Exam 5 (Ch 35- Oxygenation) Flashcards
1
Q
Oxygenation
A
Refers to how well the cells, tissues, and organs of the body are supplied with oxygen.
2
Q
The musculoskeletal and neurological systems
A
Regulate the movement of air into and out of the lungs
3
Q
The lungs oxygenate the ____
A
blood
4
Q
The heart circulates the blood throughout the body and back to the ____
A
lungs
5
Q
The pulmonary system has two major components:
A
the airway and the lungs
6
Q
The airway consists of the
A
nasal passages, mouth, pharynx, larynx, trachea, bronchi, and bronchioles.
7
Q
Airway structures do the following:
A
- Moisten the air
- Warm the air
- Filter the air
8
Q
A moist mucous membrane lining adds
A
water to inhaled air
9
Q
Blood flowing through the vascular airway walls transfers
A
body heat to the inhaled air
10
Q
Specialized cells in the lining of the airways secrete
A
sticky mucus to trap foreign particles
11
Q
Cilia
A
tiny hairlike projections from the walls of the airways
12
Q
Cilia move rhythmically to
A
sweep trapped debris up and out of the airway
13
Q
Upper airway, located above the larynx, includes:
A
the nasal passages, mouth, and pharynx
14
Q
The pharynx (throat) contains the
A
openings to the esophagus and trachea
15
Q
The trachea lies just in front of
A
the esophagus
16
Q
The epiglottis is
A
a small flap of tissue superior to the larynx
17
Q
The epiglottis closes off the
A
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
Q
The lower airway, located below the larynx, includes
A
the trachea, bronchi, and bronchioles.
19
Q
The lower airway is considered
A
sterile
20
Q
The trachea, sometimes called the windpipe, extends from
A
the larynx to where it divides to form the right and left mainstem bronchi
21
Q
As the airways branch and become smaller, they have
A
progressively thinner and less cartilage, until it disappears completely in the smaller bronchioles
22
Q
The walls of the bronchi and bronchioles contain layers of
A
smooth muscles
23
Q
Bronchospasm
A
Spasm of smooth muscles of the bronchi and bronchioles.
Narrow the airways and obstructs airflow
24
Q
The lungs are
A
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
