Pathophysiology Chapter 1: Cell Membrane and Transport

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Questions and Answers

What is the primary function of the sodium/potassium pump in cellular transport?

To generate energy for the cell through the breakdown of ATP

To maintain the electrochemical gradient across the plasma membrane (correct)

To facilitate the transport of glucose into the cell

To regulate the pH balance within the cell

Which of the following types of cellular receptors is directly linked to an ion channel?

Tyrosine kinase receptor

G-protein linked receptor

Channel linked receptor (correct)

Catalytic receptor

What is the primary mechanism by which cells maintain homeostasis?

Adjustment of cellular metabolism

Regulation of gene expression

Maintenance of a stable internal environment (correct)

Modulation of cellular transport mechanisms

Which type of cellular communication involves the release of chemical messengers that bind to receptors on adjacent cells?

Paracrine signaling Signup and view all the answers

What is the primary function of the extracellular matrix?

To regulate cellular migration and adhesion Signup and view all the answers

How do cells respond to changes in their environment?

By activating signaling pathways Signup and view all the answers

What is the primary function of the basement membrane?

To maintain the integrity of the extracellular matrix Signup and view all the answers

Which type of cellular adaptation involves changes in the structure or function of cellular components?

Metaplasia Signup and view all the answers

What is the primary difference between water soluble and lipid soluble chemical messengers in a signal transduction pathway?

Water soluble messengers require a receptor on the surface of the target cell, while lipid soluble messengers can diffuse through the plasma membrane. Signup and view all the answers

What is the primary function of negative feedback loops in the regulation of hormone secretion?

To decrease hormone production in response to a stimulus Signup and view all the answers

What is the term for the process by which the body adjusts its sensitivity to the concentration of a signaling hormone?

Downregulation Signup and view all the answers

What is the term for the movement of water from an area of high concentration to an area of low concentration?

Osmosis Signup and view all the answers

What is the term for the pressure exerted by solutes in a solution?

Osmotic pressure Signup and view all the answers

What is the primary cause of edema?

Decreased capillary oncotic pressure Signup and view all the answers

What is the primary function of the lymphatic system in maintaining water balance?

To remove excess fluid from the interstitial space Signup and view all the answers

What is the relationship between sodium, potassium, chloride, and bicarbonate in maintaining the osmotic balance of the extracellular environment?

Sodium and potassium have opposing effects, while chloride and bicarbonate have opposing effects. Signup and view all the answers

What is the term for the ability of a genetic trait to be expressed despite not being fully penetrant?

Expressivity Signup and view all the answers

What is the primary mechanism by which the carbonic acid-bicarbonate buffer system maintains pH homeostasis?

Le Chatelier's principle Signup and view all the answers

What type of epigenetic modification involves the addition of a methyl group to the cytosine residue in DNA?

DNA methylation Signup and view all the answers

What is the term for the ability of cells to adapt to changes in their environment through reversible changes in cellular structure or function?

Cellular adaptation Signup and view all the answers

What is the term for the deficiency of magnesium in the body?

Hypomagnesemia Signup and view all the answers

What is the term for the process by which cells die due to a lack of oxygen?

Hypoxia Signup and view all the answers

What is the term for the study of heritable changes in gene function that occur without a change in the underlying DNA sequence?

Epigenetics Signup and view all the answers

What is the term for the ability of a gene to be expressed in a particular individual, but not in others, despite having the same genotype?

