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Block 2 > Week 7 > Flashcards

Week 7 Flashcards

1
Q

What three regions regulate breathing rate?

Where are the respiratory centers located?

Three main groups of neurons in respiratory centers?

A

Brainstem, Cortex, Hypothalamus & Limbic System

Brainstem (pons and medulla)

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2
Q

What are the components of medullary respiratory center and their functions?

A

Pre-Botzinger Complex = Intrinsic respiratory rhythm

Dorsal Respiratory Group = Inspiration

Ventral Respiratory Group = Expiration

Nucleus Ambiguus = Motor Nucleus CN IX and CN X

Fasciculus Solitarius = Collection of smaller neurons

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3
Q

Pre-Botzinger Complex

Describe the signal it generates

A

Starts with latent period. Creesendo of action potential. Action ceases.

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4
Q

Dorsal respiratory group

What is it controlled by?

Where do nerves that control DRG terminate?

A

Pneumotaxic center and CN IX and CN X (visceral signals)

Tractus solitarus, close to the inspiratory center

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5
Q

Ventral respiratory group

When is it inactive?

A

During normal quiet breathing

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6
Q

Apneustic Center

Where is it loctated?

Function?

A

Lower pons

To stimulate breathing

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7
Q

Pneumotaxic Center

Where is it located?

Function?

A

Upper pons

Inhibits inspiration / fine tuning

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8
Q

Breathing Patterns

Type and cause

A

Apnea (transient) = lesion in temoral lobe

Apnea (permanent) = lesion in lower pons and medulla (around nucleus ambiguus)

Cheyne-Stokes = lesion in diffuse cerebral cortex, diencephalon (pyramidal tracts)

Central neurogenic hyperventilation = medial reticular formation

Ondine’s Curse (loss of automaticity) = medial reticular formation or anterolateral C2

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9
Q

Cheyne-Stokes Respirations

Describe?

Causes?

What is broken?

A

10-20 second periods of apnea followed by equal periods of hyperpnea

Seen with high altitude, severe heart disease, or severe neurological injury

Feedback mechanism

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10
Q

Receptors that control breathing

What do they respond to?

What is the response?

A

Central Chemoreceptors = H+ in CSF

Peripheral Chemoreceptors = PO2, pH, PCO2

Lung Receptors:

Pulmonary Strech Receptors (in smooth muscle) = distension => increase of expiratory time (Hering-Breuer inflation reflex)

Irritant Receptors (epithelial cells) = noxious gasses, smoke, dust, cold air => Bronchoconstriction and hyperpnea

J Receptors (“juxta-capillary”) = respond to chemicals => rapid, shallow breathing, apnea

Other Receptors:

Nasal and Upper Airway = mechanical and chemical stimulation => sneeze, cough, bronchoconstriction, and laryngeal spasm

Joint and muscle receptors = moving limbs => increase ventilation

Gamma = elongation of intercostal muscles and diaphgragm

Arterial Baroreceptors => change in BP

Pain / Temperature => Hyperventilation

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11
Q

Apneic threshold

A

The point at which rhythmic ventilation ceases at a given PC02

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12
Q

Why people with COPD might have normal CSF pH?

What forces them to breathe more?

A

They have compensatory mechanisms even they have abnormally low ventilation for atheir given PCO2

hypoxia

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13
Q

Where are peripheral chemoreceptors located?

Two types of cells in peripheral chemoreceptors?

A

Bifrucation of the common carotid arteries and around arch of the aorta

Type I (glomus) with a lot of dopamine and Type II (sustentacular) with rich capillary

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14
Q

How hypotension affects breathing?

A

Less flow to the carotid bodies and lower O2 delivery

Increase in ventilation

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15
Q

Kussmaul’s breathing

A

Rapid respiration where you are trying to get rid of CO2

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16
Q

Approach to a patient with hypoxemia

Diagram

A
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17
Q

Equation to estimate normal PaO2 based on age

Hypoxemia?

A

Normal PaO2 = 100-(0.4 x age)

PaO2 lower than normal for a person’s age

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18
Q

Alveolar gas equation

A

PAO2 = PIO2 - 1.2(PaCO2)

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19
Q

General types of gas exchange problems and their characteristics

A

Extrapulmonary (PACO2 is always increased)

Intrapulmonary

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20
Q

5 causes of hypoxemia and 2 main categories

A

Not enough O2 to alveoli (low PAO2)

Pure hypoventilation

(-) PIO2

Not enough O2 to capillary blood (poor lung architechture)

Ventilation-perfusion mismatch

Rgith-to-left shunt

Diffusion defects

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21
Q

Alveolar ventilation equation

A

PaCO2 = VCO2/VA*0.863

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22
Q

Causes for hypoventilation

A

Depression of the respiratory center (Morphine or barbituates)

Diseases of the respiratory muscles (Progressive muscular dystrophy)

Extreme obesity

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23
Q

Causes for decrease in PIO2

A

High altitude (low barometric pressure)

Respirator delivering low FIO2

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24
Q

PIO2 equation

A

FIO2*(PB-PH2O)

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25
Q

What is wasted blood?

