Exam 5 (Ch 35- Oxygenation) Flashcards Preview

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Flashcards in Exam 5 (Ch 35- Oxygenation) Deck (196):
1

Oxygenation

Refers to how well the cells, tissues, and organs of the body are supplied with oxygen.

2

The musculoskeletal and neurological systems

Regulate the movement of air into and out of the lungs

3

The lungs oxygenate the ____

blood

4

The heart circulates the blood throughout the body and back to the ____

lungs

5

The pulmonary system has two major components:

the airway and the lungs

6

The airway consists of the

nasal passages, mouth, pharynx, larynx, trachea, bronchi, and bronchioles.

7

Airway structures do the following:

-Moisten the air
-Warm the air
-Filter the air

8

A moist mucous membrane lining adds

water to inhaled air

9

Blood flowing through the vascular airway walls transfers

body heat to the inhaled air

10

Specialized cells in the lining of the airways secrete

sticky mucus to trap foreign particles

11

Cilia

tiny hairlike projections from the walls of the airways

12

Cilia move rhythmically to

sweep trapped debris up and out of the airway

13

Upper airway, located above the larynx, includes:

the nasal passages, mouth, and pharynx

14

The pharynx (throat) contains the

openings to the esophagus and trachea

15

The trachea lies just in front of

the esophagus

16

The epiglottis is

a small flap of tissue superior to the larynx

17

The epiglottis closes off the

trachea during swallowing so that food and fluids do not enter the lower airway.
It opens during breathing to allow air to move through the airway.

18

The lower airway, located below the larynx, includes

the trachea, bronchi, and bronchioles.

19

The lower airway is considered

sterile

20

The trachea, sometimes called the windpipe, extends from

the larynx to where it divides to form the right and left mainstem bronchi

21

As the airways branch and become smaller, they have

progressively thinner and less cartilage, until it disappears completely in the smaller bronchioles

22

The walls of the bronchi and bronchioles contain layers of

smooth muscles

23

Bronchospasm

Spasm of smooth muscles of the bronchi and bronchioles.
Narrow the airways and obstructs airflow

24

The lungs are

soft, spongy, cone-shaped organs.

25

Mediastinum

Separates the lungs.
Contains the heart and great vessels.

26

The right lung has ___ lobes

3

27

The left lung has ____ lobes

2

28

Apex

The upper portion of each lung; extends upward above the clavicle

29

Base

The lower portion of each lung; rests on the diaphragm

30

The lungs are composed of millions of

Alveoli

31

Alveoli

Tiny air sacs with thin walls surrounded by a fine network of capillaries.

32

Gases (oxygen and carbon dioxide) easily pass back and forth between the ___ and ____.

Alveoli & capillaries

33

Alveoli are composed of two types of cells:

Type I alveolar cells
Type II alveolar cells

34

Type I alveolar cells are the

gas exchange cells

35

Type II alveolar cells produce

surfactant

36

Surfactant

A lipoprotein that lowers the surface tension within alveoli to allow them to inflate during breathing.

37

Two major processes occur in the pulmonary system:

ventilation and respiration

38

Ventilation

the movement of air into and out of the lungs through the act of breathing

39

Respiration

The exchange of the gases oxygen and carbon dioxide in the lungs

40

Oxygenation of the blood, and ultimately of organs and tissues, depends on adequate _____.

Ventilation

41

Inhalation

Expansion of the chest cavity and lungs, which creates negative pressure inside the lungs; this causes air to be drawn in through the nose or mouth and airways.

42

Diaphragm

the major muscle of breathing; when it contracts with each inhalation, the chest cavity is pulled downward, pulling the lung bases downward with it.

43

Intercostal muscles

small muscles around the ribs that contract on inhalation and pull the ribs outward, slightly expanding the chest cavity and lungs.

44

Pleural membrane

covering that adheres to the lungs so that they can expand

45

Lung expansion creates _____ ______ and draws air in through the only opening to the outside, the trachea.

negative pressure

46

Exhalation

Diaphragm and intercostal muscles relax, allowing the chest and lungs to return to their normal resting size.

The reduction in size causes the pressure inside the chest and lungs to rise above atmospheric pressure, so air flows out of the lungs.

47

Exhalation requires no ___ or ____.

Energy, effort

48

What factors affect the adequacy of ventilation?

