Handout #1 – Intro to CVS Flashcards
Pulmonary circuit provides BF to ___ and is a ___ pressure circuit.
Lungs; low
Systemic circuit provides BF to ___ and is a ___ pressure circuit.
Tissues; high
Why are arteries and veins well suited to provide BF to/from tissues?
Larger, thicker walls to prevent O2 diffusion
Microcirculation include…
Arterioles, capillaries, and venules
Microcirculation regulates…
BF, BP, and exchange*
What are the three CV adjustments to exercise?
- Increase CO
- Redistribute CO to working muscles
- Increase Venous Return
Pacemaker of the heart
SA node
Delay station (to allow heart to fill)
AV node
What is the role of gap junctions?
Electrically connect myocytes so ventricles can contract in unison
Prolonged AP…
Aids in LV filling and prevents tetany (constant contraction)
Coronary arteries are critical to providing BF to ___
Myocytes
Capillaries in the heart are responsible for…
O2 exchange
What is the role of mitochondria in the heart?
To produce ATP
Nerves in the heart are innervated by…
Autonomic nervous system (ANS)
Two branches of autonomic nervous system are…
- Parasympathetic
- Sympathetic
PNS is innervated via ____ nerve and has ___ attachments on the heart. The PNS is also known as the ______.
Vagus nerve
2
“Brake”
SNS is innervated via ____ nerve and has ___ attachments on the heart. The SNS is also known as the ______.
Sympathetic nerve
3
“Accelerator”
How does PNS regulate the heart?
- ACh binds to M2 receptors, which activates Gi protein.
- Gi protein is inhibitory, which decreases AC activity that decreases cAMP.
- HR and conduction velocity decline as a result
How does SNS regulate the heart?
- NE binds to B receptors, which activates Gs protein.
- Gs protein is stimulatory, which increases AC activity that increases cAMP.
- Increase cAMP increases Ca++ entry
- HR and contractility increase
Why is cAMP so influential?
- cAMP regulates protein kinase A (PKA)
- PKA determines phosphorylation state of Ca++
- Ca++ is critical to excitation and contraction coupling.
All blood vessels except for ____ have the same three layer design.
Capillaries
What are the three layer of a blood vessel and what do they contain?
- Intima (inner) - endothelium
- Media (middle) - smooth muscle, collagen
- Adventitia (outside) - connective tissues and nerves (anchors artery)
Only blood vessel layer in direct contact with blood?
Intimia - Endothiel cells
Arteries have large _____ that provide ____ resistance to blood flow
Lumens; low
Why are artery walls thick?
- Withstand high pressure
- Prevent gas exchange
Arteries have _____ fibers to propel blood forward.
Elastic
Primary function of arteries vs. arterioles vs. capillaries
- Arteries - BF from heart to tissues
- Arterioles - Regulate BP and BF distribution
- Capillaries - gas/nutrient exchange
Arterioles are AKA as the _____ because of their dilation and constrictive responses.
“Stopcox”
______ cells regulate the diameter in arterioles.
Smooth muscle
The arterioles are heavily innervated by ____ nerves and have no _____ nerves.
Sympathetic; parasympathetic
Arteries ____ to effectively spread/deliver BF to tissues.
Branch
______ are the only cell that doesn’t have three layers
Capillaries
Key adaptations for capillaries are…
- Thin walls - increase exchange
- Large surface area for exchange
- Large CSA reduces BF velocity to absorb more O2
Is capillary density the same in all muscles?
No.
CD is low in glycolytic
CD is high in oxidative
What percentage of blood is housed in the veins?
70%
What are the primary functions of veins?
- BF from tissues to heart
- Regulate CO and core body temp**
**Different job compared to other blood vessels
Vein walls are comprised of _______ cells that are innervated by ____ nerves.
Smooth muscle; Sympathetic
The smooth muscles cells in veins only contain ____ receptors.
Adrenergic (a)
Do veins have parasympathetic innervation?
No.
Why do veins have valves?
To prevent back flow of blood
Muscarinic receptors respond to the binding of….
Acetylcholine (ACh)
Adrenergic receptors respond to the binding of….
Norepinephrine (NE)
Muscarinic receptors are G-coupled protein receptors involved in the ____ nervous system
parasympathetic
