Exam 3 Flashcards
(205 cards)
1
Q
What is pressure in the cardiovascular system produced by?
A
The heart
2
Q
Flow is proportional to…
A
1/R
3
Q
Why does pressure decrease as fluid travels along a tube?
A
Due to friction with wall of tube
4
Q
What does each side of the heart function as?
A
An independant pump
5
Q
What do elastic arteries serve as?
A
Pressure reservoir
6
Q
Why are arterioles the site of variable reistance?
A
Arterioles have high proportion of muscle
7
Q
Why are capillaries the site for exchange?
A
They are very thin
8
Q
Why do veins serve as a volume reservoir?
A
Systemic veins have high compliance, not very elastic
9
Q
What is allocation of blood flow to body structures determined by?
A
Changes in arteriolar resistance
10
Q
What does vasoconstriction result in?
A
Decrease in pressure downstream & increase in pressure upstream
11
Q
Why is velocity of blood flow lowest in capillaries?
A
Capillaries have large-cross sectional areas and therefore the lowest velocity. Low velocity allows time for diffusion
12
Q
What does velocity of flow depend on?
A
Total cross-sectional area of vessels
-large cross-sectional area = low velocity
13
Q
What are the 3 mechanisms of exchange at capillaries?
A
- Diffusion
- Vesicular Transport
- Bulk Flow
14
Q
What exchange occurs from diffusion?
A
Small solutes
15
Q
What exchange occurs from vesicular transport?
A
Large solutes & proteins
16
Q
What is transcytosis?
A
Combination of endocytosis, vesicular transport, & exocytosis
17
Q
What exchange occurs from bulk flow?
A
Water + Solutes
18
Q
What are the two possibilities of exchange from bulk flow?
A
- Filtration = from plasma to interstitial fluid
- Absorption = from interstitial fluid to plasma
19
Q
What is bulk flow exchange determined by?
A
-Hydrostatic pressure
-Colloid Osmotic pressure
20
Q
What is hydrostatic pressure?
A
Lower at venous end due to friction
21
Q
What is colloid osmotic pressure?
A
Osmotic pressure resulting from proteins restricted to plasma
22
Q
What is the net filtration pressure (NFP)?
A
Hydrostatic pressure (Ph) - Colloid osmotic pressure (pi)
23
Q
If NFP > 0, what happens?
A
Net filtration
24
Q
If NFP < 0, what happens?
A
Net Absorption
25
Why do we lose about 3L of fluid from plasma per day?
Filtration at arterial end usually exceeds absorption at venous end
26
What is the lymphatic system?
System of vessels & nodes that:
-returns excess interstitial fluid to the blood
-returns any filtered protein to the blood
-"filters" out pathogens
-absorbs fats in small intestine
27
What is edema?
Excess interstitial fluid - net filtration exceeds removal by lymphatic system
28
What is driving pressure?
Pressure created in ventricles, transferred to arteries
29
As blood travels through arteries --> capillaries --> veins, the pressure _______.
Decreases
30
Why do elastic arteries serve as pressure reservoir?
-stretch during systole
-elastic recoil maintains driving pressure during diastole
31
What is backward flow during diastole prevented by?
Semilunar valves
32
When does systolic pressure occur?
During ventricular systole
33
When does diastolic pressure occur?
During ventricular diastole
34
What is pulse pressure (PP)?
sBP - dBP
35
What is the equation for MAP?
2/3dBP + 1/3sBP
36
What is mean arterial pressure?
-Reflects driving pressure for blood flow to tissues
-Indicates whether there's enough pressure to perfuse all organs
37
What are the factors influencing MAP?
1. Cardiac output
2. Diameter of arterioles
3. Blood volume
4. Diameter of veins
38
What is the relationship between cardiac output and MAP?
Incr. CO = Incr. MAP
39
What is TPR?
Total peripheral resistance = resistance to flow, due to arterioles
40
What is the relationship between diameter of arterioles and MAP?
