cardiovascular / cardiorespiratory system Flashcards
what are the 2 sides of the circulatory system
arteriole - carries blood away from the heart
venule - returns blood to the heart
- capillaries connect the 2 sides to exchange materials between blood and tissues
layers of the blood vessels
- outer = tuneca externa: connective tissue
- middle = tuneca media: smooth muscle
- inner = tuneca interna: has its own 3 layers… endothelium, elastin, glycoproteins
characteristics of veins
- most blood volume is held in the veins
- returns blood from tissues to the heart
- capacitance vessels - able to expand as they accumulate additional amounts of blood
- less muscular than arteries
- average pressure in veins is 2mmHg
what to venous valves do
ensure one-way flow of blood back to the heart
what does the skeletal muscle pump do for the venous system
helps veins of the lower limbs return blood to the heart - veins pass between skeletal muscle groups which provide contractions to help move blood back
how does venous blood from the abdominal regions get to thoracic regions
- facilitated by breathing
- contraction of the diaphragm and pressure in the abdomen from breathing squeezes the veins and helps blood return to the heart
what are varicose veins
when there is dysfunction of one way valves, more blood coagulates in the lower limbs
- blood pooling forms risk of clot formation which can lead to DVT - can’t deliver nutrients therefore get death of tissue
characteristics of arteries
- brings blood from the heart to tissues
- have numerous layers of elastin fibres between the smooth muscle cells of the tunica media
- expand when the pressure of blood rises as a result of ventricle contraction
elasticity of arteries
- arteries recoil like a rubber band when BP falls during relaxation of the ventricles
- the elastic recoil drives blood during the diastolic phase when the heart is resting and not providing pressure
- small arteries and arterioles are less elastic than large ones therefore their diameter only changes slightly
systolic pressure vs diastolic pressure
systolic: maximum pressure the heart exerts while beating (expanded)
diastolic: the amount of pressure in the arterioles between beats (relaxed)
vasoconstriction vs vasodilation
vasoconstriction: narrowing of blood vessels, decrease blood flow to capillary bed
vasodilation: widening of blood vessels, increases blood flow to capillary bed
walls of the capillary bed
- composed of a single layer of endothelial cells
- lack smooth muscle and connective tissue which make it easier to exchange material between blood and tissues
what keeps distribution of materials at capillary beds in a constant state of dynamic equilibrium
net filtration pressure at the artery end (difference in hydrostatic pressure) and net oncotic pressure at the vein end (difference in osmotic pressure)
exchange of nutrients at the capillary bed
at the arterial end of the capillary oxygen, nutrients, hormones etc. are brought to the capillary
- blood pressure forces fluid out of the capillary to the fluid surrounding tissue cells
at the venous end of the capillary carbon dioxide and wastes are removed from the capillary
- fluid is drawn back into the capillary by osmotic pressure
blood flow equations
flow = driving force/resistance
- the main driving force of blood flow is the pressure difference
- doesn’t deliver blood equally to tissues
poiseulle’s law
resistance depends on 3 major factors
1. tube/blood vessel radius
2. viscosity of the blood
3. tube/blood vessel length
how does vessel radius effect blood flow
decrease radius = increase resistance = decrease blood flow
- variable with the most impact on resistance
- regulated by smooth muscle contraction
how does blood viscosity effect blood flow
more viscous = more friction = more resistance = decrease blood flow
- “thickness of blood”
- won’t change in healthy people (unless dehydrated then more viscous)
what happens to blood viscosity if there is a blood clot
increase hematocrit = increase interactions between RBC = INCREASE CLOTS = decrease vessels radius = decrease blood flow
how does vessel length effect blood flow
increase length = increase friction = increase resistance = decrease blood flow
- length doesn’t change physiologically
pulmonary vein and pulmonary artery
have opposite O2 statuses than normal veins and arteries
- pulmonary vein carries oxygenated blood TO heart
- pulmonary artery carries deoxygenated blood AWAY from heart
