Lecture 17 - Circulation Flashcards Preview

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

Flashcards in Lecture 17 - Circulation Deck (31):
1

What are the 3 pre-capillary resistance vessels?

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

2

What are the exchange vessels?

Capillaries

3

What are the post-capilalry resistance vessels?

Venules

4

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

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

5

Why do meta-arterioles not exchange CO2/O2 ?

- contain vascular smooth muscle, therefore contribute to pre-capillary resistance

6

What kind of cells are capillaries made up of?

ENDOTHELIAL cells

7

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

1. Pre - capillary

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

8

Why is velocity of capillaries so LOW?

Large cross-sectional area

9

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

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

10

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

Outside?

1. Plasma Oncotic Pressure
2. Capillary Hydrostatic Pressure

Outside:
1. Tissue Oncotic Pressure
2. Interstitial Hydrostatic Pressure

11

Why is the movement of fluid crucial for healthy tissue?

- wash away metabolites, carry glucose, nutrients, proteins

12

Describe the relation between hydrostatic & oncotic pressure on the:
1. Arteriole Side
2. Venule Side
3. Capillaries

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)

13

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

Fluid moving OUT
(net force is 7 mmHg out)

- net filtration out (which occurs in the arteries)

14

Is the hydrostatic pressure in the following areas high or low?:
1. Glomerulus
2. Lungs - alveoli
3. Lymphatics

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

15

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

Lymphatic System

- shunts blood to the RIGHT side of the heart

16

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

ALBUMIN

- exerts a high hydrostatic pressure
51% concentration but exerts 65% of the plasma oncotic pressure

17

What is the affect of Albumin on the cell?

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

and increases the osmotic force by retaining more WATER

18

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

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

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

1. decrease pre/post resistance
2. Increase pre/post resistance

1. INCREASE hydrostatic pressure


2. DECREASE hydrostatic pressure

20

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

PULMONARY EDEMA

- high hydrostatic pressure pushing fluid OUT which seeps into the alveoli

21

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

- 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

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

Pulmonary Hypertension

- no pulmonary edema since this is on the ARTERIAL side (not venous)

23

What endothelial derived mediators function to VASODILATE? Vasoconstrict?

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

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

24

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

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

What 3 factors govern lymph flow?

1. Amount of capillary filtration

2. Skeletal muscle activity (squeezed like veins)

3. Lymphatic unidirectional VALVES

26

Why is there tremendous swelling after surgery?

Destruction of the lymphatic vessels

- fluid is leaking out & is not absorbed therefore SWELLING occurs

27

What is Edema?

1. Accumulation of excess fluid within the interstitial space

28

What are some clinical manifestations of edema?

1. swelling of ankles
2. Ascites
3. Pulmonary Edema

29

What are 4 precipitating factors in Edema?

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

What are 5 possible causes of edema?

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

What are 2 reasons for Portal Hypertension?

1. Increase pressure in IVC

2. Increase resistance in Hepatic Veins