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Human Physiology > Exam 3 LO > Flashcards

Exam 3 LO Flashcards

1
Q

What are the two kinds of nephrons?

A
  1. Cortical= 80%, short loops of henle (reabsorption)
  2. Juxtamedullary= 20%, long loops of Henley ( control urine concentration)
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2
Q

Renal cortex and renal medulla: iso-osmotic or hyper osmotic

A

Cortex= iso-osmotic and medulla= hyper-osmotic

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3
Q

Describe bowman’s capsule

A

Encloses glomerular fenestrated capillaries

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4
Q

The proximal convoluted tubule within the

Loop of henle within the

Distal tubule within the

A

Renal cortex
Extends into medulla then to cortex
Renal cortex

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5
Q

Fluid from renal corpuscle enters ___

A

Proximal tubule

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6
Q

Contains the ascending and descending loops

A

Loop of henle

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7
Q

Fluid enters __ from loop of henle

A

Distal tubule

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8
Q

The distal tubule contains what cells? What do those cells do?

A

Macula densa cells, sense ions

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9
Q

Forms ducts that drain into major calyces

A

Collection duct

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10
Q

Carries blood to the glomerulus, entering the capillary

A

Afferent arteriole

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11
Q

Capillary network, positioned between 2 arterioles

A

Glomerulus

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12
Q

Carries blood away from the glomerulus (leaving capillary)

A

Efferent arteriole

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13
Q

What cells do the afferent arteriole contain? Function of cells?

A

Juxtaglomerular cells, sense mean arterial pressure

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14
Q

Short loops of henle of cortical nephrons that extend from cortex to medulla

A

Peritubular capillaries

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15
Q

What is the juxtaglomerular apparatus?

A

Coordinates ions and blood pressure; macula densa cells plus juxtaglomerular cells

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16
Q

Explain the slits of podocytes

A

Surrounded by glomerular capillaries, contain pedicels and wrap around capillaries (spaces between pedicels are filtration slits)

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17
Q

Describe the fenestrated endothelium (glomerular endothelial cells) of the filtering membrane

A

allows for filtration of ions, water, small molecules, single amino acids, and drugs

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18
Q

What is the GFR?

A

Measure of kidney function, amount of filtrate formed per minute (120-125 mL/min)

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19
Q

What is the major determinant of GFR

A

Glomerular capillary hydrostatic pressure (P gc)

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20
Q

What is the GFR regulated by

A

Auto regulation of intrinsic factors, tubuloglomerular feedback, and extrinsic factors (neural and hormones)

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21
Q

Extrinsic factors regulate what

A

Blood pressure

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22
Q

What is RAAS

A

Renin, angiotensin, aldosterone, system

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23
Q

Ways to increase the GFR?

A
  1. Vasoconstrict efferent arteriole
  2. Vasodilator afferent arteriole

(Increase filtration: increase Pgc)

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24
Q

Ways to decrease GFR?

A
  1. Vasoconstrict afferent arteriole
  2. Vasodilate efferent arteriole (blood flowing out of capillary increases)
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25
Q

Promote filtration - oppose filtration=

A

Net filtration pressure

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26
Q

What starling forces promote filtration? What values?

A

Glomerular capillary hydrostatic pressure (55 mmHg) and bowman’s space protein/oncotic pressure (0 mmHg)

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27
Q

What starling forces oppose filtration?

A

Blood plasma protein pressure (in capillary- 30 mmHg) & bowman’s space hydrostatic pressure (15 mmHg)

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28
Q

Describe basement membrane of filtering membrane. Consists of? What passes through?

