Ch 13/14 Cardiovascular Physiology (Day 1) Flashcards Preview

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Flashcards in Ch 13/14 Cardiovascular Physiology (Day 1) Deck (26):
1

Main functions of the cardiovascular system

1. Transport of respiratory gases, nutrients, and wastes

2. Communication/Regulation—hormones & temperature

3. Defense/Protection--clotting and immunity

2

Cardiovascular System Components

Blood—fluid medium
-->Cells and plasma

Heart—pump (primary motive force)
-->Septum divides left and right halves

Blood vessels—conduit/delivery system (plumbing)
--> Arteries, arterioles, capillaries, postcapillary venules, veins
-->Pulmonary and systemic circulation


Associated w/cardiovascular system:
Lymphatic System: return fluid that has leaked out back to cardiovascular system, immune function
-->Lymphatic vessels, lymphoid tissues, lymphatic organs
(spleen, thymus, tonsils, lymph nodes)

3

Diffusion

-->simple method for moving things down a concentration gradient

equation for diffusion time: t=x2/2D
(t=time, x=distance you want molecule to move, D=diffusion coefficient)

Diffusion is fast over short distances, but slow over greater distances

Why is a cardiovascular system important?
-most important function of the circulatory system is
bulk transport [overcomes limitations of diffusion]

4

Overview of Cardiovascular system

1. pulmonary circulation: blood from body to heart to lungs

2. systemic circulation: blood from heart to body back to heart

-->right and left hearts are in series – so output from each side matches the other

5

Arrangement of Circulation

-arrangements of circulation to different organs is parallel (exception: GI series in liver: liver has two sources of blood, straight from heart and from GI tract)
--> this arrangement prevents blood flow changes in one organ from affecting flow to others

-lungs get 100% of cardiac output, rest of organs share the 100%

6

Blood

the fluid medium

-Average adult volume: 5 liters
-45% formed elements (platelet cells); 55% plasma (by volume): platelets are not real cells, fragment elements
-->blood plasma + formed elements + RBCs + "buffy coat" (platelets + WBCs)

1. Arterial blood – leaving the heart; bright red, OXYGENATED
[except for pulmonary artery - taking deoxygenated blood --> lungs]
2. Venous blood – entering the heart; dark red, DEOXYGENATED
[except for pulmonary veins - carrying oxygenated blood back to the heart]

7

Plasma volume

regulated to maintain BP
[CV/renal/hypothalamo-anterior pituitary-adrenal axis]

8

Plasma osmolality

regulated to maintain solute (Na+) concentration
[CV/renal/hypothalamo-posterior pituitary axis]

9

plasma constituents

water
ions
organic molecules (AA, proteins, glucose, lipids, nitrogenous waste)
trace elements/vitamins
gases (CO2, O2)

10

What is the most important plasma protein?

Albumins
source: liver
functions: Major contributors to colloid osmotic pressure of plasma (holds fluid-determines volume), carriers for various substance

11

Formed Elements (cells)

RBCs (erythrocytes)
WBCs
Platelets (cell fragments --> clotting)

12

RBCs

"Erythrocytes": Oxygen Transport

-Small, flattened, biconcave discs, no nuclei, no mitochondria
-120-day life span
-% of blood volume (hematocrit)—index of O2 carrying capacity of blood
-heme: binds to iron --> makes red color

-->Anemia: abnormally low hematocrit or hemoglobin count

13

Blood Count

+/- 58% blood plasma
>1% white cells
42% red cell packed volume

14

WBCs

"Leukocytes"

1. Granular: have granules (ex. neutrophils, eosinophils, basophils)
2. Agranular: no granules (ex. monocytes, lymphocytes)

-Have nuclei, mitochondria
-Move in amoeboid fashion—can move from capillaries, post-capillary venules into tissues (diapedesis/extravasation)
-Major role in innate & adaptive immune systems & inflammatory response

15

Platelets

"thrombocytes"

-Smallest formed element, fragments of megakaryocytes
-No nuclei
-Short-lived (5−9 days)
-Clot blood with several other chemicals and fibrinogen
-Release serotonin (stimulates vasoconstriction)

16

Hematopoiesis

development of blood cells and platelets—begins in bone marrow

17

Thrombopoiesis

production of platelets

-The cytokine, thrombopoietin stimulates growth of megakaryocytes and maturation into platelets

18

Erythropoiesis

production of red blood cells

-Red bone marrow produces about 2.5 million RBCs/sec
-Stimulated by the hormone erythropoietin (EPO) from kidneys in response to low blood O2
-Most iron is recycled from old RBCs (by macrophages), the rest comes from the diet

19

Leukopoiesis

production of white blood cells

-Begins in bone marrow, final development requires maturation in lymphoid tissues (lymph nodes, tonsils, spleen, thymus)
-As cells differentiate, they express membrane receptors to CYTOKINES, which have both general and specific effects in determining the final cell subtype:
---Multipotent growth factor-1
---Interleukin-1
---Interleukin-3
-----> above three are all general effects on all subtypes
---Granuloctye colony stimulating factor (G-CSF) —>neutrophils
---Granulocyte-monocyte colony-stimulating factor (GM-CSF)–> monos, eos

20

Cytokines

-Signaling molecule (peptide), usually, but not exclusively, secreted by cells of the immune system (e.g. EPO comes from kidney).
-Have effects on development and function of leukocytes and other cell types.
-May operate as paracrine or autocrine (paracrine & endocrine signals)

21

Hemostasis

Cessation of bleeding when a blood vessel is damaged.

Damage exposes collagen fibers to blood, producing:
-Formation of platelet plug
-Vasoconstriction (less blood able to leak out)
-Formation of fibrin protein web mature clot (wraps around platelets)

22

Blood Clotting: platelets and blood vessel walls

Intact endothelium secretes prostacyclin and nitric oxide, which:
-Vasodilate
-Inhibit platelet aggregation
--> makes surface slippery, prevents platelets from sticking

And CD39, which:
-Breaks down ADP into AMP and Pi to inhibit platelet aggregation further
-->preserves "slippery" nature

Normal intact endothelium:
-expresses/secretes platelet inhibitory factors
-barrier function—prevents exposure of platelets to sub-endothelial, extracellular matrix molecules
-->act as if nothing is there, platelets just float by

23

Damaged Endothelium

exposes collagen

-Platelets bind to exposed collagen and Von Willebrand Factor which hold them in place
--> ACTIVATION --> GET STICKY
-Activated platelets recruit MORE platelets and form plug by secreting: (Platelet release reaction)
---ADP (sticky platelets)
---Serotonin (vasoconstriction- act upstream to close down arterioles so less blood can be lost)
---Thromboxane A2 (sticky platelets and vasoconstriction)
-Activated platelets also activate & bind to soluble plasma clotting factors

24

Formation of Platelet Plug and Clot

-Platelets bind to fibrin --> wraps around and reinforces mass of aggregated platelets which effectively plugs the defect
-RBCs become entwined in the plug-->mature, solid clot

25

Coagulation Cascade

-->don't need to know specifics, BUT... both intrinsic and extrinsic pathways converge on formation of THROMBIN (converts fibrinogen --> fibrin which aids in cross linkage of platelets in blood clotting)

26

Clot formation/dessolution

-thrombin involved in BOTH (depends on which enzymes activates it)
-as vessel heals, factors are released which digest fibrin polymers