packet 6 Flashcards Preview

A&P II > packet 6 > Flashcards

Flashcards in packet 6 Deck (36):
1

Overall function of cardiovascular system and blood flow in general is affected by

Blood Pressure
Resistance
Venous Return
Velocity and Volume

2

force exerted by circulating blood on the walls of blood vessels

blood pressure

3

systolic - diastolic
important measure of stress exerted on small arteries

pulse pressure

4

Factors that determine systemic vascular resistance

Blood viscosity
Vessel length
Radius
Laminar flow

5

7-13 mm Hg venous pressure towards heart

Pressure gradient

6

inhalation - thoracic cavity expands (pressure ) abdominal pressure , forcing blood upward
central venous pressure fluctuates

thoracic pump

7

Exercise increase venous return in many ways

heart beats faster, harder - increase cardiac output (CO) and BP
vessels of skeletal muscles, lungs and heart dilate increase flow
increase respiratory rate increase action of thoracic pump
increase skeletal muscle pump

8

venous pressure not enough force blood upward
with prolonged standing, CO may be low enough to cause dizziness or syncope the following cause

venous pooling

9

Vasoconstriction of blood vessel smooth muscle is controlled both by

the autonomic nervous system and at the local level (sympathetic increase parasympathetic decrease)

10

Four factors control arterial flow at the organ level (includes body position):

change in metabolic activity
- changes in blood flow
- stretch of arterial smooth muscle
- local chemical messengers

11

Blood pressure is a key factor for providing blood (oxygen and energy)

to organs

12

Systolic pressure must be at least 70 to sustain

kidney
filtration and adequate blood flow to the brain

13

Role of Cardiovascular center

Collection of nuclei that affect rate, force, vessel diameter

14

Signals sent out through vagus (parasympathetic)

lowers heart rate

15

help regulate heart rate & stroke volume
specific neurons regulate blood vessel diameter - sympathetic vasomotor nerves

nuclei

16

carotid and aortic sinuses sense the blood pressure in the aortic arch and internal carotid  send signal to the vasomotor center in the medulla oblongata
Other information are sent from the hypothalamus, cortex

Baroreceptors

17

Effects help maintain the blood flow to the brain at arterial pressure too low to activate the baroreceptors.

activated by hypoxia, hypocapnia, and acidosis are located in the aortic arch and carotid sinus.
Stimulated during asphyxia and severe hypotension.
Changes breathing, and include sympathetic constriction of (mainly skeletal muscle) arterioles and tachycardia resulting indirectly from the increased lung inflation.

chemoreceptors

18

Monitor blood pressure and take corrective action if it should drop.
Leads to a cascade of events eventually producing angiotensin II

kidney

19

constricts the walls of arterioles closing down capillary beds;
stimulates the proximal tubules in the kidney to reabsorb sodium ions;
stimulates the adrenal cortex to release aldosterone. Aldosterone causes the kidneys to reclaim still more sodium and thus water
stimulates the pituitary to release the ADH

Angiotensin II

20

A rise in blood pressure stretches the atria of the heart, triggers release of atrial natriuretic peptide (ANP).
ANP lowers blood pressure
The effects on the kidney reduce the reabsorption of water = increase flow of urine - the net effect = reduce blood pressure by reducing the volume of blood in the system.

heart

21

increases heart rate & force of contraction
causes vasoconstriction in skin & abdominal organs
vasodilation in cardiac & skeletal muscle

Epinephrine & norepinephrine

22

is ability to make these changes as needed by demand for O2 & waste removal

autoregulation

23

released from cells alter vessel diameter
(K+, H+, lactic acid, NO)
systemic vessels dilate in response to low levels of O2
pulmonary vessels constrict in response to low levels of O2

vasoactive substance

24

cause changes in each capillary bed
autoregulation is ability to make these changes as needed by demand for O2 & waste removal
important for tissues that have major increases in activity (brain, cardiac & skeletal muscle)

local factors

25

Constriction of arterioles leading to resistance in blood flow and strain on the heart
chronic resting BP > 140/90

hypertension

26

chronic low resting BP
caused by blood loss, dehydration, anemia

hypotension

27

Any state where cardiac output insufficient to meet metabolic needs (inadequate cardiac output = not enough O2 to meet metabolic needs)

shock and homeostasis

28

inadequate pumping of heart

cardiogenic shock

29

low venous return (LVR) shock - 3 principle forms

1. hypovolemic shock
2. obstructed shock
3. venous pooling

30

most common
loss of blood volume: trauma, burns, dehydration

hypovolemic shock

31

tumor or aneurysm

obstructed venous return shock

32

long periods of standing, sitting or widespread vasodilation

venous pooling

33

loss of vasomotor tone, vasodilation, causes from emotional shock to brainstem injury

neurogenic shock

34

bacterial toxins trigger vasodilation and increase capillary permeability

septic shock

35

severe immune reaction to antigen, histamine release, generalized vasodilation, increase capillary permeability

anaphylactic shock

36

An extremely low blood pressure
Fast but weak pulse
Dizziness, faintness or
light-headedness
Moist, clammy skin
Profuse sweating
Unconsciousness
Rapid, shallow breathing
Chest pain
Blue lips and fingernails

signs and symptoms of shock