A

consists of collagen fibers and negatively charged glycoproteins and podocytes
- allows only water and small solutes to pass through
-negative charge repels plasma proteins and prevents them from entering bowman’s space

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29
Q

Autoregulation keeps the GFR constant as mean arterial pressure changes by:
If the MAP increases…

A

afferent arteriole vasoconstricts

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30
Q

Autoregulation keeps the GFR constant as mean arterial pressure changes by:
If the MAP decreases…

A

afferent arteriole vasodilates

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31
Q

Tubuloglomerular feedback is what kind of feedback

A

negative

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32
Q

Pathway of tubuloglomerular feedback to regulate GFR…

A
  1. Stimulus: Change in the GFR- increase in GFR
  2. Receptor: Sensed by the macula densa in the distal tubule
  3. Input: Increase in sodium, chloride, and water
  4. Control center: Juxtaglomerular apparatus
  5. Ouput: NO decreases (because it is a vasodilator)
  6. Effector: afferent arteriole vasoconstricts
  7. Response: Opposes stimulus- decrease in GFR
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33
Q

Extrinsic factors regulate….
What’s an example of a hormone?

A

blood pressure; RAAS

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34
Q

Increase in blood pressure= increase GFR — which results in what action

A

to get rid of fluid

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35
Q

If an increase in BP, this causes an increase stretch in the atria, which…

A

secretes ANP from the atria and increases GFR

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36
Q

Decrease in blood pressure= decrease in GFR—which results in what action

A

to save fluid

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37
Q

If there’s a decrease in BP, this causes an increase in…

A

sympathetics (NE) and angiotension II until BP returns to normal

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38
Q

Increase in sympathetics and angiotension effects the afferent arteriole how?

A

Vasoconstricts

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39
Q

What is not found in the filtrate?

A

cells, large proteins

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40
Q

Describe the body compartments, specifically the intracellular and extracellular fluid…

A

Intracellular fluid (inside the cell)= Na+: 15 mM
K+: 150 mM
Cl-: 7 mM

Extracellular fluid (blood plasma + interstitial fluid)=
Na+: 145 mM
K+: 5 mM
Cl-: 100 mM

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41
Q

What are the different functions of kidneys?

A

excretion of waste products (urine), regulate blood, and produce hormones

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42
Q

What hormones are produced in the kidneys?

A
  1. Erythropoetin (EPO)
  2. Active vitamin D
  3. Renin
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43
Q

Function of erythropoetin?

A

increase RBC count

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44
Q

Function of active vitamin D?

A

regulates calcium

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45
Q

Describe the RAAS production and pathway:

A
  1. Decreased BP in capillaries is sensed by juxtaglomerular cells in the kidney (less stretch in afferent arteriole walls)
  2. Juxtaglomerular cells secrete renin
  3. Angiotensinogen (inactive) is secreted from liver
  4. Renin removes -inogen from angiotensinogen, forming angiotension I
  5. In blood vessel, angiotensin I is converted into angiotension II by ACE (angiotension converting enzyme)
  6. Angiotension II effects the cardiovascular system by vasoconstricting (decrease radius, increase resistance)
    AND
    Angiotension II effects the kidney, causing the adrenal gland to secrete aldosterone, sensed by macula densa cells which increase sodium reabsorption and blood volume (water retension)
  7. Increases the blood pressure in #6
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46
Q

Describe how the distal tubule participates in homeostasis of H+ (pH regulation secretion) and K+ (aldosterone regulation secretion)

A

If there’s an increase in K+ in the plasma, it is sensed by the adrenal gland which secretes aldosterone

Aldosterone enters the kidneys/collecting ducts

K+ secreted into the urine

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47
Q

Role of aldosterone

A

Secrete more K+ and reabsorb more Na+

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48
Q

Relationship between blood and urine pH

A

If the blood is too acidic, urine will be acidic & vice versa

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49
Q

When H+ levels in the blood are high, what happens in the body?

A

Body secretes H+ and reabsorbs K+

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50
Q

When H+ levels in the blood are low, what happens in the body?

A

Body reabsorbs H+ and secretes K+

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51
Q

Compare and contrast the luminal and basolateral side of the cell (what is on each side?)

A

Luminal side= aquaporins, secondary active transport between Na+ and glucose or amino acids (co-transporter), and sodium/hydrogen exchanger

Basolateral sode= aquaporins, K+ leak channels, primary active transport (Na/K ATPase), glucose or amino acid transporters in reabsorption, bicarbonate transporter

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52
Q

What kind of reabsorption: solutes/water in tubular fluid return to bloodstream by passing through the cell through aquaporins

A

Transcellular reabsorption

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53
Q

What kind of reabsorption: solutes/water in tubular fluid returns to bloodstream by moving between cells (fluid leaking)

A

Paracellular reabsorption

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54
Q

What is the direction of tubular reabsorption vs secretion?