Two reason for it?

A

Not fully oxygenated blood

Shut and low V/Q

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26
Q

Venous admixture

A

The mixing of unoxygenated blood with oxygenated blood

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27
Q

What V/Q ratio is clinically important?

What it causes?

A

The V/Q mismatch among different alveoli (not overal V/Q raito)

P(A-a) difference

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28
Q

Hemoglobin saturation equation

A

CaO2 = Hb · 1.34 · SaO2/100 + 0.003 * PaO2

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29
Q

Types of exchange defects in lungs

A

Airway obstruction (asthma, chronic bronchitis)

Shunt (Pulmonary edema, severe pneumonia)

Dead space (Embolism, Emphysema)

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30
Q

Symptoms of acute hypoxia

Symptoms of chronic hypoxia

A

Acute hypoxia

Impaired judgment, Motor incoordination, Clinical picture closely resembling that of acute alcoholism

Chronic hypoxia

Fatigue, drowsiness, apathy, Inattentiveness, Delayed reaction time, Reduced work capacity

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31
Q

Hypoxemia definition

A

Lower than normal PaO2 for a person’s age

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32
Q

What is the most common form of iron?

Which iron is most favorable for absorption?

Which iron is most availible in diet?

How infants can get their iron in diet instead of meat?

A

Most of iron are in the form of iron-oxides and metallic iron (no use)

Heme-iron from meat is most available for absorption

Most of the diet is in the form of non-heme forms of iron

Infants can obtain iron from lactoferrin in mother milk

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33
Q

Name some molecules that contain iron and their functions

A

Hemoglobin (transport)

Myoglobin (storage)

Cytochromes e.g. heme and iron-sulfur (electron transport)

Amino acid metabolism (monooxygenases) use O2 as a substrate

Inflammatory response (dioxygenases) use O2 as a substrate

34
Q

Is there a redox reaction when oxygen binds to iron?

A

No redox chemistry in binding of oxygen

35
Q

Describe fenton reaction

How is it prevented?

A

Iron is oxidized in a presence of oxygen and radical are formed

Iron is always bound to some proteins, protoporphyrins, and Fe-S centers to prevent such reactions

36
Q

How much iron is in the body?

How much iron in is a diet per day?

How much iron is abosrbed/removed per day?

A

Total 3-4 grams

10-20 mg/day in diet

1-2 mg/day absorbed

37
Q

Transferrin

To what state of iron does it bind?

How many irons does it bind?

A

Fe3+

2

38
Q

Iron losses

Daily?

Situational?

A

Daily losses

Occult blood loss (blood in feces) 50%
Sloughed enterocytes 50% (loss of iron bound to ferritin)
Biliary secretions
Skin cells

Other loss mechanisms

Menstruation
Blood donation
Hemorrhage (nosebleed)
Pregnancy

39
Q

What tranpsorts iron into villus/enterocytes of duodenum?

What molecule releases iron from heme?

What protein reduces free iron in the gut?

What protein imports free iron?

What binds ferric ion inside of cell?

What exports iron on the basolateral side?

What oxidizes iron during the export?

A

Heme transporter HT

Dioxygenase

duodenyl cytorchome b (Dcutb) ferric reductase

DMT1 transporter

Ferritin

Ferroportin (FP)

hephaestin

40
Q

Ferritin

Function?

How many irons can it bind to?

What state of iron does it bind to?

In excess, what it can aggregate into?

Application of measuring ferritin levels?

A

Iron storage protein

4500 irons per molecule

Fe3+

Hemosiderin (partially degraded ferritin with iron that looks brown)

Serum ferritin estimates iron storage (ferritin can leak out to plasma when levels are high)

41
Q

Transferrin

Bound to what state of iron?

Function?

Normal saturation?

A

Fe3+

Bound to solvate iron (Fe3+ is insoluble)

33%

42
Q

Transferrin receptors

Function?

Where is it highly expressed?

Mechanism?

What protein regulates this receptor?

A

Uptake of iron from plasama to cells

Developing RBCs (erythroblasts)

Binds to iron-transferrin and internalizes it into endosome

HFE

43
Q

Liver

Importance of liver in iron cycling

What is the function of the hormone that regulates iron and is secreted by liver?

What this hormone production is stimulated by?

A

Primary iron storage and synthesis of hepcidin

Hepcidin is inhibitor of ferroportin (it sequesters it inside of the cells)

Stimulated in inflammation and iron overload

44
Q

What is an analog of hephaestin in liver and macrophages?

A

Cerulloplasmin

45
Q

What will mitochondria ferrochetolase do?

