Cardiovascular System Flashcards
What is the anatomy of the respritatory system
- breath air through our nose and mouth/trachea/bronchi/broncioles=alveoli
Airway resistance
- as you go through system the diameter gets smaller and therefore the resistance of airflow increases as it’s harder for air to flow through the system the system overcomes this as the total cross sectional area of the branching increases the overall resistance is decreased.
Quiet inspiration
-increased thorax volume
-diaphragm flattens
-external intercostal muscles contracts
-increased elastic recoil
Quiet expiration
-passive process
-external intercostal muscles relax
-decrease pressure in thoracic cavity
Forced inspiration
- same as quiet but additional muscles used
Contraction of the accessory muscles of breathing
Scalenes – lift the upper ribs
Sternocleidomastoid – elevate the sternum Pectoralis major and minor
Serratus anterior
Latissimus dorsi
Which work to lift up ribs
Forced expiration
Forced Expiration
Contraction of thoracic and abdominal muscles and Internal intercostal muscles
Pulmonary compliance
a measure of the lungs ability to stretch and expand.
Compliance (mL/mmHg) = Volume (mL) /Pressure
(mmHg)
What is pulmonary compliance influenced by
The elasticity of the lungs:
-Due to the presence of elastin and collagen in the connective tissue in the lungs
-by age (gradual loss of elastic tissue with age increases compliance) Impacted by disease
-surface tension :Decreased by the production of surfactant
Mechanisms of breathing
-the lung walls are like a ballon in the when air is let out the rest goes with it so have a tendency to recoil inwards
-the chest walls a tennis ball when air is let out it reforms back to its shape so has a tendency to recoil Outwards
-when the chest moves the lungs go with it
Transpulmonary pressure
- the pressure inside relative to outside of a compartment (the lungs).
-required to inflate the lungs
-Contraction of inspiratory muscles expands the chest wall and increases transpulmonary pressure.
Intrapleural pressure (space between the chest wall and lungs) alveoli pressure before expiration
-intrapleural pressure is negative usually -5
-alveolar pressure is zero which equals atmospheric pressure of zero
Intrapleural pressure and a alveolar pressure during inspiration
-the chest wall expands, putting greater stretch on the lungs and Ppl becomes more negative usually from -5 to -8
- alveoli pressure becomes negative allowing us to pull in air from the atmosphere. Usually from 0 to -1
Surface tension and surfactant in the alveoli
-The walls of the alveoli are lined by a thin film of water.
-This creates a force called surface tension which tends to collapse the alveoli.
- surfactant is naturally produced and costs the alveoli reducing surface tension to prevent the lungs collapsing
Inspiratory reserve volume (IVR)
The additional volume of air that can be inspired at the end of a normal or tidal inspiration
Expiratory reserve volume (ERV)
-The additional volume of air that can be expired at the end of a normal or tidal inspiration
Tidal volume (TV)
-the amount of air breathed in and out during normal,restful breathing
Residual volume (RV)
-the volume remaining in the lung after a maximum expiration
Vital capacity (VC)
-The largest volume of air that can be expired from a maximal inspiration.
VC = ERV + TV + IRV
Inspiratory capacity( IC)
-the maximum volume of air a person can inhale starting from the end of a normal tidal expiration
IC = IRV + TV
Functional residual capacity (FRC)
The volume of air remaining in the lungs after a normal or tidal expiration.
FRC = RV + ERV
Total Lung capacity (TLC)
The maximum volume of air that the respiratory system can hold.
TLC = VC + RV
What can we interpret from spirometry results
-Forced vital capacity (FVC) is the total (maximal)
volume of air that can be breathed out of the lungs with maximum effort in one breath
-Forced expiratory volume (FEV1) is a measure of how much of this air is breathed out in the first
second.
