Biology Chapter on Acids and Bases

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Questions and Answers

What defines a strong acid in terms of dissociation?

Partially dissociates in solution

Does not dissociate at all

Completely dissociates in solution (correct)

Only dissociates under pressure

Which of the following is a characteristic of bases?

They produce H+ ions in solution

They are always strong

They accept protons (correct)

They donate protons

Which buffer mechanism is primarily used by the respiratory system to regulate blood pH?

Protein buffer system

Phosphate buffer system

Bicarbonate buffer system

Carbonic acid-bicarbonate system (correct)

What is a primary source of acid production in the body?

Cellular respiration Signup and view all the answers

Which of the following is NOT considered a biological buffer in the body?

Lactic acid Signup and view all the answers

What is the primary function of pulmonary surfactant in the alveoli?

To reduce surface tension and prevent lung collapse Signup and view all the answers

Which lipoprotein component primarily decreases surface tension in the lungs?

Phosphatidylcholine (lecithin) Signup and view all the answers

At what stage of gestation is pulmonary surfactant typically secreted into the small airspaces?

22 weeks Signup and view all the answers

Which group of surfactant proteins is responsible for hydrophilic functions in the lung?

SP-A and SP-D Signup and view all the answers

What is the primary composition percentage of lipids in pulmonary surfactant?

90% Signup and view all the answers

What role does phosphatidylglycerol play in pulmonary surfactant?

It stabilizes the lipid monolayer at the air-liquid interface. Signup and view all the answers

Which of the following is NOT a hydrophilic surfactant protein?

SP-B Signup and view all the answers

What is one effect of surfactants on surface tension in the alveoli?

Decrease surface tension, facilitating alveolar inflation Signup and view all the answers

What is the primary fuel for cellular respiration?

Glucose Signup and view all the answers

Which stage of cellular respiration directly produces ATP?

Oxidative phosphorylation Signup and view all the answers

What is a byproduct of aerobic glycolysis?

Carbon dioxide Signup and view all the answers

What happens if glucose breakdown occurs all at once?

Energy is wasted as heat Signup and view all the answers

The oxidation of glucose in the presence of oxygen is defined as what?

Aerobic glycolysis Signup and view all the answers

What are the end products of glycolysis?

2 pyruvate and ATP Signup and view all the answers

Which compound is converted to NADH during glycolysis?

NAD+ Signup and view all the answers

In which cellular compartment does oxidative decarboxylation occur?

Mitochondria Signup and view all the answers

What is the primary function of superoxide dismutase (SOD) in cellular protection?

It converts superoxide free radicals to hydrogen peroxide. Signup and view all the answers

Which antioxidant is primarily responsible for protecting cellular membranes from lipid peroxidation?

α-tocopherol Signup and view all the answers

Which of the following vitamins can regenerate other antioxidants like vitamin E from oxidation?

Ascorbic acid Signup and view all the answers

What is the role of glutathione reductase in the detoxification process?

It regenerates reduced glutathione using NADPH. Signup and view all the answers

Which metal is a cofactor specifically for the catalase enzyme?

Iron Signup and view all the answers

What condition describes the imbalance between oxidants and antioxidants in biological systems?

Oxidative stress Signup and view all the answers

Which antioxidant is specifically noted for its ability to destroy singlet oxygen?

β-carotene Signup and view all the answers

What is a key function of vitamin C aside from acting as an antioxidant?

It acts as a reducing agent for reactive oxygen species. Signup and view all the answers

Which molecule is classified as a Reactive Nitrogen Species (RNS)?

Nitric oxide (NO) Signup and view all the answers

What is the main source of Reactive Oxygen Species (ROS) in cells?

Mitochondrial electron transport chain Signup and view all the answers

Which of the following is NOT considered a free radical despite being highly reactive?

Hydrogen peroxide (H2O2) Signup and view all the answers

Which statement correctly explains the term 'free radicals beget free radicals'?

Free radicals generate more free radicals through a chain reaction. Signup and view all the answers

Which of the following is a consequence of the leakage of electrons during oxygen metabolism?

Formation of reactive molecules known as ROS Signup and view all the answers

Which of the following is NOT an exogenous source of free radicals?

Mitochondrial electron transport chain Signup and view all the answers

What types of biomolecules are primarily damaged by reactive oxygen species (ROS)?

All types including carbohydrates, lipids, proteins, and nucleic acids Signup and view all the answers

Which of the following best describes the role of peroxisomes in the generation of free radicals?

They are a significant source of endogenous free radicals. Signup and view all the answers

What role does the bicarbonate buffer system play in the body?

It is the most important buffer, maintaining blood pH. Signup and view all the answers

Which statement correctly describes the kidneys in the context of pH regulation?

They reabsorb or excrete hydrogen as needed for pH balance. Signup and view all the answers

What is the composition of a buffer as described?