The rate and depth of respirations, lung compliance and elasticity, and airway resistance.

49

Respiratory rate and depth

Rate is how fast you breathe and depth is how much your lungs expand to take in air.

These processes affect O2 AND CO2 levels in the blood

50

Hyperventilation

When a person breathes fast and deeply to move a large amount of air through the lungs, causing too much CO2 to be removed by the alveoli.

51

Mild hyperventilation can occur in response to ____.

hypoxemia

52

Hypoxemia

A low level of oxygen in the blood.

53

When blood oxygen is low, ____ increases to draw additional air (and oxygen) into the lungs

ventilation

54

As ventilation increases, ___ ___ levels fall.

carbon dioxide

55

Severe hyperventilation is usually triggered by:

Medications, central nervous system abnormalities, high altitude, heat, exercise, panic, fear, or anxiety.

56

Hypoventilation

When a decreased rate or shallow breathing moves only a small amount of air into and out of the lungs.

57

Hypoventilation predisposes to the development of _____ because less air (carrying oxygen) reaches the alveoli.

hypoxemia

58

Hypoxemia can lead to

hypoxia

59

Hypoxia

An oxygen deficiency in the body tissues

60

Lung compliance

ease of lung inflation.

61

Lungs inflate easily because

Of their stretchy elastin fibers, low water content, and low alveolar surface tension.

62

Lung compliance is reduced by conditions that cause

elastin fibers to be replaced with scar tissue (collagen), increased lung water (edema), or loss of surfactant.

63

Lung elasticity (or elastic recoil)

refers to the tendency of the elastin fibers to return to their original position away from the chest wall after being stretched
e.g. stretching a rubber band, then letting go of it

64

Alveoli that have been overstretched, as with emphysema, lose their ___ ___ over time.

elastic recoil.
This loss of elasticity allows the lungs to inflate easily but inhibits deflation, leaving stale air trapped in the alveoli.

65

Airway resistance

The resistance to airflow within the airways. The larger the diameter of the airway, the more easily air moves through it.
Normally, airway resistance is very low, so it takes little effort to move large volumes of air into and out of the lungs.

66

Respiration

Gas exchange, the oxygenation of blood and elimination of carbon dioxide in the lungs.

67

Gas exchange occurs at 2 equally essential levels:

1) at the alveolar-capillary membrane in the lungs (external), and 2) at the capillary-cellular membrane in body tissues (internal)

68

External respiration (alveolar-capillary gas ex-change)

Occurs in the alveoli of the lungs. O2 diffuses across the alveolar-capillary membrane into the blood of the pulmonary capillaries; CO2 diffuses out of the blood and into the alveoli to be exhaled.

69

Pleural effusion

fluid in the lungs

70

Pneumothorax

lung collapse

71

Asthma

bronhospasms

72

Hypoxemia

Low blood-oxygen levels.

Occurs when blood is not adequately oxygenated in the alveoli.

73

Internal respiration (capillary-tissue gas exchange)

Occurs in body organs and tissues.
Oxygen diffuses from the blood through the capillary-cellular membrane into the tissue cells, where it is used for metabolism. From the cells, CO2, a waste product of cellular metabolism, diffuses through the capillary-cellular membrane into the blood, from where it is transported to the lungs and exhaled.

74

Tissue oxygenation requires both

adequate external respiration and adequate peripheral circulation.

75

The respiratory centers in the brain stem control ____ using feedback from chemoreceptors and lung receptors.

breathing

76

Chemoreceptors

Located in the medulla of the brainstem, the carotid arteries, and the aorta detect changes in blood pH, O2, and CO2 levels, and they send messages back to the central respiratory center in the brain stem.

77

Low blood O2 levels (hypoxemia) stimulate ____ to get more oxygen into the ____.

breathing, lungs

78

Lung receptors

Located in the lung and chest wall
Sensitive to breathing patters, lung expansion, lung compliance, airway resistance, and respiratory irritants.

79

The respiratory center uses feedback from the ____ ____ to adjust ______.

lung receptors; ventilation

80

Voluntary control from the ___ ___ can override the involuntary respiratory centers, but only temporarily.

motor cortex

81

Factors that influence pulmonary function include:

developmental stage, the environment, individual and lifestyle factors, medications, and pathophysiological states.

82

Premature infants (less than 35 weeks' gestation) do not have a fully developed ____ _____ system.

alveolar surfactant.

