Chapter 19 - The Cardiovascular System - Blood Vessels

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1

Acidosis

State of abnormally high hydrogen ion concentration in the extracellular fluid.

2

Aldosterone

Hormone produced by the adrenal cortex that regulates Na+ reabsorption. Water there for followings, and blood volume increases ---> increase in Blood pressure

3

Angiotensin II

A vasoconstrictor activated by renin

Promotes release of Aldosterone and ADH (Antidiuretic Hormone)

4

Antidiuretic hormone

Promotes vasoconstriction and water conservation by the kidneys, resulting in increase of blood volume.

5

Atrial natriuretic peptide (ANP)

Acts as a vasodilator and an antagonist to aldosterone, resulting in drop in blood volume

6

Blood pressure (BP)

Force exerted by blood against a unit area of the blood vessel walls; differences in blood pressure between different areas of the circulation provide the driving force for blood circulation.

7

Cardiac output (CO)

Amount of blood pumped out of a ventricle in one minute.

8

Colloid osmotic pressure

Pressure created in a fluid by large non-diffusible molecules, such as plasma proteins that are prevented from moving through a (capillary) membrane. Such sub- stances tend to draw water to them

9

Diastolic pressure

Arterial blood pressure reached during or as a result of diastole; lowest level of any given cardiac cycle.

10

Compliance

How much the elastic arteries close to the heart stretch

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Vasomotor Tone

A state of constant moderate constriction of the arterioles

12

Hydrostatic pressure

Is the force exerted by a fluid pressing against a wall.

13

Hepatic portal system

Circulation in which the hepatic portal vein carries dissolved nutrients to the liver tissues for processing.

14

Humoral immunity

Immunity conferred by antibodies present in blood plasma and other body fluids.

15

Mechanoreceptor

Receptor sensitive to mechanical pressure such as touch, sound, or exerted by muscle contraction

16

Osmotic pressure

A measure of the tendency of water to move into a more concentrated solution.

17

Proprioceptor

Receptor located in a joint, muscle, or tendon; concerned with locomotion, posture, and muscle tone.

18

Renin

Enzyme released by the kidneys that raises blood pressure by initiating the renin-angiotensin-aldosterone mechanism.

19

Systemic circuit

System of blood vessels that serves gas exchange in the body tissues.

20

Vasomotor center

Brain area concerned with regulation of blood vessel resistance.

21

Mean arterial pressure (MAP)

the pressure that propels the blood to the tissues.

22

Elastic Arteries - (Conducting)

Thick-walled arteries (pulmonary & descending aorta)

With large lumen and found near heart

Largest diameter with most elastin

They expand and recoil to accommodate changed in blood volume which results in the blood being kept under pressure

23

Muscular Arteries - (Distributing)

Thickest tunica media of all BV

They deliver blood to specific organs

More active in vasoconstriction (due to more smooth muscle in t. media)

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Arterioles

Smallest of arteries

Regulate blood flow to the capillary beds

Most are single layer smooth muscle around the endothelial lining

25

Capillaries

Only thin tunica media

Large enough for single file RBC to pass by

Microscopic

26

Continuous capillaries

Most common

Found in skin and muscle

They are endothelial cells that provide an uninterrupted lining

27

Fenestrated capillaries

Similar to continuous

Have pores so nutrients can diffuse

Found in small intestines and kidneys (where absorption occurs)

28

Sinusoidal capillaries

"Leaky" capillaries

Irregular shaped lumens that allow passage of large molecules (proteins & blood cells)

Found in liver, blood, and marrow

29

Capillary Beds

Interweaved networks that are regulated by vasomotor nerve fibers & local chemical conditions

They can be flooded or shunted if blood is needed in other parts of body

30

Venous System

Venous vessels increase in diameter & their walls thicken at you get closer to the heart

31

Venules

Smallest - Postcapillary venule

Extremely porous so fluid and WBC from blood stream can move easily through walls

Sparse tunica media and externa

32

Veins

Wall thinner and lumen is larger than corresponding arteries

Called blood reservoir

Have semi-lunar valves; most abundant in veins in limbs

33

Venous sinuses

High specialized

Are flattened veins with thin walls and supported by tissues around them

34

Blood Flow

The actual volume of blood flowing through and area in a given period

Area of flow could be a vessel, an organ, or the entire circulation

35

Blood Pressure

Force that blood exerts on a given area of a blood vessel wall

If term is used with not specification to location of body, it is the systemic arterial blood pressure in the larges arteries near the heart

Pressure gradient keeps blood moving

36

Resistance

Opposition to blood flow. It is the measure of the amount of friction blood encounters as it passes through the blood vessels

Peripheral resistance - most resistance

Three sources: BV length, BV diameter, viscosity of blood,

37

Factor of resistance - Viscosity of blood

Is resistance to flow caused by molecular interactions within a fluid (different parts of river flowing)

Under normal conditions, blood viscosity is fairly constant

Dehydration or polycythemia will increase blood viscosity

Anemia will reduce viscosity

38

Factor of resistance - BV length

Longer the BV = more resistance

39

Factor of resistance - BV diameter

Arterioles have the smallest diameter and change diameter due to neural and chemical controls

Arterioles are major determinants of PR

40

Influencing factors of Arterial blood pressure:

1) How much the elastic arteries close to the heart stretch? (compliance)

2) The volume of blood forced into the arteries at a particular time

41

Pulse pressure

The difference between the systolic and diastolic pressures

The actual "working" pressure of the heart.

It is the amount of force given off by the heart during each cardiac cycle

42

Why is low capillary blood pressure desirable?

1) capillaries are fragile and high pressures would rupture them

2) most capillaries are extremely permeable and thus even the low capillary pressure can force solute-containing fluids (filtrate) out of the bloodstream into the interstitial space. These fluid flows are important for continuously refreshing the interstitial fluid.

43

Two systems that help venous return

1) Muscular pump

2) Respiratory pump

44

Muscular pump - Venous Return

Skeletal muscles surround deep veins. As they contract and relax, blood is "milked" through the veins, successive passing of valves each time.

45

Respiratory pump - Venous Return

Pressure changes during breathing help suck blood upwards

Inhale - lungs inflate, pressure increases in abdominal cavity, blood moves towards heart - climbing the valve stairs

Exhale - Thoracic cavity decreases, building pressure to push blood towards to heart

46

Short-term Mechanisms to control Blood pressure

1) Vasomotor Center
2) Baroreceptor-initiated reflexes
3) Chemoreceptor-initiated reflexes
4. Higher Brain Centers

47

Purpose of short-term mechanisms to control BP?

1) Regulate blood vessel diameter, heart rate, and contractility
2) Regulated by neural and local chemical conditions

48

Formula for BP

Blood pressure = cardiac output X peripheral resistance

49

What cells in the kidneys monitor alterations in blood pressure?

Granular cells

50

What is the role of the Hypothalumus in regulating Blood Pressure?

1.It excites the thirst center stimulating the individual to drink more water, rehydrating blood → restoring blood volume--> increasing blood pressure

51

What is Peyer's Patch?

1) Aggregates of lymphoid nodules located in the wall of the ileum are
2) Destroy bacteria in appendix; generate "memory" lymphocytes for long-term memory in intestine

52

Where does extra tissue fluid in Brain drain into?

Cerebrospinal Fluid -(CSF)

53

Which of the following cells would not be found in a germinal center in a lymph node?

Macrophages

54

Lymph Node Location:

B-cell Within germinal center
T-cell Deep cortex
Dendritic cells Surrounding the germinal centers
Plasma cells Medullary cords
Macrophages Lymph Sinus