A

Reabsorption= lumen to peritubular capillary (blood)
Secretion= peritubular capillary(blood) to lumen

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55
Q

What is tubular reabsorption? What is commonly reabsorbed?

A

Taking the substances out of the filtrate in Bowman’s capsule and moved back into the bloodstream

Glucose, amino acods, ions, bicarbonate

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56
Q

What is tubular secretion? What is commonly secreted?

A

removing substances the body doesn’t need

H+, toxins, drugs

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57
Q

Secreting H+ into the urine and reabsorbing bicarbonate is driven by

A

Na/K ATPase

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58
Q

A measure of the volume of plasma over time that’s filtered of a particular substance

A

Clearance

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59
Q

Clearance is defined in terms of __ not __; clearance is __

A

plasma, urine; substance specific

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60
Q

How is clearance a measure of GFR?

A

Substance is reabsorbed when clearance of substance is less than GFR (back into the blood)

Substance is secreted when clearance of substance is more than the GFR (into urine)

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61
Q

What type of substances have a clearance less than GFR

A

Amino acids, glucose, things we want! (lower clearance)

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62
Q

What type of substances have a clearance more than GFR

A

toxins, drugs (have higher clearance)

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63
Q

Compare inulin and creatinine?

A

Free filtered

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64
Q

How does the body clear inulin

A

filtration

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65
Q

How is inulin a measure of GFR

A

clearance of inlulin is the same as GFR

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66
Q

Characteristics of inulin?

A
  • Not endogenous (not reabsorbed or secreted)
  • All of inulin in bowman’s capsule is excreted
  • Some of inulin of afferent arteriole is filtered
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67
Q

Characteristics of creatinine?

A

endogenous substance but not reabsorbed; slightly secreted at proximal tubule

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68
Q

What is creatinine?

A

breakdown of creatine phosphate in muscle

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69
Q

How is creatinine a measure of GFR

A

Best clinical measure of GFR

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70
Q

The largest amount of solute and reabsorption is where

A

Proximal tubule

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71
Q

100% of organic solutes (glucose or amino acids) are…

A

reabsorbed

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72
Q

H secretion and bicarbonate reabsorption uses what system

A

carbonic anhydrase

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73
Q

What is the effect of H on the pH

A

decreases the pH

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74
Q

what is the effect of bicarbonate on the pH

A

increases pH

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75
Q

How are acids (H+) and drugs secreted?

A

through secondary active transport coupled to Na co transport (NHE)

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76
Q

Describe the reabsorption of Na+, glucose, amino acids, and water in the proximal tubule

A

Water: water moves from the lumen to the cell to the peritubular capillary by aquaporins (transcellular reabsorption) or through paracellular reabsorption

Glucose and amino acids: glucose or amino acids are reabsorbed from lumen to the cell by secondary active transporters with sodium, then enter the peritubular capillary through glucose or amino acid transporters on the basolateral side.

Sodium ion: moves from lumen to the cell by secondary active transporter with glucose or amino acids, then enter the peritubular capillary through a primary active transporter Na+/K+ ATPase.

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77
Q

Describe the secretion of the hydrogen ion in the proximal tubule

A

Hydrogen ion secreted from the cell to the lumen by secondary active transporter (Na+/H+ exchanger) in exchange for Na+.

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78
Q

The process of secreting H+ into the urine and reabsorbing the bicarbonate ion back into the blood is driven by

A

Na+/K+ ATPase

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79
Q

__ combine in a cell through carbonic anhydrase to form bicarbonate and H+

A

Co2 from blood and water from lumen

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80
Q

Describe water reabsorption and osmolarity

A

As fluid moves along, solute reabsorption is followed by water—osmolarity remains constant

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81
Q

Describe the basics of water and balance

A

Major homeostatic function
Water gains=water loss (water gains are 60% liquid and water loss is 60% urine)

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82
Q

Juxtaglomerular nephrons are most involved in…

A

Water balance

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83
Q

Describe the osmolarity of cortex?

