Anatomy of the Circulatory System Flashcards Preview

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Flashcards in Anatomy of the Circulatory System Deck (62)
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1
Q

What must all blood vessels be?

A
  • Resilient
  • Flexible
  • Remain open
2
Q

What is the common three layered structure of blood vessels?

A
  • Lumen
  • tunica intima
  • Tunica media
  • Tunica adventitia/externa
3
Q

What is tunica intima made up of?

A
  • Endothelium: simple squamous epithelium
  • Basal lamina of the epithelial cells
  • Subendothelial connective tissue
4
Q

What is the tunica media made up of?

A
  • Smooth muscle fibres in loose connective tissues

- May contain elastic fibres

5
Q

What is the tunica externa made up of?

A
  • connective tissue
  • Merges with surrounding connective tissue
  • May contain vaso vasorum (vessels that suply that vein)
6
Q

What are the differences between arteries and veins?

A
  • Arteries are under high pressure and veins are under low pressure
  • Arteries have a thicker wall
  • Arteries appear to have a smaller lumen
  • Arteries maintain their shape
  • Arteries are more resilient
  • The artery doesn’t contain valves but the vein may
7
Q

What are the three types of arteries?

A
  • Elastic (conducting)
  • Muscular (distributing)
  • Arterioles (resistance vessels)
8
Q

Give features of Elastic Arteries

A
  • large arteries such as the aorta and carotid
  • Diameter: 2.5cm
  • withstand changes in pressure during the cardiac cycle and ensure continuous flow
  • Thick tunica media with many elastic fibres and few smooth muscle cells
9
Q

Give features of Muscular arteries

A
  • Most named arteries are muscular arteries
  • Diameter: 0.5mm-0.4cm
  • distribute blood to muscle and organs
  • capable of vasodilation and vasoconstriction in order to control the rate of blood flow to suit the needs of the organisms
  • Smooth muscle cells in tunica media
  • Distinct internal (IEL) and external (EEL) elastic laminae
  • thick tunica externa
10
Q

Give features of arterioles

A
  • capable of vasoconstriction and vasodilation
  • Control Blood flow to organs
  • Involved in blood pressure control
  • Diameter: < 30 um
  • One to two layers of smooth muscle in tunica media
  • poorly defined tunica externa
11
Q

Give features of Capillaries

A
  • Connect arterioles and venules (microcirculation)
  • Site of gaseous exchange
  • Thin walls facilitate diffusion
  • Structure permits 2-way exchange
  • 8 um in diameter
  • Slow blood flow through them
12
Q

What are the three types of capillary?

A
  • Continuous
  • Fenestrated
  • Sinusoids
13
Q

Give features of Continuous capillaries

A
  • majority of them
  • no gaps between cells
  • found in skeletal and smooth muscle, CT and the lungs
14
Q

Give features of Fenestrated Capillaries

A
  • Pores penetrate the endothelium
  • Allows rapid exchange of water or larger solutes (e.g. small peptides)
  • Found in kidney, choriod plexus and endocrine glands
15
Q

Give features of Sinusoids

A
  • spaces between endothelial cells
  • Incomplete or absent basement membrane
  • exchange of large solutes i.e. plasma proteins
  • slow flow
  • found in liver
  • very leaky
16
Q

What are capillaries organised into?

A

Capillary beds

17
Q

What is flow through capillary beds controlled by?

A
  • Metarterioles
  • Precapillary sphincters
  • Arteriovenous anastomoses
18
Q

Give features of metarterioles

A
  • supplies whole capillary bed
  • each metarteriole continues as a thoroughfare channel which leads directly to a vein and had numerous capillaries leading off it
  • Constriction of the metarteriole can reduce flow to a whole capillary bed
19
Q

Give features of Precapillary sphincter

A
  • guard the entrance to each capillary
  • contraction narrows the entrance and reduces flow
  • relaxation dilates the entrance and increases flow
20
Q

give features of arteriovenous anastomoses

A
  • forms direct communication between the arteriole and venule
  • When dilated blood bypasses the capillary bed and flows directly to the venous circulation
21
Q

Give features of venules

A
  • collect blood from capillary beds and deliver it to small veins
  • diameter of around 20 um
  • small venules just have endothelium on a basement membrane
  • larger venules have an increasing number of smooth muscle cells located outside the endothelium
22
Q

How are veins classified?

