Homeostasis and Feedback Mechanisms
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Questions and Answers

Which of the following factors can contribute to the emergence of new strains of pathogens?

  • Increased hospital admissions due to a pandemic
  • Development of new antigenicity in pre-existing pathogens (correct)
  • Globalization of trade and increased urbanization
  • Introduction of a pathogen into a community with no immunity

    • What is the primary mechanism responsible for gas exchange between organisms and their environment?

  • Osmosis
  • Active transport
  • Facilitated diffusion
  • Diffusion (correct)

    • What is a key feature of a respiratory surface that enhances efficient gas exchange?

  • A small surface area to minimize energy expenditure
  • A dry surface to prevent water loss
  • A thick layer of cells to provide structural integrity
  • A large surface area to maximize the rate of diffusion (correct)

    • How does the globalization of trade contribute to the spread of infectious diseases?

    <p>It leads to increased contact between people from different regions, facilitating disease transmission (C)</p> Signup and view all the answers

    Why is a concentration gradient essential for gas exchange in organisms?

    <p>It drives the movement of gases across respiratory surfaces (D)</p> Signup and view all the answers

    What is the main function of antibiotics?

    <p>To kill or inhibit the growth of bacteria (D)</p> Signup and view all the answers

    What is the primary mechanism by which bacteria develop resistance to antibiotics?

    <p>All of the above (D)</p> Signup and view all the answers

    How does herd immunity work?

    <p>Vaccinated individuals reduce the chances of the disease spreading to non-vaccinated individuals (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of an outbreak?

    <p>A gradual and steady increase in the number of cases over a long period (A)</p> Signup and view all the answers

    How does HIV infection affect the immune system?

    <p>It destroys T helper cells, which are crucial for mounting an adaptive immune response (D)</p> Signup and view all the answers

    What is the difference between bactericidal and bacteriostatic antibiotics?

    <p>Bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics inhibit bacterial growth (A)</p> Signup and view all the answers

    What is the role of memory cells in the immune response?

    <p>Memory cells are responsible for recognizing and destroying pathogens during a secondary immune response (C)</p> Signup and view all the answers

    Why are vaccines effective in preventing disease?

    <p>Vaccines contain weakened or inactive pathogens that stimulate the immune system to produce antibodies (C)</p> Signup and view all the answers

    What happens during the refractory period of an action potential?

    <p>The neuron is unable to generate another action potential. (D)</p> Signup and view all the answers

    Which of the following is NOT a factor that influences the speed of a nerve impulse?

    <p>The type of neurotransmitter released. (D)</p> Signup and view all the answers

    What is the role of the sodium-potassium pump in maintaining resting potential?

    <p>It actively pumps sodium ions out of the cell and potassium ions into the cell. (B)</p> Signup and view all the answers

    What is the difference between an excitatory post-synaptic potential (EPSP) and an inhibitory post-synaptic potential (IPSP)?

    <p>EPSPs depolarize the postsynaptic membrane, while IPSPs hyperpolarize it. (C)</p> Signup and view all the answers

    What is the role of calcium ions (Ca+) in synaptic transmission?

    <p>Ca+ ions trigger the release of neurotransmitters from the presynaptic neuron. (B)</p> Signup and view all the answers

    What is the function of acetylcholinesterase in the synaptic cleft?

    <p>It breaks down acetylcholine into acetate and choline. (C)</p> Signup and view all the answers

    Which of the following is an example of an effector cell?

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

    What is the correct order of events in synaptic transmission?

    <p>Action potential arrives at the presynaptic terminal, Ca+ influx, neurotransmitter release, binding to receptors, postsynaptic potential. (A)</p> Signup and view all the answers

    Why is the inside of a neuron negatively charged relative to the outside at resting potential?

    <p>The presence of negatively charged proteins inside the cell. (B)</p> Signup and view all the answers

    Which of the following statements about graded potentials is TRUE?

    <p>Their strength is proportional to the strength of the stimulus. (A)</p> Signup and view all the answers

    Flashcards

    Outbreak Definition

    An outbreak occurs when a pathogen enters a community lacking immunity.

    Pathogen Mutation

    New strains of pathogens arise when existing ones change antigenically.

    Factors in Outbreak Spread

    Factors like globalization and urbanization can enhance outbreak transmission.

    Gas Exchange Process

    Organisms exchange gases with the environment through diffusion.

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    Respiratory Surface Requirements

    Respiratory surfaces must be large, thin, moist, and permeable for effective gas exchange.