A

ISO-osmotic, 300 mOSM
- fluid becomes more concentrated as it enters descending loop in medulla

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84
Q

Describe the osmolarity of medulla

A

Hyper-osmotic, concentration of solutes increase as you move further into the medulla towards bottom of loop

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85
Q

Water flows out in __ loop through aquaporins, and the filtrate becomes more __

A

Out, concentrated

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86
Q

Urine becomes less concentrated in what loop?

A

Ascending

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87
Q

What occurs in the thick ascending loop?

A

A Na/K/Cl symporter, the ions move into the cell by the symporter at the same time in same direction
- nacl is pumped into the vasa recta capillaries and K is recycled through leak channels

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88
Q

Sodium and K enter the capillary by the symport through

Cl enters the capillary from symport by the

A

Sodium potassium ATPase
Cl channel

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89
Q

__osmolarity as we go down the medulla

A

High

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90
Q

Water travels by osmosis in what part of loop of henle

A

Descending loop

91
Q

As filtrate travels up ascending limb near cortex, it becomes…

A

Less concentrated as Na, K, Cl is pumped out of lumen into capillaries

92
Q

What is a diuretic

A

Chemical that makes urine, blocks na/Cl/k symporter so that water remains in urine

93
Q

What is the countercurrent multiplier?

A

Trapped NaCl in medulla causes a high osmotic environment

94
Q

As blood enters vasa recta capillaries, the capillary becomes

A

Hyperosmotic

95
Q

In vasa recta capillary, water leaves the capillaries and plasma becomes more __ causing __

A

Concentrated, NaCl to move back into capillary to maintain high osmolarity

96
Q

Makes the loop of henle a water circulator

A

Countercurrent exchange

97
Q

Concentration gradients in the medulla are due to….

A

different transport characteristics

98
Q

__ uses concentration gradients to (re)circulate salts and urea

A

Vasa recta

99
Q

Concentrated medulla is used to…

A

save water, involving ADH

100
Q

Loop of Henle helps save water by ___ and gets rid of water by __

A

concentrating urine, diluting urine

101
Q

Dehydrations leads to an…

A

increase in ADH, increasing aquaporins

102
Q

Why is urine diluted? Concentrated?

A

No aquaporins, no ADH; aquaporins present

103
Q

ADH partakes in

A

water reabsorption

104
Q

Acts on principal cell in collecting duct

A

ADH

105
Q

How does ADH act on the principal cell?

A
  1. ADH (from blood) binds to ADH receptor (GPCR) in principal cell, causing aquaporins to move to luminal side.
  2. Water leaves the urine and enters aquaporins on the luminal side
  3. Water leaves luminal side and travels to aquaporins on the basolateral side into capillary
106
Q

Describe the negative feedback regulation of ADH secretion from posterior pituitary:
If there’s an increase in plasma volume=
If there’s a decrease in plasma volume=

A

Increase in plasma volume= increase in water, decrease in ADH= increase in diluted urine
Decrease in plasma volume= decrease in water, increase in ADH= increase in concentrated urine

107
Q

Describe how the distal tubule participates in pH homeostasis of H+ and K+

A

Some H secreted by primary active transport in intercalated discs. The H that is secreted gets exchanged for K+ by K+/H+ ATPase pump

108
Q

In the proximal tubule, H+ is secreted and gets exchanged for __ by __

A

Na+, NHE (secondary active transporter)

109
Q

If the urine and the blood are too acidic=
If the urine and the blood are too basiac=

A

more H+ secreted and more bicarbonate reabsorbed
less H+ secreted and less bicarbonate reabsorbed

110
Q

Neural vs hormonal reflexes

A

Neural: baroreceptors, fast acting, subject to position change
Hormonal: RAAS, slow acting, blood volume and sodium changes

111
Q

Compare and contrast the proximal tubule as a work horse and distal tubule as a fine tuner

A

Proximal tubule:
- Does the most reabsorption and secretion (2/3 water and ions reabsorbed, all drugs and toxins secreted, all glucose and AA reabsorbed)
- Little hormone regulation

Distal tubule:
- Maintains homeostasis
- Small Na amounts reabsorbed and K secreted
- Regulated by hormones (ADH, aldosterone)

112
Q

What occurs in the early distal tubule?