Decr. diameter = increase TRP = incr. MAP
41
How does NE change the diameter of arterioles?
Most systemic arterioles innervated by SNS neurons which release NE to incr. vasoconstriction through:
-alpha adrenergic receptors
-tonic control
42
What is the relationship between blood volume and MAP?
Incr. Blood Volume = Incr. MAP
43
What are the responses to changes in blood volume in the cardiovascular system and kidneys?
Cardiovascular system = rapid
Kidneys = slow
44
What is the cardiovascular control center? Where is it located?
Control of blood pressure & distribution of blood to tissues. Located in the medulla oblongata
45
What is the baroreceptor reflex?
-Primary reflex pathway for homeostatic control of MAP
-Rapid response
-Functioning all the time
46
What are baroreceptors?
Stretch-sensitive, respond to pressure
47
What does CVCC control?
Controls SNS output to specific regions of body to regulate blood distribution and enhance blood flow in fight-or-flight response.
48
What are the effects of the binding of NE to A-adrenergic receptors?
Widespread Vasoconstriction
49
What are the effects of the binding of Epi to B2-adrenergic receptors?
Vasodilation in skeletal muscle, heart, & liver
50
What is active hyperemia?
Local increase in blood flow due to increase in metabolic activity
51
Why is active hyperemia important for local control of distribution of blood flow?
Important strategy for tissues to regulate their own blood supply.
52
What are the paracrines causing local vasodilation?
-Incr. NO
-Incr. Adenosine
-Incr. Histamine
-Decr. O2
-Incr. CO2
-Incr. H+
53
What is cellular respiration?
Intracellular processes using oxygen to generate ATP + CO2 + H2O
54
What is external respiration?
Movement of gases between atmosphere & cells
55
What are the types of external respiration?
1. Ventilation
2. Gas exchange in the pulmonary circuit
3. Gas transport in the blood
4. Gas exchange in the systemic circuit
56
What are the functions of external respiration?
-support cellular respiration
-regulation of pH via retention or elimination of CO2
57
What is alveolar ventilation (Va)?
Volume of fresh air that reaches alveoli per minute
58
What is hyperventilation?
Increase Va
59
What is hypoventilation?
Decreased Va
60
What are the 2 outcomes if ventilation is inadequate?
-Hypoxia = insufficient O2 availability to cells
-Hypercapnia = elevated CO2 levels
61
What does gas exchange (diffusion) require at lungs & tissues?
A gradient in partial pressure.
62
What is partial pressure (Pgas)?
Pressure of a single gas
63
What is Dalton's Law?
Total pressure exerted by mixture of gases = sum of pressures exerted by individual gases
64
At sea level what is the Patm?
760 mmHg
65
What happens to Pgas and Patm at different altitudes?
Pgas & Patm change, but % gas in atmosphere is constant
66
What is the normal Po2 in our alveoli?
100 mmHg
67
What is the normal Pco2 in our alveoli?
40 mmHg
68
What happens to alveolar Po2 & Pco2 if we hypoventilate?
PO2 Decr. & PCO2 Incr.
69
What happens to alveolar Po2 & Pco2 if we hyperventilate?
PO2 Incr. & PCO2 Decr.
70
In peripheral tissues what is the PO2?
40 mmHg
71
In peripheral tissues what is the PCO2?
46 mmHg
72
What are the factors that increase alveolar gas exchange?
- Incr. partial pressure gradient
- Incr. surface area
- decr. diffusion distance
73
What are conditions that decrease alveolar gas exchange?
-Decr. surface area
- Decr. partial pressure gradient
- Incr. diffusion distance
74
What is Henry's Law?
Movement of gas from air to liquid is proportional to:
1. Solubility
2. Pressure Gradient
75
What is the Law of mass action for plasma PO2?
-Incr. Plasma PO2 causes incr. in binding
-Decr. in plasma PO2 causes decr. in binding and more release O2
76
What does the amount of O2 bound to Hb depend on?
