[ANP] Circulatory system

PULMONARY VESSELS

SYSTEMIC VESSELS

2 major classes of BVs outside the heart

BLOOD

GASES

PRESSURE

FLOW

5 Functions of circulatory system

1. Carries _______

2. Exchanges nutrients, waste products, and ______ with tissues

3. Tranports substances (e.g. AAs, hormones)

4. Regulate blood _______ (works together with heart)

5. Directs blood ______ to tissues to maintain homeostasis

CAPILLARY

• BV where diffusion of gases, nutrients, and waste products occur between the blood and tissue fluid.

• Very thin and consist only of endothelium

• Numerous and extensive in highly metabolic tissues

VEIN

BV that is thinner and contain less elastic tissues and fewer smooth muscle

ARTERY

BV that is larger, contain more elastic tissue (less muscle) then transitions to having more smooth muscle (less elastic)

TUNICA INTIMA

TUNICA MEDIA

TUNICA ADVENTITIA

3 Tunics (inner to outer)

TUICA INTIMA

• Innermost tunica

• simple squamous

• contains basement membrane and small amount of CT

• In muscular arteries, it also contains a thin layer of elastic CT

TUNICA MEDIA

• Middle tunic

• Smooth muscle cells arranged circularly around the BV

• contains elastic and collagen fibers

• In muscular arteries, a layer of elastic CT forms the outer margin

TUNICA ADVENTITIA

• Outer tunic

• dense CT

• becomes loose CT toward the outer portion of the BV wall

ELASTIC ARTERIES

• Largest diameter arteries

• Thickest walls

• Mainly composed of elastic tissue

• Ex. aorta and pulmonary trunk

• Stretches when the ventricles contract

MUSCULAR ARTERIES

• Medium sized and small arteries

• Thick walls compared to their diameter

• Most thickness is from tunica media

• Medium sized arteries AKA distributing arteries because they control blood flow to different regions

DECREASE

DECREASE

Vasoconstriction = [I/D] Diameter = [I/D] Blood flow

INCREASE

INCREASE

Vasodilation = [I/D] Diameter = [I/D] Blood flow

ARTERIOLES

• Smallest arteries with 3 tunics

• transport blood from small arteries to capillaries

PRECAPILLARY SPHINCTERS

• Smooth muscle cells that regulate blood flow in the capillary

• Located at the origin of the branches of the capillaries

VENULES

• Veins with a slightly larger diameter than capillaries

• composed of endothelium resting on a delicate CT layer

• structure simillar to capillaries

• all 3 tunics are present

TUNICA ADVENTITIA

• Predominant tunic in veins

• Provides the distensibility characteristic of veins

TRUE

[T/F] Veins that have >2mm diameter contain valves.

FALSE

[T/F] There are more valves in veins of the upper limb than lower limbs.

AORTA

• All arteries of the systemic circulation branch direct or indirectly from this artery

• 3 parts: ascending aorta, aortic arch, descending aorta

PORTAL SYSTEM

system of blood vessels that begins and ends with capillary beds and has no pumping mechanism, such as the heart, in between.

HEPATIC PORTAL SYSTEM

begins with capillaries in the viscera and ends with capillaries in the liver.

HEPATIC PORTAL VEIN

Blood entering the liver through the _________ is rich in nutrients collected from the intestines, but it may also contain a number of toxic substances that are potentially harmful to body tissues.

BLOOD PRESSURE

measure of the force blood exerts against the blood

vessel walls.

SYSTOLIC PRESSURE

Pressure exerted during ventricular contraction.

DIASTOLIC PRESSURE

Pressure during ventricular relaxation.

AUSCULTATORY METHOD

Method used to determine BP

KOROTKOFF SOUNDS

Sounds heard while taking blood pressure.

TRUE

[T/F] The difference between the systolic and diastolic pressures is decreased in the small-diameter vessels. The decrease in fluctuations in pressure is the result of increased resistance to blood flow in smaller and smaller vessels.

INCREASE

Smaller diameter of BV = [I/D] resistance to blood flow

PULSE PRESSURE

• Difference between systolic and diastolic pressures

• affected by SV and vascular compliance

INCREASE

Increase SV = [I/D] Pulse pressure

VASCULAR COMPLIANCE

• Related to the elasticity of the BV wall

• affects pulse pressure

PULSE

• Felt in arteries

• ejection of blood from LV into the aorta and produces a pressure wave

BLOOD PRESSURE

OSMOSIS

2 major forces responsible for moving fluid through the capillary wall

BLOOD PRESSURE

Forces flud out of the capillary

OSMOSIS

Forces flud in of the capillary

DECREASE

as blood flows though capillaries, blood pressure [I/D] rapidly

PRECAPILLARY SPHINCTERS

Local control of blood flow is achieved by the periodic relaxation and contraction of the precapillary sphincters.

SYMPATHETIC

___________ nerve fibers innervate most blood vessels of the body, except the capillaries and precapillary sphincters, which have no nerve supply.

INCREASE

INCREASE

[I/D] Vasomotor tone = Constrict BVs = [I/D] BP

MEAN ARTERIAL PRESSURE

• MAP

• slightly less than the average of the systolic and diastolic pressures in the aorta because diastole lasts longer than systole.

• changes over our lifetime

• CO x PR (Peripheral resistance) or SV x HR x PR