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Questions and Answers
What is the main function of the rough endoplasmic reticulum (RER)?
What is the main function of the rough endoplasmic reticulum (RER)?
Protein synthesis
Which disease is a result of a deficiency in the enzyme that metabolizes fatty substances?
Which disease is a result of a deficiency in the enzyme that metabolizes fatty substances?
The Golgi body modifies and segregates proteins for ______.
The Golgi body modifies and segregates proteins for ______.
secretion
Defects in the cell membrane can lead to hemolytic disease.
Defects in the cell membrane can lead to hemolytic disease.
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What is the primary function of the mitochondrion?
What is the primary function of the mitochondrion?
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What is the role of a sensor in the negative feedback system of homeostasis?
What is the role of a sensor in the negative feedback system of homeostasis?
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Which hormones stimulate the kidneys to reabsorb more water in the renal tubules?
Which hormones stimulate the kidneys to reabsorb more water in the renal tubules?
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Osmosis is the movement of water driven by a water concentration gradient across a membrane.
Osmosis is the movement of water driven by a water concentration gradient across a membrane.
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In the negative feedback system, the comparator interprets sensory input to determine deviations from the _________.
In the negative feedback system, the comparator interprets sensory input to determine deviations from the _________.
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Match the following homeostatic components with their functions:
Match the following homeostatic components with their functions:
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What is the main function of vasodilation in the context of kidney function?
What is the main function of vasodilation in the context of kidney function?
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Which medication is used to tell the kidney to excrete more water?
Which medication is used to tell the kidney to excrete more water?
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Is hypertonic intravenous fluid (IVF) used to promote osmosis into cells, causing them to swell?
Is hypertonic intravenous fluid (IVF) used to promote osmosis into cells, causing them to swell?
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Hemorrhaging patients can lose up to 4 L of ECF before plasma decreases by 1 L, and to replace 1 L of plasma volume, one must infuse 4 L of ___________ into the intravascular space.
Hemorrhaging patients can lose up to 4 L of ECF before plasma decreases by 1 L, and to replace 1 L of plasma volume, one must infuse 4 L of ___________ into the intravascular space.
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Match the following potassium concentration ranges with their clinical significance:
Match the following potassium concentration ranges with their clinical significance:
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What is the chromosomal abnormality associated with Down syndrome?
What is the chromosomal abnormality associated with Down syndrome?
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Which chromosomal abnormality is associated with Turner syndrome?
Which chromosomal abnormality is associated with Turner syndrome?
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Cri du chat syndrome is also known as the cry of the cat syndrome.
Cri du chat syndrome is also known as the cry of the cat syndrome.
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What is the inheritance pattern of mitochondrial genetic disorders?
What is the inheritance pattern of mitochondrial genetic disorders?
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Which type of mutation creates a STOP codon that may stop protein synthesis or result in a partial protein, potentially causing disease?
Which type of mutation creates a STOP codon that may stop protein synthesis or result in a partial protein, potentially causing disease?
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What is the main cause of mutation through short wavelengths electromagnetic waves and high energy particles?
What is the main cause of mutation through short wavelengths electromagnetic waves and high energy particles?
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Translocation occurs when portions of a chromosome break off and attach to a different location, creating a balanced translocation if no genetic information is ____.
Translocation occurs when portions of a chromosome break off and attach to a different location, creating a balanced translocation if no genetic information is ____.
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Reduced penetrance means that a mutant genotype is always fully manifested in the individual's phenotype.
Reduced penetrance means that a mutant genotype is always fully manifested in the individual's phenotype.
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What is meant by genetic expressivity?
What is meant by genetic expressivity?
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What is the primary difference between small motor units and large motor units?
What is the primary difference between small motor units and large motor units?
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Tetanus toxin blocks inhibitory nerves and allows rapid fire of excitatory motor neurons.
Tetanus toxin blocks inhibitory nerves and allows rapid fire of excitatory motor neurons.
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What is the primary function of dystrophin in muscle cells?
What is the primary function of dystrophin in muscle cells?
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Hyperkalemia results in decreased concentration gradient of $K^+$ in the serum, leading to ____________ of cardiac cells.
Hyperkalemia results in decreased concentration gradient of $K^+$ in the serum, leading to ____________ of cardiac cells.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Study Notes
Medical Homeostasis
- Body temperature, blood sugar, fluid pH, and electrolyte balance (K+, Cl-, HCO3-, Na+, Mg2+, Ca2+) are regulated through negative feedback components of homeostasis.
Set Point
- Target value of the control system, which is set to maintain homeostasis.
- Examples: O2 for respiration and ATP production, blood glucose levels.
Negative Feedback Components
- Sensors: Continuously monitor a controlled variable.
- Comparator: Interprets sensory input to determine deviations from the set point and initiates a counter response.
- Effectors: Organs that bring about change to restore the set point to normal levels.
Glucose Control
- Insulin is secreted by beta cells in the pancreas to regulate blood glucose levels.