-% saturation of Hb due to Po2
-Number of O2 binding sites (# of RBCs & Hb content per RBC)
77
What is the oxyhemoglobin saturation curve?
Shows % of available binding sites occupied determined by plasma Po2
78
Why is the shape of the oxyhemoglobin saturation curve important?
Sigmodial "S" shape important for delivering O2 to active tissues
79
What does a right shift curve in the oxyhemoglobin saturation curve mean?
Right-shifted curve occurs in active or chronically hypoxic tissues and increases O2 delivery to cells
80
What is a right shift curve in the oxyhemoglobin saturation curve caused by?
-Incr. PCo2
-Decr. pH (due to more lactic acid)
-Incr. temperature
-Incr. 2,3-BPG
81
What is 2,3-BPG?
A molecule that is a byproduct of cellular metabolism in chronically hypoxic cells
82
What are the 3 ways CO2 is transported in the blood?
1. Dissolved in plasma: 7%
2. Bound to hemoglobin: 23%
3. Converted to bicarbonate: 70%
83
What is the chemical equation for bicarbonate?
CO2 + H2O = H2CO3 = H+ + HCO3-
84
What is the law of mass action for bicarbonate?
-Hypercapnia --> right shift --> incr. H+ = acidosis
-Hypocapnia --> left shift --> decr. H+ = alkalosis
85
Where does CO2 enter RBC?
CO2 enters plasma at tissues --> enters RBC
86
Where does CO2 leave RBC?
CO2 leaves plasma at lungs --> leaves RBC
87
What are the features of ventilation?
-uses skeletal muscle
-controlled by CNS via somatic motor neurons
-rhythmic process
-does not require conscious effort
88
How is the rhythmic pattern of ventilation generated by the medulla oblongata?
-pre-Botzinger complex = "pacermaker" neurons
-Dorsal respiratory group
-Ventral respiratory group
89
What does the dorsal respiratory group of the medulla oblongata do?
Regulate inspiratory muscles
90
What does the ventral respiratory group of the medulla oblongata do?
Regulate expiratory muscles
91
What does the pontine respiratory groups do to regulate ventilation?
Smooths out rhythm
92
What are output signals of ventilation modified by?
-Voluntary input from cerebral cortex
-limbic system
-fever
-chemoreceptors
93
What do chemoreceptors do?
Monitor CO2, O2, and pH levels
94
Where are chemoreceptors located?
-Central chemoreceptors in medulla oblongata
-Peripheral chemoreceptors at carotid arteries & aorta
95
What do the central chemoreceptors do?
Sense changes in PCo2 detected as pH of CSF
96
What do the peripheral chemoreceptors do?
Sense changes in PCo2, pH, and Po2 in blood
97
What is ventilation normally controlled by?
pCO2 and pH
98
What must pO2 fall below in order to affect ventilation?
60 mmHg
99
What is the shallow water blackout effect?
Swimmers will hyperventilate before diving in order to initially lower their Co2 levels and be able to stay underwater for longer, however blackout will kick in when O2 falls too low
100
What are the mechanics of ventilation?
Air flows from regions of higher pressure to lower pressure
101
What is Boyle's Law?
Pressure is inversely related to volume of the container
102
What happens during inspiration?
1. The diaphragm contracts (flattens)
2. Thoracic volume increases
3. Lung tissue is stretched
4. Alveolar volume increases
5. Alveolar pressure decreases
6. Air moves into the lungs
103
What kind of muscle is the diaphragm? What kind of motor nerve innervates it?
Smooth muscle; somatic motor neuron
104
What happens during expiration?
1. Diaphragm relaxes (unflattens)
2. Thoracic volume decreases
3. Elastic recoil of lungs
4. Decrease in alveolar volume
5. Increase in alveolar pressure
6. Air moves out of the lungs
105
How does CO2 affect airway diameter?