A

Helps with calcium homeostasis in blood plasma

113
Q

What occurs in the LATE distal tubule? What is in the distal tubule?

A

Principal cells and intercalated discs, acid base and water balance

114
Q

Principal cells reabsorb and secrete what?

A

reabsorb Na and secrete K

115
Q

Intercalated cells reabsorb and secrete what?

A

reabsorb bicarbonate and secrete H+

116
Q

Aldosterone characteristics

A

Steroid hormone, can be long lasting when bound to albumin, slow acting

117
Q

Aldosterone is slow acting because it is involved in

A

gene transcription

118
Q

Aldosterone receptor binds to __ and regulates __

A

DNA, Na and K channels and Na/K ATPase pump

119
Q

What happens after aldosterone in the blood enters the principal cell?

A
  1. Aldosterone binds to aldosterone receptor and DNA
  2. Na, K, and Na/K ATPase are transcribed from binding
  3. Na reabsorbed entering capillary by Na/K ATPase and K is secreted
120
Q

The ability to stretch, the change in pressure needed to inflate the lung

A

Compliance

121
Q

What is surfactant’s effect on surface tension and compliance

A

Lowers the surface tension, increases compliance of the lung

122
Q

How does surfactant affect surface area and compliance

A

Decreases h bond formation to inflate the lung

123
Q

Example of high compliance in the lung and work of breathing

A

Emphysema, easy to inflate the lungs but hard to deflate

124
Q

High compliance requires what kind of change in pressure to inflate the lung? Low compliance?

A

Low pressure; higher pressure

125
Q

__ compliance = stretches easily

__ compliance= increased stiffness

A

High

Low

126
Q

Example of low compliance in the lung? Effect on work of breathing?

A

Restrictive lung disease (fibrosis), easy to deflate but harder to inflate

127
Q

Ability to return back to resting state once the force is released

A

Elastance

128
Q

What increases elastance (elastic recoil in the lung)

A

Elastin and collagen

129
Q

Relationship between compliance and elastance

A

If high compliance, low elastance
Inversely proportional

130
Q

Pressure inside a bubble (alveoli) formed by a fluid film is the function of 2 factors….

A

Surface tension and the radius

131
Q

Apply the law of laplace to alveoli in the pulmonary system…(surface tension, pressure, and radius)

A

If the radius increases, pressure decreases (inversely Proportional)
If surface tension increases, pressure increases (directly proportional)

132
Q

In the Law of LaPlace, of 2 bubbles have the same surface tension, the smaller bubble will have a…

A

Higher pressure and more surfactant

133
Q

Describe the characteristics of surfactant and explain how surfactant reduces surface tension and equalizes inflation pressures in the lung

A

Surfactant sticks polar head in between h bonds and disrupts h bonding at the air water interface, lowering surface tension in the alveoli

134
Q

__ surface tension= compliance __= __ pressure

A

Decrease, increase, decrease

135
Q

When bronchioles contract what happens to airflow and resistance

A

Decrease air flow and increase in resistance

136
Q

Apply the principals of airway resistance to the radius of airways

A

-Length and viscosity of air entering lung are constant
- radius matters the most in determining resistance

137
Q

In the upper airways, if affected by a physical obstruction what happens to resistance

A

Increases

138
Q

Bronchodilation vs bronchoconstriction: resistance? Mediated by?

A

Bronchoconstriction= increase resistance, mediates by parasympathetic neurons (muscarinic receptors), histamine, leukotrienes

Bronchodilation= decrease resistance, mediated by co2 and epinephrine (b2 receptors)

139
Q

What is ventilation perfusion matching

A

Match areas of lung receiving oxygen with blood flow to lung

140
Q

What happens in ventilation perfusion mismatch?

A

Ventilation decreases in alveoli, co2 increases, and o2 decreases leading to too much constriction and no diffusion

  • can’t remove co2 and oxygenate blood
141
Q

How to prevent hypoxic vasoconstriction

A

Blood vessels constrict and divert blood flow to a better ventilated alveoli

142
Q

What’s the danger of hypoxic vasoconstriction?

