Cardiovascular System 2 Flashcards
Vasculature
Blood vessels
Blood vessels 4 things they do…
🔸️Transport blood to tissues (gases, nutrients, and wastes are exchanged) and back to heart
🔸️Regulate blood flow to tissues
🔸️Control BP
🔸️Secrete chemicals
Pulmonary circuit transports blood from what part of the heart to where?
-transports blood from the heart (RV) to lungs
Systemic circuit transports blood from what part of the heart to where?
-transports blood from heart (LV) to the rest of body
Coronary circuit transports blood to where?
circulation of blood to myocardium
(coronary arteries & veins)
3 types of vessels
- Arteries
- Capillaries
- Veins
3 types of vessels: Arteries
🔸️distribution system of vasculature
🔸️Carry blood away from heart
3 types of vessels: Capillaries
- exchange system of vasculature
- smallest vessels
- Site of gas exchange
3 types of vessels: Veins
-collection system of vasculature
- Carry blood toward heart
3 basic layers or tunics of vessel wall:
Tunica intima
Tunica media
Tunica externa (adventitia)
Tunica intima
innermost layer
endothelial cells
Tunica media
middle layer
Smooth muscle
(VC and VD)
Tunica externa (adventitia)
Dense irregular CT
Vaso vasorum
Arteries 2 things about them?
-thicker tunica media reflects arteries’ role in controlling BP and blood flow
- more extensive internal and external elastic reflects arteries
are under much higher press.
3 classes of arteries
- Elastic (conducting) arteries
- Muscular (distributing) arteries
- Arterioles
Arteries:
Elastic (conducting) arteries
Where does it happen and what kind of pressure are they under?
🔸️aorta and immediate branches
🔸️highest pressure
Muscular (distributing) arteries
Well dev. tunica media of SMC
smaller diameter (named branches to organs)
Arterioles
smallest diameter
thin tunica media
(1-3 layers of SMC)
(Arterioles)
metarterioles
smallest arterioles that directly feed capillary beds
- precapillary sphincter SMC that encircles metarteriole-capillary junc.
Baroreceptors
(Arterioles)
pressure changes in aorta & common carotid artery
Chemoreceptors
(Arterioles)
-chemicals [O₂, CO₂, H+]
Veins
(6 things)
🔸️outnumber arteries
🔸️larger leumens
🔸️serve as blood reservoir (70% of total blood located in veins (systemic & pulmonary veins)
🔸️fewer elastic fibers
🔸️less SMC
🔸️thinner walls
Venules
(Veins)
- smallest veins; drain blood from capillary beds
Venous valves
(Veins)
prevent backflow of blood
Hemodynamics
- physiology of blood flow
-The heart provides force that drives blood through blood vessels by creating a pressure gradient
(ex. of Gradients Core Principle - Pressure is highest near heart & decreases as blood moves further away
-Blood flows down pressure gradient from area of higher P (near heart) to area of lower P (in peripheral vasculature
Blood pressure (mmHg)
(Definition)
- outward force that blood exerts on walls of blood vessels
Blood pressure Varies highest…
in large systemic arteries
Blood pressure Varies Lowest…
in large systemic veins
Blood flow (vol. of blood/min) determined by 3 things:
- Magnitude of BP gradient
- Resistance (R)
- Velocity
Blood flow:
Magnitude of BP gradient
Generally, blood flow matches C.O. (avg. 5-6 L/min)
Blood flow directly proportional to pressure gradient, (blood flow increases when pressure gradient incr.)
Blood flow:
Resistance (R)
🔸️any impedance to blood flow
🔸️Blood flow inversely proportional to R
Blood flow:
Velocity
related to X-sec. area
-incr. branching incr. total x-sec. area
- fastest in aorta, slowest in capillaries
BP influenced by 3 main factors:
1.Peripheral resistance (PR)
2. C.O.
3. Blood Volume
BP:
Peripheral resistance (PR)
- any factor that hinders blood flow
- PR is greatest further away from heart
- as PR increases, BP increases
- vessel radius, viscosity, vessel length
BP:
C.O.=
SV x HR
BP:
Blood Volume
influenced by water loss and gain
Pulmonary circuit BP is…
- 15 mmHg
Systemic circuit BP is…
95 mm Hg
Systolic BP is…
pressure averages 120 mm Hg
Diastolic BP is…
pressure averages -80 mm Hg (at rest)
Pulse pressure formula and it’s BP
= systolic - diastolic pressures
= ~ 40 mm Hg
MAP formula is?
What does MAP stand for?