High CO2 in expired air = bronchodilation
106
How does histamine affect airway diameter?
Histamine from mast cells causes bronchoconstriction
107
What influence does the parasympathetic NS have on airway diameter?
Parasympathetic --> ACh --> mAChR = constriction
108
What influence does the sympathoadrenal NS have on airway diameter?
Sympathoadrenal --> Epi (through blood) --> B2-adrenergic = dilate
109
What is compliance?
Ability of lungs to stretch
110
What is elastance?
Ability to recoil after stretch
111
What happens when compliance decreases?
Difficulty inspiring
112
What happens when elastance decreases?
Difficulty expiring
113
What does the narrowing of airways cause?
Increased resistance
114
What is tidal volume (Vt)?
Volume of air that moves during a single inspiration or expiration
115
What is inspiratory reserve volume (IRV)?
Additional Volume you can inspire above tidal volume (Vt)
116
What is expiratory reserve volume (ERV)?
Amount of air that can be forcefully exhaled after end of normal expiration
117
What is residual volume (RV)?
Volume of air remaining after maximal exhalation
118
What is the equation for vital capacity (VC)?
VC = Vt + IRV + ERV
119
What is the equation for total lung capacity (TLC)?
TLC = VC + RV
120
What is the ventilation rate (VR)?
Breaths per minute
121
What is the minute (total pulmonary) ventilation (Ve)?
Volume of air inhaled or exhaled per minute = VR x Vt
122
What are the functions of the kidney?
1. Filter Blood
2. Play role in hormonal regulation of blood pressure
3. Storage & release of urine
123
Why does the kidney filter blood?
To retain vital substances, eliminate waste, and maintain homeostasis of water & ions
124
What are the 4 processes that occur in the kidney?
1. Filtration
2. Reabsorption
3. Secretion
4. Excretion
125
What function of the kidney occurs at Bowman's capsule?
Filtration
126
What function of the kidney occurs at the proximal tubule?
Reabsorption & secretion
127
What function of the kidney occurs at the loop of henle?
Reabsorption
128
What function of the kidney occurs at the distal nephron (distal tubule + collecting duct)?
Reabsorption & Secretion; final control of water, ions & pH
129
What is the blood supply of the kidney?
Renal portal system = Afferent arteriole --> glomerulus --> efferent arteriole --> peritubular capillaries
130
What is produced from filtration in the kidney?
Filtrate = filtered plasma without proteins or RBC
131
What is filtration?
Passive leakage of plasma
132
What is the renal corpuscle?
Glomerulus + Bowman's capsule
133
What is the filtration fraction?
% of plasma passing through glomerulus that is filtered = 20%
134
What is the glomerular filtration rate (GRF)?
Volume filtered/ time
135
What are the 3 barriers that substances leaving the plasma must pass?
1. Fenestrated capillary endothelium
2. Basement membrane
3. Podocytes (filtration slits) of epithelium of Bowman's capsule
136
What is the filtration coefficient increased by?
-SA of glomerular capillaries
-Permeability of filtration slits
137
What does the GFR in the renal corpuscle depend on?
-Glomerular hydrostatic pressure (Ph) = Blood pressure
-Colloid osmotic pressure (pi)
-Capsule fluid pressure
138
What is colloid osmotic pressure?
-Due to plasma proteins
-Opposes filtration
139
What is capsule fluid pressure?
-due to fluid within Bowman's capsule
-opposes filtration
140
What are the 2 ways of auto-regulation locally controlled by the kidney to maintain GFR?
1. Autoregulation by myogenic response
2. Autoregulation by tubuloglomerular feedback
141
How does autoregulation occur by myogenic response?
If MAP is too high & GFR is too high this stretches the afferent arteriole smooth muscle
-open stretch-sensitive ion channels
-muscle cell depolarizes
-open Ca2+ channels
-vascular smooth muscle contracts
-vasoconstriction of afferent arteriole incr. resistance to flow
-blood flow through afferent arteriole decr.