A

If there’s too much vasoconstriction in the pulmonary artery, pressure and after-load increases on right side of heart (heart failure)

143
Q

What does boyles law say about pressure and volume

A

Inversely proportional

144
Q

Describe the atm and alveolar pressure at rest and the pressure gradient?

A

ATM pressure and alveolar pressure are equal, no pressure gradient, no volume or pressure change

145
Q

Describe the atm and alveolar pressure during inhalation and the pressure gradient?

A

Alveolar pressure is less than atmospheric pressure; air moves down gradient inward; lung volume increases and alveolar pressure decreases

146
Q

At the end of inhalation or exhalation: what happens to atmospheric pressure and alveolar pressure

A

They equalize

147
Q

Describe the atm and alveolar pressure at exhalation and the pressure gradient?

A

Alveolar pressure increases above atm pressure, mechanical event of relaxation decreases lung volume; increase in pressure provides gradient for air to move out of lungs

148
Q

What lung volume or capacities can’t be measured with a simple spirometer

A

Residual volume

149
Q

Volume of air inspired or expired during a single breathing cycle

A

Tidal volume

150
Q

Max volume of air inspired during inhalation

A

Inspiratory reserve volume

151
Q

Max volume of air expired during exhalation

A

Expiratory reserve volume

152
Q

Volume of air that remains in the lungs (dead space) after maximum expiration

A

Residual volume

153
Q

Volume of air in the lungs at the end of a normal expiration

A

Function residual capacity

154
Q

Functional capacity=

A

ERV + RV

155
Q

Max volume of air that can be inspired after a normal expiration

A

Inspiratory capacity

156
Q

Inspiratory capacity=

A

TV + IRV

157
Q

Maximum volume of air that can be expired after a maximum inspiration

A

Vital capacity (forced vital capacity)

158
Q

Vital capacity=

A

IRV + TV + ERV

159
Q

Total volume of air in the lungs after a max inspiration

A

Total lung capacity

160
Q

Total lung capacity=

A

Vital capacity plus residual volume (VC + RV)

161
Q

Formula for minute volume

A

Tidal volume times respiratory rate

162
Q

Average minute volume

A

5-6 l/min

163
Q

Formula for alveolar ventilation

A

(Tidal volume- dead space air) x respiratory rate

164
Q

Amount of air available for gas exchange

A

alveolar ventilation

165
Q

At rest, what happens to the intrapleural pressure?

A

Diaphragm is released, intrapleural pressure is less than atmosphere

166
Q

During inspiration, what happens to the intrapleural pressure?

A

Thoracic volume increases, intrapleural pressure decreases even more than at rest

167
Q

During expiration, what happens to the intrapleural pressure?

A

Diaphragm relaxed and volume decreases, intrapleural pressure increases and returns to baseline (still negative compared to atm pressure)

168
Q

Why is the intrapleural pressure negative?

A

Because atm pressure is set to 0, intrapleural pressure is sub atmospheric, under normal conditions it has negative pressure

169
Q

Normally, the pressure in the intrapleural space is

A

Below atmospheric pressure (increase volume, decrease pressure)

170
Q

During forced expiration, what happens to the pressure in the intrapleural space

A

Increases above atmospheric (increase pressure, decrease volume)

171
Q

Pressure an individual gas exerts on a given space

A

Partial pressure

172
Q

Partial pressure of oxygen in the atmosphere

A

160

173
Q

Partial pressure of oxygen in the alveoli

A

100 mmHg

174
Q

Partial pressure of oxygen in the artery (arterial pressure)

A

100

175
Q

Partial pressure of oxygen in the venous capillary (venous pressure)

A

40 mmHg

176
Q

Partial pressure of carbon dioxide in the atmosphere

A

Less than 1 mmHg

177
Q

Partial pressure of carbon dioxide in the alveoli

A

40 mmHg

178
Q

Partial pressure of carbon dioxide in the artery (arterial pressure)

A

40 mmHg

179
Q

Partial pressure of carbon dioxide in the venous capillaries (venous pressure)

