympathetic nervous system will stimulate the ACCELERATOR NERVE to deliver the message to the SA node.
• If a decrease in HR is needed then the Parasympathetic Nervous System will stimulate the VAGUS NERVE to deliver the message to the SA node.
How does blood circulate through the vessels ?
ARTERIES —> ARTERIOLES —> CAPILLARIES —> VENULES —> VEINS
What is the structure of ARTERIES and ARTERIOLES?
• They both have small lumen
• They both have Thick muscular walls which can withstand high pressure
• Arterioles have Pre-Capillary sphincters
What is the structure of CAPILLARIES
• Large surface area
• One cell thick walls — allows diffusion of gases
What is the structure of VENULES and VEINS?
• Low pressure
• Wide lumen
• Pocket valves to prevent back flow
What’s the structure and function of Pre-capillary Sphincters ?
STRUCTURE:
• Ring of smooth muscle surrounding the entry of a capillary bed
FUNCTION:
• They dilate and constrict the control of the blood flow through the capillary bed
What is Venous Return ?
Venous Return is the transport of blood from the capillary back to the heart through the Venules and Veins via the Superior/Inferior Vena Cava.
What is Starlings Law ?
It’s the law that STROKE VOLUME in dependant on the VENOUS RETURN
• If VR increases SV increases • If VR decreases SV decreases • SV also affects Cardiac Output (Q) so if SV increases so does Q
What are the 5 Mechanisms that help maintain VR?
• POCKET VALVES — one way valves in veins that prevent back flow and helps direct blood to the heart
• MUSCLE PUMP — contraction of muscles and exerts pressure on veins forcing blood to flow towards the heart
• RESPIRATORY PUMP — during expiration and inspiration a pressure difference between the thoracic and abdominal is created which squeezes the blood back to the heart
• SMOOTH MUSCLE — contraction and relaxation of smooth muscle helps push blood through the veins
• GRAVITY — blood from the upper body is aided by gravity
What is Blood Pooling ?
• Blood pooling occurs when venous return is not maintained following exercise and blood collects behind the pocket valves in the veins e.g “Heavy Legs”