A

According to size:

  • small <2mm in diameter
  • medium: 2-9mm in diameter
  • larger > 9mm in diameter e.g. superior and inferior vena cavae
23
Q

What are some features of veins?

A
  • under a low pressure system
  • easily distensible (can hold blood)
  • think walled
  • predominant tunica externa
  • valves to aid blood flow
24
Q

What are the 3 blood circulatory systems?

A
  • systemic
  • pulmonary
  • specialised circulatory systems
25
Q

What 3 types of specialised circulatory systems are there?

A
  • portal
  • coronary
  • foetal
26
Q

What do circulatory systems transport?

A
  • O2
  • Nutrients
  • CO
  • metabolic waste
  • cells of immune system
  • hormones
27
Q

What are some key features of the blood circulatory system?

A
  • closed circuit
  • arteries carry blood away from the heart
  • veins give blood back to the heart
  • capillaries are found between the arteries and veins and are the site of gas exchange
28
Q

Give features of the systemic circulatory system

A
  • high pressure system (arterial side)
  • takes O2 rich blood from the left side of the heart to the body tissues
  • Returns O2 poor blood from the tissues to the right side of the heart
29
Q

Give features of the Pulmonary Circulatory system

A
  • low pressure system
  • take blood low in oxygen from the right side of the heart to the lungs
  • takes blood rich in oxygen from the lungs to the left side of the heart
  • pulmonary arteries carry blood away from the heart therefore oxygen poor
  • Pulmonary veins carry blood towards the heart and are oxygen rich
30
Q

What does the lymphatic system consist of?

A
  • network of lymph vessels
  • lymph
  • lymphatic tissues and organs
    Lymphoid cells including lymphocytes and smaller number of phagocytes and other cells
31
Q

What are the functions of the lymphatic system?

A
  • Involved in the body’s defence mechanism

- Provides a mechanism for the drainage of interstitial fluid

32
Q

What are the different names for interstitial fluid?

A
  • In the capillaries it is called plasma

- in the interstitial space it is called interstitial fluid

33
Q

How does capillary exchange work?

A
  • Capillary blood pressure (CPB) pushes fluid out into the capillary into the interstitial fluid *taking nutrients, gases ect.) - filtration
  • Blood colloic osmotic pressure (BCOP) pulls fluid back into the capillary (bringing waste, gases ect.) - reabsorption. BCOP is mainly due to plasma proteins
  • CBP decreases with progression along capillary
  • BCOP (oncotic pressure) remains constant
34
Q

How much of fluid is reabsorbed in capillary exchange and what happens to the rest of the fluid?

A
  • approximately 85% is reabsorbed
  • The remainder must be removed from the interstitial space otherwise oedema will result (swelling)
  • The lymphatic system is responsible for bringing back the excess interstitial fluid. It is picked up by the lymph capillaries
35
Q

How is excess interstitial fluid removed?

A
  • lymph capillaries are blind ended tubes that are located adjacent to capillary beds
  • the excess interstitial fluid enters the lymphatic capillary and is called lymph
  • lymph passes through the lymphatic circulation and returns to the blood system
36
Q

How does lymphatic drainage work?

A
  • Lymph capillaries -> lymph vessels -> lymph trunks -> thoracic duct/ right lymphatic duct -? subclavian vein
  • lymph re-enters the blood vascular circulation
  • along the lymph vessels we have lymph nodes which filter the lymph. Foreign particles get trapped between the lymph nodes
  • Lymph nodes get enlarged if you are ill sometimes
37
Q

What does the right lymphatic duct do?