83

Surfactant

THe substance that keeps air sacs inflated for effective respiration.

84

Premature infants (less than 35 weeks' gestation) are at high risk for ___ ___ syndrome.

Respiratory distress syndrome (RDS)

85

Respiratory distress syndrome

Characterized by widespread atelectasis (collapse of alveoli)

86

Atelectasis

collapse of alveoli

87

The premature infant also has ____ ____ circulation.

immature pulmonary circulation.

88

Hypercarbia

High O2 blood levels (An excess of dissolved CO2 in the blood)
-Very high levels can have an anesthetic effect on the nervous system that can lead to coma and death (carbon dioxide narcosis)
-Can be caused by hypoventilation acute airway obstruction or dug overdose, or chronic lung disease

89

Infants born at term are also at risk for _____ ______.

Oxygenation problems
e.g., infection and airway obstruction

90

URI

Upper respiratory infections

91

Toddlers are at risk for

URIs because (1) the tonsils and adenoids are relatively large, predisposing to tonsillitis and (2) many children are exposed to new infections agents in preschool and day care.

92

Preschool and school-age children have developed mature ___, ____, and ___ systems that can adapt to moderate stress and change.

lungs, heart, and circulatory systems

93

Older adults tend to experience the following changes:

-Reduced lung expansion and less alveolar inflation
-Difficulty expelling mucus or foreign material
-Diminished ability to increase ventilation
-Declining immune response
-Gastroesophageal reflux disease

94

Environmental factors that affect oxygenation include:

stress, allergic reactions, altitude, and temperature.

95

Allergy

A hypersensitivity, or over-response, to an antigen.

96

Hay Fever

An allergic reaction affecting the eyes, nose, and/or sinuses.
-It causes the release of histamine, which is largely responsible for accumulation of nasal fluid, swollen nasal membranes, nasal congestion; and itchy, swollen, watery eyes.
-Antihistamines are effective in combating hay fever.

97

Asthma

An allergic reaction occurring in the bronchioles of the lungs.
-Slow reacting substance of anaphylaxis is released, which causes bronchoconstriction and lower airway edema and spasms, making breathing difficult and ineffective.
-Antihistamines have little effect b/c histamine is not a major factor in causing the asthmatic reaction

98

The most common serious chronic disease of childhood that can be life-threatening is:

asthma

99

Low oxygen levels at high altitudes can cause:

hypoxemia and hypoxia

100

People who live at high altitudes undergo physiological changes that facilitate oxygenation

-Ventilation
-Production of RBCs
-Lung volume and pulmonary vasculature (increase surface area for alveolar-capillary gas exchange)
-Vascularity of body tissues
-Production of hemoglobin

101

Maternal metabolism increases by approximately ____ during the last half of pregnancy, increasing the demand for O2.

15%

102

During pregnancy, the ___ ____ pushes upward against the diaphragm, limiting its downward movement.

enlarging uterus

103

The maternal respiratory rate increases in order to increase ___ _____.

minute ventilation (amount of air moved into and out of the lungs in 1 minute)

104

Obesity affects pulmonary function in the following ways:

-Respiratory infections: Excess abdominal fat presses upward on the diaphragm, preventing full chest expansion, leading to hypoventilation and dyspnea on exertion. Risk for respiratory infection increases b/c lower lung lobes are poorly ventilated and secretions not removed effectively.
-Sleep apnea: Chest expansion is limited when the person lies down. Excess neck girth and fat deposits in the upper airways leads to obstructive sleep apnea, a condition characterized by daytime sleepiness, loud snoring, and periods of apnea lasting 10- 120 seconds.

105

Effects of tobacco smoke

-Constricts bronchioles, increases fluid secretion into the airways, causes inflammation and swelling of the bronchial lining, and paralyzes cilia.
-These effects lead to reduced airflow and increased production of secretions that are not easily removed from the airways.
-Lung inflammation stimulates the release of enzymes that break down elastin and other alveolar wall components.
-Continued smoking leads to chronic bronchitis, obstruction of bronchioles and alveolar walls, and emphysema.

106

Excess use or overdose of respiratory depressants such as opioids, sedatives, antianxiety agents, and hypnotics can cause death due to

Hypoventilation, apnea, and respiratory failure.

107

Respiratory depressants generally act by depressing:

central nervous system (CNS) control of breathing or by weakening the muscles of breathing.

