Biology Homeostasis and Control Systems
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Questions and Answers

What is the primary reason rod cells provide low visual acuity?

  • Rod cells do not absorb different wavelengths of light.
  • Rod cells can only respond to high light intensity.
  • Multiple rod cells connect to a single bipolar cell. (correct)
  • Rod cells are located exclusively in the fovea.

Which type of cells allows the human brain to distinguish between separate light sources?

  • Bipolar cells
  • Cone cells (correct)
  • Rod cells
  • Peripheral cells

What happens to iodopsin in cone cells under low light conditions?

  • Iodopsin remains intact, preventing action potential generation. (correct)
  • Iodopsin is synthesized rapidly for color perception.
  • Iodopsin is broken down, causing color blindness.
  • Iodopsin loses its pigment properties.

What role does the fovea play in vision?

<p>It is the area where light is focused and visual acuity is highest. (A)</p> Signup and view all the answers

Why do cone cells only respond to high light intensity?

<p>Each cone cell connects to a single bipolar cell, allowing no spatial summation. (B)</p> Signup and view all the answers

What happens if the depolarisation does not exceed the -55 mV threshold?

<p>Nothing happens, and no action potential is generated (A)</p> Signup and view all the answers

What does the all-or-nothing principle ensure regarding action potentials?

<p>Only large stimuli can trigger responses (A)</p> Signup and view all the answers

During the refractory period, what occurs at the sodium channels?

<p>They cannot be opened because they are recovering (D)</p> Signup and view all the answers

What primarily causes the depolarisation of the neurone during an action potential?

<p>An influx of Na+ ions (C)</p> Signup and view all the answers

What is the immediate consequence of reaching the threshold of +40mV in the axon?

<p>Sodium channels close (D)</p> Signup and view all the answers

What is one key function of the refractory period in nerve impulses?

<p>It limits the frequency of action potentials being transmitted (D)</p> Signup and view all the answers

What is meant by 'discrete impulses' in the context of action potentials?

<p>They are distinct signals that do not overlap (D)</p> Signup and view all the answers

What happens to the neurone’s voltage after potassium ion channels open during repolarisation?

<p>It becomes more negative than the resting potential (C)</p> Signup and view all the answers

What role do voltage-gated channels play in the generation of a nervous impulse?

<p>They open in response to changes in voltage (C)</p> Signup and view all the answers

Which sequence correctly describes the process following a stimulus in a neurone?

<p>Voltage-gated sodium channels close, K+ exits, repolarisation occurs (B)</p> Signup and view all the answers

What would a woodlouse do when it crosses from a damp area to a dry area?

<p>Turn rapidly to return to dampness (D)</p> Signup and view all the answers

What two systems make up the nervous system?

<p>Central and peripheral (B)</p> Signup and view all the answers

What triggers the response in the nervous system according to the outlined process?

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

Which of the following receptors responds to pressure changes?

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

Where are Pacinian corpuscles primarily located in the body?

<p>In the skin, mainly in fingers and feet (B)</p> Signup and view all the answers

What is a generator potential in the context of receptor response?

<p>An electrical change in a neurone triggered by stimulation (C)</p> Signup and view all the answers

What role do channel proteins play in the Pacinian corpuscle?

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

Which of the following statements about receptors is true?

<p>Each receptor responds only to specific stimuli (B)</p> Signup and view all the answers

What is the role of pressure receptors in the aorta and carotid artery during high blood pressure?

<p>To decrease the frequency of electrical impulses. (A)</p> Signup and view all the answers

What causes the increase in heart rate when blood pressure decreases?

<p>Less stretch in pressure receptors leads to impulses sent via the sympathetic nervous system. (D)</p> Signup and view all the answers

Which part of the nervous system is involved when responding to low pH levels?

<p>Sympathetic nervous system. (A)</p> Signup and view all the answers

What is the primary outcome of activating the SAN during low blood pressure events?

