Anatomy lecture chapter 20- vessels and circulation

What are the functions of peripheral circulation

What are the functions of peripheral circulation

• Carries blood/transports substances

• Exchange of nutrients, wastes, and gases

• regulate BP

• directs blood to/from tissue

What is the order of the blood moving through vessels

• Aorta → arteries → arterioles → capillaires → venules → veins

What are the layers blood vessels

• tunica intima

• tunica media

• tunica externia

What is the tunica intima

• Endothelium

• Smooth surface for blood flow

What is the tunica media

• circular smooth muscle

• site attachment for endothelial cells

• Vasoconstriction and vasodilation

What is the tunica externa

• External connective tissue layer

• Expansion and recoil

What is the lumen

• The center channel of a tubular structure

What are some differences between arteries and veins

• Veins have valves

• Arterial walls are thicker to withstand pressure

• Veins have large lumen

What are the categories of arteries

• Large elastic arteries

• Muscular arteries

• Arterioles

What are large elastic arteries

• Elastic, so good for expanding during systole and recoil during diastole

• Found in aorta and pulmonary trunk

What are muscular arteries

• Constrict/dilate to alter blood flow to tissue areas

What are arterioles

• Small arteries, maintains BP

• Maintain slight contraction known as vasomotor tone

what are the three types of capillaries`

• continuous

• Fenestrated

• Sinusoid

What are continuous capillaries

• Has endothelial cells that create a lining, basement membrane, and small intercellular clefts

• Found in the nervous system and muscles

What are fenestrated capillaries

• Has endothelial cells that have fenestrations/pores in them (which makes it more permeable), basement membrane, and small intercellular clefts

• Found in kidney and Gi tract

What are sinusoid capillaries

• Has incomplete endothelial cells and basement membrane

• Found in bone marrow, liver and spleen

What do capillaries connect to

• The postcapillary venules

What percent of the body’s circulation volume is found in the veins at rest

55%

where is blood velocity the fastest

• Elastic arteries

  • Because it has a small cross section

Where is blood velocity the slowest

• Capillaries

  • Because it has a large cross section

What is capillary exchange

• Process where cells receive substances need (arterial blood →tissue)

• Eliminate waste (tissue →venous blood)

What is capillary exchange dependent on

• Blood flow (pressure)

• Blood content

What are the categories of capillary exchange

• diffusion, vesicular transport, bulk flow

What is difusion

• Movement down a concentration gradient

• Movement of oxygen, carbon dioxide, glucose, ions

• Pass through intercellular clefts or fenestrations (for larger solutes)

What is vesicular transport

• Movement of hormones and fatty acids via pinocytosis

What is bulk flow?

• Movement of large amounts of fluid down a pressure gradient

Filtration vs reabsoprtion

• Filtration- bulk flow from blood capillary to interstitial fluid

• Reabsorption- Bulk flow from interstitial fluid back to blood

What are the forces involved in capillary exchange

• Hydrostatic pressure (HP)- pushing pressure

• Colloid osmotic pressure- pulling pressure

What starling forces are inward

• HP if

• COP b

What starling forces are outward

• HP b

• COP if

What is net filtration pressure

• Difference between the outward and inward forces

  • If outward forces exceed inward filtration is occurring

  • If inward forces exceed outward forces reabsorption is occurring

what veins is fluid returned at

• Right and left subclavin veins

How does a balance of filtration and absorption exist?

• Blood flow (HP) to tissue and plasma protein levels (COP) must be maintained

• arteries, veins and lymphatic vessels must be obstruction free

What are some filtration and reabsorption imbalance issues

• Aging → causes capillary permeability to increase

• Liver disease → blood may not be synthesized

• Kidney disease → allows proteins to escape

• Blockage of lymphatic capillaries → inhibit reabsorption

• Removal of lymph nodes

What can occur if there is an imbalance of filtration and reabsorption

• Edema

What is blood flow proportional to

• cardiac output

What is blood pressure

• measure of force exerted by blood against blood vessel walls

What is a normal blood pressure

• Less than 120 systolic

• Less than 80 diastolic

What is pulse pressure

• Difference bewtween SBP and DBP

• Measures elasticity and recoil, representes the stress exerted on heart during systole

What is a normal pulse pressure?

• 40 mmHG

What is mean arterial pressure and how do you find it

• It is the average pressure exterted on the arteries during a cardiac cycle

• DBP + (PP/3)

Whats a good MAP

• 70-110 mmHg

• Below 60 is bad

What are normal aterial and venous capillary pressures

• Arterial- 40 mmHg

• Venous- 20 mmHg

What is the volume of blood returning to right side of heart from systemic circulation called

• venous return

What are three mechanisms of venous return

• skeletal muscle pump

• gravity

• muscles of breathing within thoracic cavity do the same things as skeletal mucle

What is the skeletal muscle pump

• Muscle bellies thicken during contraction and basically milk blood to the heart

what are the factors that affect resistance

• viscosity of blood

• vessel length

• vessel radius

How is viscosity related to resistance

• A high visocity means a higher resistance

how is vessel length related to resistance

• The longer the vessel the more resistance

What is angiogensis

• Blood vessel growth

• Related to weight → as we gain weight out vesssels lengthen, which increase resistance and BP

Does blood in vessel flow faster in the center or on the wall

• The center

what is total blood flow

• amount of blood that moves through a vessel in a given period

How is blood pressure regulated in the body

• Receptors

• Control ccenter

• effectors

What are baroreceptors vs chemoreceptors

• baroreceptors- stretch

• Chemorecptors- respond to chemical changes

What is the cardiovascular control center

• The medulla oblongata

What are the subdivisions of the cardiovascular centers

• cardioacceleratory center

• Cardioinhibittory center

• vasomotor center

What are the effectors

• Heart and vessels

how is the chemical content of the blood impacted by under perfused tissue

• A decrease in oxygen and nutrients

• an increase in carbon, lactic acid, h+