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Body Systems > S&F Blood Vessels > Flashcards

S&F Blood Vessels Flashcards

1
Q

What are the main types of blood vessels?

A

Arteries, Veins, Capillaries

Each type has distinct functions and structures.

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2
Q

What are the three layers of blood vessel structure?

A

Tunica adventitia, Tunica media, Tunica intima

These layers contribute to the overall function and resilience of blood vessels.

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3
Q

What is the function of the tunica intima?

A

It consists of:
- endothelium = simple squamous epithelium

  • basal lamina (basement membrane of the epithelium cells
  • subendothelial connective tissue = provides smooth surface for blood flow

This layer is crucial for smooth blood flow.

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4
Q

What is the primary function of arteries?

A

Carry blood under high pressure

This requires thicker walls compared to veins.

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5
Q

True or False: Veins have valves to prevent backflow.

A

True

Valves are important for maintaining unidirectional blood flow.

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6
Q

What is the diameter range of muscular arteries?

A

0.5 mm to 0.4 cm

These arteries distribute blood to muscles and organs.

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7
Q

What distinguishes elastic arteries from muscular arteries?

A

Elastic arteries have a thick tunica media with many elastic fibers

They help withstand pressure changes during the cardiac cycle.

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8
Q

What is the diameter of arterioles?

A

Less than or equal to 30 μm

Arterioles are critical in controlling blood flow and pressure.

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9
Q

Fill in the blank: Capillaries connect ______ and ______.

A

arterioles, venules

Capillaries facilitate gaseous exchange.

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10
Q

What type of capillaries have pores for rapid exchange?

A

Fenestrated capillaries

These are found in areas requiring quick absorption, like the kidneys.

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11
Q

What are sinusoidal capillaries characterized by?

A

Spaces between endothelial cells and incomplete or absent basement membrane

This structure allows for the exchange of large solutes.

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12
Q

What role do precapillary sphincters play?

A

They guard the entrance to each capillary

Their contraction and relaxation control blood flow into capillary beds.

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13
Q

What is the classification of veins based on size?

A

Small (<2mm), Medium (2-9mm), Large (>9mm)

E.g. of large = superior and inferior vena cava

The classification helps in understanding their function and structure.

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14
Q

What is the primary role of venules?

A

Collect blood from capillary beds and deliver it to small veins

Venules have a low-pressure system.

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15
Q

What are the three anatomical planes?

A

Coronal/ frontal = passes from side to side splitting body into front and back

Transverse = splits the body into upper and lower parts

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

These planes are used to describe locations and movements in the body.

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16
Q

What does the coronal plane divide?

A

Front and back of the body

It runs from side to side.

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17
Q

True or False: The transverse plane splits the body into upper and lower parts.

A

True

This plane is also known as the horizontal plane.

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18
Q

What is a metarteriole?

A

A vessel supplying a single capillary bed

Constriction of the metarteriole can reduce flow to a whole capillary bed

It leads directly to a vein and has many capillaries branching off.

19
Q

What is the function of arteriovenous anastomoses?

A

Direct communication between arteriole and venule

They allow blood to bypass the capillary bed and flow directly to venous circulation when dilated.

20
Q

What do all blood vessels have?

A

An arterial supply and a venous drainage

21
Q

What must all blood vessels be?

A

Resilient

Flexible

Always remain open

22
Q

What is the typical blood vessel structure?

A

Lumen

Tunica intima

Tunica media

Tunica adventitia/ external

23
Q

Describe the tunica media

A

Smooth muscle fibres in loose connective tissue

May contain elastic fibres

24
Q

Describe the tunica Adventia/ externa

A

Connective tissue

Merges with surrounding connective tissue (i.e. artery & vein are parallel so connective tissue will overlap)

May contain vaso vasorum (for large vessels)

25
Q

What are the features of the Tunica Intima? 4 marks

A
  • Inner layer of blood vessel
  • Endothelial lining
  • Surrounding layers of connective tissue
  • Variable numbers of elastic fibres
26
Q

What are the features of the Tunica Media? (7 marks)

A
  • Middle layer of blood vessel
  • Sheets of smooth muscle tissue in framework of loose connective tissue
  • Collagen fibres connect the 3 layers of
  • Thickest layer
  • Separated from tunica externa by elastic fibres called the external elastic membrane
  • Smooth muscle cells encircle the endothelium that lines the lumen
  • Large arteries also have arranged smooth muscle
27
Q

What are the features of the Tunica Adventia/Externa? (5 marks)

