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49 Cards in this Set

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What provides the most fuel in metabolic reactions?
- breaking P-bonds (phosphate)
ex. ATP --> ADP + P + energy
ADP --> AMP + P + energy
What is ATP?
ADP + P + e
What is ADP?
AMP + P + e
Where is the energy stored in ATP?
P-bonds
How is energy released from ATP?
ATPase is an enzyme that speeds the reaction of splitting ATP. When ATP splits, the phosphate energy is released
How does the sodium pump work?
ATPase speeds the reaction to split ATP, phosphate is released and provides energy to pump 3 Na+ OUT & 2 K+ IN (then ATP needs to be replenished)
How is ATP synthesized?
glucose --> pyruvate (by glycolysis) and begins anaerobic or aerobic metabolism
What is anaerobic metabolism?
- NO O2 present
- pyruvate becomes lactic acid which stimulates pain receptors
- takes place in CYTOSOL (gel-like substance containing organelles)
- yields: 2 ATP
What is aerobic metabolism?
- O2 is present
- pyruvate --> Acetyl CoA --> enters Kreb's cycle --> high energy electrons enter electron transfer system
- occurs in MITOCHONDRIA
- yields: 30-38 ATP
What are some other sources of energy?
- CHO - breakdown into glucose molecules
- Protein - breaks down into amino acids (amino acid group [NH3] is converted to urea and excreted in urine. Remaining organic acid enters Kreb's Cycle)
- Glycerol in fat enters glycolysis
- Fatty acid in fat converted to acetyl coA --> enter Kreb's Cycle
What are the most important requirements for energy production (ATP)?
- Glucose
- O2
What are 3 factors that can significantly reduce the production of energy (ATP)?
1. lack of glucose
2. lack of O2
3. lack of circulating volume - O2 is carried in blood, attached to Hgb
What does the respiratory system do? (relating to O2)
takes in O2
What does the circulatory system do? (relating to O2)
gets O2 to cells
- distributes O2 throughout the body and produces ATP within the cells which is then broken down for energy
What is hypoxia?
insufficient O2
(lack of O2 to cells = less ATP)
What are the causes of hypoxia?
many causes but they all relate to DEMAND > SUPPLY
How can demand for O2 increase?
- increased exercise
- increased metabolic rate (ex. increased HR, fever, hyperthyroidism)
How can supply for O2 decrease?
1. decreased availability of O2 (decreased atmosphere O2 or pressure ex. altitude - higher = less O2; decreased ventilation (gas exchange in lungs ex. lung disease; decreased O2 carrying capacity of blood ex. anemia)
2. decreased delivery of O2 - ISCHEMIA - decreased blood supply ex. blocked blood vessels, closed vessels; decreased DISSOCIATION of O2 from Hgb; increased capillary-to-cell DIFFUSION distance ex. tissue edema; decreased CARDIAC OUTPUT ex. hypovolemia
What are some causes of decreased O2 availability?
1. decreased ATMOSPHERE O2 or pressure ex. altitude - higher = less O2
2. decreased VENTILATION (gas exchange in lungs ex. lung disease
3. decreased O2 CARRYING capacity of blood ex. anemia)
What are some causes of decreased O2 delivery?
1. ISCHEMIA - decreased blood supply ex. blocked blood vessels, closed vessels
2. decreased DISSOCIATION of O2 from Hgb
3. increased capillary-to-cell DIFFUSION distance ex. tissue edema
4. decreased CARDIAC OUTPUT ex. hypovolemia
How does hypoxia affect cells?
insufficient O2 --> switch to anaerobic metabolism --> decreased ATP production and increased lactic acid --> both harm cell in slightly different ways (continue this by creating 2 arms on flow diagrams)
How does lack of ATP affect cells?
no ATP means no energy for sodium pump (therefore it will not function) --> Na+ is retained by cell --> water moves in with the Na+ --> cells become swollen --> cell can rupture
What happens when cells swell?
cell swells --> rER (rough endoplasmic reticulum) dilates --> ribosomes come off --> disrupts protein synthesis --> lack of protein for cell maintenance or function
How does lactic acid affect cells?
