Lecture 7 - Cardiovascular System Flashcards
What is the distribution of blood in the circulatory system?
Arteries (largest) –> arterioles –> capillaries –> venules –> veins
What system contains the most amount of blood?
The venous system (veins and venules)
What does the venous system function as?
A reservoir in which more blood can be added to the circulation under appropriate conditions such as exercise
What type of blood does your arteries carry?
Oxygenated Blood
What type of blood does your veins carry?
Deoyygenated Blood
Why from your artery to your capillaries does size decrease?
Decrease in pressure as you go away from the heart
What does the Venous System contain?
Most of the Blood Volume
What do Arteries provide?
Resistance to the flow of blood from the heart
What are veins able to do?
Expand, to allow for more blood to accumulate
What is the average pressure in the capillary?
2 mmHg
What is the average pressure in the artery?
100 mmHg
What is the Venous pressure?
Too low to return blood to the heart
What helps the lower limb veins return blood to the heart?
The skeletal muscle “pump
What does the skeletal muscle pump do?
Provides contractions so the veins of the lower limbs move blood back
What helps the veins from the abdominal and thoracic regions move blood to the heart?
The act of breathing and contraction/pressure of the diagram and abdomen helps the blood return to the heart
What are there in the aorta and the arteries?
Elastin between the smooth muscle cells of the tunica media.
When do these large elastic arteries expand?
When the pressure of the blood rises as a result of the ventricles contractions
What happens during relaxation of the Ventricles?
They recoil like a stretched rubber band when the pressure drops
What does the elastic recoil drive?
Blood during the diastolic phase when the heart is resting and pressure drops.
What is systolic blood pressure?
The pressure in your arteries when your heart contracts
What does vasoconstriction do?
Decrease blood flow to the capillary bed
What does vasodilation do?
Increase blood flow to capillary bed
What are the walls of the capillaries composed of?
Just one cell layer
What do the capillaries lack?
CT and MS which makes it easier to exchange materials between blood and tissue
What happens at the arteriole end of a capillary?
Blood pressure forces fluid out of the capillary to the fluid surrounding tissue cells
What happens at the venous end of the capillary?
Fluid is drawn back into the capillary by osmotic pressure
What is the major air passageway?
Nasal Cavity
What are the steps of the air passageway ?
Nasal Cavity –> Oral Cavity –> Pharynx –> Larnyx —> Trachea (entering lungs) —> Brinchea (divides into two longs) —> Lungs
What does the Nasal Cavity lead into?
The pharynx (back of throat) to connect the nasal cavity to the larynx
What happens in the larynx?
Air is going towards the lungs and food is going towards the esophagus
What does the larynx contain?
The “vocal chords” - folds in the lining tissue
What are the capillary beds responsible for?
Gas exchange
What is there to note about the pulmonary vein?
It is the only vein that carries oxygenated blood (travelling to heart)
What is there to note about the pulmonary artery?
Only artery that carries deoxygenated blood (travels away from heart)
What does the Vena Cava do?
Carries deoxygenated blood to the hearts right atrium
Where is the Resipirtory Zone?
Respiratory Bronchioles that consist of the Alveolus
What are the physical properties of the Lungs (1)?
Inspiration and Compliance (breathing in)
What happens when you breath in?
Chest expand, and your diagram contracts
What must happen in your lungs for respiration to occur?
Have compliance (ability to expand when stretched)
What is Lung Compliance
The change in lung volume per change in transpulmonary pressure = dV/dP
What will there be at any given transpulmonary pressure?
Greater or lesser expansion, depending on the compliance of the lungs
What does lung disease do?
Reduce compliance
What are the physical properties of the lungs (2)?
Expiration and Elasticity
What happens when you breath out?
Chest contract, diaphragm relaxes
For expiration to occur, what must happen?
The lungs must have elasticity
What is elasticity?
The tendency for a structure to return to its original size
What do the lungs contain high contents of?
Elastic proteins
What are the lungs always in a state of?