A weak acid and its salt or a weak base and its salt with a strong acid. Signup and view all the answers

What characterizes the 'fast' line of defense for pH regulation?

It responds rapidly within hours to regulate CO2 levels. Signup and view all the answers

What are the types of acid-base imbalances that can occur in the body?

Acidosis and alkalosis, including respiratory and metabolic forms. Signup and view all the answers

In response to a decreasing pH, what physiological action is taken by the respiratory system?

Increased respiration or hyperventilation to expel CO2. Signup and view all the answers

What is true about physiological buffers?

They include bicarbonate, phosphate, and protein systems. Signup and view all the answers

Which statement accurately describes how buffers function in the blood?

Buffers resist changes in pH by either donating or removing H+ as needed. Signup and view all the answers

Study Notes

Cellular Respiration

Cellular respiration is a metabolic pathway that breaks down glucose and produces ATP.
Glucose is the primary fuel for cellular respiration.
If glucose breakdown happens all at once, energy is wasted as heat. If it occurs in steps, energy is produced.
The process has four stages: Glycolysis, Oxidative decarboxylation, Krebs cycle, Oxidative phosphorylation (ETC).

Learning Outcomes

Understand the concept of cellular respiration.
Differentiate between aerobic and anaerobic glycolysis.
Identify the source of ATP in the body.

Case Study

A young woman (approximately age 35) was found unconscious near a doorway in a house that was filled with smoke after a fire.
Her blood pressure was 70/50 mmHg, pulse 120/min, and respiration rate 30/min.
She had no response to pain, was unconscious and flaccid.
The woman was being administered 100% oxygen via face mask and improved but was lethargic and disoriented.

Photosynthesis

Energy from sunlight drives the synthesis of glucose from CO2 and H2O.
Oxygen is released as a byproduct.

Respiration & Cellular Respiration

Respiration is the process of exchanging gases, while cellular respiration breaks down glucose for energy at the cellular level.
Diagrams show components of the respiratory and cellular systems.

Cycles

Glucose, in the presence of oxygen, produces ATP through several steps.
Glycolysis occurs in the cytoplasm. It breaks down glucose into pyruvate.
Oxidative decarboxylation converts pyruvate into acetyl CoA, entering the mitochondria.
The Krebs cycle further oxidizes acetyl CoA to carbon dioxide, generating energy carriers (NADH, FADH2).
Oxidative phosphorylation (ETC) utilizes energy carriers to create a proton gradient across the inner mitochondrial membrane to generate ATP.

Aerobic Glycolysis

This is glucose oxidation in the presence of oxygen.
Cells transfer energy in organic compounds to ATP.
Carbon dioxide and water are released as byproducts (waste products of respiration).

Glycolysis

Glycolysis is the breakdown of glucose into pyruvate in the cytoplasm.
This process produces ATP (2 molecules).
NAD+ is converted to NADH during this step (2 molecules).

Oxidative Decarboxylation

Pyruvate molecules produced from glycolysis enter the mitochondria.
Within the mitochondria, they are converted to acetyl CoA and 2 NADH are generated.

Krebs Cycle

A series of chemical reactions that release stored energy by oxidizing acetyl CoA derived from CHO, lipids, and proteins.
The acetyl group of acetyl-CoA is oxidized, forming CO2 and energy.
Energy production happens by coupling to the compounds 3 NAD+ and 1 FAD+ and 1 ATP molecule for each pyruvate.
Results in reduced 3 NADH molecules, and reduced to 1 FADH2 molecule.

Oxidative Phosphorylation (ETC)

A group of protein complexes act in the last stage of cellular respiration and is found in the inner mitochondrial membrane.
These complexes shuttle electrons from NADH and FADH2 to molecular oxygen, converting them to NAD+ and FAD.
This process creates a proton gradient, providing energy for oxidative phosphorylation that synthesizes ATP.
Oxygen is the final electron acceptor and combines with protons to form water.

Importance of ETC

Transferring electrons regenerates empty NAD+ and FAD+ to be used again.
Transfer of protons across the membrane establishes a gradient.
This gradient provides energy for oxidative phosphorylation to synthesize ATP.
Oxygen accepts electrons at the end of the electron transport chain and combines with protons to form water. This is the final electron acceptor for the system.

Total ATP Production (Aerobic)

The complete aerobic oxidation of one glucose molecule generates approximately 38 ATP molecules through glycolysis, intermediate stage, Krebs cycle, and the electron transport chain.

Anaerobic Glycolysis

Glucose oxidation happens in the absence of oxygen.
A source of energy for red blood cells and contracting muscles.

Aerobic vs. Anaerobic Respiration

Aerobic respiration requires oxygen and yields 38 ATP molecules.
Anaerobic respiration does not require oxygen and produces only 2 ATP molecules.

Cellular Pathway

Diagram depicts the pathway from glucose to pyruvate (via aerobic or anaerobic pathways).
Outcomes (CO2, H2O, or lactate) are different.