A

46 mmHg

180
Q

Oxygen is high in the __ and low in the ___

Carbon dioxide is high in __ and low in the ___

A

Alveoli, venous capillaries

Venous capillaries, alveoli

181
Q

Alveolar partial pressures or oxygen and carbon dioxide closely resemble venous blood in

A

Hypo ventilation

182
Q

During hypoventilation, what’s the relationship between oxygen and carbon dioxide

A

Low oxygen and high carbon dioxide partial pressures

183
Q

Alveolar partial pressures of carbon dioxide and oxygen levels more closely resemble the atmosphere

A

Hyperventilation

184
Q

Normal ventilation is

A

4.2 L/min

185
Q

During hyperventilation, what’s the relationship between oxygen and carbon dioxide

A

Low carbon dioxide and high oxygen partial pressures

186
Q

Explain the steps of oxygen released at the tissues

A
  1. At rest, cellular o2 levels are 40 mmHg.
  2. O2 moves from dissolved down pressure gradient (100 mmHg to 40 mmHg)
  3. Drop in oxygen pressure allows some oxygen to unbind hemoglobin and move into the plasma (increasing partial pressure)
  4. O2 continues to move down its gradient and oxygen unbinds hemoglobin increasing partial pressure until hemoglobin reaches 75% saturation. (25% released to tissues)
  5. Once RBC saturation reaches 75% , no more oxygen can be released and oxygen in plasma moves into the cell until cell PO2 equals PO2 dissolved in plasma (40 mmHg)
187
Q

Each hemoglobin binds

A

4 oxygen molecules

188
Q

If partial pressure of plasma increases, what happens to hemoglobin percent saturation?

A

Increase (more oxygen can bind hemoglobin)

189
Q

Using the oxygen hemoglobin binding curve…

Describe a resting cell, what’s the partial pressure of oxygen?

A

40 mmHg, once hemoglobin reaches the cell it begins releasing oxygen into the tissues to make atp

190
Q

In a resting cell, when does hemoglobin go back to the lung to get more oxygen

A

When 25% oxygen is released

191
Q

In the alveoli what percent of hemoglobin is bound to oxygen in the lung?

A

98%

192
Q

What happens during exercise in relation to the oxygen hemoglobin binding curve?

A

Hemoglobin releases more oxygen into tissues than in resting cell to meet demands of the tissue based on environment

193
Q

What is the main parameter that affects affinity of hemoglobin with oxygen

A

Metabolism

194
Q

Increase in metabolism= __ tissue demand for oxygen

A

Increase

195
Q

In a __ ward shift…..

As percent saturation of oxygen __, more oxygen is released into tissues

A

right, Decreases

196
Q

Examples of rightward shifts

A

Low blood ph, high temperature, high blood co2 partial pressure, and added BPG

197
Q

A higher blood pco2 allows more…

A

Oxygen to diffuse off RBC

198
Q

Inserts itself into hemoglobin and traps it into a state of release (found in smokers)

A

2-3 BPG

199
Q

In a __ shift…

Release less oxygen, hold onto more oxygen (tightly bound)

A

Left

200
Q

To get hemoglobin to let go of oxygen, need a….

A

Lower pressure

201
Q

Examples of leftward shifts

A

High blood ph, low temperature, low blood PCO2, no BPG

LOWER METABOLISM

202
Q

Describe the transport of oxygen into the blood….

A
  1. When you breathe oxygen, it enters the alveoli ( p alveoli= 100 mmHg)
  2. Oxygen moves down pressure gradient out of alveoli into plasma (60 mmHg) until the gradient has equalized 100 mmHg (p alveoli=p plasma o2)
  3. Once oxygen is in the plasma, it binds hemoglobin in RBC (decreasing the pO2 in plasma hack to 60 mmHg)
  4. Oxygen continues to move down pressure gradient into plasma and bind hemoglobin until the hemoglobin reaches 98% saturation
  5. Once the last oxygen molecule fills the last binding site of hemoglobin, more oxygen than replaces the oxygen bound to hemoglobin
203
Q

