Chapter 4 Flashcards
What are the 4 chambers of the heart and where are they located?
Two atria at the top, two ventricles at the bottom
What are the 3 layers of the heart?
Pericardium, myocardium, endocardium
Where is the bicuspid valve located?
Between left atrium and left ventricle
Where is tricuspid valve located?
Between right atrium and right ventricle
What is the role of the semi lunar valves?
Preventing backflow of blood into the heart from the pulmonary artery and aorta, and to only allow blood to flow in one direction through the heart
Where are the venae Cavae and pulmonary artery located on the heart?
Right side
Where the pulmonary veins and aorta located on the heart?
Left side
Describe how a cardiac contraction is initiated
Impulse from SA node travels down atrial mycardium until it reaches AV node in wall of atrial septum. Atrial walls then contract. AV node then conducts impulse through bundle of his to Purkinje fibres which cause both ventricles to contract
What is diastole?
Relaxed heart muscle allows chambers to fill with blood. Cuspid valves open, semilunar closed.
Describe the 2 types of systole
Atrial systole, SA node impulse causes atria to force blood past cuspid valves into the ventricles, semilunar closed.
Ventricular systole, impulse reaches AV node, cuspid valves close, semilunar open, blood pushed out into pulmonary artery
Give formular for MHR
220-age
Describe the HR responses to exercise
Anticipatory rise due to adrenaline
Sharp rise in initial anaerobic work due to proprioreceptor stimulation
Steady state and recovery of o debt
Continued high hr due to maximal workloads
Rapid recovery due to cessation of proprioreceptive stimuli
Slow recovery as metabolite are cleared
Describe the SV responses to exercise
Anticipatory rise due to adrenaline
Increase as exercise commences, due to increased venous return and increased myocardial contraction
As intensity increases SV may drop slightly, but an increase in hr will correct this and level it out
List the 3 neural control factors
Chemoreceptor reflexes
Baroreceptor reflexes
Proprioceptor reflexes
What are Chemoreceptor reflexes?
Receptors in blood vessels which detect chemical changes in blood
What are proprioceptor reflexes?
Found in muscle spindles, respond to mechanical stimuli
What are baroreceptor reflexes?
Receptors in blood vessels detect changes in blood pressure
What are the hormonal factors affecting hr? Describe their effect
Noradrenaline and adrenaline accelerate hr and increase strength of ventricular contraction
Acetylcholine slows hr
Thyroid and glucagon increase hr
Increased glucagon levels assist breakdown of glycogen to make glucose to fuel muscular contractions
What are the intrinsic factors affecting venous return
Myocardial temperature, which affects the speed of impulse transmission and hence heart rate
Define venous return
The volume of blood returning to the heart during each cardiac cycle
What is the sympathetic influence on the heart rate?
SNS releases adrenaline and noradrenaline onto sa node to speed up hr
What is the parasympathetic influence on hr?
PNS releases acetylcholine on SA node to slow HR
What are the long term adaptations of the heart to aerobic exercise?
Hypertrophy, which increases SV
Bradycardia
HR will decline much faster than for an untrained person after exercise
What is he venous return mechanism?
The process by which blood returns back to the heart