<p>Increase in the frequency of electrical impulses. (C)</p> Signup and view all the answers

Which statement accurately describes the role of chemoreceptors?

<p>They sense changes in the concentration of chemicals in the blood. (A)</p> Signup and view all the answers

What physiological change occurs as a response to increased heart rate?

<p>Enhanced removal of carbon dioxide. (A)</p> Signup and view all the answers

How do the pacinian corpuscles function as receptors?

<p>They detect pressure changes on the skin. (B)</p> Signup and view all the answers

Which primary physiological response occurs due to the detection of high blood pressure?

<p>Decreased heart rate via the SAN. (D)</p> Signup and view all the answers

Where are most cone cells located in the eye?

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

What distinguishes rod cells from cone cells?

<p>Rod cells respond better at lower light intensities (A)</p> Signup and view all the answers

What role does the sinoatrial node (SAN) play in the cardiac cycle?

<p>It functions as a pacemaker for initiating contraction (C)</p> Signup and view all the answers

How does the atrioventricular node (AVN) contribute to heart contraction?

<p>It releases a wave of depolarization after receiving signals from the SAN (D)</p> Signup and view all the answers

What function does the non-conductive layer serve in the cardiac conduction system?

<p>It prevents the wave of depolarization from reaching the ventricles immediately (B)</p> Signup and view all the answers

What is meant by the term 'myogenic' in relation to cardiac muscle?

<p>The muscle can initiate its own contractions (D)</p> Signup and view all the answers

What is the function of Purkyne fibers in the heart?

<p>They transmit depolarization throughout the ventricles (B)</p> Signup and view all the answers

What is the primary function of cone cells in the visual system?

<p>They allow for color vision and function in bright light (B)</p> Signup and view all the answers

Flashcards

Woodlouse response to dryness

Woodlice rapidly turn to find damp areas and move straight to find one if completely dry.

Nervous System Parts

The nervous system is made up of the peripheral nervous system (PNS) and central nervous system (CNS). The PNS includes receptors, sensory and motor neurons, while the CNS includes the brain and spine.

Receptor Response

Each receptor only responds to specific stimuli, causing a generator potential potentially leading to a response.

Pacinian Corpuscle

A pressure-sensitive receptor in the skin, especially fingers and feet.

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Simple Reflex Pathway

Stimulus -> Receptor -> Coordinator -> Effector -> Response

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Stimulus

A change in the environment that causes a response.

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Generator Potential

A change in electrical potential that can trigger a response in a sensory neuron.

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Sensory Neuron

A nerve cell that transmits sensory information from a receptor.

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Spatial Summation (Rods)

Many rod cells connect to a single bipolar cell in the retina, allowing detection of light even in low-light conditions.

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Low Visual Acuity (Rods)

Rod cells cannot distinguish separate light sources because multiple rods connect to the same bipolar cell. This results in blurry vision in low-light conditions.

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High Visual Acuity (Cones)

Cone cells have one-to-one connections to bipolar cells, allowing the brain to distinguish separate light sources. This leads to sharp vision in high light conditions.

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Cone Cell Iodopsin

Different types of cone cells contain iodopsin pigment (red, green, blue) which absorb different wavelengths of light.

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Fovea

The area of the retina with the highest concentration of cone cells, receiving the most light intensity.

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Cone cells location

Cone cells are located near the fovea.

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Rod cells location

Rod cells are located further away from the fovea.

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Sinoatrial node (SAN)

The pacemaker of the heart, located in the right atrium.

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Atrioventricular node (AVN)

Located near the border of the ventricles, involved in heart's electrical conduction.

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Wave of depolarization

Electrical signal that causes muscle contraction in the heart.

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Non-conductive layer

A layer that prevents the electrical signal from going directly to the ventricles from the atria.

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Myogenic cardiac muscle

Cardiac muscle that initiates its own contractions.