MAP = diastolic pressure + 1/3 (pulse pressure)
Mean Arterial Pressure
Increase venous return: (4 things)
- Venous valves
- SMC in vein walls VC by SNS
- Skeletal muscle pumps
- Respiratory pump
Neural and Hormonal control
ANS
SNS & PSN
Neural and Hormonal control
ANS: SNS
SNS release Epi & NEpi ➡️ VC ➡️ increase BP
Neural and Hormonal Control
ANS: PSN
PSN ➡️ Ach ➡️ decreases C.O. ➡️ Decreases BP
Baroreceptor reflex: Location and is sent by which CN to where? & what response happens?
Carotid sinus & aortic arch→ via CN IX (Glossopharyngeal Nerve) to medulla oblongata→ PSN response by decr. BP or SNS response by increasing BP
Peripheral chemoreceptors
play a role in reg. breathing, but also affect BP; receptors respond to O2
Central chemoreceptors
Respond to decreases in pH in brain. Triggers another feedback loop that indirectly increases SNS; →VC and increase BP
Hormones that control PR (3 things)
- Adrenal medulla
- Atria
- Angiotensin II
Adrenal medulla→
Epi, NEpi → VC
Atria→
ANP→VD
Angiotensin II →
VC
Hormones that reg. blood volume
(RAAS)
Kidneys →Renin→Angiotensin II→aldosterone→conserve H₂O
Kidneys → ADH (Antidiuretic Hormone) → conserve H2O
Hypertension
(Disorder of BP)
🔸️Hypertension >140/90
Essential (primary) hypertension - cause is unknown
Secondary hypertension - cause can be determined
Hypotension
(Disorder of BP)
systolic pressure < 90 mm Hg
diastolic pressure < 60 mm Hg
Circulatory shock
= severe hypotension
- due to hypovolemia
Capillary Exchange via:
- Diffusion & osmosis (gaps)
- Diffusion (membranes)
- Transcytosis (Active process, ATP needed)
What are the 3 types of capillaries -
- Continuous Capillaries
- Fenestrated capillaries
-Sinusoidal Capillaries
Continuous Capillaries
skin, nervous, CT, muscle
Most capillaries
Fenestrated capillaries
kidneys, endocrine, S.I.
Sinusoidal Capillaries
liver, lymphoid
Autoregulation (self-regulation)
- ensures that the correct amount of blood is delivered to match a tissue’s level of
activity
At rest, ~25% of the body’s capillary beds are fully open
Filtration
drives movement of water across cap. wall (passive process)
Hydrostatic pressure (HP)
moves water out of cap.
35 mmHg (arterial end) → 15 mmHg (venule end)
Osmotic pressure (OP)
draws fluid into cap.
25 mmHg throughout cap. bed
Osmotic pressure (Definition)
- Solute particles in a solution exert a force, or “pull,” on water molecules called osmotic pressure (OP)
- Osmotic pressure is determined by # of particles, not their size
Capillary net filtration pressure (NFP)
- colloid OP and HP gradient drive water in opposite directions
Net Filtration Pressure (NFP) formula:
HP- COP = NFP
NFP is not exactly even at 2 ends of cap. bed
- overall NFP favors filtration of water out of capillary
Excess fluid in interstitium returned to blood via lymphatic system
Net Filtration Pressure (NFP)
At arteriolar end:
At arteriolar end:
35 mm Hg - 22 mmHg = 13 mmHg (out of cap.)
Net Filtration Pressure (NFP)
At venule end:
At venule end:
15 mmHg - 22 mmHg = -7 mmHg (into cap.)
Edema =
(Swelling)
excessive amt. of H₂O in interstitial fluid
Edema cause:
-increase in CHP gradient due to HT
-decrease in COP due to liver disease, cancer, or starvation
- Peripheral edema - in hands and feet due to gravity
- Ascites - accumulation of interstitial fluid in abdomen
Vasa vasorum
are small blood vessels that supply the walls of larger blood vessels with gas exchange, nutrients, and waste
Baroreceptor reflex what does it do?
cardiovascular reflex that regulates blood pressure by adjusting heart rate and blood vessel resistance
Hormones that control C.O.
Epi
NEpi
Thyroid hormone
Hypovolemia
A condition in which the liquid portion of the blood (plasma) is too low.
Pulse
Pressure changes causes arteries to expand and recoil with each heart beat
Pulsation/min =
HR (heart rate)
Hepatic portal circulation:
- Drains nutrient-rich, oxygen-poor blood from digestive organs
Superior and inferior mesenteric veins
→ hepatic portal vein [A stop on the way to the hecart]
Liver then detoxifies substances including drugs - blood then goes to
Blood flow through capillary beds:
When precapillary sphincters are open:
Blood goes through capillary beds and thoroughfare channels
Blood flow through capillary beds:
When precapillary sphincters are closed:
Blood only goes through thoroughfare channel
