Biology Chapter 3 Quiz: Homeostasis and Transport
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Questions and Answers

What is defined as the study of the normal functioning of a living organism and its component parts?

  • Physiology (correct)
  • Psychology
  • Anatomy
  • Pathology

Which of the following sequences correctly lists the levels of organization in biological systems?

  • Molecules → Cells → Atoms → Tissues → Organ Systems → Organism
  • Atoms → Tissues → Molecules → Organs → Organ Systems → Organism
  • Cells → Tissues → Molecules → Organs → Organ Systems → Organism
  • Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism (correct)

What happens when homeostasis is disturbed for prolonged periods?

  • Improved immune function
  • Disease and sickness occur (correct)
  • Enhanced metabolic activities
  • Increased growth rate

Which type of feedback system reverses a change to help maintain homeostasis?

<p>Negative feedback (D)</p> Signup and view all the answers

Which process requires energy and involves vesicles for transport?

<p>Vesicular transport (B)</p> Signup and view all the answers

What characterizes movement through channels compared to facilitated diffusion?

<p>Channels allow simultaneous passage of many ions (D)</p> Signup and view all the answers

Which type of transport requires carrier proteins and can be both active and passive?

<p>Protein-mediated transport (D)</p> Signup and view all the answers

What factor does NOT contribute to chemical disequilibrium in the body despite osmotic equilibrium?

<p>Volume of water (A)</p> Signup and view all the answers

What is the primary function of neurohormones?

<p>To release hormones directly into the bloodstream (B)</p> Signup and view all the answers

Which type of receptor is associated with vasodilation in skeletal muscle blood vessels?

<p>Beta receptors (B)</p> Signup and view all the answers

What is the coding method for stimulus intensity in neural reflexes?

<p>Frequency of action potentials (B)</p> Signup and view all the answers

Which characteristic differentiates the speed of endocrine reflexes from neural reflexes?

<p>Neural reflexes are very fast, occurring in milliseconds (B)</p> Signup and view all the answers

How does specificity differ between neural and endocrine reflexes?

<p>Endocrine reflexes have broad specificity affecting all cells with appropriate receptors (A)</p> Signup and view all the answers

What is the minimum stimulus strength required to generate a detectable response in a receptor called?

<p>Threshold (C)</p> Signup and view all the answers

Which of the following contributes to determining the location of a stimulus in the central nervous system?

<p>The termination points of neurons in the brain (C)</p> Signup and view all the answers

What is the typical duration of action for neural reflexes compared to endocrine reflexes?

<p>Neural reflexes are short-lived while endocrine reflexes last longer (B)</p> Signup and view all the answers

Which of the following is a lipophobic ligand's general sequence of action?

<p>Trigger a rapid cellular response through cell surface receptors (B)</p> Signup and view all the answers

How do tonic receptors respond to a continuous stimulus?

<p>They continue to generate action potentials as long as the stimulus is present. (B)</p> Signup and view all the answers

Which ligands are released by neurons to modulate the activity of other neurons?

<p>Neurotransmitters (A)</p> Signup and view all the answers

What type of pain is transmitted by fast fibers?

<p>Localized, sharp pain (C)</p> Signup and view all the answers

Which mechanism enhances the sensory perception of specific stimuli through the activation of surrounding neurons?

<p>Lateral inhibition (B)</p> Signup and view all the answers

What characterizes phasic receptors when exposed to a stimulus?

<p>They only respond initially and at the end of the stimulus. (C)</p> Signup and view all the answers

What is a common feature of nociceptors?

<p>They specifically detect harmful stimuli. (D)</p> Signup and view all the answers

How does receptor adaptation affect the perception of stimulus duration?

<p>It can distort how long the stimulus is perceived. (C)</p> Signup and view all the answers

What type of control does the parasympathetic division primarily provide?

<p>Involuntary control related to rest-and-digest (B)</p> Signup and view all the answers

Which type of neurons are found in the somatic motor system?

<p>Single neuron from the CNS to the target (B)</p> Signup and view all the answers

Which neurotransmitter is used by both the sympathetic and parasympathetic divisions at the preganglionic level?

<p>Acetylcholine (A)</p> Signup and view all the answers

Where are the ganglia of the sympathetic division generally located?

<p>Close to the spinal cord (D)</p> Signup and view all the answers

In the contractile cycle, what occurs immediately after cross-bridge formation?

<p>Power stroke occurs and ADP is released from myosin (A)</p> Signup and view all the answers

What role does calcium play in excitation-contraction coupling?

