Body Fluids and Electrolytes Overview

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Questions and Answers

Which statement accurately describes the function of buffers in the body?

Buffers are only composed of strong acids.

Buffers release hydrogen ions when pH decreases. (correct)

Buffers act instantaneously to prevent changes in hydrogen concentration. (correct)

Buffers can eliminate excess acids and bases from the body.

What makes up the bicarbonate buffer system in the plasma?

Sulfuric acid and sodium bicarbonate

Protein and amino acids

Carbonic acid and bicarbonate ions (correct)

Sodium ions and potassium ions

Which component primarily regulates the concentration of carbonic acid in the bicarbonate buffer system?

Digestive system

Respiration (correct)

Kidneys

Liver

How does the protein buffer system contribute to pH regulation?

By using amino acids to bind or release hydrogen ions Signup and view all the answers

Which of the following statements about the bicarbonate ion is correct?

It serves as a pH regulator in extracellular fluid. Signup and view all the answers

What is one of the primary roles of the kidneys in pH regulation?

Removal of metabolic acids Signup and view all the answers

What process occurs as the body breaks down food into building blocks?

Catabolism Signup and view all the answers

Where do water-soluble building blocks get absorbed in the digestive system?

Jejunum Signup and view all the answers

Which of the following is NOT a function of hepatocytes?

Production of hormones Signup and view all the answers

What does the hepatic portal system connect?

Digestive tract and liver Signup and view all the answers

What is the composition of blood flowing into the liver from the hepatic portal vein?

70% nutrient-rich blood and 30% deoxygenated blood Signup and view all the answers

Which metabolic process involves the production of glycogen from glucose?

Glycogenesis Signup and view all the answers

What role do Kupffer cells play in the liver?

Remove damaged erythrocytes and microorganisms Signup and view all the answers

What percentage of body weight is represented by intracellular fluid (ICF)?

40% Signup and view all the answers

What is the main cation in extracellular fluid (ECF) that affects plasma osmolarity?

Sodium Signup and view all the answers

What is the primary driving force for thirst during dehydration?

Osmoreceptor activation Signup and view all the answers

Which hormone is primarily responsible for reducing urinary loss of water during dehydration?

Antidiuretic hormone (ADH) Signup and view all the answers

How is the balance of water intake and output commonly maintained in the body?

Intake equals output Signup and view all the answers

What is the typical pH range of blood required for enzyme activity?

7.35 to 7.45 Signup and view all the answers

Which statement accurately describes the relationship between osmolarity and water concentration in ICF and ECF?

Osmolarity and water concentration are the same in ICF and ECF Signup and view all the answers

Which of the following solutes are classified as non-electrolytes?

Creatinine and urea Signup and view all the answers

What is the primary function of low-density lipoproteins (LDL)?

Transport cholesterol to cells and arteries Signup and view all the answers

What is produced during glycolysis?

ATP and pyruvate Signup and view all the answers

What is the role of oxygen in aerobic respiration?

It is the final electron acceptor in the electron transport chain Signup and view all the answers

What is a potential consequence of the incomplete breakdown of lipids in the liver?

Ketoacidosis due to acetoacetic acid Signup and view all the answers

How much ATP can be generated from one glucose during the complete oxidation process?

32 ATP Signup and view all the answers

What is the primary metabolic pathway that occurs in cells without oxygen?

Anaerobic fermentation Signup and view all the answers

What body temperature range is considered normal?

36-37.5 C˚ Signup and view all the answers

Which hormone is the most important control factor for the basic metabolic rate?

Thyroxine Signup and view all the answers

What is the process by which amino groups are removed from amino acids called?

Deamination Signup and view all the answers

How much of the energy produced during ATP generation is typically lost as heat?

60-70% Signup and view all the answers

Study Notes

Body Fluids

Water accounts for approximately 60% of the body fluids in men and 55% in women.
Women have less water due to more adipose tissue.
Body fluids are divided into intracellular fluid (ICF) and extracellular fluid (ECF).
ICF comprises 2/3 of body fluids, found inside cells, and accounts for 40% of body weight.
ECF comprises 1/3 of body fluids, found outside cells, and includes interstitial fluid, plasma, and lymph.
Plasma is the link between intracellular and extracellular environments, and water is exchanged through osmosis.

Electrolytes

Electrolytes dissociate into free ions, such as Na+ (cations) and Cl- (anions), contributing to fluid osmolarity.
Non-electrolytes, like glucose, lipids, creatinine, and urea, do not dissociate and lack a charge.

Electrolyte Distribution

Sodium is the main cation in ECF and is the dominant electrolyte for plasma osmolarity.
Potassium is the main cation in ICF and is the dominant electrolyte for intracellular osmolarity.

Sodium-Potassium Pump

The sodium-potassium pump actively transports Na+ and K+, maintaining distinct concentrations using ATP and oxygen.
This pump ensures that the osmolarity of ECF and ICF remains equal, thus maintaining water concentration.

Water Balance

Daily water intake (2.5L) equals daily water output (2.5L), with sources including food, fluids, and metabolic processes.
Osmoreceptors in the hypothalamus detect increases in plasma osmolarity (decrease in saliva), triggering thirst.
Angiotensin II and antidiuretic hormone (ADH) enhance thirst and reduce urinary water loss.
Dehydration lowers blood volume.

Water Output

Water output occurs via feces, expired air, cutaneous transpiration, sweat, and urine.
The kidneys are the primary regulators of body fluid composition, adjusting tubular reabsorption of water and electrolytes through hormones like ADH, aldosterone, angiotensin, and ANP.

