Anatomy lecture chapter 20- vessels and 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+