<p>Binds to troponin to expose binding sites on actin (D)</p> Signup and view all the answers

What distinguishes the receptors used by the postganglionic neurons in the sympathetic division from those in the parasympathetic division?

<p>Sympathetic uses adrenergic receptors, while parasympathetic uses muscarinic receptors (B)</p> Signup and view all the answers

How does the anatomical structure of the autonomic nervous system compare to the somatic motor system?

<p>The autonomic nervous system involves more complex pathways with multiple neurons (C)</p> Signup and view all the answers

What defines a chemical signal as a hormone?

<p>Secreted by a cell into the blood affecting distant targets at low concentrations. (A)</p> Signup and view all the answers

Which statement correctly compares peptide and steroid hormone synthesis?

<p>Peptide hormones are synthesized in advance and stored, whereas steroid hormones are synthesized on demand with no storage. (D)</p> Signup and view all the answers

Where are the receptors for peptide hormones generally located?

<p>On the cell surface of the target cell. (C)</p> Signup and view all the answers

Which hormones act similarly to peptide hormones?

<p>Catecholamines. (B)</p> Signup and view all the answers

What characterizes the action of steroid hormones compared to peptide hormones?

<p>Steroid hormones regulate gene expression, creating slower but longer-lasting effects. (D)</p> Signup and view all the answers

How do peptide hormones typically enter the bloodstream?

<p>Exocytosis of secretory vesicles. (B)</p> Signup and view all the answers

What is a common misconception about melatonin?

<p>It helps regulate blood glucose levels. (A)</p> Signup and view all the answers

What role does the nervous system play in endocrine reflexes?

<p>It triggers hormone release through neural signals. (B)</p> Signup and view all the answers

What is released during the power stroke of muscle contraction?

<p>ADP and Pi (B)</p> Signup and view all the answers

What is optimal length (Lo) in muscle contraction?

<p>The length where myosin and actin overlap for maximal tension (A)</p> Signup and view all the answers

What initiates the contraction of smooth muscle?

<p>Calcium entry followed by activation of MLCK (C)</p> Signup and view all the answers

How does a muscle achieve graded contractions?

<p>By altering the frequency of action potentials in a motor neuron (C)</p> Signup and view all the answers

What happens during the resetting phase of a muscle contraction?

<p>New ATP binds to myosin, causing it to detach (D)</p> Signup and view all the answers

What role does myosin light chain phosphatase (MLCP) play in muscle relaxation?

<p>Dephosphorylates myosin, reducing cross-bridge cycling (B)</p> Signup and view all the answers

What occurs when a muscle is overstretched?

<p>Reduced cross-bridge formation leads to weak contraction (D)</p> Signup and view all the answers

What primarily determines the efficiency of muscle function?

<p>The initial length of the muscle near optimal length (A)</p> Signup and view all the answers

Flashcards

Physiology

The study of how living organisms and their parts function normally.

Homeostasis

Maintaining a stable internal environment despite external changes.

Negative Feedback

A process that reverses changes to restore a system to its set point.

Positive Feedback

A process that amplifies changes to push a system further away from its set point.

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Osmotic Equilibrium

When the concentration of water is equal on both sides of a membrane.

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Simple Diffusion

Passive movement of molecules down their concentration gradient.

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Facilitated Diffusion

Passive transport of molecules across a membrane with the help of a carrier protein.

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Active Transport

Movement of molecules against their concentration gradient, requiring energy.

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Lipophilic Ligand Binding

When a fat-soluble ligand binds to an intracellular receptor, it triggers a slower response by changing gene activity.

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Lipophobic Ligand Binding

When a water-soluble ligand binds to a cell surface receptor, it triggers a rapid cellular response.

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Alpha Receptors

These receptors bind epinephrine and are found in intestinal blood vessels, causing vasoconstriction (narrowing of blood vessels).

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Beta Receptors

These receptors bind epinephrine and are found in skeletal muscle blood vessels, causing vasodilation (widening of blood vessels).

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Neural Reflex Speed

Neural reflexes are very fast, taking only milliseconds to occur.

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Endocrine Reflex Specificity

Endocrine reflexes are less specific than neural reflexes, affecting all cells with the appropriate receptors.

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Stimulus Intensity Coding in Neural Reflexes

The intensity of a stimulus in neural reflexes is coded by the frequency of action potentials. A stronger stimulus means more frequent action potentials.

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Endocrine Reflex Duration

Endocrine reflexes have a longer duration of action compared to neural reflexes, lasting for minutes to hours.