-decr. GFR
142
How does autoregulation by tubuloglomerular feedback happen?
If GFR too high there is faster fluid flow through tubules
-incr. NaCl detected by macula densa cells
-release paracrine signal to vasoconstrict afferent arteriole
-decr. GFR
143
What are juxtaglomerular apparatus?
Specialized region where distal tubule & afferent arteriole meet for regulation of GFR & MAP
144
What are macula densa cells?
Part of JGA in wall of tubule
145
What are granular cells?
Part of JGA in wall of arteriole
146
What happens under sympathetic input to neural & hormonal effects on GFR?
Incr. Epi, NEpi cause vasoconstriction of afferent arteriole to maintain high MAP and decr. GFR to decr. urine production and maintain blood volume
147
What is the primary driving force for most reabsorption?
Na+
148
What happens during reabsorption?
Filtrate --> interstitial fluid --> blood in peritubular capillaries
149
How is Na+ reabsorbed?
Diffuses passively from filtrate into tubule cell via carriers then actively transported into interstitial fluid
150
Why is Na+ the primary driving force for most reabsorption?
-Anions follow Na+
-Water follows solutes by osmosis
151
What is the Na+-linked transport used for?
Used for reabsorption of many valuable substances such as glucose that is reabsorbed by SGLT transporter against its concentration gradient
152
What is the transport maximum (Tm)?
Transport rate at saturation
153
What is the renal threshold?
Plasma concentration at which saturation occurs
154
What is secretion?
Active transport from blood to filtrate
155
How is secretion different from filitration?
It is selective via carrier proteins
156
What is secretion important for?
K+ & H+ homeostasis in the collecting duct
157
What decreases secretion of a molecule?
Molecules competing for carriers
158
What is excretion?
Removal from the body
159
What is urine?
Filtrate that leaves the collecting duct
160
What is the equation for excretion?
Excretion = Filtration - Reabsorption + Secretion
161
What is the renal handling of a substance?
An accounting of how much reabsorption and/or secretion of that substance occurs
162
What is clearance of a substance?
Volume of plasma cleared of that substance per minute
163
If clearance of X = GFR what is happening?
X is neither reabsorbed nor secreted
164
If clearance of X is < GFR, what is happening?
Net reabsorption of X
165
If clearance of X is > than GFR, what is happening?
Net secretion of X
166
What is micturition?
Urination
167
What occurs at rest regarding micturition?
-Somatic motor neurons to external sphincter tonically active (=contracted)
-Internal sphincter (smooth muscle) passively closed
168
What is the micturition reflex and what activates it?
Stretch receptors in the bladder wall activate micturition reflex:
-parasympathetic neurons cause contraction of smooth muscle in bladder wall which mechanically opens internal sphincter
-somatic motor neurons to external sphincter inhibited (=no contraction)
169
What is the voluntary inhibition of micturition?
The cerebral cortex stimulates an excitatory input to somatic motor neurons causing them to contract/close external sphincter to override reflex inhibition
170
Why is Na+ the most important ECF solute?
Primary determinant of ECF volume
171
What is Na+ in ECF controlled by?
Aldosteron, ANP, angiotensin II
172
What is K+ controlled by?
Aldosterone
173
What is K+ a major determinant of?
Resting Vm
174
What does dysregulation of ECF osmolarity causes?
Hypo/hypertonic environment which causes the cell to swell or shrink
175
What is ECF osmolarity controlled by?
Vasopressin & thirst
176
What is ECF volume controlled by?
Regulating Na+
177
What does dysregulation of ECF volume cause?
Alters MAP (hypertension/hypotension)
178
ECF osmolarity & volume can change ______________.
Independently
179
What is the cardiovascular response to changes in blood volume?
-Fast, neural control
-Can't be sustained
-Can't add/remove fluid
180
What is the renal response to change in blood volume?
