Lecture 5- Structure and Function of Blood Vessels

Question 1

what supply do all tissues have

Answer 1

arterial supply

Question 2

what drainage do all tissues have

Answer 2

venous drainage

Question 3

3 core functions of blood vessels

Answer 3

-resilient
-flexible
-always remain open

Question 4

what is the standard blood vessel structure

Answer 4

tunica intima->tunica media-> tunica adventitia/ externa

Question 5

what epithelium is found in the tunica intima?

Answer 5

simple squamous epithelium

Question 6

endothelium

Answer 6

epithelium that lines blood vessels

Question 7

what do the epithelial cells in the tunica intima have

Answer 7

basal lamina (extracellular matrix of epithelial cells)

Question 8

what connective tissue is found in the tunica intima

Answer 8

subendothelial connective tissue

Question 9

what is found in the loose connective tissue of the tunica media

Answer 9

smooth muscle fibres

Question 10

which fibres may the tunica media contain

Answer 10

elastic fibres

Question 11

structure of the tunica externa/adventia

Answer 11

Connective tissue
Merges with surrounding connective tissue
May contain vaso vasorum (vessles of the vessels)

Question 12

why do arteries have thick walls

Answer 12

blood is under high pressure

Question 13

what do arteries resemble and what do veins resemble

Answer 13

arteries- garden hoses (smaller lumen)
veins- fire hoses (larger lumen)

Question 14

why do valves have thin walls

Answer 14

as blood travels under low pressure

Question 15

which is more resilient: arteries or veins?

Answer 15

arteries

Question 16

what are the 3 types of arteries

Answer 16

elastic (conducting)
muscular (distributing)
arterioles (resistance vessels)

Question 17

examples of elastic (conducting) arteries

Answer 17

aorta, brachiocephalic and common carotid

Question 18

diameter of elastic (conducting arteries )

Answer 18

up to 2.5 cm

Question 19

function of elastic (conducting arteries)

Answer 19

withstand changes in pressure during the cardiac cycle and ensure continuous blood flow

Question 20

structural adaptations of elastic ( conducting arteries)

Answer 20

thick tunica media with many elastic fibers and few smooth muscle cells

Question 21

examples of muscular (distributing) arteries

Answer 21

brachial and femoral arteries

Question 22

diameter of muscular (distributing) arteries

Answer 22

0.5 mm – 0.4 cm

Question 23

function of muscular (distributing) arteries

Answer 23

-Distribute blood to muscles and organs
-Capable of vasodilation and vasoconstriction
in order to control the rate of blood flow to
suit the needs of the organ
-e.g contracting muscles during exercise- dilate blood vessels

Question 24

structural adaptations of muscular (distributing) arteries

Answer 24

smooth muscle cells in tunica media
distinct internal (IEL) & external elastic laminae (EEL)
thick tunica externa

Question 25

diameter of arterioles (resistance vessels)

Question 26

function of arterioles (resistance vessels)

Answer 26

-Capable of vasoconstriction & vasodilation -Control blood flow to organs -Involved in blood pressure control

Question 27

structural adaptations of arterioles (resistance) vessels

Answer 27

one to two layers of smooth muscle cells in tunica media poorly defined tunica externa

Question 28

functions of capillaries

Answer 28

Connect arterioles and venules (microcirculation) Site of gaseous exchange

Question 29

why are there thin walls of capillaries

Answer 29

facilitate diffusion

Question 30

why is blood flow through the capillaries slow

Answer 30

ensures enough time for exchange of gases

Question 31

what exchange does the structure of capillaries allow

Answer 31

2 way exchange

Question 32

diameter of capillaries

Answer 32

8-μm (micrometres) in diameter

Question 33

what else aids the thin walls of the capillaries

Answer 33

endothelium and basement membrane

Question 34

what are the 3 types of capillaries

Answer 34

continuous fenestrated sinusoidal

Question 35

features of continuous capillaries

Answer 35

no gaps between cells, all next to each other Skeletal and smooth muscle, CT, and the lungs

Question 36

features of fenestrated capillaries

Answer 36

- Pores penetrate the endothelial lining - Rapid exchange of water or large solutes (e.g. small peptides) - Absorption (kidney, choroid plexus and endocrine glands

Question 37

choroid plexus

Answer 37

area where we produce cerebral spinal fluid in the brain

Question 38

intracellular clefts

Answer 38

gaps between adjacent cells of fenestrated capillaries

Question 39

features of sinusoidal capillaries

Answer 39

* Spaces between endothelial cells * Incomplete or absent BM * Exchange of large solutes i.e. plasma proteins * Specialised lining cells (e.g. in the liver, phagocytic cells engulf damaged RBCs) * Blood moves slowly through sinusoids

Question 40

how are capillaries organised

Answer 40

into groups called capillary beds

Question 41

what do capillary beds allow

Answer 41

allow slow flow between arteriole and venule to allow exchange of gases and nutrients

Question 42

what supplies a single capillary bed

Answer 42

metarteriole

Question 43

structure of metarteriole

Answer 43

Each metarteriole continues as a thoroughfare channel which leads directly to a vein and has numerous capillaries leading off it

Question 44

what can reduce flow to a whole capillary bed

Answer 44

constriction of the metarteriole

Question 45

precapillary sphincter

Answer 45

guards the entrance to each capillary (controls entrance diameter)

Question 46

constriction of the precapillary sphincter

Answer 46

narrows the entrance therefore reduces flow

Question 47

relaxation of the precapillary sphincter

Answer 47

relaxation dilates entrance therefore increases flow

Question 48

arteriovenous anastomosoes

Answer 48

Form direct communication between the arteriole and venule (no capillaries tunning off them)

Question 49

dilated arteriovenous anastomoses

Answer 49

blood bypasses the capillary bed and flows directly to the venous circulation

Question 50

venules

Answer 50

collect blood from capillary beds and deliver it to small veins

Question 51

diameter of venules

Answer 51

varies, average 20 m

Question 52

structural adaptations of venules

Answer 52

Small– endothelium on a basement membrane Larger– increasing numbers of smooth muscle cells located outside endothelium

Question 53

how are veins (capacitance vessels) classified

Answer 53

according to size Small < 2mm in diameter Medium 2-9 mm in diameter Large > 9mm in diameter e.g. superior and inferior vena cava

Question 54

features of veins

Answer 54

low-pressure system easily distensible (capacitance- can store/ hold more blood in the vein)

Question 55

structural adaptations of veins

Answer 55

Thin walled Tunica externa is predominant Valves to aid blood flow

Question 56

anatomical planes- sagittal

Answer 56

passes from front to back splitting body into right and left sides

Question 57

anatomical planes- coronal/frontal

Answer 57

passes from side to side-splitting body into front and back

Question 58

anatomical planes - transverse/ horizontal

Answer 58

splits the body into upper and lower parts

Question 59

anterior

Answer 59

passes from front to back splitting the body into right and left sides

Question 60

distal

Answer 60

a direction away from the point of attachment or origin e.g. for a limb, away from its attachment to its trunk

Question 61

inferior

Answer 61

Below, in reference to a particular structure, with the body in the anatomical position.

Question 62

lateral

Answer 62

pertaining to the side

Question 63

medial

Answer 63

towards the midline of the body

Question 64

posterior (dorsal)

Answer 64

towards the back

Question 65

superior

Answer 65

Above, in reference to a portion of the body in the anatomical position

Question 66

anatomical position

Answer 66

An anatomical reference position; the body viewed from the anterior surface with the palms facing forward.