Chapter 5 Heart and monitoring heart function Flashcards
Outline the benefit of a mass transport system
- moves substances around the body quickly
- shortens diffusion distance
Explain why a pumping mechanism required for a mass transport system
due to a higher demand for nutrients and production of waste (due to higher metabolic rate)
State the function of the atrioventricular valves
to prevent backflow of blood into atria from the ventricle during ventricular systole
State the function of the semilunar valves
to prevent blackflow of blood into the ventricles from the arteries during ventricular diastole
Describe the events that occur during atrial systole
- atria contract –> increased pressure
- ventricles in diastole
- AV valves open/semi-lunar valves close
- blood flows from A–>V (70% passive)
Describe the events occur during ventricular systole?
atrial diastole –> decreased pressure
ventricles in systole
AV valves close/semi-lunar valves open
blood flows from V–>arteries
Describe the events occur during total diastole
atrial diastole –> increased pressure
ventricles in diastole
AV valves open/semi-lunar valves close
blood flows passively from vena cave–>A
Explain how is the cardiac cycle controlled
the sinoatrial node (SAN) sends a wave of excitation to both atria –> atrial systole
band of fibrous collagen tissue prevents conduction of wave of excitation
atrioventricular node (AVN) delays w.o.e. and then sends out second w.o.e. from top of ventricular septum down the Bundle of His to the apex and then up the walls
causes upward contractions
Explain why monitoring heart function is so important
to look for heart/vascular diseases
to look for risk factors that contribute to CHD
Define the term stroke volume
the volume of blood pumped out of the left ventricle during the cardiac cycle
60-80cm^3
Define the term cardiac output
the volume of blood pumped out of the left ventricle each minute
State how is cardiac output calculated
stroke volume x heart rate
Describe the term ‘pulse’
the expansion of the artery wall during ventricular systole
during diastole, the elastic recoils
The pulse can be taken at radial, temporal and carotid artery or in the groin (femoral artery)
Explain how age affects the HR
decreases with age
children have faster h.r. due to growth
Exlpain how diet can affect the HR
cholesterol can block coronary arteries
saturated fats increase risk of strokes and heart disease
fruit/veg/starchy foods decrease h.r.
Explain how exercise can affect the HR
during activity + in recovery = exercise increases HR
post activity = exercise increases the strength of cardiac muscle resulting in a decreased HR
Describe how cardiac monitors can be used to analyse heart activity
electrodes placed on skin on opposites sides of the heart
result = electocardiogram
corresponds to electrical activity and pressure
State the key stages of an electrocardiogram
P = atrial excitation from SAN –> atrial systole
QRS = ventricular systole
T = repolarisation of cardiac muscle during diastole
Describe how an electrocardiogram can indicate heart abnormalities
raised ST = heart attack
small P = atrial fibrillation
deep S = ventricular hypertrophy (incr. muscle thickness)
short gaps = tachycardia
long gaps = brachycardia
Define a myocardial infarction?
when the blood supply to cardiac muscle is totally/partially cut off, preventing aerobic respiration in muscle cells
State the symptoms of a myocardial infarction
faint pulse
chest pain
nausea
ashen skin
irregular or rapid pulse
Define a cardiac arrest
When the heart no longer functions usefully as a pump
Describe what is ventricular fibrillation
rapid uncontrolled contraction of the muscles in the ventricles –> no effective movement of the blood
Describe an atheroma
a build of of WBCs that have taken up LDLs and become deposited in the lining of the artery WALLS
deposits cholesterol, dead fibres and muscle cells
restricts blood flow –> myocardial infarction
Explain how high levels of saturated fats lead to coronary heart disease
raises LDL and LDL:HDL ratio
LDLs deposit cholesterol in wall of coronary artery
causing an atheromatous plaque
reduces lumen size which reduces oxygen supply to cardiac muscle
–> coronary thrombosis
–> myocardial infarction
Label the diagram
Label the diagram
Describe the characteristics of cardiac muscle (6 marks)
o Specialised muscle as doesn’t rhythm require nerve stimulation to contract i.e. myogenic
o Muscle contracts in regular rhythm
o Does not fatigue or require rest (unlike skeleatl muscle)
o Specialised striated muscle (fainter striations compared to skeletal muscle)
o Fibres are branched and uninucleated
o Cardiac muscle cells interconnect resulting in simultaneously contraction
o Contraction speed = intermediate [compared to skeletal (rapid) and smooth (slow)]
o Length of contraction = intermediate [compared to skeletal (short) and smooth (long)]
o Cardiomyocytes (cardiac muscle cells) supplied with oxygen & glucose by coronary artery if it becomes blocked -> heart attack
Describe th function of the aorta
Carries oxygenated blood from LV to the body
At high pressure (as it has to force the blood over a large distance hence overall there is a higher resitance within the blood vessels)
Largest artery
Describe the function of the atria
Contract to generate a force to move blood at low pressure into the ventricles
Pressure is low as walls of atria are thin (less cardiac muscle)
LA: forces oxygenated blood into LV (short distance so low pressure)
RA forces deoxygenated blood into RV (short distance so low pressure)
Both atria always contract simultaneously
Describe the function of the ventricles
Contract to generate a force to move blood at high pressure out of the heart
LV: forces oxygenated blood into aorta at high pressure
Pressure is high as LV wall is the thickest (of all 4 chambers) i.e. most cardiac muscle
RV: forces deoxygenated blood into pulmonary artery at lower pressure than LV (if it was the same the pressure would be too high when it reaches the avleoli and would rupture the alveoli)
Both ventricles always contract simultaneously
State the type of valve and the function of the aortic valve
= semi-lunar valve
- found between the LV and the aorta
- prevents backflow of blood from aorta to LV during ventricular diastole
State the type of valve and the function of the pulmonary valve
= semi-lunar valve
* found between the RV and the pulmonary artery
* prevents backflow of blood from pulmonary to RV during ventricular diastole
Name the 2 atrioventricular valves
Bucuspid
Tricuspid
REMEMBER: LAB RAT (LA = bicuspid, RA = tricupsid)
Descirbe the role of the tricuspid valve
- Located between RA and RV
- Prevents backflow of blood from RV to RA during ventricular systole
- Close when pressure of RV > pressure of RA
- Ensures deoxygenated blood flows into pulmonary artery
Describe the role of the bicuspid valve
- Located between LA and LV
- Prevents backflow of blood from LV to LA during ventricular systole
- Close when pressure of LV > pressure of LA
- Ensures oxygenated blood flows into aorta
Describe the role of the septum
Separates RHS from LHS of heart
Keeps oxygenated blood separated from deoxygeanted blood