Week 9 Flashcards
What are the three major mechanisms of acid-base balance?
- Buffering systems
- Exhalation of CO2
- Modulation of H+ and HCO3- in the kidneys
What role do buffering systems play in acid-base balance?
They help maintain the pH of body fluids
Why is maintaining optimum pH crucial?
To prevent denaturing of proteins and loss of function
What happens to protein structure when there is a large increase or decrease in H+ concentration?
Disruption of bonding mechanisms leads to protein unfolding and denaturing
What are acids defined as in terms of hydrogen ions?
Hydrogen ion (proton) donors
What is the pH scale range?
From 0 (extremely acidic) to 14 (extremely basic)
What is the pH at which a solution contains 0.0000001 mol/L of hydrogen ions?
pH 7
What are the two types of protein buffer systems mentioned?
- Hemoglobin in RBCs
- Albumin in plasma
What are the two ions involved in the phosphate buffer system?
- Dihydrogen phosphate (H2PO4-)
- Monohydrogen phosphate (HPO4^2-)
What is the function of dihydrogen phosphate in the phosphate buffer system?
It functions as a weak acid and buffers hydroxide ions (OH-) by donating a H+
How does monohydrogen phosphate act in the phosphate buffer system?
It acts as a weak base and binds H+ in solution to form dihydrogen phosphate
What are the limitations of the buffering systems?
They are rapid in action but temporary in nature and have limited capacity
What is the role of the renal system in acid-base balance?
It can secrete hydrogen ions to reduce acidity, maintaining blood pH
What ions are involved in the renal secretion of H+?
- Bicarbonate ions
- Ammonia (NH3)
- Monohydrogen phosphate (HPO4^2-)
True or False: Acids reduce the concentration of H+ in a solution.
False
Fill in the blank: Bases are H+ _______.
acceptors
What is the effect of increased acidity on proteins?
Causes denaturing of proteins and loss of function
What happens at pH 5 compared to pH 6?
pH 5 contains 10 times more H+ and is 10x more acidic than pH 6
What is the dissociation of hydrochloric acid (HCl)?
HCl dissociates to H+ and Cl-
What is the role of bicarbonate in the proximal tubule?
It is involved in the secretion of H+
What are the consequences of protein denaturation?
Alters protein shape and reduces function
What is the role of minerals in biochemical reactions?
Minerals can be part of enzymes that catalyze biochemical reactions
Minerals are essential for various physiological processes
Name two important functions of minerals.
- Play an important part in immunity
- Essential for muscle contraction and cell activation
Minerals are vital for overall health and physiological functions
How are minerals classified based on daily requirements?
- MacroMinerals: > 100 mg per day
- Microminerals: < 100 mg per day
This classification helps in understanding dietary needs
What is the most abundant mineral in the body?
Calcium
Calcium plays a crucial role in bone health and various bodily functions
What percentage of calcium in the body is found in bones?
Around 96%
Calcium combines with phosphate to form the inorganic component of bones
In what forms is calcium present in the blood?
- Free calcium
- Bound to plasma proteins
These forms are important for various physiological functions
What is the daily requirement of calcium?
1000 mg per day
Adequate calcium intake is essential for maintaining bone density
What do calcium and phosphate ions form in the body?
A lattice structure
This structure is crucial for the extracellular matrix of bone
What is the role of calcium in neurotransmitter release?
Triggers exocytosis of synaptic vesicles containing neurotransmitter
Calcium enters the axon terminal to facilitate this process
Name a function of calcium related to muscle activity.
Role in muscle contraction
Calcium is essential for initiating muscle contraction
What is Factor IV in blood clotting?
Calcium
Calcium is crucial in the blood clotting cascade
What does thrombin do in the clotting process?
Converts fibrinogen to insoluble fibrin
This forms a network that stabilizes the blood clot
What substance prevents blood clotting?
EDTA
EDTA is commonly used in laboratory settings to prevent clot formation
What percentage of phosphate in the body is combined with and used in bones?
85%
The remaining 15% exists as ions.
List the ions that make up the remaining 15% of phosphate.
- Не рОй-
- Н РОц -
- PO,3-
These ions are important for various physiological functions.
What is one of the functions of phosphate ions in the body?
Function as buffers
Buffers help maintain pH levels in biological systems.
What are most ions in the body bound to?
- Lipids (phospholipids)
- Proteins
- Carbohydrates
- Nucleic acids
- ATP
These bindings are crucial for cellular functions.
What is the relationship between calcium and phosphate in the human body?
They have a close association
Bones act as a reservoir for calcium and phosphate.