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    Secondary Immune Response

    The immune response that occurs upon re-exposure to a pathogen, faster and more potent than the primary response.

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    Immunodeficiency

    A state where the immune system is compromised or absent, leading to vulnerability to infections.

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    AIDS

    Acquired Immunodeficiency Syndrome caused by HIV, leading to reduced lymphocyte count and impaired immune response.

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    HIV Infection

    HIV infects TH cells, becoming active after a period of inactivity, destroying the TH cells during activation.

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    Zoonosis

    An infectious disease that can be transmitted from animals to humans.

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    Antibiotics

    Biological compounds targeting prokaryotic cells, either killing bacteria or inhibiting their growth.

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    Antibiotic Resistance

    The ability of some bacteria to survive antibiotics; often due to gene exchange among bacteria.

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    Vaccines

    Weakened forms of pathogens that trigger an immune response, preparing the body for actual infection.

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    Membrane Potential

    The potential difference in charge across a neuron's plasma membrane.

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    Resting Potential

    The state of a neuron when not firing, typically around -70mV.

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    Action Potential

    A rapid change in membrane polarity during nerve firing, reaching +30mV.

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    Depolarization

    The process of inside the neuron becoming more positive during an action potential.

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    Repolarization

    The return of the membrane potential to resting state after depolarization.

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    Nerve Impulse

    A wave of action potentials that travels along the axon.

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    Synapse

    The junction between two neurons or neuron and effector cell.

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    Neurotransmitter

    Chemicals released from presynaptic neurons to convey signals to postsynaptic neurons.

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    Acetylcholine

    A neurotransmitter essential for muscle contraction and heart rate regulation.

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    Graded Potentials

    Changes in membrane potential in response to neurotransmitter binding, can be excitatory or inhibitory.

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    Study Notes

    Homeostasis

    • Maintains a constant internal environment within physiological limits.
    • Preserves equilibrium within cells.
    • Uses both nervous and endocrine communication systems.
    • Disease occurs if homeostasis isn't maintained.

    Negative Feedback

    • A feedback loop uses an outcome as input.
    • Feedback loops can be positive (reinforce input) or negative (oppose input).
    • Negative feedback maintains equilibrium.

    Vital Functions

    • Internal equilibrium maintained by regulating:
      • Blood glucose (75-95 mg/dL).
      • Body temperature (36-38°C).
      • Blood pH (7.35-7.45).
      • Blood osmotic concentration (varies with body size).
    • Physiological activities affect these levels.
      • Circadian rhythms.
      • Physical activity.
      • Eating and fasting.

    Blood Sugar Regulation

    • High blood glucose damages cells due to hypertonicity.
    • Blood sugar checked by chemoreceptors.
    • Pancreatic hormones control blood glucose levels.
      • Insulin lowers blood glucose.
      • Glucagon raises blood glucose.

    Thermoregulation

    • Vasodilation for heat loss (promotes blood flow).
    • Sweating for evaporative cooling (evaporation absorbs heat).
    • Vasoconstriction to maintain heat (reduces blood flow).
    • Shivering produces heat.
    • Hair erection traps warm air to conserve heat.
    • Uncoupled respiration in brown adipose tissue produces heat.

    Circadian Rhythms

    • Physiological responses to a day-night cycle.
    • Controlled by melatonin from the pineal gland.
    • Light inhibits melatonin.
    • Melatonin promotes sleep in diurnal animals, activity in nocturnal animals.
    • Useful for jet lag management.

    Physical Exertion

    • Epinephrine (adrenaline) is a stress hormone.
    • Released from adrenal glands.
    • Prepares the body for exertion.
      • Elevates heart rate to pump more blood.
      • Dilates arterioles to skeletal muscles.
      • Increases ventilation for more oxygen uptake.

    Digestive Control

    • Food movement controlled by voluntary and involuntary nerve pathways.
    • The CNS initiates swallowing and egestion.
    • Peristalsis (involuntary movement) involves longitudinal smooth muscles.

    Body Systems Integration

    • Interactions between organ systems create new functionalities.
    • Coordination between various organ systems is essential for multicellular organisms.

    Communication

    • Animals have two communication systems: nervous and endocrine.
      • Nervous system transmits electrochemical impulses.
      • Endocrine system releases hormones directly into the bloodstream.