A
  • Outer layer of blood vessel
  • Made up of connective tissue
  • In arteries, has collagen fibres with scattered bands of elastic fibres
  • In veins, it is thicker than the tunica media and contains a network of elastic fibres and bundles of smooth muscle cells
  • The connective tissue blend into those of adjacent tissues to stabilise and anchor the blood vessel
28
Q

Outline the blood vessel structure of an artery

A

General appearance = usually round with relatively thick wall

Tunica Intima
- Endothelium = usually rippled due to vessel constriction
- Internal Elastic membrane is present

Tunica Media
- Is thick and dominated by smooth muscle cells and elastic fibres
- External elastic membrane is present

Tunica Externa
- Has collagen & elastic fibres

29
Q

Outline the blood vessel structure of a vein

A

General appearance = usually flattened or collapsed with relatively thin wall

Tunica Intima
- Endothelium = often smooth
- Internal elastic membrane is absent

Tunica Media
- Is thin and dominated by smooth muscle cells and collagen fibres
- External elastic membrane is absent

Tunica Externa
- Has collagen & elastic fibres and smooth muscle cells

30
Q

What is the primary function of veins?

A

Carry blood under low pressure to the heart

Have thin walls and may have valves to prevent backflow

Low pressure system

Easily distensible (capacitance) = can hold more blood

31
Q

Compare veins to arteries (6 marks)

A

Artery:
-has a thicker wall
-appears to have a small lumen
-maintains its shape
-is more resilient
-does not contain valves

32
Q

What are the 3 types of arteries?

A

Elastic (conducting)

Muscular (distributing)

Arterioles (resistance vessels)

33
Q

Describe Elastic (conducting) arteries

A

E.g. aorta, brachiocephalic & common carotid

  • Diameter = up to 2.5cm
  • Withstands changes in pressure during the cardiac cycle and ensures continuous blood flow when heart contracts/relaxes

Structural adaptations
- Thick tunica media
- With many elastic fibres (can withstand highest blood pressure in the body)
- Few smooth muscle cells encircle

34
Q

Describe Muscular (distributing) arteries

A

E.g. brachial & femoral

  • Diameter = 0.5mm - 0.4cm
  • 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

Structural adaptations
- Lots of smooth muscle cells in tunica media
- Distinct internal (IEL) & external (EEL) elastic laminae
- Thick tunica media

35
Q

Describe arterioles (resistance vessels)

A
  • Diameter = <30 um
  • Capable of vasodilation and vasoconstriction
  • Control blood flow to organs
  • Involved in blood pressure control
  • Main control point for blood flow into the capillary beds

Structural adaptations
- One to two layers of smooth muscle cells in tunica media
- Poorly defined tunica externa

36
Q

What are capillaries?

A
  • Smallest blood vessel
  • Connect arterioles and venules
  • Site of gaseous exchange
  • Thin walls facilitate diffusion
  • Blood flow through capillaries is slow
  • Structure permits 2-way exchange (fluid moves in and out)
  • 8 um in diameter
  • Found near almost every cell
37
Q

What are the different types of capillaries?

A

Continuous

Fenestrated

Sinusoidal

38
Q

What are continuous capillaries?

A
  • Majority of capillaries are continuous
  • Cells are all next to each other with no gaps
  • E.g. skeletal and smooth muscle, CT and the lungs
39
Q

What are fenestrated capillaries?

A
  • These are more permeable
  • Pores penetrate the endothelial lining
  • Rapid exchange of water or large solutes (e.g. small peptides)
  • Involved in absorption
  • Found in kidney, choroid plexus and endocrine glands
40
Q

What are sinusoidal capillaries?

A
  • These are leakier
  • In spaces between endothelial cells
  • Incomplete or absent basement membrane
  • Exchange of large solutes i.e. plasma proteins
  • Found in specialised lining cells (e.g. in the liver, phagocytic cells engulf damaged RBCs)
  • Blood moves slowly through sinusoids
41
Q

What is flow through the capillary beds controlled by?

A

Metarterioles

Precapillary sphincters

Arteriovenous anastomoses

42
Q

What is the role of precapillary sphincters?

A

Guard the entrance to each capillary

Contraction narrows entrance = reduced flow
Relaxation dilates entrance = increased flow

43
Q

What are the structural adaptations of venules?

A
  • Smallest vein
  • Diameter = varies, average 20 um
  • Small = endothelium on basement membrane
  • Larger = increasing number of smooth muscle cells located outside of endothelium
44
Q

What are structural adaptations of veins?

A
  • Thin walled
  • Tunica externa is predominant
  • Valves to aid blood flow from lower parts of body moving up (facilitate one-way blood flow)

Body Systems (19 decks)

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