Lecture 13 Flashcards
(33 cards)
Why do we eat?
To replenish storage of molecules that our body need
For growth and tissue repair
To take the chemical bond energy in food molecules, and attach phosphate group to ADP, creating ATP
Energy is obtained from the food we eat
What is energy and where does it come from?
Energy is required to maintain the structure and function of the living cells
The energy is derived from oxidation of carbohydrates, lipids and protein in diets
Energy liberated is converted into ATP, which is known as the energy currency of the living cells
Each gram of carbohydrate and protein gives about 4 Kcal on oxidation, while each gram of fat gives about 9 Kcal
How do the food we take in and the oxygen we respire, produce energy to continue the process of life?
The food we take in is oxidized by the oxygen we breath and by enzymes present in the body
What is biological oxidation?
The primary function of biological oxidation is to provide usable energy in living cells
Biological oxidation is catalyzed by enzymes called oxidoreductase, which function in combination with coenzymes and/or electron carrier proteins
Most of the energy liberated in biological oxidation is stored in high-energy compounds
Example: Adenosine triphosphate (ATP)
ATP transports chemical energy within cells for metabolism
Describe oxidation and reduction
Biological oxidation in cells is related to the transfer of reducing equivalents
Hydrogen atoms or electrons
Oxygen is the final acceptor of reducing equivalents
Resulting in atoms having their oxidation number (oxidation state) changed
What can oxidation be?
Gain of oxygen Loss of electron(s) Loss of hydrogen An increase in oxidation number During oxidation energy is released
Example of oxidation – Lactic acid to Pyruvic acid
What is reduction?
Reduction is the opposite of oxidation – Gain of hydrogen Gain of electron(s) Loss of oxygen Decrease in oxidation number
Both oxidation and reduction always occur together
What is cellular resipration?
Respiration:
Breathing in oxygen and breathing out carbon dioxide
Exchange of gases
It is how cells take the energy from food and make it into ATP
How is cellular respiration done?
Cells convert biochemical energy from molecules in carbohydrates, fatty acids and amino acids – (nutrients), into ATP, and then release waste products – CO2 and H2O
Done through oxidation-reduction reaction
Example:
Glucose + O2 = ATP (energy); CO2 + H2O
Creating ATP is a cellular process - Cellular Respiration – within the cells
Nutrients include, glucose, amino acids and fatty acids, and a common oxidizing agent
Respiration is one of the key ways a cell gains useful energy
The energy released in respiration is used to synthesize ATP to store this energy
What is Aerobic respiration
requires oxygen in order to generate energy ATP
done in the mitochondria
What is Anaerobic respiration
oxygen is not required
in the cytoplasm
What happens in cellular respiration
The reducing equivalents (Hydrogen and electrons) from various metabolic intermediates are transferred to coenzymes NAD and FAD to produce NADH and FADH2 respectively
Energy is stored as
ATP
NADH (“nicotinamide adenine dinucleotide (NAD) + hydrogen (H).”
FADH2 - Flavin adenine dinucleotide
FADH2, is a cofactor that is created during the Krebs cycle and utilized during the last part of respiration, the electron transport chain
Oxygen is added to glucose (oxidation)
Oxidation-reduction reaction
Where does cellular respiration occur
The mitochondria generate most of the cell’s supply of ATP
Glucose and oxygen are outside the cell
O2 goes through the phospholipid bilayer - diffuse into the cytoplasm and into the mitochondria
Glucose goes through the glucose protein channel of the cell membrane
Glucose is partially broken down for energy in the cytoplasm and then continues into the mitochondria
How is glucose broken down
Glycolysis:A series of reactions that extract (harvest) energy from glucose by splitting it into two three-carbon molecules called pyruvates
Break down takes place in the cytoplasm of the cell
At the end of glycolysis — ATP, NADH are produced – coenzymes that transport electrons from the cytosol to the inner mitochondria
O2 not required – anaerobic pathway
Oxidation takes place (electron transfer)
What can be done with pyruvates
Pyruvate can be oxidized or can be reduced
If oxidized – aerobic condition – Acetyl CoA is produced
Important in the Citric Acid Cycle
Each reaction in glycolysis is catalyzed by its own enzyme
What are the steps of the Krebs cycle?
Pyruvate enters the Krebs cycle as Acetyl Coenzyme A – (acetyl CoA)
Acetyl CoA is degraded into two molecules of CO2 and a molecule of coenzyme A
ATP, NADH and FADH2 are produced – transport electrons
Cycle takes place in the mitochondria of the cell
What is the electron transport chain?
Electrons are carried by NADH molecule
NADH and FADH2 are converted to ATP (the main form of energy used by cells)
Activity is in the mitochondria
O2 is needed at the end of the chain – aerobic
What is Arterial Blood Gas Test (ABG)
Measure the pH, the level of oxygen and carbon dioxide in the blood from an artery
Checks how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood
Use blood drawn from an artery, where the oxygen and carbon dioxide levels can be measured before they enter body tissues
What is impacted by ABG - What else should be measured
Used to determine the partial pressure of dissolved gases in the blood
The pH of the blood
The partial pressure of carbon dioxide – pCO2
The partial pressure of Oxygen – pO2
The bicarbonate level – HCO3
Oxygen Saturation - O2 Saturation
Determine gas exchange levels in the blood related to lung function
Exchange takes place in the capillary blood vessels
What does the pH measure from the ABG
The pH measures hydrogen ions (H+) in the blood
The pH of blood is usually between 7.35 and 7.45
A pH of less than 7.0 is called acid and a pH greater than 7.0 is called basic (alkaline). So blood is slightly basic
What does the PCO2 measure from the ABG
PCO2 – Partial pressure of carbon dioxide
This measures the pressure of carbon dioxide dissolved in the blood and how well carbon dioxide is able to move out of the body
What does the PO2 measure from the ABG
PO2 – Partial pressure of oxygen
This measures the pressure of oxygen dissolved in the blood and how well oxygen is able to move from the airspace of the lungs into the blood
What does the HCO3 measure from the ABG
HCO3 – Bicarbonate
Bicarbonate is a chemical (buffer) that keeps the pH of blood from becoming too acidic or too basic
What does the O2CT measure from the ABG
O2CT – Oxygen Content and O2Sat – Oxygen Saturation values
O2 content measures the amount of oxygen in the blood
Oxygen saturation measures how much of the hemoglobin in the red blood cells is carrying oxygen (O2)
