Pathophysiology midterm 1 選擇題 (同一份) 總複習

Introduction to Pathophysiology and Cellular Basis of Disease

• Disease is dynamic, involving an interplay between cause, injury, and the body's response to that injury.
• Initial signs of disease manifest when physical parameters fall outside the normal range.
• Etiology refers to the cause of disease, while pathogenesis describes the physiological development of the disease process.
• Factors affecting pathogenesis include time, quantity of exposure, and the location of injury.
• Morphological changes arise from chronic injuries, leading to observable clinical manifestations (e.g., damage to pancreas results in diabetes mellitus).

Clinical Manifestations

• Observable consequences of disease are categorized into signs (measurable and objective, e.g., rash, fever) and symptoms (subjective experiences reported by the patient, e.g., nausea, pain).
• Critical stages in the disease progression include:
  • Latent period: Between injury and onset of symptoms.
  • Prodromal period: First appearance of symptoms.
  • Acute period: Peak of symptoms, followed by recovery or chronic phase.

Causes of Disease

• Extrinsic injuries: Induced by inanimate (physical agents, chemical exposure) or animate (infectious organisms) factors.
• Intrinsic injuries: Include inherited, congenital, metabolic, degenerative, and immunologic causes.
• Idiopathic conditions lack a known cause.

Cellular Function and Homeostasis

• Body functions depend on specialized cells organized into tissues and organs, requiring interdependent cellular responses to maintain functionality.
• Maintaining cellular homeostasis involves regulating:
  • Cell volume via water and osmolyte balance, particularly sodium and potassium.
  • Electrolyte levels controlled by the Renin-angiotensin system.
  • pH levels critical for enzyme function and metabolic processes.

Fluid Balance and Edema

• Total body water (TBW) generally accounts for about 60% of body weight, varying with age and body fat percentage.
• Edema can result from decreased plasma oncotic pressure (e.g., low albumin levels), increased capillary permeability, or lymphatic obstructions.
• Starling forces determine fluid movement across capillaries: balances between capillary blood pressure and osmotic pressures.

Acid-Base Balance

• Acids donate H+ ions; bases absorb them. pH is measured on a scale from 0 to 14, indicating acidity or alkalinity.
• Major buffer systems, like bicarbonate and hemoglobin, help stabilize pH levels.
• The lungs manage carbon dioxide levels; kidneys control bicarbonate and hydrogen ion concentration.
• Conditions of acidosis or alkalosis can occur due to respiratory or metabolic imbalances, with compensatory mechanisms involving opposite organ systems.

Cellular Metabolism

• Three steps of cellular metabolism produce ATP: glycolysis, citric acid cycle (Krebs), and oxidative phosphorylation.
• Different transport mechanisms, including passive and active transport, regulate cellular materials.

Cellular Injury and Adaptation

• Cellular responses to injury can include adaptive changes (e.g., atrophy, hypertrophy) or irreversible injury leading to necrosis.
• Types of necrosis include coagulative, liquefactive, and caseous necrosis depending on tissue death characteristics.
• Apoptosis or programmed cell death occurs in response to certain triggers, such as viral infections or DNA damage.

Nervous System Function

• Major divisions of the central nervous system (CNS) include the spinal cord, brain stem, cerebellum, diencephalon, and cerebrum.
• The somatosensory map aids in understanding how sensory inputs are processed, especially for those who are blind, highlighting brain plasticity.
• Key areas for language processing exist in the brain, like Wernicke’s area (language comprehension) and Broca’s area (speech production). Damage to these areas results in aphasias, affecting communication capabilities.### Understanding Neurological Concepts
• "Can Understand, Cannot Express": A condition often associated with strokes affecting specific brain areas.
• Brodmann’s Areas: Specific regions in the brain linked to various body functions.

Central Nervous System (CNS) Anatomy

• Glial Cells: Non-neuronal cells providing support in the nervous system. Types include:
  • Astrocytes: Form the blood-brain barrier (BBB) by surrounding capillaries.
  • Oligodendrocytes: Responsible for myelination of CNS axons.
  • Ependymal Cells: Line cerebral ventricles and communicate with CSF.

Meninges and Cerebrospinal Fluid (CSF)

• Meninges: Protective membranes (dura mater, arachnoid, pia mater) that encase the brain.
• Cerebral Ventricles: Produce and secrete CSF, crucial for cushioning the brain.
  • Choroid Plexus: Specialized tissue in ventricles responsible for CSF production.
• CSF Composition: Lower sodium and potassium compared to plasma, influencing neuronal excitability and seizure potential.

Blood-Brain Barrier (BBB)

• Structure: Comprised of tight junctions between endothelial cells, a basement membrane, and astrocyte end-feet.
• Function: Filters substances entering the brain; allows selective permeability for water, O2, and lipids, while tightly regulating ions.

Neurotransmitter Systems

• Norepinephrine System: Originates from the locus coeruleus; influences wakefulness, attention, and regulated by inhibition.
• Serotonin System: Arises from the raphe nuclei; regulates mood, sleep, temperature control, and motor excitation.
• Dopamine System: Key circuits include:
  • Substantia Nigra: Modifies voluntary motor control.
  • Ventral Tegmental Area: Involved in reward and motivation.
• Acetylcholine (ACh): Plays a role in sleep/wake states and cognitive processing.

Peripheral Nervous System (PNS)

• Cranial Nerves: 12 pairs involving both sensory and motor functions; specific nerves dedicated to particular sensory modalities.
• Spinal Nerves: 31 pairs that control both sensory and motor functions; dorsal roots carry sensory input, while ventral roots transmit motor commands.