108

Ex of respiratory depressants:

general anesthetics, opioids (e.g., morphine), antianxiety drugs (e.g. diazepam), sedative-hypnotics (e.g. barbiturates), neuromuscular blocking agents, and magnesium sulfate.

109

Hypocarbia (hypocapnia)

A low level of dissolved CO2 in the blood. In most cases (except high altitude), blood O2 levels remain normal
-Caused by Hyperventilation
-Severe hypocarbia stimulates the nervous system, leading to muscle twitching or spasm (especially in the hands and feet) and numbness and tingling in the face and lips

110

To determine adequacy of tissue oxygenation, you must assess both:

circulation and tissue/organ function.

111

Poor peripheral circulation is characterized by

weak or absent pulses; mottling (skin marbling); pale, ashen, or cyanotic skin and mucous membranes; and cool skin temperature.

112

Upper respiratory infections (URIs) and influenza are both caused by

viruses

113

URI symptoms include:

stuffy nose, sore throat, cough, sneezing, tearing, and a mild fever.
-Colds are more common in children, and tend to decline with age. Rarely dangerous to healthy adults and children

114

Influenza

Highly infectious and usually more severe than the common cold and may involve the lower airways.
-Cold-like symptom: headache, fatigue, weakness, exhaustion, and high fever
-Most flu fatalities occur in children younger than age 2 and older adults.

115

Lower respiratory tract infections

-Acute bronchitis, respiratory syncytial virus (RSV), pneumonia, and tuberculosis
-More severe in children, older adults, and people with impaired immunity or lung function.

116

Structural abnormalities

Anything that restricts or limits the free movement of the chest wall (fractured ribs, kyphosis), interruptions in the chest cavity that inhibit inflation of the lungs (pneumothorax), or a collection of fluid (blood, lymph, pus) in the pleural space that inhibits lung expansion.

117

Airway inflammation and obstruction

Allergic reactions (asthma) or irritation from smoke or other irritants may cause airway inflammation.
-Obstruction may be mechanical or due to spasm (laryngospasm)

118

Atelectasis

Anything that reduces ventilation (e.g., tumor, obstructed airway) can cause atelectasis, or alveolar collapse

119

Alveolar-Capillary Membrane Disorders

Characterized by a change in the consistency of the lung tissue, especially at the alveolar level. THe alveoli become stiff and difficult to ventilate, and gas exchange is impaired. Pulmonary edema, acute respiratory distress syndrome (ARDS), and pulmonary fibrosis

120

For gas exchange to occur in the alveoli, there must be

adequate blood flow through the pulmonary circulation.

121

The most common causes of impaired pulmonary circulation are:

pulmonary embolus and pulmonary hypertension

122

Pulmonary embolus

Obstruction of pulmonary arterial circulation by a foreign substance (e.g., a blood clot, air, or fat).

123

Pulmonary hypertension

Elevated pressure within the pulmonary arterial system.

124

Signs of increased respiratory effort:

-Nasal flaring
-Retractions: visible "sinking in" of intercostal, supraclavicular, and subcostal tissue
-Use of accessory muscles
-Grunting
-Body positioning
-Paroxysmal nocturnal dyspnea: sudden awakening due to SOB during sleep.
-Conversation dyspnea: Inability to speak complete sentences w/o stopping to breathe
-Stridor
-Wheezing
-Diminished or absent breath sounds

125

Orthopnea

Difficulty breathing when lying down

126

Paroxysmal nocturnal dyspnea

Sudden awakening due to SOB that begins during sleep. P/t feels panic and extreme dyspnea and must sit upright to ease breathing

127

Dyspnea

Shortness of breath or difficult or labored breathing

128

Conversational dyspnea

The inability to speak complete sentences without stopping to breathe.

129

Stridor

A high-pitched, harsh, crowing, inspiratory sound caused by partial obstruction of the larynx or trachea.

130

Wheezing

A musical sound produced by air passing through partially obstructed small airways. It is often heard in patients with asthma and lung congestion.

131

Diminished or absent breath sounds

In a patient experienced dyspnea these are signs of worsening ventilation and oxygenation.

132

___ is a normal protective response to known respiratory irritant or when food or fluid accidentally gets into the airways.

