lecture four: cardiopulmonary system Flashcards
components of the cardiovascular system
heart, vasculature, blood
functions of the cardiovascular system
- delivers oxygen and nutrients to cells and organs in the body
- transports hormones to target cells
- removes metabolic waste (i.e. carbon dioxide)
- protects body against disease through circulation of WBCs, antibodies, and complement cells
- regulates body temp
main function of the heart
to pump blood to the body!
vasculature of the cardiovascular system
- closed network of vessels that transports blood throughout the body
- three types of vessels
- arteries: transport blood away from the heart
- veins: transport blood toward the heart
- capillaries: connection between arteries and veins to allow for exchange of oxygen, nutrients, and waste
cycle of blood flow
deoxygenated blood from body travels into R atrium —> through tricuspid valve to R ventricle —> through pulmonary artery to lungs —> oxygenated blood through pulmonary vein to L atrium —> through mitral valve into L ventricle —> through aorta out to body
when does vasculature development begin?
begins 3-4 weeks after conception
vasculogenesis
- formation of arteries and veins
- mesodermal cells differentiate into vessels
- occurs ONLY during embryonic development
angiogenesis
- formation of vascular branches from existing blood vessels
- occurs during embryonic development AND throughout life (i.e. during healing)
vasculature anatomy
- 3 blood vessel layers
- tunica externa (adventitia): outer connective tissue layer
- tunica media: middle smooth muscle layer
- tunica intima: inner endothelial layer
large elastic arteries
- i.e. aorta, left common carotid artery
- located in tunica media
- contain elastic fibers to allow for expansion and recoil
- maintains constant flow of blood during diastole
medium muscular arteries
- i.e. femoral artery, axillary artery
- located in tunica media
- contains smooth muscle fibers to allow for regulation of diameter and control of blood flow to different parts of the body
small arteries and arterioles
- controls filling of capillaries
what are the three classes of veins?
large veins, medium/small veins, and venules
distinguishing features of veins
- larger and more compliant than arteries
- thin walls (especially the tunica media)
- large lumens (larger blood reservoir)
- one way valves present
- typically located in veins inferior to heart
- facilitate blood flow toward heart
- affected by autonomic nervous system and skeletal muscle pump
autonomic nervous system regulates ______ and _______
BP and peripheral vascular resistance
sympathetic nervous system
increase HR and cause vasoconstriction
parasympathetic nervous system
decrease HR and cause vasodilation
baroreceptors
- located in aorta and carotid sinus
- detect changes in BP
chemoreceptors
- located in aorta and carotid bodies
- detect changes in pH and O2
the heart develops approximately _______ after conception
3 weeks
(recognizable structure after 20 days - heart tube that begins to elongate)
circulation begins at approximately _________ (rhythmic pulsations of primitive heart tube)
- 4 weeks gestation
- week 3: heart and vessels develop
- week 4: heart begins to beat and pump blood
- week 7: heart forms into a 4 chamber structure
shunting systems
- small passages for blood to travel through in order to bypass body parts that are not yet developed
- foramen ovale
- R atrium —> L atrium
- ductus arteriosus
- R pulmonary artery —> aorta
- ductus venous
- inferior vena cava —> umbilical vein
- foramen ovale
neonatal circulation development
- shunting systems close and form new structures
- foramen ovale —> fossa ovalis
- ductus arteriosus —> ligaments arteriosum
- umbilical vein —> ligamentum teres
- ductus venous —> ligamentum venosum
- umbilical arteries —> lateral umbilical ligaments
*watch videos from slide!