Spinal Reflexes and Cord Anatomy

• Reflex Arcs: Involve afferent sensory neurons and efferent motor neurons for quick responses; can operate independently of brain input.
• Ascending/Descending Tracts: Ascend via dorsal roots (sensory) and descend via ventral roots (motor); white matter comprises myelinated axons, gray matter contains neuron cell bodies.

Autonomic Nervous System (ANS)

• Divisions: Parasympathetic (rest and digest) vs. sympathetic (fight or flight); both systems use two-neuron pathways to reach target organs.
• Preganglionic Neurons: Sympathetic originates in the spinal cord (T1-L3), while parasympathetic arises from cranial nerves (III, VII, IX, X) and sacral spinal cord.

Neurotransmitters of the ANS

• Acetylcholine and Norepinephrine play crucial roles in mediating responses for both sympathetic and parasympathetic systems through various receptor types.

Endocrine System Overview

• Function: Hormonal signaling is wireless, impacting multiple body functions by binding to specific receptors.
• Types of Hormones: Include peptide/protein, amino acid-derived, and steroid hormones, each with distinct production and transport mechanisms.
• Central and Peripheral Endocrine Glands: Central glands (hypothalamus, pituitary) play vital roles in hormone release; peripheral glands serve dedicated endocrine functions.

Hormone Actions and Effects

• Hormonal Action: Includes altering channel permeability, second-messenger systems, and gene activation to elicit physiological responses.
• ADH (Vasopressin): Important for water reabsorption in kidneys and vasoconstriction effects.

These notes highlight crucial neurological, physiological, and hormonal functions essential for understanding the body's systems.### Hormonal Functions and Types

• Hormones, like T3 and T4, can act both as hormones and neurotransmitters depending on their release method.
• T3 is the only active form of thyroid hormone; T4 requires the removal of an iodine atom to become active.
• Thyroid hormones are lipid-soluble and can cross cell membranes to influence gene expression, particularly those regulating energy consumption and metabolic rate.
• Hyperthyroidism can induce anxiety in affected individuals.

Steroid Hormone Synthesis

• Steroid hormones are synthesized from cholesterol, which can be dietary or produced by the liver.
• Cholesterol, being a fat, is transported in the blood via lipoproteins (LDL) and binds to receptors on endocrine cells.
• Inside endocrine cells, LDL is internalized and metabolized into pregnenolone, which can be converted into various hormones like aldosterone, cortisol, estradiol, and testosterone, with each step requiring specific enzymes.

Peptide Hormones and Signaling

• Peptide hormones cannot cross cell membranes; they activate second messenger pathways such as cAMP or Ca²⁺, initiating cellular responses.
• In contrast, steroids directly enter the nucleus to influence gene expression, as seen with thyroid hormones that increase metabolism via proteins like Na/K ATP pumps.

Hormonal Secretion Control

• Hormonal secretion is regulated by negative feedback; the level of hormone in the bloodstream determines if additional production is necessary.
• Hierarchical control involves a sequence where one hormone regulates the release of another from different glands.
• For example, the hypothalamus signals the anterior pituitary, which then communicates with peripheral glands like the thyroid.

Hypothalamus and Pituitary Interaction

• The posterior pituitary is an extension of the hypothalamus and releases vasopressin and oxytocin directly into capillaries.
• The anterior pituitary functions as a true endocrine gland, releasing several hormones like TSH, ACTH, prolactin, growth hormone, LH, and FSH, controlled by hormones from the hypothalamus.

Growth Hormone (GH) Regulation

• GH release is regulated by hormones from the hypothalamus, specifically GHRH, which stimulates GH release, and somatostatin, which inhibits it.
• GH is primarily released during non-REM sleep and follows a circadian rhythm, with higher pulses occurring at night.
• Quality and quantity of sleep significantly influence GH release, affecting overall health.

Thyroid Gland Anatomy and Function

• The thyroid gland contains follicular cells that synthesize thyroid hormones, stored in colloid, and can regulate metabolic rate and sympathetic activity.
• Parafollicular (C) cells in the thyroid release calcitonin, which regulates calcium levels in the body.
• T3, derived from T4 through enzymatic conversion, binds to thyroid hormone receptors to influence energy-consuming processes like Na+/K+ pump activity and gluconeogenesis.

Adrenal Gland Structure and Hormones

• The adrenal glands, located atop each kidney, consist of two main regions: the adrenal medulla and adrenal cortex.
• The adrenal medulla produces catecholamines (mainly epinephrine and norepinephrine) as part of the sympathetic nervous system response.
• The adrenal cortex produces steroid hormones, divided into three zones: zona glomerulosa (mineralocorticoids), zona fasciculata (glucocorticoids), and zona reticularis (sex hormones).

Effects of Cortisol

• Cortisol, a glucocorticoid synthesized in the zona fasciculata, mediates the stress response by elevating blood glucose levels.
• It promotes the breakdown of muscle and bone to release free amino acids and calcium, respectively, while also preventing insulin from lowering blood glucose.
• Additionally, cortisol enhances sodium retention, potassium loss, and vasoconstriction, contributing to blood pressure regulation, while serving anti-inflammatory functions and increasing brain excitability for quick responses.

Cortisol Secretion Patterns

• Cortisol levels are lowest in the evening and peak just before waking, aiding the body's natural wake-up process.