Cough

133

Cough becomes significant if it ___, is ___, or is ____.

persists, recurring, productive

134

White or clear sputum

Usually present in viral infections

135

Yellow or green sputum

A sign of infection

136

Black sputum

Caused by coal dust, smoke, or soot inhalation

137

Rust colored sputum

Associated with pneumococcal pneumonia, tuberculosis, and possibly the appearance of blood

138

Hemoptysis

The coughing up of blood or bloody sputum.

139

Pink and frothy sputum

associated with pulmonary edema

140

Foul-smelling sputum usually indicates

bacterial infection

141

Tuberculin skin testing

Widely used to detect exposure and antibody formation to the tubercle bacillus
-A positive skin test is defined as an area of induration (hardness) at the test site.

142

Allergy Testing

Uses skin testing to identify antigens that may cause hypersensitivity reactions in susceptible individuals.
-Testing is performed by scratching antigen samples onto the skin.

143

Pulse oximetry

Noninvasive estimate of arterial blood oxygen saturation

144

SaO2

reflects the percentage of hemoglobin molecules carrying oxygen.
Normal value:95%-100%
Values below 94% are considered abnormal in healthy people

145

Capnography

Measures the carbon dioxide in inhaled and exhaled air
-More reliable indicator of respiratory depression than pulse oximetry

146

Situation in which capnography is used:

-When pt is receiving opioids
-During general anesthesia
-For critical care pts
-In obstructive sleep apnea
-Monitoring some infants with respiratory distress
-For adjusting parameter setting in mechanically ventilated patients
-For validating endotracheal tube placement (if placed correctly, little or no CO2 will be present

147

CO2 Detectors

Chemically treated paper that changes color when exposed to CO2.
Do not give exact reading, but can measure only a range of values.

148

Spirometry

Measure of air that moves into and out of the lungs.

149

Arterial blood gas (ABG)

Measures the levels of oxygen and carbon dioxide in arterial blood.
-An artery (usually brachial, radial, or femoral) is used to obtain the blood sample.
-Measures pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), saturation of oxygen (SaO2), and bicarbonate (HCO3) level.

150

3 values that are important when assessing the degrees to which the tissues are receiving oxygen:

-Hemoglobin
-PO2
-SaO2

151

hemoglobin

Iron-containing pigment of red blood cells that, as oxyhemoglobin, carries oxygen in the blood

152

PO2 (Partial pressure of oxygen)

amount of oxygen available to combine with hemoglobin to make oxyhemoglobin

153

SaO2 (Saturation of oxygen)

Reflects oxygen that is actually bound to hemoglobin

154

PCO2 (Partial pressure of carbon dioxide)

Measure of the CO2 dissolved in the blood
-Normal PCO2 is 35 to 45 mm Hg.

155

FIO2 (Fraction of Inspired Oxygen)

Percentage of oxygen in the air the patient is inhaling.
Normal room air is usually 21% oxygen (FIO2=21%)

156

Peak expiratory flow rate (PEFR)

Measures the amount of air that can be exhaled with forcible effort.

157

Bronchodilators

-Relax the smooth muscles lining the airways
-Can be administered as oral or inhaled medicines

Ex: Beta-2 adrenergic agonists, anticholinergics, methylxanthine

158

Respiratory anti-inflammatory agents

-Combat inflammation in the airways
-Important in treating and controlling respiratory conditions characterized by hypersensitive airways and airway inflammation (asthma)

Ex: Corticosteroids, Cromolyn, leukotriene modifiers

159

Nasal decongestants

-Relieve stuffy, blocked nasal passages by constricting local blood vessels through stimulation of alpha-1 adrenergic nerve receptors in the vessels
-Have systemic adrenergic effects causing elevated blood pressure, tachycardia, and palpitation, especially in those with history of cardiovascular conditions

Ex. Ephedrine, pseudoephedrine, phenylephrine

160

Antihistamines

-Prevent the effects of histamine release
-Used to treat upper respiratory and nasal allergy symptoms

Ex: Diphenhydramin (Benadryl), chlorpheniramine, brompheniramine, loratadine (Claritin), fexofenadine (allegra), cetirizine (Zyrtec)

161

Cough preparation

-Antitussives reduce the frequency of an involuntary, hacking, nonproductive cough
-Expectorants help make coughing more productive
-The goal is to reduce the frequency of dry, unproductive coughing while making voluntary coughing more productive.