Which hormones are involved in the regulation of calcium and phosphate?
- Parathyroid hormone
- Calcitriol
- Calcitonin
These hormones play key roles in maintaining calcium and phosphate levels.
What triggers the release of parathyroid hormone?
Low blood calcium levels
Parathyroid hormone helps to increase blood calcium levels.
What effect does parathyroid hormone have on osteoclasts?
Stimulates osteoclasts to increase resorption of bone
This process releases calcium and phosphate ions from the bone matrix.
Fill in the blank: The bones provide a bank where calcium and phosphate can be _______.
deposited
This storage is essential for maintaining mineral balance in the body.
What effect does PTH have on phosphate reabsorption?
PTH reduces phosphate reabsorption in the proximal tubule, leading to increased phosphate excretion in urine.
How does PTH influence calcitriol production?
PTH increases calcitriol production, which enhances both calcium and phosphate absorption in the gut.
What is the primary function of calcitonin?
Calcitonin acts to decrease calcium levels in the blood by reducing the activity of osteoclasts and decreasing gut absorption of calcium.
Where is sulphur primarily found?
Sulphur is found in oxidized form as sulphate (SO4^2-), in plants, water, and in the amino acids methionine and cysteine.
Which B vitamins are associated with sulphur?
Sulphur is associated with B1, B3, and B7.
What are sulphites used for?
Sulphites are used in food and beverage preservation to prevent oxidation.
What percentage of the body’s total magnesium is found in bone matrix?
Around 50-60% of the body’s total magnesium is found in bone matrix as magnesium salts.
What are the major metabolic roles of magnesium?
Magnesium has major metabolic roles in the production of DNA, nerve function, and acts as a cofactor in enzymes.
How does magnesium facilitate nerve conduction?
Magnesium facilitates nerve conduction via NMDA receptors.
What functions does magnesium support in the body?
Magnesium supports muscle contraction, normal heart rhythm, and modulates insulin secretion and intracellular signaling.
Fill in the blank: PTH increases calcitriol production, which enhances both calcium and _______ absorption in the gut.
phosphate
True or False: Calcitonin increases calcium levels in the blood.
False
What percentage of iron is found in haemoglobin?
65%
Haemoglobin is the protein in red blood cells responsible for transporting oxygen.
What percentage of iron is found in myoglobin?
15%
Myoglobin is a protein that carries oxygen in muscle cells.
What is the form in which 20% of iron is stored in tissues?
Haemosiderin
Haemosiderin is an intracellular, insoluble form of stored iron.
Why is free iron considered dangerous?
It catalyses the formation of free radicals
Free radicals can cause oxidative damage to cells.
How is iron regulated in the body?
Iron is not regulated by secretion
The body primarily regulates iron levels through absorption and storage.
What condition results from too little iron?
Anaemia
Anaemia is a condition characterized by a deficiency of red blood cells or hemoglobin.
What condition can arise from too much iron absorption in the digestive system?
Haemochromatosis
Haemochromatosis is a disorder where excess iron builds up in the body, potentially leading to organ damage.
What is the primary solvent in the body?
Water
Water is the largest component of the body, making up 40-75% of total mass.
What are the main roles of water in the body?
- Medium for biochemical reactions
- Excellent solvent due to polarity
- High heat capacity aiding thermoregulation
Disruptions to water balance can lead to dehydration or overhydration.
What percentage of fluids do lean adults contain?
55 - 60%
These fluids are divided into intracellular and extracellular compartments.
What are the two main compartments of body fluids?
- Intracellular fluid (ICF) - 33% of total fluid
- Extracellular fluid (ECF) - 13% of total fluid
ECF consists of 80% interstitial fluid and 20% plasma.
What is the main characteristic of fluid balance in the body?
Fluid is separated by either cell membranes or blood vessel walls
Fluid can pass through cell membranes and capillaries.
What does fluid balance rely on?
The ratio of water molecules to solutes
Many solutes are electrolytes that dissociate into ions.
What happens to water in relation to solute concentration?
Water will move to an area of higher solute concentration
This process is known as osmosis.
How can water be retained in a specific location in the body?
By maintaining solute concentration
Different solutes are present in ICF and ECF.
Which organ tightly controls the solute concentration of water?
Kidneys
This is achieved through reabsorption or secretion of solutes.
What is the primary function of diuretics?
Increase the production of urine
Diuretics stimulate diuresis.
Name three xanthines that have diuretic properties.
- Caffeine
- Theophylline
- Theobromine
Xanthines inhibit Na+ reabsorption and promote water loss.