Inhibition of Cellular Respiration

Inhibition can occur through blocking the flow of glycolysis or oxidative phosphorylation.
Pyruvate kinase deficiency is an autosomal recessive disease affecting red blood cells, which depend on glycolysis for ATP production.

Inhibition of Oxidative Phosphorylation

Inhibitors block the electron flow through the electron transport chain (ETC) or phosphorylation processes.
Examples include Rotenone, Antimycin A, Cyanide (CN), and Carbon monoxide (CO).
Oligomycin inhibits ATP synthase (complex V).

Uncouplers

Uncouplers disrupt the proton gradient, hindering ATP synthesis.
Examples include Ca injection, high-dose aspirin, high levels of thyroid hormones, and progesterone.

Case Study (Smoke Inhalation)

A young woman, experiencing smoke inhalation, is presented.
The cause of impairment is related to cyanide blocking the electron transport chain and preventing oxygen utilization.
This leads to anaerobic metabolism and metabolic acidosis as well as contributing to the symptoms observed.

pH and Acid-Base Balance

Students will be able to differentiate between acids and bases, define pH and its scale, list sources of acid production, and understand how the body defends against pH changes through buffers, the respiratory system, and the renal system.
Disturbances in pH balance can lead to acidosis or alkalosis, each presenting with a range of possible symptoms.

Important Buffer Systems in the Body

Bicarbonate, phosphate, and protein systems are important physiological buffers.

Buffer Systems (1st Line of Defense)

They help maintain stable pH when acids or bases are added.
Buffers are solutions resisting pH changes with small additions of acid or base.
They comprise a "taker" and a "giver" part which respectively remove H+ or donate H+ to regulate pH.

Respiratory System (2nd Line of Defense)

The lungs adjust acid/base balance quickly by controlling CO2 removal.
If pH falls (acidosis), rapid respiration occurs to remove CO2.
If pH rises (alkalosis), slow respiration minimizes CO2 loss.

Kidneys (Final Line of Defense)

The kidneys control pH by excreting or reabsorbing hydrogen ions/bicarbonate.

Reference Range of Arterial Blood Gases (ABG)

Table provides the normal physiological ranges of pH, PaO2, PaCO2, HCO3, and SaO2.

Acid-base Imbalance

Acidosis/alkalosis is the result of an imbalance between the body's acid and base production/removal mechanisms.

Respiratory Acidosis

Characterized by a low blood pH and increased carbon dioxide levels, often due to impaired lung function (e.g., asthma)
Reduced ventilation and increased CO2 level due to breathing disorders.

Respiratory Alkalosis

Characterized by a high blood pH and decreased carbon dioxide levels.
Rapid breathing (hyperventilating) often due to stress or panic results in excessive CO2 loss.

Metabolic Acidosis

Produced when the body generates excessive amounts of acids or loses the ability to neutralize or eliminate them.
Excessive acid production or loss of buffer capacity in the body contribute to metabolic acidosis, for example, lactic acidosis or diabetic ketoacidosis.

Metabolic Alkalosis

Characterized by a high blood pH and increased levels of bicarbonate due to an excessive loss of acid (vomiting) or gain of bicarbonate in the body.

The Respiratory Parameter of ABG

Summarized table representing how the respiratory parameter of ABG assists in determining and identifying acid/base imbalance through the measures of pH/PCO2/HCO3-.

Pulmonary Surfactants

Complex formed by type II alveolar cells.
Secreted into airspaces around week 22 of gestation for lung maturity.
It decreases surface tension in the alveoli, reducing the pressure needed to re-inflate alveoli.

Surfactant Insufficiency

Associated with Respiratory Distress Syndrome (RDS) and neonatal death in preterm infants.
Management involves administering glucocorticoids before delivery to accelerate lung maturation, or synthetic surfactant after birth.

Testing Lung Maturity

Evaluation of fetal pulmonary maturation is important for risk stratification.

Measurement of L/S Ratio by Thin Layer Chromatography (TLC)

The L/S ratio (lecithin/sphingomyelin) is a standard method for assessing lung maturity.

Phosphatidylglycerol (PG) Assay

Detects Phosphatidylglycerol antibodies in amniotic fluid to determine lung maturity.

Types of Antioxidants

Enzymatic and non-enzymatic antioxidants neutralize reactive oxygen species (ROS).

Oxidative Stress

Imbalance between oxidants (ROS) and antioxidants causes oxidative stress.

Antioxidant Mechanisms

Preventing generation of ROS/free radicals (preventive), breaking down chain reaction of ROS/free radicals (chain-breaking), and repairing the damage caused by free radicals (repair).

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Description

Test your knowledge on the characteristics of acids and bases, their role in biological systems, and the mechanisms that regulate blood pH. This quiz covers essential concepts regarding dissociation, buffer systems, and acid sources in the body.