Class Notes (923,841)
CA (543,275)
UTSC (33,027)
BIOC34H3 (123)
Stephen Reid (105)
Lecture 7

Lecture 7

12 Pages
69 Views

Department
Biological Sciences
Course Code
BIOC34H3
Professor
Stephen Reid

This preview shows pages 1-3. Sign up to view the full 12 pages of the document.
Resistance in the Circulation
Resistance: The degree to which flow is hindered.
For any given 'PIf resistance n, then flow ;
If resistance ;, then flow n
Flow = Pressure Gradient / Resistance
= 'P/R
«for any given singleblood vessel.
Pulmonary Arterial pressure is the driving force of the pulmonary circuit while MAP is
the driving force of the systemic circulation.
Total peripheral resistance = resistance of the blood vessels in the entire circulation, as a
whole. If you want to increase flow in general, systemically, you want to increase blood
pressure, by altering overall resistance to flow in the entire circulatory system.
Factors Affecting Vascular Resistance
1. Vessel Radius*** (primary regulator)
adrenergic control
not regulated
2. Blood Vessel Length (during growth)
The primary thing affecting the resistance to flow is the radius of that vessel (controlled
by adrenergic receptors and circulating adrenaline and noradrenaline).
It is on the arterioles and the beginning of capillaries that we start to see these rings of
muscle that are important for controlling diameter Æ altering resistance to flow. The
www.notesolution.com
arteries are the pressure reservoirs, but most of the blood is in the venous system Æ veins
are blood reservoirs, which is also why they are called capacitants.
Factors Affecting Vascular Resistance
3. Blood Viscosity
haematocrit; Percentage of blood volume
occupied by cells (red and white blood cells)
temperature; viscosity decreases by 2% for every °C decrease in temperature.
From a core body point of view though, we have a constant body temperature.
flow rate; as flow rate decreases, viscosity increases due to increases in
cell to cell and protein to cell interactions that cause red blood cells to
adhere to one another.
A measure or index of the internal friction of adjacent fluid layers
sliding past one another as well as the friction generated between
the fluid and the wall of the vessel.
As haematocrit increases;
viscosity increases.
Viscosity is essentially a measure of friction. It can be altered by changing the hematocrit
(red & white blood cells). Normal hematocrit is 45%.
Factors Affecting Vascular Resistance
4. Laminar Versus Turbulent Blood Flow
Laminar FlowTurbulence increases vascular
resistance and decreases blood
flow.
:HGRQ¶WRIWHQVHHWXUEXOHQWIORZ$WKHURVFOHURVLVVWHQRVLVRIKHDUWYDOYHVFDQFDXVH
turbulent blood flow, but under normal healthy conditions, our blood flow is laminar.
www.notesolution.com
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Resistance in the Circulation Resistance: The degree to which flow is hindered. If resistance nthen flow ; For any given P If resistance ;, then flow n for any given single blood vessel. Flow = Pressure Gradient Resistance = PR Pulmonary Arterial pressure is the driving force of the pulmonary circuit while MAP is the driving force of the systemic circulation. Total peripheral resistance = resistance of the blood vessels in the entire circulation, as a whole. If you want to increase flow in general, systemically, you want to increase blood pressure, by altering overall resistance to flow in the entire circulatory system. Factors Affecting Vascular Resistance 1. Vessel Radius*** (primary regulator) adrenergic control 2. Blood Vessel Length (during growt not regulated The primary thing affecting the resistance to flow is the radius of that vessel (controlled by adrenergic receptors and circulating adrenaline and noradrenaline). It is on the arterioles and the beginning of capillaries that we start to see these rings of muscle that are important for controlling diameter altering resistance to flow. The www.notesolution.comarteries are the pressure reservoirs, but most of the blood is in the venous system veins are blood reservoirs, which is also why they are called capacitants. Factors Affecting Vascular Resistance 3. Blood Viscosity A measure or index of the internal friction of adjacent fluid layers sliding past one another as well as the friction generated between the fluid and the wall of the vessel. haematocrit; Percentage of blood volume occupied by cells (red and white blood cells) As haematocrit increases; viscosity increases. temperature; viscosity decreases by 2% for every C decrease in temperature. From a core body point of view though, we have a constant body temperature. flow rateas flow rate decreases, viscosity increases due to increases in cell to cell and protein to cell interactions that cause red blood cells to adhere to one another. Viscosity is essentially a measure of friction. It can be altered by changing the hematocrit (red & white blood cells). Normal hematocrit is 45%. Factors Affecting Vascular Resistance 4. Laminar Versus Turbulent Blood Flow Laminar Flow Turbulence increases vascular resistance and decreases blood flow. :0439419038009:7-:O0391O4Z 9K0748.O0748L8890348L841K0,79;,O;08.,3.,:80 turbulent blood flow, but under normal healthy conditions, our blood flow is laminar. www.notesolution.com
More Less
Unlock Document


Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit