CV VIII Flashcards
Where are peripheral chemoreceptors located
Aortic arch and carotid artery
What do peripheral chemoreceptors do to influence CV function
Sense alterations in blood-gas concentrations (O2, CO2), and changes in blood pH
Send info back to CVCC which results in change in autonomic output to return blood gas levels to normal
What does peripheral chemoreceptor activation change
Ventilation within the respiratory system
Bring in more O2 of get rid of CO2
Changes CO to transport O2
What is vasovagal syncope
Fainting in response to sudden emotional distress, sight of blood, phlebotomy (needle insertion), acute pain
What alters CV function in response to emotional distress
Hypothalamus
What does vasovagal syncope result in
Large increase in parasympathetic output (decrease CO)
Decrease sympathetic (decrease in peripheral resistance, fall in BP fails to activate baroreceptor)
Why do you faint in vasovagal syncope
Decreased CO and decrease peripheral resistance cause fall in MAP
Parasympathetic decrease in HR
What is bulk flow
Mass movement of fluid and any dissolved solutes as result of hydrostatic or osmotic pressure gradients
Absorption
If bulk flow is resulting in fluid moving into capillaries
Filtration
If bulk flow is resulting in movement of fluid out of the capillaries
What caused filtration
Hydrostatic pressure (PH)
Pressure of in blood vessels drives fluid out through pores and cell junctions
What causes absorption
Colloid osmotic pressure or on oncotic pressure
What is colloid osmotic pressure or oncotic pressure
Pressure that draws fluid in created by plasma proteins in blood
When is absorption zero
Oncotic/colloid osmotic pressure in capillary exceeds interstitial space
When is filtration zero
When hydrostatic pressure in vessels decreases as blood travels through the capillaries due to resistance encountered and exceeds interstitial hydrostatic pressure
What causes net filtration
At arterial end hydrostatic pressure exceeds colloid osmotic pressure
What cause absorption
At venous end colloid osmotic pressure exceeds hydrostatic pressure
Net filtration from the entire capillary network results in
Loss of 3L fluid/day from blood
Net pressure= hydrostatic pressure - colloid osmotic pressure
What do lymphatic vessels assist with
Assist CV system with returning fluid and proteins lost through capillaries (so we don’t lose 3L/day)
Where are lymphatic vessels
Associate with most capillaries through body
What do lymphatic nodes contain
Immune cells
What are lymphatic vessels composed of
Single endothelial layer
Large interendothelial junctions that act as one-way valves
What causes lymphatic micro valves to open in initial lymphatic segment
Interstitial hydrostatic pressure is higher than inside the lymphatic
What causes lymphatic micro valves to close and secondary valves to open
As fills with fluid, lymphatic hydrostatic pressure exceeds interstitial
What does the smooth muscle of lymphatics do
Contracts to propel fluid one and assists one way valves in preventing back flow
Edema
Abnormal accumulation of fluid in interstitial space
What are 2 causes of edema
- Inadequate lymph drainage (obstructions within lymph nodes)
- Disruption in normal balance between capillary filtration and absorption (filtration>absorption)
Velocity of blood=
Flow rate/c.s. Area
Why does velocity decrease as it flow down branching vessels
With each branch the two new branches always have higher x-sec area then the parent vessel (together, individually smaller)
What does the rate of blood flow affect
Efficiency of exchange between blood and interstitial fluid
What does slow velocity of blood flow in capillaries ensure
Adequate gas and nutrient exchange
Cv disease
Disorders of heart and blood vessels
Play role in 1/3 of deaths in US
How much of US will have CV disease by 2030
40%
What are uncontrolled risk factors of CV disease
Age, sex, family history of early CVD, genetics
Controlled risk factors of CVD
Cigarette smoking, obesity, sedentary lifestyle and untreated hypertension
What are combination of both uncontrollable and controlled risk factors
Diabetes, hyperlipedimia
Atherosclerosis
Inflammatory process leading to hardening or narrowing of arteries
What is contributing factor to atherosclerosis
Elevated blood cholesterol
Chol not readily soluble in aqueous solutions, joins lipoproteins
Two types of lipoproteins
High density lipoproteins - cholesterol complexes (HDL-C) healthy
Low density lipoproteins - cholesterol complexes (LDL-C) bad cholesterol
What are LDL-C necessary fo
Transport in cells, LDL-C’s proteins are digested to amino acids and freed chol used to make cell membrane and steroid hormones
But excess is brought to tissues
What is first stage of atherosclerosis
- Excess LDL brought chol + other lipids to tissues in high pressure vessels
- taken up by endothelial cells in connective tissue layer
- macrophages form and ingest chol and turn to foam cells
Fatty streak of atherosclerosis
Macrophages cause smooth muscle cells to proliferate
- narrows lumen
Stable fibrous plaque stage of atherosclerosis
Stable bubble in wall of artery
- fibrous connective tissue formed around
- Calcification, hardens wall
What is vulnerable plaque stage
- breakdown of tissue
- clot forms where endothelial layer ruptured
- creates blockage
