Fluid and Acid-Base Balance Study Guide

What percentage of total body water is found in intracellular fluid (ICF)?

67% of total body water.

What is the volume of intracellular fluid (ICF) in the body?

Approximately 18.425 liters.

What percentage of total body water is found in extracellular fluid (ECF)?

33% of total body water.

What is the volume of extracellular fluid (ECF) in the body?

Approximately 9.075 liters.

What are the two subcompartments of extracellular fluid (ECF) and their respective volumes?

Plasma: 25% of ECF (2.269 liters); Interstitial Fluid: 75% of ECF (6.806 liters).

What is the primary ionic composition difference between intracellular fluid (ICF) and extracellular fluid (ECF)?

ICF has high concentrations of potassium (K⁺) and proteins, while ECF has higher concentrations of sodium (Na⁺), chloride (Cl⁻), bicarbonate (HCO₃⁻), and calcium (Ca²⁺).

How do protein carriers facilitate movement between fluid compartments?

They bind to molecules on one side of the membrane, change the molecule, and release it on the other side, functioning through passive or active transport.

What are the types of protein carriers involved in transport across cell membranes?

Uniporters, symporters, and antiporters.

What regulates sodium (Na⁺) balance in the body?

Primarily regulated by the kidneys through the action of aldosterone.

How is potassium (K⁺) balance regulated?

Regulated by the kidneys, with aldosterone promoting potassium excretion.

What hormones regulate calcium (Ca²⁺) levels in the body?

Parathyroid hormone (PTH), calcitonin, and vitamin D.

What role do kidneys play in regulating hydrogen ions (H⁺)?

Kidneys secrete and reabsorb hydrogen ions and bicarbonate.

How is water balance regulated in the body?

Regulated by antidiuretic hormone (ADH), which controls water reabsorption in the kidneys.

What mechanisms are involved in regulating extracellular fluid (ECF) volume and osmolarity?

Blood pressure, RAAS system, ADH, and osmoreceptors in the hypothalamus.

What triggers the release of ADH?

Osmoreceptors detect changes in osmolarity and trigger ADH release.

What is the difference between water loss/gain and combined water-solute loss/gain?

Water loss/gain refers to the movement of water alone, while combined water-solute loss/gain refers to the movement of both water and solutes.

What are common causes of water loss?

Evaporation through skin, exhalation, urination, and sweating.

What are common ways the body gains water?

Drinking fluids, metabolic water production, and absorption through food.

What are scenarios that lead to combined water-solute loss?

Diarrhea, vomiting, excessive sweating, and blood loss.

What are scenarios that lead to combined water-solute gain?

Intravenous fluids, electrolyte-rich drinks, and nutrient absorption.

What is the body's response to dehydration?

Increased thirst mechanism and release of ADH to conserve water.

What is dehydration?

A condition resulting from excessive water loss.

What hormonal response is involved in water reabsorption?

Activation of the Renin-Angiotensin-Aldosterone System (RAAS).

What is overhydration and its potential consequence?

Excessive water intake leading to hyponatremia.

What is combined water-solute loss?

Loss of both water and electrolytes, leading to electrolyte imbalance.

What compensatory mechanism is activated in response to low blood pressure or low sodium?

The Renin-Angiotensin-Aldosterone Pathway.

What happens during the conversion of Angiotensinogen?

It is converted into Angiotensin I.

What is the role of Angiotensin II in the body?

It causes vasoconstriction and stimulates aldosterone release.

How does aldosterone affect sodium levels?

It increases sodium reabsorption in the kidneys.

What distinguishes strong acids from weak acids?

Strong acids completely dissociate in water, while weak acids partially dissociate.

What is the primary buffer system in the blood?

The Bicarbonate Buffer System, which involves HCO₃⁻ and H₂CO₃.

What is the function of the Phosphate Buffer System?

It helps maintain pH balance in the kidneys and intracellular fluids.

How do proteins function in the Protein Buffer System?

They can accept or donate hydrogen ions to help maintain pH balance.