congenital heart disease
- 1% of live births have congenital heart disease
- leading non-infectious cause of death in first year of life
- embryonic heart development
cardiovascular development (infancy and childhood part one)
- left side of heart becomes predominant (left ventricular wall becomes twice as thick by adulthood)
- heart is initially oriented horizontally —> changes to vertical orientation with lung expansion and growth
- heart size increases at similar rate as body weight increase
heart volume in infancy and childhood
- 40 mL at birth —> 80 mL at 6 months —> 160 mL at age 2
- ratio of heart volume to body weight remains constant = 10 mL/kg of body weight
cardiovascular development (infancy and childhood part two)
- changes in myocytes (cardiac muscle fibers)
- increase in
- cross-sectional area of muscle fibers
- number of myofibrils per cross sectional area
- force production
- increased contraction of myoctye
- myofibrils mature and change from a random orientation to being oriented in the same direction
- stroke volume —> increased efficiency
- no increase in number of myocytes
- increase in
cardiovascular development (infancy and childhood part three)
- vascular changes
- increased heart vascularization
- at birth 1 vessel for every 6 muscle fibers
- adulthood 1:1 ratio
- increase in size of arteries and veins and body weight and height increases
- increased heart vascularization
in infancy and childhood, fetal hemoglobin (Hb) levels are ________ post-natal Hb levels
- greater than (>)
- fetal blood has more Hb and less O2 saturation —> as infant’s lungs begin to function, blood has less Hb and more O2 saturation
O2 saturation in umbilical vein
70%
O2 saturation in arterial blood after birth
97%
Hb levels from newborn to adulthood
- newborn Hb levels: 20g / 100 mL
- 3 to 6 month old Hb levels: 10g / 100 mL
- adult Hb levels: 14 to 16 g / mL
in infancy and childhood, blood volume _______
- INCREASES
- 300 to 400 mL at birth to 5 L in adults
in infancy and childhood, stroke volume _______
- INCREASES
- directly proportional to heart size
- 4 mL at birth, 40 mL in children, 60 mL in adults
in infancy and childhood, heart rate _______
- DECREASES
- in newborns, heart rate is faster to compensate for lower stroke volume (110 bpm)
- at 1 years old, heart rate decreases to 105 bpm
in infancy and childhood, blood pressure _______
- INCREASES
- influenced by development of autonomic nervous system and peripheral vascular resistance
- increase is strongly related to increase in height and weight
cardiovascular development in adolescence
- heart size and weight continue to grow
- left ventricular size increases as body mass increases
- increased stroke volume as left ventricle can pump more blood with each heartbeat
- as body weight increases, BP increases
- gender differences noted (boys > girls)
- left ventricular size increases as body mass increases
cardiovascular development in adulthood
- heart size may increase due to fatty deposition
- most evident in women (increase seen between 30s-60s)
changes in heart with aging
- decrease in number of myocytes but increase in size (increased fat deposition)
- decrease in number of pacemaker cells in sinioatrial node —> slower HR
- fibrous tissue and fat deposition can develop in pacemaker pathways
- left ventricular wall becomes thicker —> decreased SV
- heart and vascular system become less compliant (stiffer)
- myocardium becomes darker
- increased aging pigment lipofuscan
- thickening and calcification of valves
changes in blood and vessels with aging
- vessels
- thicker, stiffer, and less flexible
- increased peripheral resistance of blood vessels —> increased BP —> heart works harder —> heart musculature and walls become thicker
- blood
- decreased blood volume due to decrease in fluid with aging
- decreased number of RBCs
- number of most WBCs typically remains the same
- lymphocytes decrease in number —> decreased ability to fight infection and impaired immune function
adult heart disease
- leading cause of death
- 1 million heart attacks a year
- 5 million adults with heart failure
pulmonary system components
- lungs
- site of gas exchange (bring in oxygen and remove carbon dioxide)
- airways
- pathway for air to lungs
- blood vessels
- transport oxygen and carbon dioxide
- thorax
- provide mechanical force
primary function of pulmonary system
gas exchange!
