exam 2: blood vessels, lymphatic system, immune system

what allows blood to travel throughout the body?

blood vessels

what direction of pressure does blood flow through?

high to low pressure

what are the three main types of arteries?

1. elastic arteries

2. muscular arteries

3. aristotles

structure and function of elastic arteries

structure: higher percentage of elastic fibers

function: to propel blood during ventricular diastole

structure and function of muscular arteries

structure: higher percentage of smooth muscle

function: to control distribution of blood

structure and function of aristotles

structure: thin walls, smooth muscle for vascular tone, microscopic arteries

function: site of greatest resistance, regulates blood pressure and distribution of blood flow

what are capillaries? function?

• thin walled vessels

• exchange between blood and tissues

three types of capillaries

• continuous capillaries

• fenestrated capillaries

• sinusoidal capillaries

structure and function of continuous capillaries

• most common type

• complete endothelial lining

• allows for exchange of water and small molecules

structure and function of fenestrated capillaries

• pores in endothelial lining

• found in small intestine and kidneys

• allows for exchange of fluid and large molecules

structure and function of sinusoidal capillaries

• least common

• gaps in endothelial lining and basement membrane, found in spleen, liver, an red bone marrow

• allow for exchange of plasma proteins and cells

what are venules?

extremely small veins

define blood flow + its drive

• movement of blood throughout body

• driven by blood pressure

what is flow rate influenced by?

pressure gradient

what is systolic pressure?

pressure of blood being pushed against artery walls during ventricular systole

what is diastolic pressure?

pressure of blood being pushed against artery walls during ventricular diastole

what is blood volume? what characterizes it?

• amount of blood within vascular system

• hypovolemia - lower blood volume

• hypervolemia - higher blood pressure

what is velocity? what is it slow in and why?

• speed of flow

• capillaries, slower blood flow allows room for exchange of molecules

what assistance do veins need to move blood towards the heart?

• skeletal muscle pump - muscle compresses veins

• respiratory pump - alternating pressures milk blood towards the heart

what are the methods of capillary exchange? briefly explain

1. diffusion

• primary method

• molecules flow from high to low concentrations

• can be simple diffusion or facilitated

2. transcytosis

• movement through endothelial cell

• endocytosis coupled with exocytosis

3. bulk flow

• exchange of fluid between blood and tissues

• driven by hydrostatic and osmotic pressures

functions of the lymphatic system

• produces, maintains, and distributes lymphocytes

• transports excess fluid from interstitial spaces back to bloodstream

• provides immunity

• contains phagocytic cells and lymphocytes

what are the lymphatic/immune system parts?

• lymphatic vessels

• lymph nodes

• spleen

• tonsils

• thymus

What is called lymph? What is returned?

the interstitial fluid that goes into lymphatic vessels (lymphatics)

In what way does the lymphatic system go?

one-way towards the heart

functions of lymph capillaries? what are they absent in?

• take proteins, pathogens, cell debris, and cancer cells

• pathogens move through lymphatics

• absent in CNS, teeth, bone marrow, bones

where are lacteals found? their function?

small intestine; absorb fatty acids (chyle)

what do larger vessels lead to?

lymph nodes and form larger lymphatic trunks

what does the thoracic duct receives?

lymph from lower limbs/portion of the body, left side of head, neck, and thorax

what does the thoracic duct empty into?

left subclavian vein

where does the thoracic duct arise from?

anteriorly to lumbar vertebrae (first two) as an enlarged sac (cisternae chyle)

what does the right lymphatic duct receive from?

receives lymph from right side of head, neck, right upper limb, right thorax

what does the right lymphatic duct empty into?

right subclavian vein near right jugular vein

what is lymph similar to? how?

• tissue fluid

• consists of water and dissolved substances

• similar to plasma as well

what is lymphangitis? what are common signs?

• inflammation of lymphatic vessels + vasa vasorum

• seen as red lines under skin (sometimes), and uncomfortable

what causes movement of lymph?

• influenced by muscular activity

• under low hydrostatic pressure

what does movement of lymph help do? if it doesn’t move, what happens (state term)?

• movement stabilizes lymph volume in interstitial spaces

• lack of movement causes accumulation of interstitial fluid called edema

what is lymphedema? what are the causes?

• severe localized edema

• causes include removal of lymphatics during cancer surgery and blockage of lymphatic vessels

what do lymphocytes arise in? what are the different types?

• arise in red bone marrow

• B and T cells

what are T cells activated by?

• macrophages (destroy foreign substances)

• dendrite cells

what do dendrite cells do?

capture antigens and deliver them to lymph; activate T cells

what do reticular cells do?

• produce stroma (reticular fiber)

• support other cells in lymphoid organs

components and functions of lymphoid tissues and organs

• made of mostly reticular connective tissue and contains lymphocytes, allowing them to multiply

• give lymphocytes and macrophages areas to watch for particles

what are the two types of lymphoid tissues and organs

lymphoid tissue and lymphoid follicles