How does alcohol affect water resorption?
Inhibits ADH secretion, reduces water resorption
Alcohol increases water loss.
What triggers the release of renin in the kidneys?
Loss of water detected by baroreceptors
This is part of the Renin-Angiotensin-Aldosterone system (RAAS).
What are the main extracellular solutes that regulate body fluid volume?
- Sodium (Na+)
- Chloride (Cl-)
Their regulation is crucial for maintaining fluid balance.
What happens to fluid volume and blood pressure with increased sodium consumption?
Higher fluid volume and blood pressure
Increased Na+ leads to more water retention due to osmosis.
What is the relationship between sodium excretion and water loss?
The more Na+ we excrete, the more water we lose
This occurs due to osmosis.
Which hormones dictate sodium concentration in the body?
- Angiotensin II
- Aldosterone
- Atrial natriuretic peptide
These hormones regulate Na+ reabsorption.
What effect does angiotensin II have on sodium reabsorption?
Increases Na+ reabsorption
This helps to retain fluid and maintain blood pressure.
What is the role of aldosterone in sodium regulation?
Increases Na+ reabsorption
Aldosterone is crucial for maintaining sodium balance.
What effect does atrial natriuretic peptide have on sodium reabsorption?
Reduces Na+ reabsorption
This hormone promotes the excretion of sodium.
What is the primary function of diuretics?
Increase the production of urine
Diuretics stimulate diuresis.
Name three xanthines that have diuretic properties.
- Caffeine
- Theophylline
- Theobromine
Xanthines inhibit Na+ reabsorption and promote water loss.
How does alcohol affect water resorption?
Inhibits ADH secretion, reduces water resorption
Alcohol increases water loss.
What triggers the release of renin in the kidneys?
Loss of water detected by baroreceptors
This is part of the Renin-Angiotensin-Aldosterone system (RAAS).
What are the main extracellular solutes that regulate body fluid volume?
- Sodium (Na+)
- Chloride (Cl-)
Their regulation is crucial for maintaining fluid balance.
What happens to fluid volume and blood pressure with increased sodium consumption?
Higher fluid volume and blood pressure
Increased Na+ leads to more water retention due to osmosis.
What is the relationship between sodium excretion and water loss?
The more Na+ we excrete, the more water we lose
This occurs due to osmosis.
Which hormones dictate sodium concentration in the body?
- Angiotensin II
- Aldosterone
- Atrial natriuretic peptide
These hormones regulate Na+ reabsorption.
What effect does angiotensin II have on sodium reabsorption?
Increases Na+ reabsorption
This helps to retain fluid and maintain blood pressure.
What is the role of aldosterone in sodium regulation?
Increases Na+ reabsorption
Aldosterone is crucial for maintaining sodium balance.
What effect does atrial natriuretic peptide have on sodium reabsorption?
Reduces Na+ reabsorption
This hormone promotes the excretion of sodium.
What is the primary regulator of water reabsorption?
Antidiuretic hormone (ADH)
ADH is secreted from the posterior pituitary gland.
What role do aquaporins play in the kidneys?
They promote the insertion of water channels in collecting ducts
Aquaporins facilitate water reabsorption.
How does antidiuretic hormone affect sweat loss?
Reduces water lost in sweat
ADH also acts as a vasoconstrictor.
What happens to urine composition when fluid and solute intake varies?
We maintain a stable fluid/solute concentration
Urine is generally more dilute than body fluids.
What is the typical osmolality of urine compared to body fluids?
Urine has a lower solute concentration than body fluids
This is due to a higher intake of water.
What occurs when a person is overhydrated?
Produces larger volumes of dilute urine
This helps excrete the excess water.
What occurs when a person is dehydrated?
Conserves much of the water content
The body retains water to maintain homeostasis.
What is the osmolality of blood when filtered in the glomerulus?
300 mOsm/kg
The filtrate has the same ratio of water to solutes as the blood.
Where is the osmolality lowest in the kidney?
In the renal cortex
The osmolality here is approximately 300 mOsm/kg.
How does osmolality change in the kidney?
It becomes greater towards the inner medullary region
The osmolality can reach up to 1200 mOsm/kg.
What is the significance of the nephron loop in osmolality?
It has the biggest difference in osmolality
This affects water reabsorption across tubular cells.
Fill in the blank: The osmolality of tubular fluid in the kidneys varies, with the biggest difference in the _______.
nephron loop
True or False: The interstitial fluid osmolality in the kidney is the same throughout.
False
Osmolality varies depending on location within the kidney.
