Integrative Physiology & Cell Structure

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Questions and Answers

What is the primary function of tight junctions in epithelial cells?

Allow free passage of ions and water

Facilitate communication between adjacent cells

Anchor cells in areas subject to stretching

Create barriers limiting material movement between cells (correct)

Which type of protein is primarily involved in desmosome function?

Peripheral proteins

Connexin proteins

Integrins

Cadherins (correct)

What structure facilitates direct passage of molecules between adjacent cells?

Integral proteins

Tight junctions

Desmosomes

Gap junctions (correct)

How do tight junctions control the passage of molecules and ions?

By sealing cells beneath the apical surface Signup and view all the answers

What type of cellular pathways do absorptive-digestive cells utilize for nutrient uptake?

Transcellular and paracellular paths Signup and view all the answers

What is the approximate distance maintained between plasma membranes by desmosomes?

20 nm Signup and view all the answers

What type of signaling do endocrine cells primarily utilize?

Hormonal signaling released into the blood Signup and view all the answers

What does net diffusion refer to in biological systems?

Movement of molecules achieving balance between compartments Signup and view all the answers

What is the primary role of homeostasis in physiological processes?

To adapt to changes while preserving stability. Signup and view all the answers

What characterizes unsaturated fatty acids in phospholipid molecules?

They typically have a bent structure. Signup and view all the answers

Which of the following best describes the fluid-mosaic model of the plasma membrane?

It emphasizes that lipids and proteins can move freely within the membrane. Signup and view all the answers

How do cholesterol molecules affect the fluidity of the plasma membrane?

They maintain intermediate membrane fluidity. Signup and view all the answers

Which of the following statements about feedback mechanisms is true?

Positive feedback systems amplify physiological changes. Signup and view all the answers

What defines the amphipathic nature of membrane phospholipids?

They possess both hydrophilic and hydrophobic properties. Signup and view all the answers

What is a key function of plasma membranes in cells?

To regulate passage of substances into and out of cells. Signup and view all the answers

What role do integral proteins play in the cell membrane?

They are involved in transport across the membrane. Signup and view all the answers

What role do transport systems in epithelial cells play in organ function?

Promoting nutrient uptake and waste removal Signup and view all the answers

Which statement accurately describes the neuron?

It is the functional unit of the nervous system. Signup and view all the answers

What is the main function of Schwann cells in the peripheral nervous system (PNS)?

To form myelin sheaths around axons Signup and view all the answers

What is a significant outcome of spinal cord injuries in the central nervous system (CNS)?

Loss of myelin sheaths impairs signal transmission. Signup and view all the answers

Which statement describes the ability of axons in the peripheral nervous system following injury?

They can regenerate if the cell body is intact. Signup and view all the answers

What is the resting membrane potential primarily influenced by?

Concentration differences of ions across the membrane Signup and view all the answers

What are the main roles of glial cells in the central nervous system?

Providing support and regulatory functions Signup and view all the answers

Which motor proteins are involved in axonal transport?

Dynein and kinesin Signup and view all the answers

What factors determine synaptic efficacy in the nervous system?

Neurotransmitter availability and receptor activation Signup and view all the answers

Which statement best describes the differences between afferent, efferent, and interneurons?

Interneurons integrate and process information, making up the majority of neural cells. Signup and view all the answers

How does the autonomic nervous system (ANS) contribute to homeostasis?

Using both sympathetic and parasympathetic divisions to balance physiological demands. Signup and view all the answers

Which of the following statements about neurotransmitters in the ANS is correct?

Neurotransmitters have unique roles in achieving different bodily responses. Signup and view all the answers

What is the significance of reflex arcs in the nervous system?

They demonstrate that many bodily processes function automatically. Signup and view all the answers

What primarily maintains the resting membrane potential in neurons?

Unequal distribution of ions across the cell membrane Signup and view all the answers

What role does the Na+/K+-ATPase pump play in maintaining the membrane potential?

It creates a concentration gradient for Na+ and K+ ions. Signup and view all the answers

Which of the following best describes the resting membrane potential in neurons?

Typically around -70 mV, close to the equilibrium potential for K+. Signup and view all the answers

What happens to graded potentials as they propagate away from the site of initial depolarization?

They decrease in size due to charge leakage. Signup and view all the answers

How are graded potentials classified based on the changes in ion channel activity?

As either depolarizing or hyperpolarizing potentials. Signup and view all the answers

Which ion is predominantly responsible for leakage that causes the decrease in graded potential size?

K+ (Potassium) Signup and view all the answers

What effect does stimulus strength have on the magnitude of graded potentials?

