L25 Cardiovascular and Respiratory Physiology Flashcards
how many loops are in the circulatory system?
2
explain the pulmonary loop function
1) Deoxygenated blood flows from body into right atrium and right ventricle
2) blood is pumped to pulomnary artery to lungs
3) blood becomes oxygenated
4) blood flows into left side of heart
5) systemic cirulation begins - oxygenated blood pumped out of aorta
what is the circulation of blood?
unidirectional
what does the diaphragm do?
separates thoracic cavity form abdominal cavity
what is plasma?
water-like, functions as a solvent
55% water, 45% cellular contents
what is found in plasma?
electrolytes, ions, albumin proteins, immunoglobulins, apoliproteins, fibrinogen clotting proteins, nutrients, hormones
what is the role of albumin proteins?
regulation of osmosis and pH
What is the role of apoliproteins?
to carry lipids
what are red blood cells called?
erthryocytes
what are platelets?
cell fragments from megakaryocytes
how much does the heart weigh?
250-350g
what is the function of atria?
priming pumps that deliver blood through AV valves into ventricles
what does right ventricle do?
pumps blood to pulomary circuit via pulmonary artery
what does left ventricle do?
pumps blood through systemic circuit via aorta
what is the cardiac cycle?
heart beat
what is the systole phase of cardiac cycle?
contraction of heart
what is the diastole phase of cardiac cycle?
relaxation of heart (takes twice aslong)
how long is the average cardiac cycle?
0.8 seconds
how to calculate heart rate when cycle time = 0.8 seconds
60/0.8 = 75 beats per min
what causes lupdup sound from heart?
valve closure
what is cardiac output?
the volume of blood pumped by ventricle each minute
how is cardiac output calculated?
heart rate x stroke volume
70bpm x 70ml/beat = 4900ml
what is our entire blood volume?
5 litres, therefore our blood volume is being pumped around our body twice per minute (2 systems)
why do females have lower cardiac output?
smaller heart size
how does the sympathetic nervous system effect heart?
speeds up heart rate during exercise, increased stroke volume and strength of contraction
how does parasympathetic nervous system effect heart?
it slows down heart rate via SA node
where is SA node located?
right atrium where vena cava empties
what does P wave represent?
artial depolarisation/ systole phase caused by SA electrical excitation
P-R interval represents?
signals/ electrical excitation are delayed at AV node
QRS Complex represents?
signal spreads through ventricles causing depolarisation and contraction - blood pumped through body
T-wave represents?
ventricular repolarisation and relaxation
how do we calculate ECG/heart rate?
R-R interval/60 seconds
what is tachycardia?
constantly high heart rate
what is bradycardia?
constantly slow heart rate
how small are capillaries?
8 microns in diameter
what is haemodynamics?
the movement and flow of blood around circulation how it moves from pulmonary to systemic circuit
what allows the movement of blood?
pressure gradients
what type of relationship occurs between veolcity and surface area?
inverse relationship
what law allows us to breathe?
Boyle’s Law
what is boyle’s law?
at constant temp, pressure and volume are inversely related (when pressure increases, volume decreases)
describe inhalation
1) diaphragm contracts
2) it moves down and lung volume increases
3) pressure in lung decreases below atmp
4) pressure gradient causes inhalation
describe exhalation
1) diaphragm relaxes
2) it moves up, lung volume decreases
3) pressure in lung increases above atmp
4) this pressure gradient causes exhalation
what does spirometry do?
measures lung volumes and capacity FEV1
What is the average tidal volume?
500mls
IRV definition?
forced inhalation volume
ERV definition?
forced exhalation volume
Vital Capacity definiton?
forced inhalation followed by forced exhalation, VC= IRV + ERV + TV(normal)
residual volume definiton?
lungs are never fully empty, over 1L of air left trapped by alveoli
what is a sign of pulmonary disease?
not being able to exhale 80% of vital capacity in the first second FEV1
what is important of carbon dioxide diffusion across capillaries?
they are completely independent of one another
what do gaseous partial pressures depend on?
level of metabolism
where does gas exchange occur?
capillaries
what is the partial pressure of O2 in air?
160mls of mercury, 21% O2 in air = 160mls of mecury in air
what happens partial pressures of CO2 and O2 in alveloi capillaries?
Pp of O2 decreases and Pp of CO2 increases because external air is mixing with internal air composition
how is CO2 transported around the body?
7% via plasma, 93% via globin part of haemoglobin
what controls our drive to breathe?
carbon dixoide
in bodily tissues we have 40mls of mercury haemoglobin, 70% saturation what is it during exercise?
decreases to <20mls Hg, great capacity for O2 delivery
what happens the relationship between haemoglobin and O2 during exercise?
Bohr shift - CO2 produced during exercise, decreases blood pH, decreases affinity of haemoglobin for O2
HOWEVER, lower pH gives O2 greater capacity to be delivered to tissues from haemoglobin
what happens when pH level falls due to increased CO2 during exercise?
cerebrospinal fluid signals medulla causing increased rate and depth of breathing - increasing O2 uptake
how much oxygen do we consume regularly vs exercising?
regularly: 250mls/ excerising males: 3600/4000/5100mls
how is oxygen consumption measured?
VO2 max
what is VO2 max dependent on?
performance of cardiovascular and respiratory system
what is hypoxia?
body senses change in oxygen at around 88mmHg Pp of oxygen at high altitudes
hypertension?
higher than normal blood pressure
