Oxygen - friend or foe? Flashcards
what are the functions of ATP?
Transport substances across cell membranes
muscle contraction
energy for the cells
which organ uses the most energy?
liver
what oxidation?
addition of oxygen or removal of electrons
what is reduction?
removal of oxygen or addition of electrons
what is respiration?
the process of breaking down organic molecules to harvest chemical energy
breaking down of sucrose
requires sucrase
produces D-fructose and D-glucose
breaking down of lactose
requires lactase
produces D-galactose and D-glucose
what happens in glycolysis?
storage as glycogen
conversion to nucleotides and fatty acids
generation of ATP energy
anaerobic respiration
produces lactate
generates less ATP
Glycolytic enzyme
mutation-associated demonstrated or possible defects
Hexokinase 1
nonspherocytic hemolytic anemia
Hexokinase 2
nonspherocytic hemolytic anemia
insulin resistance
possible cause of increased glycolysis in cancer cells
Glucokinase
gestational diabetes, hyperinsulinism of the newborn
maturity-onset diabetes of the young
phosphoglucose isomerase
nonspherocytic hemolytic anemia
Phosphofructokinase
exercise intolerance and compensated hemolysis - tarui disease
Aldolase B
hereditary fructose intolerance
triosephosphate isomerase
multisystem disease
lethality in early childhood
glyceraldehyde 3-phosphate dehydrogenase
diverse nonglycolytic functions, could be involved in prostate cancer, age-related neurodegenerative disease
phosphoglycerokinase
chronic hemolytic anemia
phosphoglycerate mutase
exercise intolerance
enolase 1
deregulation of c-myc oncogene
pyruvate kinase
alpha-hereditary hemolytic anemia
Tarui’s disease
phosphofructokinase deficiency
affects skeletal muscle
autosomal recessive
symptoms of Tarui’s disease
muscle pain
fatigue on everyday activity
fixed contractures with rhabdomyolysis
risk of acute renal failure
what is the treatment for taruis disease?
no specific treatment
maintain healthy diet
control weight
take regular gentle aerobic exercise
fumarase deficiency
very rare
causes micocephaly
frontal bossing
micrognathia
examples of mitochondrial disease
mitochondrial myopathy diabetes mellitus at early age deafness at early age leber's hereditary optic neuropathy leigh syndrome neuropathy, ataxia, retinitis pigmentosa and ptosis dementia myoclonic epilepsy with ragged red fibres mitochondrial DNA depletion syndrome
Leber’s hereditary optic neuropathy
visual loss in young adulthood
degeneration of the optic nerves and retina
Leigh syndrome
seizures
altered states of consciousness
dementia
ventilatory failure
myoclonic epilepsy with ragged red fibres
progressive myoclonic epilepsy short stature hearing loss lactic acidosis exercise intolerance
oxygen cascade
the process of declining oxygen tension from atmosphere to mitochondria
disruption of oxygen cascade
at any point of the cascade will lead to insufficient availability of oxygen to meet energetic demands = hypoxia
what is in the oxygen cascade?
air - alveoli - end capillary - arterial blood - tissue capillary - cell - mitochondira
what are the different types of hypoxia?
hypoxic
anaemic
circulatory
histotoxic
hypoxic hypoxia
low pp O2
inadequate haemoglobin sats
pulmonary diseases
high altitude
anaemic hypoxia
decreased O2 carrying capacity of blood
anaemia
CO poisoning
circulatory hypoxia
decreased O2 delivery to tissues
cardiac failure
hypotension
shock
histotoxic hypoxia
inability to use oxygen
normal O2 delivery
cyanide poisoning
mitochondrial disease
cellular effects of hypoxia
early/ reversible and late/ irreversible
what are the early/ reversible effects of hypoxia?
mitochondrial ATP production stops anaerobic glycolysis begins cellular ATP depletion sodium pump fails protein synthesis fails accumulation of sodium ions water enters the cells and causes swelling
what are the late/ irreversible effects of hypoxia?
cell and organelles swell
membrane integrity fails
mitochondrial pores open > apoptosis
leakage of cell proteins > necrosis
How are reactive oxygen species formed?
O2 is a strong oxidising agent
partial reduction of oxygen yields reactive oxygen species
ROS - the players
partial reduction of oxygen yields:
superoxide anion radical
hydrogen peroxide
ROS species can react together to form further ROS - hydroxyl radicals
Exception
singlet oxygen is a ROS but not a radical or from other ROS species
where do ROS come from?
mitochondria
what are some other sources of ROS?
Endogenous and exogenous
what are endogenous sources of ROS?
mitochondrial respiratory chain respiratory burst and NADH oxidase xanthine oxidase lipoxygenases glucose oxidase myeloperoxidase nitric oxide synthase cyclo-oxygenase transition metas
what are exogenous sources of ROS?
pollutants radiation cigarette smoking food and nutrients drugs xenobiotics
what do ROS do?
damage cells by causes free radial substitution chain reactions
cause cancer
cellular antioxidant defences
antioxidant enzyme systems
located in organelles and cytosol - isoforms
what are the antioxidant enzyme systems?
superoxide dismutase
catalase
glutathione peroxidase
oxidative stress
to prevent this there needs to be a balance between ROS production and ROS removal
what can oxidative stress do?
cause a whole host of diseases - asthma, vasospasm, atherosclerosis. cancer, inflammatory diseases, alzheimer’s and parkinson’s, rheumatoid arthritis, dermatitis, ischemic bowel
immune cells and ROS
immune cells kill pathogens with ROS
hyperbaric oxygen
patient inhales 100% oxygen at higher atmospheric pressure
15 times more oxygen received
how does hyperbaric oxygen work?
under pressure more oxygen is forced into the tissues so new blood vessels grow
plasma can carry 100% oxygen under pressure
red blood cells flow into new blood cells
extra oxygen is diffused to the tissues from the new blood vessels
what can be hyperbaric oxygen be used for?
wound healing- diabetic ulcers and other ulcers/ infected wounds
the bends - decompression sickness
what is photodynamic therapy?
uses photosensitiser which becomes activated when red light or daylight is shone onto the skin where it is applied. Causes changes in the oxygen molecules - oxidisation forming ROS in abnormal skin cells. The ROS kill abnormal cells.
There is minimal damage to normal cells
what is decompression sickness?
dissolved gases coming out of solution and forming bubbles inside the body on depressurisation
causes joint pain, rashes , paralysis and death.
when are ROS useful?
used as signalling molecules
what does nitric oxide do?
vasodilation
what can ROS damage?
DNA
lipids
proteins
what does carbon monoxide poisoning cause?
cherry red colour to skin
what is basal metabolic rate?
metabolic rate at rest