Acid-Base Balance

Blood pH ranges from 7.35 to 7.45, with enzymes sensitive to pH fluctuations.
Hydrogen ions (H+) originate from metabolism and ingested nutrients.
pH above 7.45 indicates alkalosis, while below 7.35 indicates acidosis.

Maintaining pH

pH is maintained by three mechanisms: buffers, lungs, and kidneys.
Buffers are chemicals that regulate pH by binding or releasing H+ ions, preventing dramatic pH changes.
The lungs regulate CO2 and H2O levels, while the kidneys control H+ and HCO3- levels.

Major Chemical Buffers

The protein buffer system operates in ICF using amino acids as weak acids or bases.
The bicarbonate buffer system operates in ECF, using a mix of carbonic acid (H2CO3) and bicarbonate (HCO3-) for buffering.
The phosphate buffer system operates in CSF and urine.

Regulation of Bicarbonate

The kidneys are the primary regulators of overall pH, removing metabolic acids and controlling bicarbonate levels.
They can reabsorb or secrete bicarbonate ions, generating new ones if needed, taking hours to days to restore pH.

Metabolism

Metabolism comprises chemical reactions essential for life, requiring enzymes.
Catabolism involves the breakdown of food into building blocks and the release of energy for ATP production.
Anabolism uses building blocks and ATP to create molecules.
Anabolism equals catabolism results in weight stability.

Nutrient Absorption

Water-soluble building blocks are absorbed into the jejunum capillaries and transported to the liver via the hepatic portal vein.
Lipids are absorbed into the lacteal of the villi and enter the lymphatic system.

Hepatic Portal System

This system connects capillary beds of the digestive tract to the liver.
Blood from the stomach, intestines, pancreas, and spleen is inspected by the liver before entering the inferior vena cava.

Liver Anatomy

The liver contains lobules, hexagonal cylinders composed of hepatocytes radiating outwards from a central Vein.
Plates of hepatocytes are separated by sinusoids, blood-filled channels lined with fenestrated epithelial cells.
Blood from the hepatic portal vein (70%) and hepatic artery (30%) permeates the sinusoids.

Hepatocytes

Hepatocytes absorb nutrients for metabolism or storage.
They remove, degrade, and detoxify hormones, toxins, and medications using SER.
Kupffer cells, macrophages in the liver, remove damaged erythrocytes and microorganisms.
Hepatocytes synthesize and secrete plasma proteins, clotting factors, cholesterol (85%), bile, and angiotensinogen.
They also store vitamins (A, D, E, K) and iron (Fe).
They play a crucial role in maintaining blood glucose levels.

Blood Glucose Regulation

Hepatocytes maintain blood glucose levels between 4 to 8 mmols/L through glycogenesis (glycogen production), glycogenolysis (glycogen breakdown), and gluconeogenesis (glucose synthesis from lipids and amino acids).

Lipoproteins

Hepatocytes synthesize lipoproteins to transport cholesterol and fatty acids in the blood.
Lipoproteins consist of a protein coat and phospholipids, with higher protein content correlating to higher density.
VLDL transports triglycerides to adipose tissue, becoming LDL.
LDL transports cholesterol to cells, including arteries.
HDL transports cholesterol from cells and arteries back to the liver for elimination in bile.

ATP Production

Glucose is the primary catabolic product of carbohydrate digestion.
ATP is generated using glucose through a series of small steps, using energy to add phosphate to ADP.
One glucose molecule yields 32 ATP.

ATP Production Pathways

Glycolysis: occurs in the cytosol, breaking down glucose into two pyruvate molecules, producing 2 ATP and NADH.
Anaerobic Fermentation: occurs in the cytosol, converting pyruvate to lactic acid without oxygen, allowing glycolysis to continue.
Aerobic Respiration: occurs in the mitochondria, using pyruvate, the citric acid cycle, and electron transport chain to generate 28 ATP with oxygen as the final electron acceptor.

Lipid Metabolism

Lipids are broken down to acetic acid, entering the citric acid cycle.
Incomplete lipid breakdown leads to ketoacidosis due to an accumulation of acetoacetic acid and acetone (sweet breath).

Protein Metabolism

Hepatocytes shift amino groups (NH2) between molecules.
Amino acids can be converted to glucose or fat, used for ATP production, or synthesize non-essential amino acids.

Amino Acid Deamination

Deamination removes amino groups, resulting in ammonia being converted to urea by hepatocytes, which is then excreted in urine.

Thermoregulation

60% of energy generated during ATP production is lost as heat.
The basic metabolic rate measures the heat produced by the body (60 to 72 kcal/hour).
Thyroxine is the most important regulator of metabolic rate.

Body Temperature

Normal core body temperature ranges from 36 to 37.5°C, supporting enzyme functionality.
Blood facilitates heat exchange between the core and shell.
The core temperature remains relatively constant, whereas the shell temperature fluctuates substantially.

Hypothalamus Thermostat

The hypothalamus receives sensory information from peripheral (skin) and central (hypothalamus, blood) thermoreceptors.
It initiates heat gain or loss mechanisms to maintain body temperature.

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Description

This quiz explores the crucial concepts of body fluids, their composition, and the role of electrolytes. Learn about intracellular and extracellular fluids, along with the distribution and functions of key electrolytes like sodium and potassium. Test your knowledge on how these elements contribute to overall body function.