    Receptors

    • Specialized cells that detect specific stimuli.
      • Photoreceptors detect light.
      • Thermoreceptors detect temperature changes.
      • Chemoreceptors detect chemicals.
      • Mechanoreceptors detect pressure, touch, and stretch.

    Effectors

    • Organs or cells that respond to stimuli.
      • Muscles (by contraction).
      • Glands (by secretion)

    Nervous System

    • Two main parts:
      • CNS (brain and spinal cord) - information processing center.
      • PNS (peripheral nerves) - links CNS to receptors and effectors.
    • Nerve cells (neurons) transfer information.
    • Stimulus-response pathways.
    • Electrical impulses from receptors to CNS, then to effectors via motor neurons.

    Spinal Cord

    • Column of nerve fibres with connections to the central processing unit (brain).
    • Acts as an integration center for reflex actions (involuntary responses).
    • Does not require communication with the brain for some actions.

    Reflex Actions

    • Rapid, involuntary responses to stimuli, using skeletal muscles .
    • Reflex arcs bypass the brain, using only the spinal cord.
    • An example is pain response.

    Brain

    • Integrates and coordinates bodily functions, including memory, emotions, and consciousness.
    • Three main parts:
      • Cerebrum – high-level functioning.
      • Cerebellum - balance, coordination, proprioception.
      • Brainstem - connects brain to spinal cord, controls involuntary processes.

    Endocrine System

    • Network of ductless glands releasing hormones into the bloodstream
    • Hypothalamus - homeostasis control center, connects nervous and endocrine systems.
    • Pituitary gland - regulates other endocrine glands.

    Immune System

    • Protects against pathogenic infections
    • Surface barriers prevent pathogen entry.
    • Innate immunity (non-specific and non-adaptive), responds to all pathogens similarly.
    • Adaptive immunity (specific and adaptive) responds to specific pathogens and creates memory.

    Pathogens

    • Agents causing disease – can be cellular or acellular.

    Disease

    • Illness with characteristic symptoms, caused by various factors.

    Immunodeficiency

    • Weakened immune system; susceptibility to infections.

    Zoonotic Diseases

    • Infectious diseases transmitted between animals and humans.

    Antibiotics

    • Biological compounds targeting prokaryotic metabolism.

    Antibiotic Resistance

    • Some bacteria develop resistance to antibiotics.
    • Broad spectrum use encourages resistance.

    Vaccines & Immunization

    • Weakened pathogens that trigger an immune response and immunity.
    • Create memory cells for a faster response upon re-exposure.
    • Herd immunity protects those not immunized.

    Respiratory System

    • Exchange of gases with the environment.
    • Essential for cellular respiration.
    • Specialized surfaces maximizing gas diffusion.

    Circulatory System

    • Transports materials around the body.
    • Contains three types of blood cells: red blood cells, white blood cells, and platelets.
    • Blood is the fluid transporting materials.
    • Blood vessels (arteries, veins, capillaries) transport blood.
    • Heart, the pump, drives blood circulation.

    Heart

    • A muscular pump for blood movement through the body.

    Blood Vessels

    • Arteries take blood away from heart, high pressure.
    • Veins carry blood back to heart, low pressure.
    • Capillaries are small vessels for material exchange.
    • Valves prevent backflow in veins.

    Pulse

    • Blood surge through arteries that correspond with heart contractions.

    Lung Capacity

    • Measurement of air volumes in the lungs.

    Nerve Impulse Sped

    • Impulse speed depends on axon diameter and myelination.
    • Myelination allows faster jumps along nerve fibers.

    Synapses

    • Junction between neurons, or neuron and effector, where signals are transmitted.

    Membrane Potential

    • Difference in charge across a neuron's membrane.
    • Essential for electrical signals in neurons.

    Action Potential

    • Rapid change in membrane potential that triggers a nerve impulse.
    • Depolarization and repolarization are steps in the action potential.

    Neurotransmitters

    • Chemicals that transmit signals across synapses.
    • Important for muscle contractions and other functions.

    Graded Potentials

    • Changes in membrane potential that don't reach the action potential threshold.

    Covid-19

    • Novel coronavirus, caused a global pandemic
    • Epidemiologists analyzed data to manage the spread (percentage change and percentage differences).

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    System Regulation PDF

    Description

    This quiz explores the concepts of homeostasis, highlighting its importance in maintaining a stable internal environment. It covers negative feedback mechanisms and vital functions such as blood glucose regulation. Test your understanding of how physiological activities interact with these processes.

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