A

loads iron into Hb-heme molecule in RBC precurosors

46
Q

Diagram comparing different handling of irons by different cells

A
47
Q

How gene expression of ferritin is regulated by iron?

A

Iron Response element on mRNA bound at low iron concentrations. It has only 3 irons bound to iron-sulfur centers

Iron Response protein bounds to iron. It has 4 irons bound to iron-sulfur centers.

48
Q

Hemochromatosis

What is it?

Which tissues are affected?

What is the most common cause?

A

Inappropriate increase in intestinal iron absorption that leads to tissue damage

Liver (cirrhosis)
Pancreas (diabetes)
Skin (bronze; bronze diabetes)

Autosomal recessive allele (primary)
HFE Protein is MHC class 1 gene
Regulate iron uptake and storage

49
Q

Iron poisoning in children <6

Cause?

Treatment?

Mechanism of toxicity?

A

Swallowing too many pills

Treatment with strong laxative and chelator (desferal)

Toxicity to is due to free iron not bound to transferrin leading to lipid perodixation that results in damage of blood vessels and mitochondria

50
Q

Most common cause of anemia?

Signs of that anemia?

A

Iron deficiency anemia

Weakness and pallor; exercise intolerance
First sign in the blood smear

51
Q

Major sites of heme biosynthesis

A

Erythroid cells (85%)

Hepatocytes (15%) for cytochromes in detox and ETC

52
Q

Erythropoesis

What stimulates it?

What is required for it?

What are significant steps in this process?

What proceeses are present in mature erythorcytes?

What is Polycythemia?

A

Hypoxia

Requires Iron, Hb, heme

Stem cells can come erythroblasts. Enucleated erythroid cell (reticulocyte) leaves bone marrow. Reticulocytes lose mitochondria and ribosomes.

Glycolysis, Pentose phosphate shunt, Reductive capacity

Polycythemia is an excessive proliferation of erythrocytes

53
Q

HIF-1

Stand for?

Function?

Types of a moleucle?

How is it activated / inactived?

Enzymes that active it?

Activated genes?

A

Hypoxia-Inducing-Factor

Ensures cell surival under hypoxic condition

Transcription Factor

Phosphorylated / Hydroxylated and then Ubq

Prolyl hydroxylase

**Oxygen transport **(Erythorpotein , Transferrin, Transferrin receptors, Ceruloplasmin), Anaerobic energy (glucose uptake and glycolysis), Vasculogenesis, Respiration

54
Q

Prolyl hydroxylase

Function?

Catalytic domains?

Required susbtrates?

Required catalyst?

Where used up O2 goes to?

A

Cause HIF-1 hydroxylation and Ubq

PHDs (proline hydroxylase domain) that are dioxygenases

Require O2 and 2-oxoglutrate (a-ketoglutarate)

Fe2+ stablized in II state by Vit C

One oxygen goes to HIF the second one reacts with 2-oxoglutarate giving succinate and CO2

55
Q

Steps in heme synthesis

A

Succinyl-CoA and Glycine are coupled together by delta-aminolevulinate synthase (ALAS1) produces delta-aminolevulinate (ALA)

Two molecules of ALA are dehydrated to form porphobilinogen

Four molecuels of porphobilinogen condense and cyclize caralyzed by uroporhhyrinogen syntheases loss of -4 NH3+ resulting molecule has acetyl and propionate groups

All acetate side groups are converted to methyl by uroporphyrinogen decarboxylase

Some of proprionyl side groups are convrted to **vinyl **by coproporphyrinogen oxidase

Now, Protoporphyrinogen IX is acted on by Protoporphyrinogen oxidase double bond making the molecule red forming Protoporphyrin

Ferochetolase incorporates Fe2+ into the ring

56
Q

Location of heme biosynthesis

A

Heme biosynthesis occurs in two compartments. It starts in mitochondria (ALAS1) then cytosol and then back to mitochondria.

57
Q

What is the result of lack of the first enzyme in heme biosynthesis (ALAS1)

What about enzymes 3-8?

A

Lack of ALAS1 leads to anemia

Lack of enzymes 3-8 leads to porphyrias (genetic abnormality in heme pathway)

58
Q

Porphyrias

What is it?

Symptoms?

A

genetic abnormality in heme pathway

Deficiency of products (may lead to photosensititvity)
Accumulation of reactants (neuropsychiatric symptoms)

59
Q

Two isoforms of ALAS and how they are controlled?

A

ALAS-N (ALAS non-specific or ALAS-1) in liver

Under the feedback “classical” inhibition by heme
Increased by inducers that require heme (e.g. P450)

ALAS-2 in erythroid in erythroid cells

Heme does not decreases heme production
Increases during differentiation

60
Q

What is the rate limiting and first step in heme catabolism?

