Exam 3 material- BI208

Literally everything that I have in my notes

inner most tunica

tunica intima

middle tunica

tunica media

outermost tunica

tunica externa

Tunica externa (adventitia) info

Not in small vessels, contains collagen, elastin, and neurons.

Tunica intima info

Simple squamous epithelium, resists clotting→ blood moves though nicely. Sits on lamina propria (CT)/basement membrane.

Tunica media info

Largest/thickest layer and is made of smooth muscle.

what do arteries do?

Carry blood away from the heart

What do veins do?

Carry blood towards the heart

Smooth muscle

non-striated

actin and myosin are found here just less organized

Involuntary

influenced by nervous system but also local factors such as pH levels, O2 levels etc.

T or F, Smooth muscle controls blood flow?

True, through vasoconstriction and vasodilation

vasoconstriction

contracted smooth muscle (lower blood flow)

Vasodilation

Relaxed smooth muscle (higher blood flow)

Sympathetic Nervous system innervates

* primary NT= NE (norepinephrine)
* smooth muscle never fully relaxed
* increased NE→ increased contraction
* less NE→ less contraction

Blood flow to capillaries

Driven by pressure from heart (high to low pressure)

Arteries

* expand as blood enters (absorbs pressure)
* smooth muscle contracts to expel blood forward (releases pressure)

Arterial system

1. elastic (conducting) biggest
2. muscular (distributing)
3. Arterials (smallest)

Elastic arteries

compliant and distensible

very elastic

lots of elastin and collagen

ex: aorta

muscular arteries

Huge tunica media

carry blood to specific organs

smallest of the named arteries

less elastin, more smooth muscle

Arterioles

largest have three layers

smallest have no tunica externa

constantly changing diameter → distribution of blood into capillaries

Capillaries

Smallest vessels

some can only fit 1 RBC at a time

tunica intima only → endothelium

3 types of capillaries

continuous, fenestrated and sinusoidal

continuous capillaries

most common in body

mostly just endothelial cells

tight junctions= endothelial cells are tightly held together

blood brain barrier

allow nutrient and waste exchange

fenestrated capillaries

“little window” - pores

more material in and out of blood (Protein and hormones)

found in small intestine, kidney, and endocrine glands

Sinusoidal capillaries

Very large fenestrated capillaries

whole cells or huge molecules move through

found in liver and bone marrow

Capillaries form beds that are

Interweaving networks

Capillary beds closed

pre-capillary sphincter contracted

closes off this capillary bed

no blood flow

Capillary beds open

Pre-capillary sphincter relaxed

blood flows through capillary beds

sphincters respond to local factors

why are capillary beds not always open?

Not enough blood

Venous system

Return blood to heart from capillaries

small to longest : venules, veins

Venules

capillaries merge to form venules

smallest and porous- allow cells in and out (diapedesis)

Veins

venules merge together to form veins

three distinct tunics

larger lumen than arteries → less resistance to flow

pressure does not cause flow here

venous blood pressure

no pulse, very low pressure, yet blood is still pushed back up to the heart due to valves

what pumps keep the blood moving?

1. skeletal muscular pump
2. respiratory pump

Skeletal muscular pump

micro contractions occur all the time

propel blood out of limbs, increases movement increases pump

Respiratory pump

movement of diaphragm

blood movement up torso

exercise increases pump activity→ increase venous return

If diaphragm goes up what happens to thoracic and abdominal pressure?

Thoracic goes up

abdominal goes down

If diaphragm goes down what happens to thoracic and abdominal pressure?

Thoracic goes down

abdominal goes up

factors that influence blood circulation

amount of blood flow in a minute= circulation (ml/min)


1. global →flows through while body in 1 min (CO)
2. regional→ through one organ
3. local→ through a single capillary/vessel

Blood flow is

Directly proportional to pressure

inversely proportional to resistance

If resistance increases, what happens to slow? What if pressure increases?

Resistance increasing→ flow decreases

Pressure increases→ flow increases

Peripheral resistance to flow

amount of resistance depends on vessel diameter, turbulence, vessel length, and viscosity.

Vessel diameter

laminar flow→flow in straight line

diameter always changing→ smooth muscle

as diameter decreases, flow decreases

faster flow in middle, slower on the edges

vasoconstriction has

high flow and low resistance

vasodilation has

low flow and high resistance

4th power rule

resistance to flow is equal to 1/r^4 (r=radius)

Turbulence

increased turbulence= increased resistance which decreases flow.

When an artery branches or rapid change in vessel size

Length of vessel

the longer the vessel→more resistance

increased body fat does what to resistance?

increases resistance

Viscosity

Viscosity up→ resistance up→ flow down

thickness of blood

polycythemia (lots of RBC)

Anemia

How do you change flow without changing R or delta P

Change heartrate

change SV= (EDV-ESV)

Blood pressure

related to the force and rate of heartbeat and diameter and elasticity of arterial wall.

Hypotension

BP less than 90/60

Orthostatic hypotension

temporary such as standing up too quickly

chronic hypotension

Poor nutrition likely

Hypertension

High BP 140/90

transient →exercise, fever, anger

\~30% of 50 year olds

the silent killer

can be hypervolemic leading to increased CO (too much blood)

Increased peripheral resistance

stress, partially clogged arteries, obesity etc. increases resistance → decreased flow

Circulatory shock

Extreme low BP

Caused by extreme dehydration, blood loss, or immune response

Circulatory shock immune response

Anaphylactic shock- response to allergen

septic shock- bacterial infection in blood

systemic dilation

Control of BP

Short term- heart rate and vessel diameter

long term- blood volume

increased BV= Increased BP

Decreased BV= Decreased BP