A
  • drains lymph from the right side of the head, the thorax and upper limb
  • lymph leaves lymphatic duct and goes to the right subclavian vein
38
Q

What does the Thoracic duct do?

A
  • drains lymph from the remainder of the body

- Lymph then goes into the left subclavian vein

39
Q

How are the tunica media, tunica intima and tunica externa bound together

A

with collagen fibres

40
Q

How is the tunica media separated from the tunica externa?

A

By a thin band of elastic fibres called the external elastic membrane

41
Q

What is the difference between the tunica externa in arteries and veins?

A
  • In arteries the tunica externa contains collagen fibres with scattered bands of elastic fibres
  • In veins it is generally thicker than the tunica media and contains networks of elastic fibres and bundles of smooth muscle cells
42
Q

why does the lumen of arteries sometimes have a pleated appearance?

A

Because when an artery constricts it’s endothelium folds

43
Q

Why are arterioles also called resistance vessels?

A

As the force opposing blood flow is called resistance

44
Q

when do aneurysms occur?

A

When local blood pressure exceeds the capacity of the elastic components of the arterial walls the result is an aneurysm or bulge in the weakened wall of the artery

45
Q

What is arterial anastomosis?

A

When more than one artery supplies blood to a capillary bed and the multiple arteries fuse before giving rise to arterioles

46
Q

What are collaterals?

A

Multiple arteries that supply blood to a capillary bed

47
Q

What does it mean when exchange occurs between blood and interstitial fluid in continuous capillaries by bulk transport?

A

the movement of materials by endocytosis or exocytosis at the inner endothelial surface

48
Q

What is angiogenesis?

A

The formation of new blood vessels from pre-existing vessels and occurs under the direction of the vascular endothelial growth factor

49
Q

How do Lymphatic Capillaries vary from blood capillaries?

A
  • they are closed at one end
  • they have larger luminal diameters
  • have thinner walls
  • have flattened or irregular outline in sectional view
  • they are lined by endothelial cells but the basement membrane is incomplete or absent
  • they are not tightly bound together but do overlap. The region of overlap acts as a one way valve
50
Q

What helps lymph flow?

A
  • contractions of the skeletal muscles surrounding the vessels
  • valves
51
Q

What are the two sets of lymphatic vessels that collect lymph from the lymphatic capillaries and what is the difference between them?

A
  • Superficial lymphatics: located closer to the skin
  • Deep lymphatics: accompany deep arteries and veins supplying skeletal muscles and other organs of the neck limbs, trunk and walls of visceral organs
52
Q

What do lymphocytes do?

A

Respond to specific invading pathogens as well as to abnormal body cells and foreign proteins. They eliminate these threats or render them harmless through a combination of physical and chemical attacks

53
Q

What are lymphoid tissues?

A

Connective tissues dominated by lymphocytes

54
Q

Where do lymphoid nodules occur?

A

In the connective tissue deep to the epithelia lining the respiratory tract where they are known as tonsils

55
Q

What are the tonsils?

A

Large lymphoid nodules in the wall of the pharynx. Most people have 5

56
Q

What is tonsillitis?

A

An inflammation of the tonsils (especially the palatine tonsils)

57
Q

What is the mucosa-associated lymphoid tissue (MALT)

A

The collection of lymphoid tissues that protect the epithelia of the digestive, respiratory, urinary and reproductive systems

58
Q

What are aggregated lymphoid nodules?

A

Clusters of lymphoid nodules deep to the epithelial lining of the intestine

59
Q

What are a few examples of lymphoid organs?

A

lymph nodes, thymus and spleen

60
Q

Where do blood vessels and nerves reach the lymph nodes?

A

At a shallow indentation called the hilum

61
Q

what is the typical lymph node shaped like?

A

Kidney bean

62
Q

What is capitance?

A

Word explaining the relationship between the volume of blood in a blood vessel and pressure