Stronger stimuli result in a greater magnitude of graded potentials. Signup and view all the answers

What characterizes action potentials in comparison to graded potentials?

They are large changes that occur rapidly. Signup and view all the answers

Study Notes

Integrative Physiology & Homeostasis

Integrative physiology examines interactions between biological levels (cells to organ systems).
Homeostasis is dynamic, crucial for survival, and involves adapting to maintain stability.
Negative and positive feedback mechanisms regulate bodily functions.
Circadian rhythms influence physiological processes, impacting homeostasis.

Plasma Membranes & Cell Structure

Plasma membrane functions: regulate substance passage, detect chemical messengers, link adjacent cells, and anchor cells to the extracellular matrix.
Phospholipids: two fatty acid chains, amphipathic nature affects membrane fluidity; saturated chains are straight, unsaturated are bent.
Membrane composition: phospholipid bilayer with nonpolar fatty acid chains inside and polar regions facing outward; cholesterol influences fluidity.
Fluid-Mosaic Model: describes the dynamic nature of the plasma membrane.
Membrane proteins: integral proteins (amphipathic, form channels or transmit signals) and peripheral proteins (on membrane surface, bound to integral proteins).

Membrane Junctions

Desmosomes: hold cells together in areas subject to stretching (e.g., skin); plasma membranes separated by ~20 nm, cadherins anchor to dense plaques.
Tight junctions: create barriers limiting material movement between cells (e.g., gut epithelium); fuse adjacent cell membranes, sealing cells beneath the apical surface.
Gap junctions: allow communication between cells via small molecules; connexin proteins form pores (connexons).
Integrins: transmembrane proteins linking extracellular matrix to adjacent cell proteins.

Epithelium & Transport

Simple epithelium: includes absorptive-digestive cells, mucin-secreting cells, endocrine cells (secrete into blood), and paracrine cells (affect nearby cells).
Transcellular and paracellular paths: two routes for water and solute movement across epithelium.
Simple diffusion: movement of substances from high to low concentration.
Physiological importance of transport: crucial for nutrient uptake, waste removal, and overall cellular health.

Nervous System Structure & Function

Nervous system divisions: central nervous system (CNS: brain, spinal cord) and peripheral nervous system (PNS: nerves connecting CNS to body).
Neuron: functional unit of the nervous system; axonal transport uses dynein and kinesin motor proteins along microtubules.
Neuron types: pre- and postsynaptic neurons for chemical and electrical signal transmission.
Glial cells (CNS): astrocytes, microglia, ependymal cells, oligodendrocytes; support and regulate neuronal function.
Schwann cells (PNS): myelinate axons, speeding signal conduction.

Nervous System Injury & Regeneration

PNS axon regeneration: possible if the cell body isn't damaged.
CNS spinal cord injuries: typically result in myelin loss, impairing signal transmission; limited axon regeneration and functional recovery.

Resting Membrane Potential

Resting membrane potential: maintained by unequal ion distribution (Na+, K+, Cl-); typically around -70 mV.
Na+/K+-ATPase pump: establishes Na+ and K+ concentration gradients.
Membrane permeability: determines resting potential.
Membrane potential changes: depolarization, repolarization, hyperpolarization.
Graded potentials: localized changes in membrane potential varying in magnitude, depending on stimulus strength.

Graded Potentials & Stimulus Strength

Graded potentials: can be depolarizing or hyperpolarizing.
Magnitude: proportional to stimulus strength.
Distance decay: decrease in size with distance due to charge leakage.

Ion Distribution in Neurons

Ion	Extracellular Concentration (mM)	Intracellular Concentration (mM)
Na+	145	15
Cl-	107	10
K+	5	150

Action Potentials & Synaptic Transmission

Action potentials: rapid, large changes in membrane potential.
Synaptic strength: depends on neurotransmitter availability and receptor activation.
Toxins (tetanus, botulinum): disrupt neurotransmission.
Neuron classification: afferent, efferent, and interneurons.
Autonomic nervous system: sympathetic and parasympathetic divisions maintain homeostasis.
Neurotransmitter diversity: varies between sympathetic and parasympathetic pathways.
Neural organization: PNS and CNS; spinal cord pathways in reflexes.
Simple neural circuits: autonomic reflex arcs operate independently of conscious control.

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Description

Explore the concepts of integrative physiology and homeostasis, focusing on how biological systems interact and maintain stability. This quiz also covers the structure and function of plasma membranes, including their composition, the Fluid-Mosaic Model, and the role of membrane proteins.