A

Heme oxygenase (rate-limiting reaction) to break the ring open

61
Q

What is the function of biliverdin reductase?

Where does this reaction occur?

A

Convert biliverdin (green) to bilirubin (yellow)

Reticuloendothelial cells

62
Q

Bilirubin

Where is it produced?

How is it transported to liver?

How is it converted to soluble form in a liver?

A

Produced in periphreal tissues

In blood binds to albumin

Hepatocytes convert bilirubin to a polar form (UDP-Glucose + 2NAD+) to UDP-Glucorionic acid

Transferase adds the glucorionic acid and releases UDP (two cycles)

Bilirbuin diglucuronide (conjugated form)

63
Q

What are two components of Heme

Functional groups of heme?

Function of hemoglobin with respect to iron?

How many salt bridges stabilize T state?

A

Heme = Fe+2-protoporphyrin IX

proprionyl, methyl and vinyl

Proection from oxidation and allow reverisble binding

8

64
Q

What can change the Hb-O2 dissociation curve?

A

pH (H+ stabilize salt bridges)
CO2 ( deoxy-Hb by reacting with terminal amino groups to form carbamoylated-Hb, Carbamate participates in salt bridge)
Temperature
BPG (competitive binding with oxygen)

65
Q

Bohr vs. Haldane

A

Bohr said CO2/H+ weaken O2 binding to Hb

Haldane said O2 weakens CO2/H+ binding to Hb

66
Q

Carbohydrate metabolism in the RBC

A

Glycolysis = ATP for ion pumps and NADH for reduction of methemoglobin

2,3-BPG metabolism (unique to RBC) = Sacrifices ATP production in glycolysis

67
Q

How CO affects O2 binding

A
68
Q

What is methamoglobin

When is it present?

How does it affect oxygen binding?

A

Oxidized iron with heme

Chemicals or drugs

Increases O2 binding

69
Q

How SaO2 can be measured?

A

Directly by oximeter and pulse-ox (may not distinguish between different hemoglobins) machines

Calculated from PaO2 if normal

70
Q

O2 content equation

A
71
Q

Hypoxia vs. hypoxemia

A

Hypoxia = Impaired O2 delivery to the tissues

Hypoxemia = Low CaO2 in blood caused by reduction in PaO2, SaO2 or [Hb]

72
Q

All oxygen equations

A
73
Q

Type of flow in pulmonary arteries?

When is it lost?

A

Pulsatil

Hypertension

74
Q

How pulmonary vascular resistance is reduced during inspiration?

A

Recruitment of alveoli

Distension of alveoli

Expansion of lungs

75
Q

Swam-Ganz catheter

Function?

A

measures static fluid pressure in pulmonary circuit
normal values = 8-12 mm Hg

76
Q

West zones of lungs

How supine position affects blood flow?

How mild exercise affect blood flow?

A

Increases apical flow

Decreased resistance and increased overall flow

77
Q

How hypoxia affects blood vessels in lungs?

Effect of NO on lungs?

High altitude?

Factors that inihbit vasoconstriction?

A

Contraction of arteriolar smooth muscle walls in hypoxic region (Direct blood to less hypoxic regions)

Vasodilation

General vasoconstriction

CO, PVR (+), Hypothermia, acidosis/alkalosis, anesthetics, Ca++ blockers

78
Q

Stages of edema in lungs

A

Interstitial edema
transport of excess fluid goes to hilar lymph nodes

Alveolar edema
when capacity of the lymphatics is exceeded

79
Q

Types of pulmonary edema

A

High-Altitude Pulmonary Edema

does cause hypoxia-induced vasoconstriction at pre-capillary sites

Neurogenic Pulmonary Edema

increased intracranial pressure leads to increase pulmonary capillary pressure; can cause trauma to capillaries; increased capillary permeability

80
Q

Adult Respiratory Distress Syndrome (ARDS)

What is it?

Causes?

Treatment?

A

accumulation of proteinaceous fluid in the alveoli due to a number of causes; V-Q mismatch

severe trauma, sepsis, pancreatitis, pneumonia, pneumonia

Low-volume respirator

81
Q

Transfusion-Related Acute Lung Injury (TRALI)

What is it?

Mechanism?

Symptoms?

A

Variant of ARDS ; Occurs with massive blood product transfusion, most commonly fresh frozen plasma

anti-granulocyte antibodies

develops within 1-2 hours of transfusion ; fever, tachycardia, tachypnea ; development of pink, frothy sputum ; patients usually extubated within 48h

82
Q

Metabolic functions of Lungs

A

Angiotensin I->II activation by ACE in endothelial cells

Inactivation of bradykinin (ACE)

Serotonin (uptake)

Prostaglandin E1 /E2/F2 (keeps ductus arteriosus)
Norepinephrine
Arachidonic acid

Synthesis of surfactnat & collagen framework

Block 2 (7 decks)

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