Ch 21 - structure and function of arteries, veins , lymphatics and related organs Flashcards
what is the function of elastic fibers in arteries? what about vascular smooth muscle? (VSM)
- elastic fibers allow arteries to stretch and recoil
- VSM is responsible for vasodilation and vasoconstriction
what propels the blood forward through an artery?
- the recoil you get with diastole after the expansion of the artery in systole
what are the palpable arteries of the upper limbs?
brachial, radial and ulnar
what are the palpable arteries of the lower limbs?
femoral, popliteal, posterior tibial, dorsalis pedis
what is ischemia? what does complete blockage result in? what dose partial blockage result in?
- insufficient oxygen supply to some tissue became of a blockage in a blood vessel
- death of distal tissue
- insufficient supply especially seen when demand increases (like during exercise)
what is PAD? what commonly causes it? what uncommonly causes it?
- disease of noncoronary arteries (usually the ones supplying the limbs)
- usually caused by atherosclerosis
- sometimes caused by embolism, arterial dissection and hyper-coagulable states
what is the course of veins like?
the course of veins is parallel to the arteries but blood flow is the opposite
what does the body have more of–veins or arteries? which are closer to the skin surface?
the body has more veins and they are closer to the skin surface
how many sets of veins does each arm have? where is the one most responsible for venous return?
- each arm has two sets of veins: superficial and deep
- the superficial veins lie in the subcutaneous tissue and are mostly responsible for venous return
what veins responsible for most of the venous return from the lower limbs? what kind of veins are they?
- the femoral and popliteal veins
- these are superficial veins
what are the superficial veins in the leg? where does blood flow from them into?
- small and great saphenous
- blood flows from them into the deep veins
what are perforator veins?
veins that connect the superficial veins to the deep veins
what kind of system is venous flow? what are the three mechanisms used by veins to get blood flowing back to the heart?
- low pressure system
- skeletal muscle contraction
- pressure gradient created by breathing
- intraluminal valves
how does breathing create a pressure gradient?
inspiration makes thoracic pressure decrease and abdominal pressure increase
how do intraluminal valves work?
the open towards the heart and close tightly when they are filled to prevent back flow of blood
in the legs, what is the intraluminal valve mechanism called?
the calf pump or peripheral heart
how does the calf pump work?
when we walk, the gastrocnemius and soleus muscle squeeze the veins and direct blood flow towards heart–> because of the valves the blood only flows one way
why are veins called capacitance vessels? what is this mechanism compensatory of?
- because of their ability to stretch
- it is a compensatory system to reduce stress to the heart
what people are at risk for venous stasis?
people that have to do prolonged standing, sitting or bed rest
what are other factors that increase risk for venous disease?
hypercoagulable states and vein wall trauma
what is a hypercoagulable state?
condition where you have greater chance of developing a blood clot
what creates incompetent valves?
varicose and dilated veins
what do varicose or dilated veins increase? what does this lead to?
they increase venous pressure which further dilates the valves
who gets varicose veins?
- genetic predisposition
- obesity
- women after multiple pregnancies
what is the function of the lymphatic?
drain excess fluid and plasma proteins from the interstitial spaces back to the bloodstream
what does the lymphatic system conserve?
fluid and plasma proteins that leak out of capillaries
what does the lymphatic system form?
a major part of immune system that defends body against disease
what does lymphatic system absorb?
lipids from the intestinal tract
where do the lymphatic vessels converge and drain off into?
the thoracic duct and the right lymphatic duct
where does the right lymphatic duct empties into?
the right subclavian vein
where does the thoracic duct empty into?
the left subclavian vein
what would happen without lymphatic drainage?
fluid would build up in the interstitial spaces and cause edema
what are lymph nodes?
small oval clumps of lymphatic tissues located at intervals along vessels
what do lymph nodes do?
they filter fluid before it is returned to the bloodstream
what are the four functions of the spleen?
- destroy old red blood cells
- make antibodies
- store red blood cells
- filter out microorganisms
what do the tonsils do?
they respond to local inflammation
what is the function of the thymus?
developing B and T cells