- Insulin stimulates the insertion of GLUT transporters to facilitate glucose uptake.
- Glycogen is stored in the liver and broken down to glucose when needed.
Blood Pressure Control
- Controlled variable: Mean arterial blood pressure (MAP).
- Set point: MAP = 95 mm Hg.
- Sensor: Intravascular pressure sensor located in the carotid sinus.
- Comparator: CNS site in the medulla oblongata.
- Effectors: Cardiac rate and contractility, vascular tone, and urinary fluid excretion.
Osmosis
- Water movement driven by a water concentration gradient across a membrane.
- Hypertonic IVF: promotes osmosis of fluid out of the cell, causing it to shrink.
- Isotonic IVF: does not promote osmosis, increasing extracellular volume without changing cell size or concentration.
- Hypotonic IVF: promotes osmosis of extracellular fluid into the cell, causing it to swell.
Electrical Potentials
- Movement of ions across the cell membrane creates a charge imbalance between the intracellular fluid (ICF) and extracellular fluid (ECF).
- This charge imbalance creates a voltage difference across the cell membrane, known as the membrane potential (Vm).
- Typical nerve cell has a resting Vm = -70 mV.
Diffusion and Equilibrium Potentials
- More sodium outside the cell than inside, and more potassium inside the cell than outside.
- Sodium pump maintains the balance of sodium and potassium ions.
- Most cells at rest have minimal permeability to Na+ or Ca2+, and significant permeability to K+.
Cellular Bioenergetics
- Energy is stored in molecular bonds between phosphoric acid molecules and other organic compounds.
- High-energy phosphate compounds contain phosphate bonds that release energy when hydrolyzed.
- Compounds such as ATP, NAD, and NADP are used to store energy.
Cellular Respiration
- Glycolysis: breakdown of glucose to pyruvate or lactate, producing ATP.
- Fatty acid oxidation: metabolized to acetyl-CoA.
- Amino acid catabolism: from proteins can be ketogenic or glucogenic.
- Gluconeogenesis: non-carbohydrate source of energy.
- Citric acid cycle: acetyl-CoA metabolized to CO2 and H+, while consuming O2 and producing ATP and H2O.
Hydrolysis of ATP
- ATP is hydrolyzed to ADP and Pi, releasing energy.
Oxidation of Acetyl-CoA
- Produces ATP, CO2, and H2O while consuming H2O.### Cellular Stress and Hypertrophy
- Cellular stress leads to changes in morphology and hypertrophy, increasing tissue mass by increasing cell size
- Enlargement of the nucleolus indicates increased contractile protein synthesis and cell growth, an early indicator of cardiac hypertrophy
- Mature cardiac cells (myocites) lose the ability to undergo mitosis, leading to heart failure, cardiovascular disease, and anemia
Chromosomal DNA Abnormalities
- Turner syndrome: affects only females, resulting from a missing or partially missing X chromosome (XO)
- Klinefelter syndrome: one extra copy of the X chromosome is present in males (XXY), resulting in phenotypic abnormalities (tall stature, gynecomastia, and a more gynecoid pelvis structure)
- Sickle cell anemia: mutation of the Hb-beta gene on chromosome 11, causing an inability of Hb to carry oxygen and resulting in abnormal RBC shape
Rough Endoplasmic Reticulum (RER)
- Involved in protein synthesis
- Alterations in RER homeostasis (cellular stress) lead to abnormal increased protein synthesis, accumulation of misfolded proteins, and alterations in calcium balance, associated with:
- Alzheimer's disease
- Parkinson's disease
- Amyotrophic lateral sclerosis (Lou Gehrig's disease)
- Type 2 diabetes
- Atherosclerosis
- Nonalcoholic fatty liver disease
- Alcoholic liver disease
- Cancer
Smooth Endoplasmic Reticulum (SER)
- No ribosomes
- Involved in steroid hormone production (more prominent in testes, adrenal cortex, and ovaries)
- Involved in lipid and carbohydrate synthesis
- Liver has more SER for metabolic and detoxification processes
- Stress on SER can interfere with signaling, leading to:
- Type 2 diabetes
- Atherosclerosis
- Alcoholic and nonalcoholic fatty liver disease
- Endocrine disorders
- Cancer
Golgi Body
- Functions, modifies, and segregates proteins for secretion
- Synthesizes lysosomes
- Associated with neurodegenerative diseases:
- Parkinson's disease: broken ribbon formation of Golgi causes malfunction in intracellular functions and alters cytoskeleton
- Alzheimer's disease: degenerative brain disease causing dementia
- Amyotrophic lateral sclerosis: progressive disease atrophying motor neurons in the spinal cord and brain
Lysosomes
- Malfunctioning protein packaging and breakdown, associated with:
- ALS and Parkinson's: buildup of unusable proteins becomes toxic
- Tay-Sachs disease: deficiency in the enzyme that metabolizes fatty substances, inherited and progressively destroys nerve cells in the brain and spinal cord
- Fabry disease: deficiency in alpha-galactosidase
- Gaucher disease: deficiency in galactocerebrosidase
Mitochondria