- lactic acid means there is a high [H+] and low pH --> change in pH --> protein shape is affected --> enzymes don't work (functional) & cell falls apart (structural)
What are the effects of decreased pH?
- changes protein shapes/ability to function
- causes LYSOSOMES to swell and release their contents that include lysozymes (enzymes that digest the cell ex. hydrolases) --> cellular digestion occurs by auto-digestion
What are lysozymes?
enzymes that digest the cell
ex. hydrolases
What are the consequences of hypoxia?
- cell death = infarction
- time of infarction depends on the severity of the lack of O2 (approximately 20 mins before there is IRREVERSIBLE injury)
What does infarction mean?
cell death
What does ischemic mean?
decreased blood supply (ex. blocked blood vessels or closed vessels
What is reversible injury?
- recovery is possible
- function and/or structure can be restored
What is irreversible injury?
- recovery is not possible
- cell death (infarction) will occur
At which point with hypoxia injury does damage become irreversible?
- it depends on the cell and the person
(approx. 20 mins)
What are some effects of hypoxia at organism level?
1. cell death - loss of tissue function if enough cells die
2. pGs (prostaglandins) synthesized from damaged CM - stimulates pain receptors and stimulates inflammation
3. lactic acid from anaerobic metabolism - stimulates pain receptors and causes metabolic acidosis if widespread
What are some effects of loss of ATP?
- fatigue - lack of ATP production - decreased energy
- weakness - lack of ATP production - decreased energy
- dizziness - decreased ATP production --> altered Na+ pump --> alters depolarization causing dizziness
- numbness/tingling of peripheral nerves (PARASTHESIA) - decreased ATP production --> altered Na+ pump --> alters depolarization causing numbness/tingling
- HPA activation!!
What is parasthesia?
numbness/tingling of peripheral nerves
What causes dizziness, weakness, numbness & tingling?
decreased ATP production --> altered Na+ pump --> alters depolarization --> dizziness, numbness/tingling
What are the cardiovascular effects associated with HPA axis? (also include how this relates to O2)
CATACHOLAMINES cause:
- VSM (vascular smooth muscle) vasoconstriction --> blood O2 is shunted to core --> pale/cool periphery --> this will affect peripheral hypoxia
- SA node stimulated by epinephrine to deliver O2 --> increases firing rate --> increased HR
What are the respiratory effects associated with HPA axis? (also include how this relates to O2)
CATACHOLAMINES:
- BSM (bronchial smooth muscle): bronchodilation --> increases O2
- respiratory center stimulated --> increases respiratory rate & effort --> increases O2
Do all the S&S of HPA help correct hypoxia?
No. Only the cardiovascular and respiratory system are helping to address the problem. (other S&S of HPA are still present though ex. sweating)
How can hypoxia be treated?
- reverse the cause of hypoxia/ischemia
- give supplemental O2 (guided by O2 saturation level [>95%] and also guided by pO2
Where do free radicals come from?
- free radicals are contained in lysosomes
- also byproduct of metabolism
What are free radicals?
- highly charged molecule
- very unstable molecule
- it wants to bind with everything
- initiates chain reactions
What are some examples of free radicals?
superoxide, peroxide, hydroxyl
What makes a cell more susceptible to free radicals?
hypoxia can disrupt normal cell processes, making the cell more vulnerable to free radicals
What are free radicals useful for?
for WBCs to destroy targets
What is the MOA of free radical damage?
1. damages cell membranes by attacking their DOUBLE BONDS (peroxidation) --> cell membrane gets leaky (ex. mitochondrial membrane - more Ca+ enters and disrupts function)
2. Damages proteins - interferes with cross-linking of amino acids
3. Creates lesions in DNA
Explain reperfusion injury.
- cells are damaged during ischemia (decreased blood flow) and this causes the cells to be more vulnerable to free radicals
- if reperfusion occurs, more O2 is produced but free radicals are also produced as a result of the changes
- the cells cannot handle the free radicals and this causes cell membrane damage
What are some examples of antioxidants?
vitamin C, vitamin E
What are antioxidants?
they neutralize free radicals
- can help to prevent reperfusion injury