Elastic tension as they are stuck to the cell wall
What happens to this elastic tension?
Increase during inspiration where the lungs stretch and is reduced by elastic recoil during expiration
When can the lungs inflate?
Only when they are attached to the inner wall of the chest
What happens to a person who has wounded chest?
They cannot inflate the lung on the wounded side, even though they can’t ventilate
What is the pleural membranes?
The attachment of the outer lung surface to the inner surface of the chest cavity
What are the layers of the PM?
One PM layer is attached to the surface of the lungs while the other layer is attached to the inner wall of the chest cavity
What do the PMs do?
Produce a mucous-rich lubricating fluid (pleural fluid) into the pleural space
What does the plural fluid do?
Holds the two pleural membranes together (holds the lungs attached to the inner wall of the thoracic cavity)
What is another function of the pleural fluid?
Makes the lungs slide easier in the thoracic cavity
What is the 3rd Physical Property of the Lungs?
Surface Tension
What is Surface tension exerted from?
Fluid in the Alveoli
What does the fluid contain?
Surfactant
What is Surfactant?
A mixture of hydrophobic and hydrophilic proteins secreted into the alveoli by type II alveolar cells
What does surfactant do?
Lower surface tension to prevent the alveoli from collapsing during expiration
What do Alveoli’s have the tendency to do?
Collapse
What does surfactant do?
Prevents the alveolis from collapsing
When is surfactant produced in fetal life?
Later on
What happens with pre-mature babies?
Surfactant does not get produced in time and their alveoli collapses as a result
What is Tidal Volume?
Volume of Gas, inspired or expired, in an unforced respiratory cycle (not thinking about it)
What is a typical Tidal Volume?
Around 500m/s
What is your Inspiratory Volume?
Max. volume of gas that can be inspired during forced breathing in addition to tidal volume
What is your Expiratory Volume?
Max volume of gas that can be expired during forced breathing in addition to tidal volume
What is Residual Volume?
Max volume of gas remaining in your lungs after max expiration (expiratory volume)
What is your Anatomical Dead Space?
Dead Volume - where no gas exchange occurs
Where does no gas exchange occur?
Nose, mouth, larynx, trachea, bronchi, bronchioles
What is the 4th Physical property of the lungs?
Lung capacities and volumes
What is the percentage of fresh air if the anatomical dead space is 150m/s and the tidal volume is 500m/s?
500 - 150 = 350
350/500 x 100% = 70%
What is Hemoglobin?
Contains Fe and is present in Red Blood Cells
What can hemoglobin do?
Combine with O2 and release it when needed
What can hemoglobin act as?
O2 shuttle from lungs to body tissue
What happens in the lungs?
CO2 diffuses from the blood into the alveoli causing blood CO2 levels to be low and reducing the acidity in the lungs (higher pH)
What happens in the tissue?
Blood CO2 levels are high (excreting it) and O2 levels are low (using it) which causes the pH in the tissues to be more acidic
What does the acidity of the plasma determine?
Whether hemoglobin will combine with O2 to form oxyhemoglobin (low acidity/higher pH in lungs) or if O2 will be released from oxyhemoglobin (higher acidity/lower pH in tissues)
What is another shuttler of hemoglobin?
It can bind CO2 and act as a shuttle from body tissues to lungs (reverse as O2 shuttle)
What happens in the lungs?
O2 is entering the blood and CO2 is leaving the blood
What is the pathway of the O2 entering the blood?
O2 dissolves in the lining fluid film of the alveoli, diffuses through the walls of the alveoli and blood capillaries into the plasma, then it diffuses Ito RBCS
What happens when O2 diffuses into RBCs?
It combines chemically with Hb to form oxyhemoglobin
Where does oxyhemoglobin formation occur?
In the lungs as blood CO2 levels are low
What happens in the body tissues?
O2 is being used by the cells and CO2 is being produced
What is O2 released from?
Oxyhemoglobin and diffuses into body tissues
