Module 3: Circulatory System

Question 1

principle of circulatory system

Answer 1

continuous movement of body fluids
transport of oxygen and nutrients to tissues
Transport of CO2 and other metabolic waste products from tissues
Temp regulation
Distribution of molecules (hormones, immune system cells)

Made up of cardiovascular and lymphatic system

Question 2

Lymphatic system

Answer 2

made up of lymphatic vessels and lymph nodes
Vessels drain excess tissue fluids from interstitial tissues at capillary beds to form lymph (when venous side of capillary bed does not reabsorb the tissue fluid)
Lymph filtered through lymph nodes and returned to blood

Question 3

What is lymph composed of

Answer 3

water, lytes, protein plasma

metabolic wastes, leukocytes, lipids

Question 4

Lymphatic capillaries

Answer 4

collection of excess tissue fluid and protein

Thin wall thickness
Basement membrane may not be continuous =
NO tunica media
Tunica adventitia is very thin (only trace amounts of connective tissue)

Question 5

Large lymphatic vessels

Answer 5

carry lymph through the system to the ducts where they empty into the bloodstream

Thin wall thickness
Tunica intima consists of endothelium with some elastic tissue and valves
Tunica media is a few layers of smooth muscle and connective tissue
Tunica adventitia is slightly thicker (smooth muscle and connective tissue)

Question 6

3 layers of walls of heart, blood vessels, lymphatics

Answer 6

INNER
Tunica Intima
Tunica Media
Tunica Adventitia
OUTER

Question 7

Tunica intima

Answer 7

innermost lining
single layer of flattened epithelial cells (endothelium)
Supported by basement membrane and some connective tissue
Ex. Endocardium of heart

Question 8

Tunica Media

Answer 8

middle layer of muscle
Smooth muscle fibers in vessels as well as elastin
Not present in small vessels and capillaries

Ex. myocardium of heart

Question 9

Tunica Adventitia

Answer 9

Outer loose connective tissue

ex. epicardium

Question 10

Arteries

Answer 10

distributes blood from heart to capillary beds throughout body
Cyclic pumping action produces blood flow
Expansion and recoil of arterial wall is facilitated by elastic tissue in walls
Flow regulated by controlling diameter of vessels (by sympathetic nervous system and adrenal medullary hormones)

Question 11

Elastic arteries

Answer 11

major distribution vessels that maintain diastolic pressure
Ex. Aorta, carotid and subclavian artery and most pulmonary arterial vessels

Substantially thicker tunica intimate (Elastic fibres and smooth muscle) than muscular arteries
Tunica Media is major portion of wall (elastic lamina between layers of smooth muscle)
Tunica Adventitia: Thinnest layer (elastic and collagen fibres)

Question 12

Muscular arteries

Answer 12

main distributing branches of arterial tree
Ex. Radial arteries
Function: Move blood under high pressure to all parts of body

Tunica intima: Thin with internal elastic lamina
Tunica Media: smooth muscle with some elastic fibres in larger vessels
Tunica Adventitia: variable thickness, composed of elastic and collagen fibers

Question 13

Arterioles

Answer 13

terminal branches of arterial tree
Reduce pressure and regulate blood supply to capillary beds
Tunica intima: Thin with internal elastic lamina (absent in small vessels)
Tunica media: Thickest layer, smooth muscle fibres
Tunica adventitia: Thin; collagen and elastic fibers

Question 14

Transition between arterial types is

Answer 14

gradual

Question 15

Capillaries

Answer 15

smallest arteriole → capillary → venuole
Nutrients and oxygen to cells of body, and taking away waste products
Only slightly larger than diameter of RBC

total wall thickness is very thin
Tunica intima: very thin
Tunica media: absent
Tunica adventitia: Very thin, only a few fibres of connective tissue

Question 16

Metarterioles

Answer 16

slightly larger capillaries

Similar structure to capillaries but have a discontinuous layer of smooth muscle cells

Question 17

Veins

Answer 17

return blood to heart
low pressure collecting system

respiratory inspiration → negative pressure within the thorax and within the right atrium of heart
Venues return from extremities aided by contraction of skeletal muscles
Expiration → pressure gradient is reversed and blood tends to flow in opposite direction (prevented from doing so by presence of valves)

Question 18

Venules

Answer 18

collection of blood from capillaries
release plasma and WBC into tissues (acute inflammatory response)

Total thickness is THIN
Tunica intima: thin (endothelium and basement membrane)
Tunica media: Absent in small venules; 1-2 layers of smooth muscle in larger venules
Tunica adventitia: very thin layer of collagen fibers

Question 19

Small and medium veins

Answer 19

carry blood under low pressure to the heart

Total thickness is THIN
Tunica intima: endothelial lining, basement membrane, small amount of connective tissue and elastic lamina with valves present in med veins
Tunica media: thin, smooth muscle with some connective and elastic fibres
Tunica adventitia: thick, both connective and elastic fibers

Question 20

large veins

Answer 20

return of blood under reduced pressure to heart (ex. vena cava)

Overall vessel wall is thin
Tunica intima: thin, endothelium, basement membrane, some connective and elastic fibers
Tunica media: thin, few layers of smooth muscle and some elastic fibres
Tunica adventitia: thick, smooth muscle, collagen and elastic fibers

Question 21

Vasa vasorum

Answer 21

provides blood distribution to large blood vessels

“blood supply to the tissue of the vessel”