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Hormone Criteria

A chemical signal is considered a hormone if it's secreted by a cell into the blood, travels to distant targets, acts at very low concentrations, and influences processes like growth, development, homeostasis, or metabolism.

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Peptide Hormone Synthesis

Peptide hormones are made in advance as preprohormones and are cleaved into active hormones before being stored in secretory vesicles.

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Steroid Hormone Synthesis

Steroid hormones are synthesized on demand from cholesterol and are not stored.

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Peptide Hormone Receptors

Peptide hormone receptors are located on the cell surface and activate second messenger pathways, leading to rapid responses.

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Steroid Hormone Receptors

Steroid hormone receptors are found in the cytoplasm or nucleus and regulate gene expression, leading to slower but longer-lasting effects.

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Catecholamines

Catecholamines are amine hormones derived from tyrosine and act like peptide hormones, with examples including epinephrine and norepinephrine.

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Thyroid Hormones

Thyroid hormones are amine hormones derived from two tyrosine molecules and act like steroid hormones, with examples including thyroxine (T4) and triiodothyronine (T3).

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Melatonin

Melatonin is an amine hormone derived from tryptophan and regulates circadian rhythms.

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Receptor Threshold

The minimum stimulus strength required to activate a sensory receptor and generate a detectable signal.

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Receptive Field

The specific area where a stimulus activates a sensory neuron.

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Sensory Acuity

The ability to discriminate between two stimuli as being separate. Smaller receptive fields lead to greater sensory acuity.

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Receptor Potential

A graded potential produced in a sensory receptor in response to a stimulus.

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Modality

The type of stimulus that a sensory neuron detects. It's determined by which sensory neurons are activated and where they terminate in the brain.

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Location

The specific spot where a stimulus occurred. This is determined by which receptive fields are activated.

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Intensity

The strength of a stimulus. It's determined by the number of receptors activated (population coding) and the frequency of action potentials generated (frequency coding).

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Duration

How long a stimulus lasts. It's determined by how long action potentials continue to be generated in response to a stimulus.

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Somatic Motor System

The part of the nervous system responsible for voluntary control of skeletal muscles.

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Sympathetic Nervous System

The part of the autonomic nervous system responsible for "fight-or-flight" responses.

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Parasympathetic Nervous System

The part of the autonomic nervous system responsible for "rest-and-digest" functions.

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Preganglionic Neuron

The first neuron in the sympathetic or parasympathetic pathway, originating in the CNS.

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Postganglionic Neuron

The second neuron in the sympathetic or parasympathetic pathway, originating in the ganglion.

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Excitation-Contraction Coupling

The process of converting an electrical signal (action potential) into a mechanical contraction in muscle fibers.

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Sarcoplasmic Reticulum (SR)

A network of membrane-bound sacs within muscle fibers that stores and releases calcium ions.

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Cross-Bridge Formation

The attachment of a myosin head to an actin filament, initiating the muscle contraction cycle.

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Power Stroke

The stage of muscle contraction where myosin heads pivot, pulling actin towards the center of the sarcomere, releasing ADP and Pi.

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Muscle Length and Force

The force a muscle generates depends on its initial length. Optimal length allows for maximum overlap of actin and myosin, but stretching or shortening the muscle reduces force.

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Length-Tension Relationship

Describes how a muscle's ability to generate force changes as its length changes. It shows that maximal force is produced at an optimal length.

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Motor Unit

A single motor neuron and all the muscle fibers it innervates. It's the functional unit of muscle contraction.

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Graded Contractions

The ability of a muscle to generate varying levels of force by recruiting different numbers of motor units.

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Smooth Muscle Contraction

The process of smooth muscle shortening, involving calcium entry, calmodulin activation, myosin light chain kinase (MLCK) activation, and myosin phosphorylation.

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Smooth Muscle Relaxation

The process of smooth muscle lengthening, involving calcium removal, myosin light chain phosphatase (MLCP) activation, and myosin dephosphorylation.

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Calmodulin (CaM)

A calcium-binding protein in smooth muscle that activates myosin light chain kinase (MLCK) upon binding calcium.