- Converts chemical energy in food to ATP
- Regulates immunity, Ca2+ homeostasis, and apoptosis
- Associated with:
- Cyanide: disrupts ETC, preventing ATP formation using oxygen
- Leigh syndrome: genetic disorder causing CNS degeneration due to abnormal mitochondrial energy production
- Epilepsy and encephalopathy: certain types
Centriole
- Duplication necessary for cell division
- Organizes mitotic spindles during mitosis
- Abnormalities linked to neurodegeneration, autoimmune disorders, and solid breast tumors
- Increase in centrioles: hallmark of cancer
- Structural defects linked to changes in gene expression
Microtubules
- Long, hollow structures forming part of the cytoskeleton
- Give shape to cells
- Protein subunits alpha tubulin and beta tubulin
- In cytoplasm
- Assist movement of proteins and organelles within cells
- Form spindles that transport chromosomes during mitosis
- Partially compose cilia and flagella of sperm
- Primary ciliary dyskinesia: inherited problem with cilia formation, leading to abnormal movement of cilia
Microfilaments
- Smaller version of microtubules
- Actin filaments wound in a spiral
- Allow for intra-cell movements and support cell structure
- Keep cell organelles bound in one place
- Allow for muscle contraction by binding to myosin (thicker filament, contractile protein)
- Associated with:
- Giant axonal neuropathy: rare genetic disorder affecting both CNS and PNS
Cytoplasm
- Within cell membrane
- 85% water
- Maintains cell shape, intracellular movement, and material exchange
- Dehydration: loss of cellular water causes cell collapse, affecting cell function
Cell (Plasma) Membrane
- Outer membrane surrounding cell cytoplasm and intracellular structures
- Physical barrier, selective permeability, endo- and exocytosis, and cell signaling
- Cell growth, metabolism, and regulation
- Defects associated with:
- Cancer
- Hemolytic disease
- Cystic fibrosis
Membrane Protein
- May be embedded (integral) or peripheral
- Provides passage or selective permeability
- Contributes to preservation of electrochemical gradients
- Associated with:
- Cystic fibrosis: transmembrane conductance regulator protein (CFTR) regulates flow of chloride and sodium across cell membrane in lungs and GI tract
Skeletal Muscle
- Develops force by contraction
- Muscle columns (fascicles) contain bundles of muscle cells (fibers)
- Each multi-nucleated cell behaves as a single unit, containing many myofibrils
- Sarcomere: fundamental unit of skeletal muscle, with repeated striated pattern segments### Motor Neurons and Muscle Fibers
- Small motor units: motor neurons branch to only a few muscle fibers, allowing for fine control (e.g., hand and eye muscles)
- Large motor units: motor neurons branch to many muscle fibers, resulting in coarse control (e.g., postural trunk muscles)
Sliding Filament Theory (Skeletal Muscle Contraction)
- Thin filaments (actin) slide over thick filaments (myosin) to cause muscle contraction
- Mechanism of skeletal muscle contraction:
- Relaxed: tropomyosin-troponin complexes block myosin attachment sites on actin
- Stimulation: Ca2+ binds to troponin, exposing myosin attachment sites on actin
- Contraction: myosin cross-bridges bind to actin, using energy from ATP hydrolysis and cycling through structural changes
- Rigor mortis: no ATP, myosin heads can't be released from actin binding, and no muscle relaxation occurs
Force of Skeletal Muscular Contraction
- Controlled by frequency of action potentials (temporal summation):
- Low frequency: brief contraction and relaxation
- High frequency: tetanic contraction, maximal cross-bridge attachments
- Controlled by number of active motor neurons (spatial summation):
- Small motor units: easily excitable, reach few muscle fibers
- Large motor units: require stronger CNS stimulation, reach many muscle fibers
Skeletal Muscle Diversity
- Slow and fast twitch fibers:
- Different myosin and protein types, resulting in varying contraction speeds
- Different proportions of slow and fast twitch fibers in different muscles (e.g., postural muscles: more slow twitch, extraocular muscles: more fast twitch)
- Genetic differences affecting muscle fiber types and training-induced changes
Tetanus Toxin and Duchenne Muscular Dystrophy
- Tetanus toxin: produced by Clostridium tetani, blocks inhibitory nerves, causing rapid fire of excitatory motor neurons and uncontrolled muscular contraction
- Duchenne Muscular Dystrophy:
- Lack of dystrophin, a protein linking sarcolemma to myofilaments
- X-linked inheritance, more common in genetic males
- Progressive muscle inheritance and eventual death from respiratory failure
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Description
Test your understanding of medical homeostasis, including body temperature, blood sugar, fluid pH, and electrolyte balance. Learn about negative feedback components and the role of set points in maintaining bodily functions.