-they use a predicted value of this based on age weights etc… and actual values need to be a %greater than this for them to be healthy usually 80%
Partial pressure
- important in predicting movement of gas or changes in different parts of the lungs
-air moves from high partial pressure to low partial pressures
Obstructive lung disease: Asthma
-Inflammation of the trachea, bronchi and terminal bronchioles
-Increased thickness of airway smooth muscle
-increased mucus secretion therefore increase in air resistance in the airways
Restrictive lung disorders: Pneumothorax
-Characterised by a loss in lung volume
-Air enters the pleural space from outside of the chest and
migrates from the environment to to the pleural cavity until an equilibrium in pressure is reached
-therefore lack of pressure change means the lungs cannot expand and so the lung is compressed
Diagnosing pulmonary diseases using spirometer
results
-Obstructive Lung Diseases: Decreased FVC, significantly reduced FEV₁, and a decreased FEV₁/FVC ratio.
-Restrictive Lung Diseases: Decreased FVC, reduced or normal FEV₁, and a normal or increased FEV₁/FVC ratio.
The cardiovascular system
-consists of the heart and blood vessels ( Arteries, and arterioles ,Veins and Venules, Capillaries)
Pulmonary circulation
Deoxygenated blood circulates into the pulmonary artery to the lungs to become oxygenated and transported back to the heart.
Systemic circulation
Oxygenated blood from the heart circulates through the arteries around the body to the tissues and then back to the heart.
The capillaries
-thin layer of endothelial cells for gas exchange
-has collagen and Lamin for strength
-pressure in the capillaries is reduced and cross-sectional area increases because of branching which reduces air flow for gas exchange
Transport of oxygen and carbon dioxide
- 98% of oxygen=Hb and 2% dissolved in plasma
-10% of CO2 in plasma and 80% bicarbonate. HCO3-
Factors affecting Hb saturation
-pH/CO2
-Temperature
-2,3 – diphosphoglycerate (DPG)
-lower the partial pressure easier for O2 to dissociate
Describe the cardiac cycle
Blood enters the atria via the vena cava and pulmonary vein
-At atrial systole the atria contracts which decreases their volume and increase their pressure pushing blood into the ventricles through the mitral value
the atria relaxes(diastole). The ventricular systole occurs decreasing their volume and their pressure becomes higher than in the artful so the mitral values shut and the aortic value open
blood is forced out into the pulmonary artery and aorta
when both atria and ventricles are in diastole the aortic value close
Aortic root velocity graph explanation
-increase when blood from the left ventricle is emptied into the aorta and decrease when the blood is transported around the volume decreasing the volume
Spread of electrical activity in the heart
-Sino-atrial node initiates a wave of excitation
-wave spreads over atrial walls
-this causes the atria to contract
the contaction is synchronised
-The wave of ecitation passes to the atrio-ventricular node which causes a delay to ensure the atria is fully emptied
-excitation spreads down the Bundle of is to the purkyne tissues surrounding the ventricle walls
-this causes the ventricles to contract
ECG Graph
P wace, QRS complex, T wave
-p=atrial contraction
-QRS-ventricular contraction
-T=ventricular diastole
Arterial blood pressure
- consist of systole BP and Diastole BP
-Systolic BP occurs during ventricular contractions and increases substantially with exercise.
-Diastolic BP represents arterial pressure between contractions.
Cardiac output
- the amount of blood pumped by the heart minute (litres/min)
- = heart rate x stroke volume
Stroke volume
the amount of blood pumped out of the heart after one contraction
Factors affecting blood pressure
-Cardiac output – a higher cardiac output increases the volume of blood in the vessels and increases pressure in the vessels.
- total peripheral resistance – increased resistance and blood pressure occurs if there is a decrease in the diameter of the blood vessels.
-Blood viscosity – more viscous blood offers more resistance to flow resulting in an increase in blood pressure.
Mean arterial blood pressure
Cardiac output x total peripheral resistance
Autonomic control of the respiratory system
- impulses are sent from the respiratory control centre
-impulses go from the intercostal nerves to external intercostal muscles
-from the phrenic nerve to the diaphragm
Central chemoreceptors
-Located in the brainstem and medulla
Sense increases in PCO2
Slowly detect decreases in arterial pH
Peripheral chemoreceptors
-Located in:
1) the carotid bodies in the neck
2) aortic bodies in the thorax
Primarily sensitive to decreases in arterial PO2 Can be stimulated by high PCO2 and low pH
Effects of exersize on Hb curve
Exercise causes a rightward shift in Hb saturation
Increased body temperature
Increased pCO2
Reduced pH
Increased oxygen availability to the muscles
