Circulation 2 Flashcards
Blood vessel structure: Large Vein/Artery
- Tunica externa
- Tunica media
- Tunica intima
- Endothelium
Blood vessel structure: Vein/Artery
- Tunica externa
- Tunica media
- Tunica intima
- Endothelium
Blood vessel structure: Venule/Arteriole
- Tunica media
2. Endothelium
Blood vessel structure: Capillaries
- Tunica intima
2. Endothelium
Arteries maintain ___ pressure
high
Fluctuation in pressure within the cardiovascular system is dampened by what?
Elasticity of the arteries
Veins maintain ___ pressure
low
Characteristics of veins:
- Thin-walled
- Low velocity
- Low pressure
How does blood move through veins
Skeletal muscle pushes blood
What prevents backflow in veins
One-way valves
What is compliance
A measure of how easily a structure can be stretched
How is compliance calculated?
Change in volume/Change in pressure
At rest, how much blood do mammals hold in their veins?
60%
How is blood volume in the vein adjusted?
Venomotor tone
What will happen if you increase venomotor tone?
Increase venous blood return to the heart
What monitors blood pressure and signals to the medulla oblongata
Baroreceptors
What is MAP
Mean arterial pressure
Baroreceptor/MAP pathway:
- Increased MAP
- Causes increased baroreceptor firing
- Stimulate medulla via afferent neurons
- Causes decreased sympathetic output (& increased parasympathetic)
- Decreases norepinephrine release from adrenal medulla
- Which causes 3 things:
a. Vasodilation of arteriolar smooth muscle
a1. Which decreases peripheral resistance
b. Decreases force of contraction in ventricular myocardium
b1. Which decreases CO
c. SA node firing decreases
c1. Which causes decreased heart rate
c2. Which causes decreased CO - All of #6 causes decreased MAP
What regulates blood pressure homeostasis
Baroreceptors
What homeostatic response happens to increased blood pressure
- Decreased heart rate
- Decreased stroke volume
- Vasodilation
What homeostatic response happens to decreased blood pressure
- Increased heart rate
- Increased stroke volume
- Vasoconstriction
Balance of what influences blood volume and pressure
Salt and water intake/output
What role do chemoreceptors play
Detect changes in partial pressures of O2, (Po2), CO2, (Pco2) as these can affect heart rate
Where are chemoreceptors located
Aorta & Carotid artery
What homeostatic response happens to low Pco2, high Po2, and high pH
- Heart rate decreases
- Stroke volume decreases
- Respiration rate decreases
What homeostatic response happens to high Pco2, low Po2, and low pH
- Heart rate increases
- Stroke volume increases
- Respiration rate increases
Cardiac output & Total peripheral resistance both affect what
Blood pressure
What is TPR?
Total Peripheral Resistance
What regulates total peripheral resistance
Constriction & dilation of arterioles
When you adjust TPR, what is adjusted in conjunction
Cardiac output (inversely proportional)
Do different tissues have the same metabolic needs
No, different tissues each have different metabolic needs
Rank tissue metabolic needs from highest to lowest
- Heart
- Kidney
- Brain
- Liver
- Muscle, fat, other organs
Do different tissues have the same metabolic needs
No, different tissues each have different metabolic needs
Rank tissue metabolic needs from highest to lowest
- Heart
- Kidney
- Brain
- Liver
- Muscle, fat, other organs
What types of regulation do capillaries and flow through them undergo
Neuronal & Hormonal
Based on physiological demand what do capillaries do
Open & close
What are the two mechanisms that control flow through capillaries
- Contraction/relaxation of tunica media layer in the arteriole wall
- Precapillary sphincters
What are precapillary sphincters
Rings of smooth muscle that control the blood flow between arterioles and venules
Where are precapillary sphincters located
At the entrance of capillary beds
Some blood flows directly from arterioles to venules by
bypassing the capillary bed
Local control of blood flow is done by
Tissue metabolites affecting smooth muscle contraction and blood flow
Types of capillaries
- Continuous capillary (no pores)
- Fenestrated capillary (with pores)
- Sinusoidal capillary (mixture of both)
What enhances delivery of material across the capillary wall
Slow rate of blood flow & thin walls
3 ways material is delivered across the capillary wall
- Simple diffusion
- Endocytosis and exocytosis (Transcytosis)
- Paracellular pathway
What is the paracellular pathway
Hydrostatic pressure solutes and water across capillary walls through the gaps between adjacent endothelial cells. The size of the solutes moving across depends on the size of the gap
What is transcytosis
Can be either endocytosis or exocytosis through endothelial cells
Structure of lymphatic system:
- Comes from both pulmonary & systemic circuit capillaries.
- Contains lymph nodes & valves
- Pumps back into the inferior vena cava
What are lymphatic capillaries
Closed-ended tubules that form vast networks in intercellular spaces
What is lymph
Fluid that enters the lymphatic capillaries
Pathway of lymph:
Lymph capillaries–>Lymph ducts–>Lymph nodes–>Filtration–>Veins
3 functions of the lymphatic system:
- Transports interstitial (tissue) fluid back to the blood
- Transports absorbed fat from small intestine to the blood
- Helps provide immunological defenses against pathogens
