Lecture 13 Flashcards Preview

MLAB103 > Lecture 13 > Flashcards

Flashcards in Lecture 13 Deck (33)
Loading flashcards...

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?

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
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
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)


Describe gas exchange in the body

Gases will diffuse from a region of higher to lower partial pressure
Gas exchange:
O2 from the alveoli to the blood (capillaries)
O2 from the blood to the tissues
CO2 from the tissues to the blood
CO2 from the blood to the lungs


Describe O2 Transportation in the body

In the blood, O2 binds to hemoglobin (red blood cells) and is transported to the tissues
Known as oxyhemoglobin
O2 is used in tissues for metabolic functions
Hemoglobin (HGB, HBG, Hb, HHb) can be reused – pick up more O2


Describe CO2 Transportation in the body

CO2 is produced in the tissues (waste product)
Diffuse into the red blood cells (RBC)
CO2 react with water in the RBC to produce carbonic acid
Carbonic acid ionize to produce H+ and HCO3−
Most of the HCO3− circulate in the plasma
HCO3− combines with H+ in the lungs to form carbonic acid
Carbonic acid (H2CO3) decomposes to form H2O and CO2
CO2 exhaled from the lungs
Some CO2 can also react with Hb to form carbaminohemoglobin
Carbaminohemoglobin will decompose into Hb and CO2 in the lungs
CO2 is exhaled from the lungs
Hb is recycled


Why is ABG test done?

Check for severe breathing problems and lung disease, such as asthma, cystic fibrosis, or chronic obstructive pulmonary disease (COPD)
Monitor treatment for lung disease
Check if extra oxygen or help with breathing (mechanical ventilation) is needed
Measure the acid-base level in the blood
People who have heart failure, kidney failure, uncontrolled diabetes, sleep disorders, severe infections, or after a drug overdose


Patient Preparation of ABG

If the Patient is on Oxygen therapy, the oxygen may be turned off for 20 minutes before the blood test. This is called a "room air" test
If the patient can't breathe without the oxygen, the oxygen must not be turned off
Test done by doctors, respiratory therapist
Note: Procurement of arterial blood gas is NOT done by Medical Technologist or MLA/T in Canada


Test Procedure of ABG

A sample of blood from an artery is usually taken from the inside of the wrist (radial artery), but it can also be taken from an artery in the groin (femoral artery) or on the inside of the arm above the elbow crease (brachial artery)
Arterial blood collection causes patient discomfort and other medical complications