Penetrance Signup and view all the answers

Study Notes

The Cell Membrane, Transport, and Cellular Adhesion

Homeostasis is the maintenance of a stable internal environment despite changes in the external environment, and it's essential for the normal functioning of the human body.
The cell membrane is composed of phospholipids and proteins, and their distribution influences membrane permeability to ions, hydrophilic, and hydrophobic compounds.
Transport mechanisms across the cell membrane include:
- Passive transport: diffusion, facilitated diffusion, osmosis
- Active transport: uses energy to move solutes against a gradient, e.g., sodium/potassium pump
The sodium/potassium pump uses energy from Na+ and K+ electrochemical gradients to drive the net movement of other solutes, such as Na+/glucose co-transport and Na+/Ca2+ exchange or counter-transport.
Mechanisms that bind cells together include:
- Extracellular matrix
- Basement membrane
- Cell adhesion molecules
- Specialized cell junctions

Mechanisms of Cellular Communication and Signal Transduction

A chemical/cellular messenger is a molecule that transmits a signal from one cell to another.
Cellular receptors have specific characteristics and play a crucial role in cellular communication.
Cells communicate through:
- Contact-dependent mechanisms
- Hormonal mechanisms
- Paracrine mechanisms
- Autocrine mechanisms
- Neurohormonal and neurotransmitter mechanisms
Solubility of a chemical messenger influences its transport and mechanism of communication with a cell.
There are three classes of plasma membrane receptors:
- Channel-linked receptors
- Catalytic receptors
- G-protein-linked receptors
Signal transduction pathways involve:
- Binding of a chemical messenger to a receptor
- Activation of a signaling cascade
- Response to the signal
Regulation of hormone secretion occurs through positive-feedback and negative-feedback loops.

Sodium, Chloride, and Water Balance

Total body water (TBW) is divided into:
- Intracellular fluid (ICF)
- Extracellular fluid (ECF)
- Interstitial fluid
- Blood plasma
TBW decreases with age.
Osmosis is the movement of water from a higher to a lower solute concentration.
Osmolality, osmolality, tonicity, osmotic pressure, and oncotic pressure are important concepts in understanding water balance.
Water movement across bodily fluid compartments is driven by solute concentration, affecting cell volume in iso-tonic, hyper-tonic, and hypo-tonic solutions.
Forces controlling fluid movement across the capillary wall include:
- Capillary hydrostatic pressure
- Interstitial oncotic pressure
- Capillary oncotic pressure
- Interstitial hydrostatic pressure
Edema develops due to:
- Decreased capillary oncotic pressure
- Increased capillary permeability
- Increased capillary hydrostatic pressure
- Lymphatic obstruction
Electrolyte distribution:
- Intracellular fluid: high in K+, low in Na+
- Extracellular fluid: high in Na+, low in K+
Sodium, potassium, chloride, and bicarbonate maintain osmotic balance in the extracellular environment.

Acid-Base Balance

Physiologic buffering systems maintain pH homeostasis.
Le Chatelier's principle applies to alterations in the carbonic acid-bicarbonate buffer.

Mechanisms of Inheritance

Genetic terms include:
- Dominance
- Recessiveness
- Incomplete dominance
- Codominance
- Polygenic inheritance
Inheritance patterns include:
- Autosomal dominant
- Autosomal recessive
- X-linked dominant
- X-linked recessive
- Mitochondrial inheritance
Penetrance and expressivity describe the degree to which a genotype is expressed phenotypically.
DNA mutations can cause diseases, and their outcomes depend on the type of mutation.
Epigenetics involves:
- DNA methylation
- Histone modification
- Chromatin remodeling
Epigenetic modifications influence gene expression and disease development.

Cellular Adaptation, Injury, and Death

Cellular adaptations include:
- Hypertrophy
- Hyperplasia
- Atrophy
- Metaplasia
- Dysplasia
Cell injury and death can occur due to:
- ATP depletion
- Reactive oxygen species
- Calcium entry
- Mitochondrial damage
- Membrane damage
- Protein misfolding
- DNA damage
Reversible cell injury can progress to irreversible cell injury and death.
Mechanisms of cell injury include:
- Ischemia and hypoxia
- Ischemia-reperfusion
- Free radicals and reactive oxygen species

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Description

Understand the importance of homeostasis, cell membrane composition, and transport mechanisms in the human body. Learn about phospholipids and proteins' influence on membrane permeability.