What role does the respiratory system play in acid-base balance?

It regulates carbon dioxide levels, influencing blood pH.

What is respiratory compensation?

The body's ability to alter breathing patterns to balance pH.

How does the urinary system contribute to acid-base balance?

By filtering and excreting excess hydrogen ions and reabsorbing bicarbonate.

What is metabolic acidosis?

A condition where the body accumulates acid or loses bicarbonate significantly.

What causes respiratory acidosis?

Excess carbon dioxide in the blood due to inadequate respiration.

What are common causes of metabolic acidosis?

Kidney failure, diabetic ketoacidosis, and lactic acidosis.

What is the role of ammonia in acid-base balance?

It forms ammonium to help remove hydrogen ions.

What is the bicarbonate buffer mechanism?

It helps maintain acid-base balance by using HCO₃⁻ to accept or donate hydrogen ions.

What is the phosphate buffer mechanism?

It helps maintain acid-base balance by using phosphate to accept or donate hydrogen ions.

What is the significance of maintaining homeostasis in acid-base balance?

It is essential for normal cellular function and overall health.

What is Metabolic Alkalosis and what causes it?

Metabolic Alkalosis occurs when there is an excessive loss of acid or an increase in bicarbonate, caused by prolonged vomiting, diuretic use, or excessive bicarbonate intake.

What is Respiratory Alkalosis and what typically causes it?

Respiratory Alkalosis is due to a decrease in CO₂ levels in the blood, often caused by hyperventilation due to anxiety, fever, or high altitude.

What is the difference between Compensated and Uncompensated Acidosis/Alkalosis?

Compensated Acidosis/Alkalosis means the body has adjusted to the imbalance, normalizing pH levels, while Uncompensated means the body has not adjusted, leaving pH levels abnormal.

What are the normal pH, PaCO2, and HCO3- ranges in arterial blood gas interpretation?

Normal pH is 7.35-7.45, PaCO2 is 35-45 mmHg, and HCO3- is 22-26 mEq/L.

What indicates Partial Compensation in acid-base balance?

Partial Compensation occurs when pH is still abnormal, but the opposite system is attempting to correct it.

What indicates Full Compensation in acid-base balance?

Full Compensation occurs when pH is normal, but PaCO2 and HCO3- levels are abnormal.

What are the two main divisions of the Nervous System?

The two main divisions are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

What is the role of the Central Nervous System (CNS)?

The CNS, consisting of the brain and spinal cord, integrates sensory data and issues motor commands.

What is the function of the Sensory (Afferent) Division of the PNS?

The Sensory Division transmits signals from receptors to the Central Nervous System.

What does the Motor (Efferent) Division of the PNS do?

The Motor Division transmits signals from the Central Nervous System to effectors such as muscles and glands.

What is the difference between the Somatic and Autonomic Nervous Systems?

The Somatic Nervous System controls voluntary actions of skeletal muscles, while the Autonomic Nervous System controls involuntary actions of smooth muscle, cardiac muscle, and glands.

What are the two divisions of the Autonomic Nervous System?

The two divisions are the Sympathetic Division (fight or flight) and the Parasympathetic Division (rest and digest).

What are the three structural types of neurons?

The three structural types are Multipolar (many dendrites, one axon), Bipolar (one dendrite, one axon), and Unipolar (single process).

What are the three functional types of neurons?

The three functional types are Sensory (Afferent) neurons, Motor (Efferent) neurons, and Interneurons.

What are the functions of Astrocytes in the CNS?

Astrocytes maintain the blood-brain barrier, facilitate nutrient exchange, and provide structural support.

What is the role of Oligodendrocytes?

Oligodendrocytes form the myelin sheath in the Central Nervous System.

What is the function of Microglia?

Microglia provide immune defense in the Central Nervous System.

What is the purpose of Ependymal Cells?

Ependymal Cells produce and circulate cerebrospinal fluid (CSF).

What do Schwann Cells do in the PNS?

Schwann Cells form the myelin sheath in the Peripheral Nervous System.