162

Respiratory medications promote:

ventilation and oxygenation
-major types include bronchodilators, corticosteroids, cough preparations, decongestants, antihistamines, and mucolytics

163

Incentive spirometers

Encourage patients to take deep breaths by reaching a goal-directed volume of air. Usually reserved for patients at risk for developing atelectasis or pneumonia

164

Mobilizing secretions:

Deep breathing, coughing exercises, and hydration

165

Nebulizer

Device that turns liquids into an aerosol mist that can be inhaled directly into the lungs. Often used to deliver medications to the lungs, but can be used to deliver moisture to the airways and lungs.

166

Humidifiers

Device that delivers small water droplets from a reservoir.

167

Chest physiotherapy

Moves secretions to the large, central airways for expectoration or suctioning.

168

Postural drainage

Positioning to promote drainage from the lungs. Uses gravity to drain the lungs. Affected area will be placed in an uppermost position so that secretions drain down toward the large, central airways

169

Chest Percussion

Rhythmic clapping of the chest wall using cupped hands

170

Chest vibration

Vibrations of the chest wall with the palms of the hands.

171

Oxygen is supplied in several ways:

-Wall outlets: connected to a large central tank of oxygen
-Compressed O2 in portable tanks
-Liquid oxygen units: often used for home O2 therapy
-Oxygen concentrator: removes nitrogen from room air and concentrates O2.

172

Oxygen concentrators can deliver flow up to:

4L/min to create an FIO2 of approx. 36%
-Concentrations are higher at lower flow rates (e.g., FIO2 of 95% at 1L/min)

173

Low-flow devices:

nasal cannula, simple face masks, and rebreather masks

174

High-flow devices:

Venturi masks, aerosol face masks, face tents, and tracheostomy collars
-Capable of reaching up to 100% O2 concentration

175

Tracheostomy

Surgical opening into the trachea through the neck

176

Transtracheal catheter

Catheter placed into the tracheostomy to deliver O2 directly into the trachea
-Oxygen cannot be humidified through this device, is rarely used b/c of this.

177

Oxygen toxicity can develop when:

O2 concentration of more than 50% are administered for longer than 48 to 72 hours.
-Prolonged used of high O2 concentrations reduces surfactant production which leads to alveolar collapse and reduced lung elasticity.

178

Perfusion

Circulation of blood to all body regions

179

Pericardium

Sac of connective tissue encasing the heart

180

Atria

2 top chambers of the heart with thin walls that receive blood into the heart

181

Ventricles

2 bottom chambers of the heart with thick walls that pump blood out of the heart

182

Base

broadest side of the heart, which houses the atria, faces upward

183

Apex

tip of the heat, which houses the ventricles, faces downward

184

Deoxygenated blood from ___ and ___ flows through the ___ system into the ___ side of the heart and then into the pulmonary circulation.

organs, tissues; venous; right

185

Newly oxygenated blood flows from the ____ into the ___ side of the heart and out into the ___ circulation.

lungs; left; arterial

186

Cardiac cycle

sequence of mechanical events that occurs during a single heartbeat

187

Sinoatrial (SA) node

Acts as the pacemaker.
Located in the right atrium, it initiates an impulse that triggers each heartbeat.

188

Atrioventricular (AV) node

There is a slight delay..
Impulses pass into the left and right bundles of His and into the Purkinje fibers to the ventricles.
Stimulates myocardial fibers to create a unified cardiac muscle contraction strong enough to pump blood out of a heart chamber.

189

If the SA node fails, the ___ ___ can take over as the pacemaker, but it generally triggers a slower hear rate.

AV

190

Vascular system composed of:

Arteries, veins, and capillaries

191

Arteries

thick, elastic walls that allow them to stretch during cardiac contraction (systole) and to recoil when the heart relaxes (diastole).

192

Arterioles

Smaller branches of arteries. Primarily smooth muscle and thinner than arteries.
Constrict or dilate to vary the amount of blood flowing into capillaries and help maintain blood pressure

193

Capillaries

Microscopic vessels, created as arterioles branch into smaller and smaller vessels. Connect the arterial and venous systems and carry blood from arterioles to venules.

194

Venous system

Returns deoxygenated blood to the heart

195

Veins and venules

thin, muscular, but inelastic walls that collapse easily

196

The heart has its own blood supply through the ___ ___.

coronary arteries