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FHB Exam 1 - Cardiovascular Physiology > Lecture 17 - Circulation > Flashcards

Lecture 17 - Circulation Flashcards

1
Q

What are the 3 pre-capillary resistance vessels?

A
  1. Arterioles
  2. Metaarterioles
  3. pre-capillary Sphincters
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2
Q

What are the exchange vessels?

A

Capillaries

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3
Q

What are the post-capilalry resistance vessels?

A

Venules

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4
Q

What are the main characteristics that allow Capillaries to have great blood flow?

A
  1. Low velocity
  2. Intermittent (some open/closed)
  3. Direction (pressure gradient)
  4. NOT UNIFORM
  5. Rouleuax formation
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5
Q

Why do meta-arterioles not exchange CO2/O2 ?

A
  • contain vascular smooth muscle, therefore contribute to pre-capillary resistance
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6
Q

What kind of cells are capillaries made up of?

A

ENDOTHELIAL cells

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7
Q

Most resistance is on the pre or post-capillary side? Why is this?

A
  1. Pre - capillary

2. Post-capillary side has little smooth muscle & cannot control resistance much (4:1 ratio)

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8
Q

Why is velocity of capillaries so LOW?

A

Large cross-sectional area

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9
Q

What is the Rouleaux formation? How is this related to sickle cell anemia?

A
  1. RBC’s lineup on an angle to allow optimal O2/CO2 exchange

2. Sickle cells do not have Rolex formation and thus POOR O2/CO2 exchange

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10
Q

Transcapilalry Fluid exchange: What are two determinants of pressure INSIDE capillaries?

Outside?

A
  1. Plasma Oncotic Pressure
  2. Capillary Hydrostatic Pressure

Outside:

  1. Tissue Oncotic Pressure
  2. Interstitial Hydrostatic Pressure
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11
Q

Why is the movement of fluid crucial for healthy tissue?

A
  • wash away metabolites, carry glucose, nutrients, proteins
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12
Q

Describe the relation between hydrostatic & oncotic pressure on the:

  1. Arteriole Side
  2. Venule Side
  3. Capillaries
A

Arteriole:
Hydrostatic > Oncotic
- fluid OUT(filtration)

Venule:
Hydrostatic < Oncotic
- fluid IN (absorption)

Capillaries:
Hydrostatic > Oncotic
- fluid moves out at the pre-capillary and moves in at the post-capillary (as you move across the capillary bed)

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13
Q

If hydrostatic pressure is 32, and oncotic pressure is 25 which direction is fluid moving?

A

Fluid moving OUT
(net force is 7 mmHg out)

  • net filtration out (which occurs in the arteries)
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14
Q

Is the hydrostatic pressure in the following areas high or low?:

  1. Glomerulus
  2. Lungs - alveoli
  3. Lymphatics
A
  1. HIGH hydrostatic pressure - pushing fluid OUT (filtration)
  2. LOW hydrostatic pressure (fluid in- to keep alveoli dry & prevent fluid in interstitum aka pulmonary edema)
  3. low Hydrostatic pressure so fluid moves IN
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15
Q

Where does extra fluid go that is washed out of the interstitium? Where is it shunted from here?

A

Lymphatic System

  • shunts blood to the RIGHT side of the heart
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16
Q

What is of greatest importance for oncotic force & determines Oncotic pressure in the CAPILLARIES?

A

ALBUMIN

  • exerts a high hydrostatic pressure
    51% concentration but exerts 65% of the plasma oncotic pressure
17
Q

What is the affect of Albumin on the cell?

A
  • positively charged so it attracts CHLORIDE (-)
  • which retains SODIUM

and increases the osmotic force by retaining more WATER

18
Q

What exerts a large effect on capillary HYDROSTATIC pressure? Why?

A
  1. VENULES
  2. Has low post-capillary resistance

arteries have HIGH pre-capillary resistance so the hydrostatic pressure is low
- less moving out, less to contribute to Hydrostatic pressure

19
Q

Determine the Capillary hydrostatic pressure based on the pre/post-capillary resistance ratio:

  1. decrease pre/post resistance
  2. Increase pre/post resistance
A
  1. INCREASE hydrostatic pressure

2. DECREASE hydrostatic pressure

20
Q

What occurs if the Left Ventricle does not contract & fluid backs up into the Pulmonary veins?

A

PULMONARY EDEMA

  • high hydrostatic pressure pushing fluid OUT which seeps into the alveoli
21
Q

What occurs if there is an increase in Afterload on the Left Ventricle and blood backs up all the way to the Right Atrium?

A
  • backs up to Vena Cava (IVC, SVC)

PORTAL HYPERTENSION!!

  • CIRRHOSIS OF THE LIVER
    also: increased venous pressure in the viscera & patient gets ASCITES
  • accumulation of fluid in abdomen & ankles
22
Q

What is a common problem that occurs after Right Heart Failure?

A

Pulmonary Hypertension

  • no pulmonary edema since this is on the ARTERIAL side (not venous)
23
Q

What endothelial derived mediators function to VASODILATE? Vasoconstrict?

A
  1. Prostacyclins
  2. EDRF
  3. Nitric Oxide
  4. Metabolites

Constrict:
Endothelin!
- activates PLC to release IP3 and increase Calcium

24
Q

Describe the following of lymphatics:

  1. Flow of tissue fluid back to the heart
  2. Mechanism of control
  3. structure
  4. Where the collecting vessels end
A
  1. UNIDIRECTIONAL
  2. VALVES
  3. non-fenestrated endothelium (no smooth muscle & little basal lamina)
  4. return to SUBCLAVIAN on the right side of the heart
25
Q

What 3 factors govern lymph flow?

A
  1. Amount of capillary filtration
  2. Skeletal muscle activity (squeezed like veins)
  3. Lymphatic unidirectional VALVES
26
Q

Why is there tremendous swelling after surgery?

A

Destruction of the lymphatic vessels

  • fluid is leaking out & is not absorbed therefore SWELLING occurs
27
Q

What is Edema?

A
  1. Accumulation of excess fluid within the interstitial space
28
Q

What are some clinical manifestations of edema?

A
  1. swelling of ankles
  2. Ascites
  3. Pulmonary Edema
29
Q

What are 4 precipitating factors in Edema?

A
  1. Decrease in oncotic pressure (liver disease = less albumin made)
  2. Increase Capillary hydrostatic Pressure (venous system: CHF - fluid backs up)
  3. Increased capillary permeability = BURNS
  4. Lymphatic obstruction (parasites)
    - mechanical obstruction of venous return = tumor
30
Q

What are 5 possible causes of edema?

A
  1. CHF
  2. Mechanical obstruction of Venous return
  3. Renal disease (loss of protein)
  4. Liver disease (lack of albumin made)
  5. BURN!!! (increases capillary permeability)
31
Q

What are 2 reasons for Portal Hypertension?

A
  1. Increase pressure in IVC

2. Increase resistance in Hepatic Veins

FHB Exam 1 - Cardiovascular Physiology (26 decks)

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