Bound content is dependent on the

A

Oxygen in plasma: number of binding sites and percent saturation of hemoglobin

204
Q

All of the oxygen content in the blood

A

Total oxygen content

205
Q

Available hemoglobin bound to oxygen

A

Percent saturation

206
Q

directly proportional to the number of hemoglobin molecules and number of binding sites on hemoglobin occupied by oxygen

A

Bound content

207
Q

Bound content formula

A

Number of hemoglobin molecules x percent saturation

208
Q

Mary has 12% of hemoglobin
Frank had 13% of hemoglobin

Both have an alveolar pO2 of 100 mmHG:

  1. Who is more saturated?
  2. Who has a higher total content?
  3. Who has a higher dissolved content?
  4. Who has high bound content?
A
  1. Both, because when pO2= 100 mmHg, both have 98% saturation
  2. Frank, he has more hemoglobin percentage
  3. Both, because alveolar pO2 is proportional to dissolved content pO2
  4. Frank because has more hemoglobin, more bound oxygen
209
Q

Co2 highest concentration is in the ___ , with a pressure of ___

A

Cell, 46 mmHg

210
Q

As co2 increases, it favors the production of

A

H and bicarbonate

211
Q

What are the steps for the transport of CO2

A
  1. Co2 diffuses out of cells into capillaries-plasma(46 to 40 mmHg)
  2. Some (7%) of co2 remains dissolved in plasma and some (23%) binds hemoglobin
  3. Most co2 is converted into bicarbonate and H through carbonic anhydrase
  4. Hemoglobin buffers H
  5. Bicarbonate enters the plasma in exchange for Cl entering the RBC (chloride shift) by secondary active transport.
  6. At lungs, dissolved co2 diffuses out of plasma (46 mmHg) into lungs (40 mmHg) until co2 levels equal 40 mmHg
  7. Co2 unbinds from hemoglobin and diffuses out of RBC
  8. Carbonic acid reaction reverses, pulling bicarbonate back into RBC and Cl back out- converting bicarbonate back to co2
212
Q

Major control center for breathing ___

Responsible for fine tuning control of breathing ___

A

Medulla, pons

213
Q

When the medulla and pons are activated by the chemoreceptors, they innervate…

A

Somatic motor neurons for inspiration and expiration

214
Q

Inspiration somatic motor neurons innervate…..

Whereas

Expiration somatic motor neurons innervate…

A

External intercostals and diaphragm

Internal intercostals and abdominal muscles

215
Q

Three parts of medulla

A

dorsal and ventral respiratory group and pre bot complex

216
Q

What part of the medulla is in charge of inspiratory ventilation (regular respiration)

A

DRG

217
Q

What part of the medulla is responsible for expiratory ventilation (often when forced)

A

VRG

218
Q

What part of the medulla is an intrinsic pattern generator (pacemaker), cells set respiration rate

A

Pre bot complex

219
Q

Discuss the mechanism of plasma levels of oxygen in the control of ventilation…

A
  1. Low oxygen in plasma allows less oxygen to diffuse into chemoreceptors (below 60)
  2. K channels close in response to low oxygen
  3. Cell depolarizes
  4. Depolarization opens VG Calcium channels and calcium enters the cell.
  5. Calcium in cell triggers the exocytosis is of neurotransmitters
  6. Neurotransmitters bind receptor on sensory neuron, triggering an action potential
  7. AP signals medullary centers to increase ventilation
220
Q

Describe the location & function of central chemoreceptors

A

Respond to changes in Co2 only, in medulla, activated by H+

221
Q

When co2 levels are high, __ levels are high

A

H+

222
Q

When there’s an increase in co2 in the plasma, there more ___ in the CSF

A

H and bicarbonate

223
Q

In cerebral capillary (blood brain barrier), some H ions cannot go into the CSF. Why?

A

There’s no transporter for diffusion of H ion, h found in CSF is only from co2

224
Q

Describe the location & function of peripheral chemoreceptors

A

Respond to changes in o2, co2, and ph (H+) in arterial side
-located in aortic arch and carotid bodies
-Sends signals to afferent sensory neurons, then to medulla and pons

Human Physiology (14 decks)

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