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Bundle of His

A group of specialized heart cells that transmit electrical signals from the atria to the ventricles.

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Pressure Receptors

Specialized cells found in the walls of the aorta and carotid artery that detect changes in blood pressure.

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High Blood Pressure Response

When high blood pressure is detected by pressure receptors in the aorta and carotid artery, the body sends signals to decrease heart rate to lower the pressure.

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Low Blood Pressure Response

When low blood pressure is detected by pressure receptors, the body sends signals to increase heart rate and pump blood faster, thereby increasing pressure.

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Chemoreceptors

Specialized cells that detect changes in chemical concentrations, such as the acidity (pH) of blood.

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Low pH Response

When chemoreceptors detect a low pH (acidic) environment, the body increases heart rate to deliver more blood to the lungs for faster carbon dioxide removal.

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SAN (Sinoatrial Node)

The natural pacemaker of the heart, located in the right atrium, responsible for generating electrical impulses that regulate heart rate.

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Sympathetic Nervous System

Part of the autonomic nervous system responsible for stimulating the 'fight or flight' response, including increasing heart rate in situations of stress.

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Parasympathetic Nervous System

Part of the autonomic nervous system responsible for 'rest and digest' functions, including slowing down heart rate during relaxation.

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Resting Potential

The electrical charge difference across a neuron's membrane when it's not transmitting a signal, typically around -70mV.

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Depolarization

The process of the neuron's membrane becoming less negative, moving towards a more positive charge.

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Action Potential

A rapid, short-lasting change in the neuron's membrane potential, where the charge quickly rises to +40mV and then falls back to the resting potential.

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Repolarization

The stage after depolarization, where the neuron's membrane potential returns to a negative charge, back towards the resting potential.

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What causes a neuron to become more permeable to Na+?

A stimulus triggers the opening of voltage-gated sodium channels in the neuron's membrane, allowing Na+ to diffuse into the axon.

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-55mV threshold

The minimum depolarization needed for an action potential to be generated in a neuron. If the depolarization doesn't reach this threshold, no action potential occurs.

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All-or-nothing principle

A neuron either fires a full action potential with maximum voltage or it doesn't fire at all. The strength of the stimulus doesn't affect the voltage of the action potential, but it does affect the frequency of firing.

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Refractory period

A brief period after an action potential where the neuron is unresponsive to further stimulation. This ensures that action potentials are discrete and travel in one direction.

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Discrete impulses

Individual, separate action potentials that are not merged together. This is ensured by the refractory period.

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What is the importance of the all-or-nothing principle in nervous system function?

The all-or-nothing principle prevents neurons from responding to every slight change in the environment, making them selective and avoiding overwhelming the system. It ensures that only strong enough stimuli evoke a response, leading to more efficient information processing.

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Study Notes

  • Homeostasis is maintaining a constant internal environment in organisms.
  • Control systems maintain temperature, blood pH, blood glucose and water potential within limits.
  • Homeostasis is vital for enzyme function and metabolic reactions.
  • Negative feedback mechanisms return systems to their normal level when there is a deviation.
  • Blood glucose regulation involves the pancreas and its hormones insulin and glucagon to maintain blood glucose levels.
  • Osmoregulation control of water potential in the blood, involving the hypothalamus and posterior pituitary gland.
  • Maintaining blood water potential, too little water causes shrinkage and too much causes swelling of cells, so homeostasis is needed to maintain a balance.
  • ADH increases water permeability of the collecting duct in the kidney, increasing water absorption and making urine more concentrated.
  • Receptors are essential in detecting changes to trigger a response.

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Organisms Responding to Changes - Missestruch 2021 PDF

Description

This quiz covers the essential concepts of homeostasis, including control systems for temperature, blood glucose, and water potential. Learn about the importance of negative feedback mechanisms in maintaining internal balance, and the role of hormones like insulin and ADH. Test your understanding of how organisms regulate their internal environment for optimal function.

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