-Slow, mainly endocrine controlled
-Can remove fluid
181
What is the behavioral response to changes in blood volume?
-Thirst/drinking
-Slow
-Can add fluid
182
How is ECF osmolarity maintained?
-High EDF osmolarity stimulates thirst to intake fluid
-Varying urine concentration
183
What are the 3 key features of controlling urine concentration?
1. Filtrate entering collecting duct is dilute
2. Collecting duct is surrounded by medullary interstitial fluid with osmotic gradient
3. Amount of reabsorption is regulated by altering permeability of collecting duct
184
What is the osmotic gradient in the collecting duct?
-Reabsorbs water from collecting duct by osmosis
-Filtrate (becoming urine) traveling deeper through medullar becomes progressively more concentrated
185
What does the Loop of Henle function as in the production of interstitial osmotic gradient?
Countercurrent multiplier: self-reinforcing = "multiplier" effect
186
What does the thick portion of the ascending limb do?
-Actively reabsorbs Na+ & Cl- into interstitial fluid
-Not permeable to water
-Increases osmolarity of interstitial fluid
-Decreases osmolarity of filtrate as it ascends towards cortex
187
What does the descending limb do?
-Passive reabsorption of water into interstitial fluid
-Impermeable to solutes
-Decreases osmolarity of interstitial fluid
-Increases osmolarity of filtrate progressively as it descends into medulla
188
What is the vasa recta?
Peritubular capillaries associated with loop of Henle
189
What does the vasa recta do?
-removes water & solutes reabsorbed by loop of Henle
-has similar osmotic gradient
190
What is vasopressin?
Antidiuretic hormone secreted from the posterior pituitary
191
What does vasopressin do?
-Causes collecting duct cells to insert aquaporin channels in membrane to increase. collecting duct permeability to water
192
What happens to vasopressin if ECF osmolarity is too high?
Increase vasopressin secretion to increase permeability leads to more concentrated urine
193
What happens to vasopressin if ECF osmolarity is too low?
Decr. in vasopressin secretion decreases permeability to dilute the urine
194
What is the stimulus causing vasopressin secretion?
-An incr. in ECF osmolarity causes osmoreceptors in hypothalamus to shrink
-decr. blood pressure
-decr. in blood volume
-Angiotensin II
195
What is Aldosterone?
Secreted by adrenal cortex and acts on principal (P) cells of distal nephron to causes incr. of Na+ reabsorption and K+ secretion
196
What is the secretion of Aldosterone stimulated by?
Decr. blood pressure via RAAS pathway & incr. K+
197
What is the Renin-Angiotensin-Aldosterone System (RAAS)?
An endocrine pathway promoting an incr. in MAP
198
What is angiotensinogen?
Inactive plasma protein
199
What is renin?
Enzyme secreted by granular cells that converts angiotensinogen to angiotensin I
200
What is renin secreted in response too?
-Decr. MAP dectected by granular cells
-Decr. of GFR and decr. of NaCl detected by macula dense
-Decr. MAP through CVCC to incr. sympathetic input
201
How is angiotensin I converted to angiotensin II?
Using angiotensin converting enzyme
202
What does angiotensin II do?
Raises MAP by:
-incr. aldosterone secretion to incr. Na+ reabs. to incr. ECF volume
-incr. vasopressin secretion to incr. H2O reabs. to incr. ECF volume
-incr. thirst to incr. ECF volume
203
How does angiotensin interact with the CVCC?
-incr. HR, SV, TPR
-incr. vasoconstriction
-incr. Na+ reabs.
204
How does the atrial natriuretic peptide increase blood volume?
-in response to stretch of atria, indicates incr. of blood volume
205
How does the atrial natriuretic peptide decrease blood volume and MAP?
-decr. vasopressin, renin, and aldosterone
-CVCC: decr. HR, SV, TPR
-vasodilate afferent arteriole to incr. GFR
-decr. Na+ reabs.