conducting zone of pulmonary system
- passageway for air to travel into and out of lungs
- nose, pharynx, larynx, trachea, bronchi, and bronchioles
respiratory zone of pulmonary system
- located deep in the lungs
- respiratory bronchioles, alveolar ducts, and alveoli
the respiratory center is in the _________
brain stem (medulla oblongata and pons)
the sympathetic nervous system system does bronchial ___________ while the parasympathetic nervous system system does bronchial ___________
dilation; constriction
chemoreceptors detect changes in ________, __________, and ________
blood pH, carbon dioxide, oxygen
control of ventilation
- stretch receptors in the lungs
- sensory and motor nerves for muscles of ventilation
- intercostal muscles and diaphragm
tidal volume
amount of air inhaled or exhaled at rest with each breath
residual volume
amount of air remaining in lungs following expiration
minute ventilation
total volume of air inspired and expired in one minute
prenatal pulmonary development
- 4 to 8 wks of gestation
- differentiation of trachea and bronchi
- lung buds form
- bronchi begin to form in the lungs
neonatal pulmonary development
- 8 weeks to 7 months
- 6 wks: primitive alveoli form and development continues until birth
- 8 wks: conducting zone developed
- 24 wks: surfactant is produced
- 26 to 28 wks: viable respiratory zone (vascularized terminal sacs and surfactant)
pulmonary development at birth
- rib cage is horizontal and ventilatory muscles are not fully developed
- lack of efficient diaphragmatic breathing
pulmonary development following achievement of sitting
- ribs become angled
- diaphragm forms a dome shape
- ventilatory muscles become stronger
- increased efficiency of breathing
during pulmonary development in infancy and childhood, there is an _______ in the number of _______ (until age 8) and _____________
increase; alveoli; pulmonary vascularization
airways are _________ in children
- SMALLER
- decreased smooth muscle in bronchiole walls until age 3–4 yrs
- decreased alveolar elasticity until puberty
- decreased collateral ventilation mechanism
- implications
- increased occurrence of bronchiole collapse
- decreased lung compliance and distensibility —> increased work of breathing
- increased risk of respiratory infections until age 6-8 years
adolescence pulmonary development
- increased size of proximal airways and vasculature
- increase in alveolar size, elastic fibers in alveolar walls, and capillaries to alveoli
- increased gas exchange
- 19 years old: smooth muscle in arterial walls of alveoli are fully developed
- efficient control of blood flow through vasoconstriction and vasodilation
functional impairments in pulmonary development are evident beginning in the _____ decade of life
7th (60s)
thoracic wall and muscular changes in adulthood and aging
- stiffer bony thorax, thoracic kyphosis, and decreased joint mobility
- decreased expansion of chest wall during breathing
- decreased strength and endurance of inspiratory muscles (accessory breathing muscles must work harder)
- altered length-tension relationship of muscles due to structural changes in thoracic cavity (changes lead to increased work of breathing)
lung changes in adulthood and aging
- decreased compliance and elasticity due to changes in collagen and elastin
- decrease in vital capacity (~75%) and increase in residual volume (~70%) by age 70 due to impaired elastic recoil
- total lung volume does not change
- body responds to these changes with an increase in breathing rate in order to increase minute ventilation
alveolar changes in adulthood and aging
- decreased elasticity —> increased susceptibility to collapse during expiration
- increased size of lungs and alveoli due to increased residual volume —> more time required for inspired air to reach alveoli
- increased number of mucous glands and mucus in airway —> more resistance to airflow
vascular changes in adulthood and aging
- smaller capillary bed around alveoli
- decreased blood volume/flow in capillary bed
in adulthood and aging, pulmonary system is working _________ and ______ oxygen is delivered to the body
harder, less
cardiovascular system adaptations to long term exercise
- increased
- maximum cardiac output and stroke volume
- plasma volume
- hemoglobin
- HDL
- decreased
- resting heart rate
- systolic and diastolic BP
- LDL
HDL cholesterol (high density lipoprotein)
- “good” cholesterol
- absorbs cholesterol in blood and carries it back to liver where it is flushed from the body
- high levels of HDL can lower risk for heart disease and stroke
LDL cholesterol (low density lipoprotein)
- “bad” cholesterol
- makes up most of your body’s cholesterol
- high levels raise risk for heart disease and stroke
pulmonary system adaptations to long term exercise
- increased
- minute ventilation (due to increased tidal volume and breathing frequency)
- vital capacity
- tidal volume
- decreased
- inspiration/expiratory reserve
- respiratory rate at sub maximal exercise
_________, _________, and _________ reflect the efficiency of the cardiopulmonary system
cardiac output, minute ventilation, maximal aerobic capacity
cardiac output
- efficiency of the cardiovascular system
- SV x HR = cardiac output
minute ventilation
- efficiency of the pulmonary system
- tidal volume x respiratory rate = minute ventilation
maximal aerobic capacity
- maximal ability of an individual’s body to transport and use oxygen for energy production
- determined by level of cardiovascular and pulmonary fitness