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Study Notes

Chapter 1

  • Physiology is the study of the normal functioning of a living organism and its component parts
  • Levels of organization: Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism
  • Homeostasis is the maintenance of a relatively stable internal environment despite external changes. Disease occurs when homeostasis is disrupted for prolonged periods
  • Negative feedback: A process that reverses a change to bring a system back to its set point. (Example: Regulation of body temperature)
  • Positive feedback: A process that amplifies or increases a change, pushing the system further away from its set point. (Example: Childbirth)
  • Feedforward control: A process that anticipates changes in a system and activates mechanisms to prevent deviations before they happen. (Example: Salivation before eating)
  • Osmotic equilibrium: The total concentration of solutes is the same on both sides of the cell membrane; no net water movement occurs
  • Chemical disequilibrium: Different solutes are unevenly distributed across the cell membrane (e.g., Sodium higher outside, Potassium inside)
  • Electrical disequilibrium: Ions contribute to charge differences across the membrane, creating a resting membrane potential of approximately -70 mV. This is maintained by ion channels and pumps (e.g., Na+/K+ ATPase).

Chapter 5

  • Osmotic Equilibrium means the total concentration of solutes is the same on both sides of the cell membrane.
  • Chemical Disequilibrium: Different solutes are unevenly distributed across the cell membrane.
  • Electrical Disequilibrium: Different charge across the membrane caused by the uneven distribution of ions.

Chapter 6

  • Local communication includes: Gap junctions, Contact-dependent signals, and diffusing chemicals
  • Long-distance communication includes: Blood transport and Neurochemicals
  • Paracrine signaling: Chemical signals released by a cell that affect nearby cells
  • Autocrine signaling: A cell releases a chemical that acts on itself

Chapter 7

  • Hormones affect distant targets in the body (blood transport)

  • Four criteria for a chemical signal to be a hormone:

    • Secreted into the blood
    • Transported to a distant target
    • Acts at low concentrations
    • Affects growth, development, homeostasis, or metabolism

  • Peptide hormones are synthesized in advance as preprohormones, stored in vesicles, and released by exocytosis.

  • Steroid hormones are synthesized on demand from cholesterol and immediately diffuse out of the cell.

Chapter 8

  • Neural Reflexes are fast (milliseconds), highly specific, use electrical and chemical signals, and are short-lived. Stimulus intensity coded by frequency of action potentials

  • Endocrine Reflexes are slow (minutes/hours), broad, utilize chemical signals (hormones), and are longer-lasting. Stimulus intensity coded by hormone concentration

  • The central nervous system (CNS) processes information and coordinates activity

  • The peripheral nervous system (PNS) transmits sensory input to the CNS and motor output from the CNS

  • Afferent division: Sensory input from receptors to the CNS

  • Efferent division: Motor output from CNS to effectors.

Chapter 10

  • Transduction: The process where physical stimuli are converted into electrical signals.
  • Threshold: The minimum stimulus strength needed to initiate a response.
  • Receptive field: Area where the stimulus activates neurons; smaller receptive fields allow for greater acuity.
  • Receptor potential/graded potential: A graded potential produced in the sensory neuron in response to a stimulus

Chapter 11

  • Adrenal medulla is the inner region of adrenal glands located atop the kidneys.
  • It consists of chromaffin cells, modified postganglionic sympathetic neurons
  • Primarily secretes epinephrine (approximately 90%), and norepinephrine (approximately 10%), in response to stress (fight-or-flight)
  • These hormones are neurohormones released directly into the bloodstream, eliciting systemic effects.

Chapter 12

  • Muscle contraction and relaxation use the sliding filament mechanism
  • Power stroke: Myosin heads pivot, pulling actin filaments toward the center of the sarcomere.
  • Release: A new ATP molecule binds to myosin, causing detachment from actin.
  • Resetting: ATP is hydrolyzed, re-cocking the myosin head for the next cycle.

Chapter 13

  • Four ways to classify neural reflex pathways:
    • By the efferent division of the nervous system (somatic vs. autonomic)
    • By the CNS location (spinal vs. cranial)
    • By whether the reflex is innate or learned
    • By the number of neurons in the pathway (monosynaptic vs. polysynaptic)
  • Stretch reflex: a monosynaptic reflex arc that maintains muscle length

Other

  • Long-term potentiation (LTP) is an enhanced synaptic transmission that is thought to play a role in learning and memory; mediated by AMPA and NMDA receptors.
  • Cerebrospinal fluid (CSF) is produced by the choroid plexus, flows through ventricles, and circulates around the brain and spinal cord.
  • Blood-brain barrier (BBB) protects the brain from fluctuations in blood composition, maintains a stable environment for neuronal function and prevents unnecessary inflammation in the CNS

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Description

Test your understanding of the normal functioning of living organisms and their systems in biology. This quiz covers topics such as homeostasis, levels of organization, and types of transport mechanisms. Evaluate your knowledge of neurohormones, feedback systems, and reflexes.

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