LP #105 The Circulatory System

Question 1

• complex network of vessels
• basic fxn: deliver oxygen & nutrients to the cells, & remove tissue wastes
• primary role n maintaining homeostasis

Answer 1

Circulatory system

Question 2

2 components to circulatory system

Answer 2

• cardiovascular-2-way system:
• delivers blood to tissues
• removes it from tissues returns it to heart
• lymphatic- one-way:
• removes excess fluid from tissues & returns it general circulation

Question 3

Vascular system is a network consisting of 3 types of blood vessels:

Answer 3

1. arteries: carry blood away from heart
2. Blood capillaries: site of exchange of o2/ nutrients & sates
   * extensive network
3. Veins: return blood to heart

Question 4

Carry fluid that leaks out of blood vessels into interstitial spaces & transports it back to heart=

Answer 4

Lymphatic vessels

Question 5

3 lymphatic vessels=

Answer 5

1. lymph capillaries
2. lymphatic collecting vessels
3. lymphatic trunks

Question 6

Tunica: layer

• inner layer?
• middle layer?
• outer layer?

Answer 6

1. Tunica intima
2. Tunica media
3. Tunica adventitia

Question 7

• aka tunica interna
• inner most layer
• composition: simple squamous cells; form a smooth endothelial surface- reduces friction to blood flow
• in direct contact with blood

Answer 7

Tunica intima

Question 8

• middle & largest layer
• composition: mostly smooth muscle fibers arranged in circular layers
• responds to sympathetic Innervation
• changes to diameter of bv lumen (vasodilation/ vasoconstriction)

Answer 8

Tunica media

Question 9

• aka tunica adventitia
• outermost layer, relatively thin
• composition: loosely arranged collagen fibres
• protect & anchor vessel to surrounding structures
• forms mesh network containing nerve fibres, small blood vessels & lymphatic vessels that serve the artery itself

Answer 9

Tunica externa

Question 10

• carry blood away from heart
• diverge from large to small vessels
• systemic arterial blood is oxygenated
• arteries begin in heart and end, via arterioles, in capillary beds
• relative size of layers varies between types of aa

Answer 10

Arteries

Question 11

Types of arteries

Answer 11

1. elastic (conducting)
2. muscular (distributing)
3. arterioles

Question 12

• large diameter blood vessels
• carry blood from heart
• contain mostly elastin in tunica media

Answer 12

Elastic (conducting)

Question 13

• smaller diameter blood vessels

- contain more smooth mm than elastin

Answer 13

Muscular (distributing)

Question 14

• smallest diameter blood vessels

- contain mostly smooth mm

Answer 14

Arterioles

Question 15

• carry blood towards heart
• converge from small to larger vessels
• systemic venous blood is deoxygenated
• veins begin in capillary beds (as venules) & end in heart

Answer 15

Veins

Question 16

Types of veins

Answer 16

1. Venules

2. Veins

Question 17

• small vessels
• transport blood from tissues to larger veins
• endothelium covered by fibroblastic cells
• thin tunic intima & tunica externa
• porous

Answer 17

Venules

Question 18

• small, thin vessels in tissues
• tunica externa is thickest layer
• tunica media relatively thin
• large lumen
• contain valves

Answer 18

Veins

Question 19

Structures of veins determine fxns:

• large lumen:?
• little muscle:?
• valves:?

Answer 19

1. Blood reservoir
2. Need help returning blood to heart (mostly against gravity)
3. (Extensions of Tuncia intima) prevent back flow of blood

Question 20

Mechanisms that assist venous return

Answer 20

• skeletal mm contractions
• breathing
• valves

Question 21

• smallest blood vessels
• walls are 1 cell thick: Tuncia intima only
• fxn: site of gas/fluid exchange betweeen arterial & venous sides of circulatory system

Answer 21

Capillaries

Question 22

Types of capillaries

Answer 22

1. Continuous
2. Fenestrated
3. Sinusoidal

Question 23

• cells joined by tight junctions
• intercellular clefts: breaks b/w cells
• limited passage of fluids & volutes
• found in:
• skin
• mms
• brain

Answer 23

Continuous

Question 24

• large pores covered by network of proteins (basal lamina)
• allow larger organic molecules & greater volume o fluid to flow into interstitial space
• found where absorption/ secretion is required, ex.
• intestine
• endocrine glands

Answer 24

Fenestrated

Question 25

• leaky: large intercellular clefts
• passage of proteins & blood cells into interstitial space
• found where passage of large particles is necessary, ex.
• liver
• bone marrow
• lymphoid tissue

Question 26

-capillary bed=

Answer 26

Large capillary network

Question 27

2 components of capillary bed

Answer 27

• vascular shunts

- true capillaries

Question 28

• short vessels b/w arterioles & venule
• main thoroughfare from one side of capillary bed to other
• also known as a metarteriole

Answer 28

Vascular shunt

Question 29

• side-spread network of blood vessels

- reach all tissue areas

Answer 29

True capillaries

Question 30

• leads into metarteriole
• joints to postcapillary venule that drains capillary beds
• feeds capillary bed

Answer 30

Terminal arteriole

Question 31

• found between metarterioles & capillaries
• smooth mm rings that constrict lumen to restrict blood flow to capillaries
• minimize BF to areas requiring less blood at a given time

Answer 31

Pre-capillary sphincters

Question 32

• many tissues receive blood from more than one vessel
• anatomical & physiological redundancy
• margining of 2 or mor blood vessels to a region is called an anastomosis
• both arteries & veins anastomose
• veins more than arteries

Answer 32

Vascular anastomoses

Question 33

• cyclical from heart to lungs & back to heart
• in pulmonary circuit:
• arteries carry deoxygenated blood away from heart (to lungs)
• veins carry freshly oxygenated blood to heart (from lungs)

Answer 33

Pulmonary system

Question 34

• returns leaked fluid (lymph) to general circulation
• important in maintaining fluid balance
• 3-4L of lymph produced daily (2/3 blood vol)
• lymphatic system is one-way system (unlike cardiovascular system)
• as lymph travels toward venous system (ultimately into subclavian veins), it is cleansed by WBC-rich lymph nodes

Answer 34

Lymphatic system

Question 35

lymphatic system:

Adaptations?

Answer 35

• minivalves

- anchors

Question 36

Lymph flows into progressively larger vessels:

Answer 36

Lymph capillaries 
To 
Collecting vessels 
To 
Trunks 
To 
Ducts

Question 37

Lymphatic system:

• larger vessels have same 3 tunics as veins, but much thinner
• lymphatic valves have many more valves than veins
• mechanisms hat assist lymph return: ?

Answer 37

• skeletal mm contractions
• breathing
• valves
• movement of surrounding tissue

*both components of the circulatory system are important o maintaining fluid balance in the body.