What are the protective structures of the Nervous System?

The protective structures include bone (skull and vertebrae), meninges (dura mater, arachnoid mater, pia mater), cerebrospinal fluid (CSF), and the blood-brain barrier.

What is the function of the Blood-Brain Barrier?

The Blood-Brain Barrier protects the brain from toxins and pathogens and regulates nutrient transport.

What are the major functions of the Brain Stem?

The Brain Stem includes the Midbrain (visual/auditory reflexes, motor control), Pons (relays info and controls breathing), and Medulla Oblongata (autonomic functions like heart rate and respiration).

What is the role of the Cerebellum?

The Cerebellum coordinates movement, balance, and motor learning.

What are the primary functions of the cerebellum?

Coordinates movement, balance, and motor learning.

What are the higher brain functions associated with the cerebrum?

Higher brain functions include decision making, personality, planning movement, initiating voluntary movement, processing tactile input, integrating sensory information, language comprehension, speech production, processing sound, and processing taste.

What is the role of the prefrontal cortex?

Decision making and personality.

What does the primary motor cortex do?

Initiates voluntary movement.

What is the function of the somatosensory cortex?

Processes tactile input.

What does the somatosensory association area integrate?

Integrates sensory information.

What is the function of Wernicke's area?

Language comprehension.

What is the role of Broca's area?

Speech production.

What does the primary auditory cortex process?

Processes sound.

What is the function of the gustatory cortex?

Processes taste.

What are the key functions of the limbic system?

Emotion and memory.

What does the reticular system control?

Arousal and consciousness.

What is the function of the thalamus?

Relay station for sensory information.

What role does the hypothalamus play in the body?

Homeostasis and endocrine control.

What are the components of a simple reflex arc?

Receptor, sensory neuron, integration center, motor neuron, effector.

What is the difference between basic and conditioned reflexes?

Basic reflexes are inborn and automatic (e.g., knee-jerk), while conditioned reflexes are learned (e.g., Pavlov's dog).

What neurotransmitter is released at sympathetic ganglia?

Acetylcholine (ACh) at ganglia (nicotinic receptors) and norepinephrine (NE) at effectors (adrenergic receptors).

What are the effects of the sympathetic nervous system on the heart and lungs?

Sympathetic increases heart rate (↑HR) and causes bronchodilation.

What are the effects of the parasympathetic nervous system on the heart and lungs?

Parasympathetic decreases heart rate (↓HR) and causes bronchoconstriction.

What is the difference between cholinergic and adrenergic synapses?

Cholinergic synapses release acetylcholine (ACh), while adrenergic synapses release norepinephrine (NE) or epinephrine (Epi).

What are the types of receptors in the autonomic nervous system?

Nicotinic (excitatory), muscarinic (excitatory/inhibitory), alpha (usually excitatory), and beta (usually inhibitory).

What distinguishes sympathetic from parasympathetic nervous systems?

Sympathetic is thoracolumbar and associated with fight/flight responses, while parasympathetic is craniosacral and associated with rest/digest responses.

What are the two types of ion channels in neurons?

Ligand-gated channels open in response to chemicals and are found in dendrites; voltage-gated channels open with changes in membrane potential and are found in axons.

What is the resting membrane potential primarily influenced by?

The permeability of the membrane to potassium (K+), making it closer to K+ equilibrium potential.

What is the sequence of events during an action potential?

Rest → Depolarization (Na+) → Peak → Repolarization (K+) → Hyperpolarization → Rest.

What is the refractory period in neuron firing?

The time when a neuron cannot fire or is less likely to fire.

What factors affect the speed of action potentials?

Axon diameter (larger = faster) and myelination (more = faster).

What are the steps of synaptic transmission?

Action potential arrives → Ca2+ channels open → vesicles fuse → neurotransmitter released → binds receptors → signal generated.

What is a clinical application example related to synaptic transmission?

Multiple Sclerosis: Demyelination slows or blocks action potentials, leading to muscle weakness and fatigue.