what are the air passage ways of the body
- nasal cavity
- pharynx
- larynx
- oral cavity
- trachea
- bronchus
- lungs
they pharynx and larynx
- the nasal cavity leads to the pharynx (throat)
- the pharynx is a muscular passage connecting the nasal cavity with the larynx
- the larynx is where air is diverted toward the lungs and food towards the esophagus
- the larynx also contains vocal cords (which are not actually cords by folds in the lining tissue of the larynx)
conducting zone and respiratory zone of the respiratory system
conducting zone: trachea, primary bronchus, terminal bronchioles
respiratory zone: terminal bronchiole, respiratory bronchioles and alveolar sacs
- gas exchange occurs at the respiratory bronchioles
- alveoli are air sacks that increase SA in the lungs to use for gas exchange
- the trachea warms and humidifies air
What are the physical properties of the lungs
- inspiration and compliance
- expiration and elasticity
- surface tension
- lunch volumes and capacities
what is lung compliance
compliance affects the ability of the lungs to expand during inspiration
- change in volume per change in trans pulmonary pressure
- lung disease reduces compliance - anything that produces a resistance to distension
what is intrapulmonary pressure
pressure in the alveoli and airways of the lungs
what is inspiration
breathing in (inhaling) - chest expands and diaphragm contracts
- for inspiration to occur, the lungs must be able to expand when stretched (must have high compliance)
what is expiration
breathing out (exhaling) - chest contracts and diaphragm expands
- for expiration to occur, the lungs must get smaller when tension is released (have elasticity)
what is lung elasticity
- the tendency of a structure to return to its initial size after being distended
- the lungs have a high content of elastin protein therefore are very elastic and resist distension
- lungs are always in a state of elastic tension because they are normally stuck to the chest wall
- tension is released by elastic recoil when
lungs need to be attached to the inner wall of the chest cavity to inflate
- chest wounds prevent inflation, even if the individual continues to ventilate
- there will be movement of air but not of the lungs
what can cause a lung to collapse
Pneumothorax
air enters the pleural space - increase in intrapleural pressure - trans pulmonary pressure is abolished
what keeps the lungs against the chest wall
intrapulmonary pressure > intrapleural pressure
(pressure inside > pressure outside)
what are pleural membranes
make up the outer lung surface and inner surface of the chest cavity
- visceral layer = attached to outside of lung
- parietal layer = attached to inside of chest
what is pleural fluid
- a mucus-rich fluid produced by the PMs that lies between the 2 membranes
- hold the 2 membranes together - holds lungs attached to the inner wall of the thoracic cavity
- acts as a lubricant that allows the lungs to slide easily as they inflate and deflate
what causes surface tension of the lungs
- exerted by fluid in the alveoli
- created by attraction between water molecules in the fluid which pulls them tightly together
- surface tension would cause the alveoli to collapse
what is sufficant
a mixture of phospholipids and hydrophobic sufficant proteins, secreted into the alveoli by type II alveolar cells
- lowers surface tension in alveoli - prevents them from collapsing during expiration
surfactant and babies
- surfactant is produced in late fetal life, premature babies sometimes lack surfactant and their alveoli are collapsed as a result
what are the 4 types of lung volumes
tidal volume, inspiratory reserve, expiratory reserve, residual volume
what are the 4 types of lung capacities
total lung capacity, vital capacity, inspiratory capacity, functional residual capacity
tidal volume
volume of gas inspired or expired in an unforced respiratory cycle
- increase in tidal volume = increase in fresh air = increase in O2
inspiratory reserve
max volume of gas that can be inspired during forced breathing in ADDITION to tidal volume
expiratory reserve
max volume of gas that can be expired during forced breathing in ADDITION to tidal volume
residual volume
volume of gas remaining in the lungs after max expiration
total lung capacity
total amount of gas in the lungs after max inspiration
vital capacity
max amount of gas expired after max inspiration
inspiratory capacity
max amount of gas that can be inspired after normal tidal expiration