• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

43 Cards in this Set

  • Front
  • Back
What are the functions of the vascular system?
Transport O2 and nutrients and waste products (e.g. lactic acid and CO2)
Transport defence cells, hormones, growth factors
Regulate distribution of blood
Blood pressure and temperature
Wound healing
What are the 3 layers of blood vessels?
Tunica intima
Tunica media
Tunica adventitia
What is the tunica intima composed of?
Endothelium (simple squamous epithelium on basement membrane)
What is the tunica media composed of?
Smooth muscle and connective tissue
What is the tunica adventitia composed of?
Connective tissue - collagen and elastin
Sometimes vaso vasorum - blood vessels supplying vessel wall (lymphatics and nerves too)
Give examples of elastic arteries
Pulmonary artery
Give examples of muscular arteries
Most arteries, size variation
Describe the structure of elastic arteries
Tunica intima - thin, endothelium with layer of collagenous tissue rich in elastin, myointimal cells (atherosclerosis) and fibroblasts
Tunica media - broad, elastin, collagen and smooth muscle fibres
Tunica adventitia - relatively thin, vasa vasorum - lymphatics, nerves, elastin and type 1 collagen
What is the function of elastic arteries?
Shock absorption in response to high pulse pressure - distension during systole, recoil during diastole
Maintains smooth blood flow and blood pressure
Describe the structure of muscular arteries
Two well defined elastic sheets - internal elastic lamina between tunica intima and media, external elastic lamina between tunica media and adventitia
Tunica media usually equal to or smaller then tunica adventitia
Tunica adventitia - collagen and elastin, broad
What is the function of muscular arteries?
Control or adjust blood flow distribution and blood pessure by nervous control and vasodilation/constriction respectively
Describe the structure of arterioles
Lumen diameter usually <0.3mm and fewer than 6 layers of smooth muscle
Tunica intima and adventitia layers quite insignificant
What is the function of arterioles?
Regulate blood pressure and blood flow to capillary beds
What does increased vasoconstriction in arterioles cause?
Increased peripheral resistance -> increased blood pressure
How do arteries protected by the skull differ?
Thin t. media (no need for protection, already protected)
Thick inner elastic lamina
How are arteries in the penis specialised?
Helicine arteries
Extensively branched and coiled
Smooth muscle cushions - valves for erection
How do umbilical arteries differ?
No inner elastic lamina
Inner longitudinal and outer circular smooth muscle layer
How are arteries in the lung specialised?
Less elastin and muscle due to lower pressure in pulmonary circulation
Describe the structure of capillaries
Endothelium, basement membrane and CT
Diameter of 3-10µm
Flattened cells pericytes present - progenitor CT cells: fibroblasts, macrophages, smooth muscle - contractile or regulatory
What does the density of capillaries in a tissue represent?
How metabolically active a tissue is
What are the 3 different types of capillaries?
Describe where continuous capillaries are found and how exchange occurs
Lungs, muscle, skin, exocrine glands, nervous tissue
Passive diffusion - gases, ions and small molecules
Pinocytic vesicles - proteins and some lipids
Intercellular passage - via intercellular space between endothelial cells
Describe where fenestrated capillaries are found and how exchange occurs
Kidneys, intestines, endocrine glands
Pores - much greater permeability, macromolecules smaller than plasma proteins
Fewer, if any, pericytes
Describe where sinusoidal capillaries are found and how exchange occurs
Spleen and liver
Large spaces between endothelial cells allowing large particles like RBCs and proteins to pass through
Name numbers
Name numbers
1 - arteriole
2 - metarteriole
3 - precapillary sphincters
4 - thoroughfare channel
5 - venule
6 - arteriovenous shunt
What is a metarteriole?
Connects a terminal arteriole and venule
Capillary bed branches off arteriole end and reemerge into thoroughfare channel
What happens if the precapillary sphincters close?
Blood bypasses capillary bed through arteriovenous shunts
What happens if the arteriovenous shunt smooth muscle or metarteriole smooth muscle contracts?
Blood flows into capillary network
Why is the arteriovenous shunt contraction/precapillary sphincter shutting an important mechanism?
For tissue with intermittent blood flow e.g. digestive system
Temperature regulation
Describe the 3 types of venules
Postcapillary venules - drain several capillaries, wider diameter, blood almost stagnant but inflammation, allergies, temperature
Collecting venules - larger diameter and greater number of pericytes
Muscular venules - 3 layer structure, 1-2 muscle layers
What are valves in veins made up of?
Fibroelastic infolding of tunica intima
Why are veins considered blood reservoirs?
Up to 65% of body's blood in veins
Describe small/medium and large veins
Small/medium - t. media 2-3 layers of smooth muscle and t. adventitia contains longitudinal collagen fibres
Large - NO VALVES, t. intima some elastic fibres, t. media poorly developed with circular muscle except vena cava where it is longitudinal, t. adventitia very thick with vaso vasorum, lymphatics, collagen, elastin
How are veins that have to cope with high hydrostatic pressure specialised?
Thick tunica media
e.g. teat veins, limb veins
How are veins specialised in protected regions?
No tunica media
e.g. bones, penile erectile tissue
Do endothelial cells retain their ability to repair and divide throughout life?
How do endothelial cells respond to injury?
Produce Vascular Endothelial Growth Factor (VEGF) which acts on VEGF receptor
- manipulated by tumours
How do veins respond to age?
Loss of elasticity, thickening, fragmentation, atherosclerotic plaques, calcification of t. media
What are the 3 forms of control of blood vessels?
Neural control - sympathetic postganglionic fibres - noradrenaline - α-1 adrenergic receptors = vasoconstriction - β-2 adrenergic receptors (blood vessels in skeletal muscle) - vasodilation
Endocrine - catecholamines from adrenal medulla - vasoconstriction (except skeletal muscle)
Autoregulation - local control in response to local O2/lactic acid concentrations
Which vessel?
Which vessel?
Elastic artery
Which vessel?
Which vessel?
Muscular artery
Which vessel?
Which vessel?
Small and medium veins
Which vessel?
Which vessel?
Large vein