Biology Chapter: Coordination and Response
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Questions and Answers

What is the primary role of the nervous system?

  • To coordinate body functions using electrical signals (correct)
  • To transport oxygen to body tissues
  • To digest food and absorb nutrients
  • To produce hormones for growth and development

Which of the following best describes the central nervous system (CNS)?

  • Nerves that extend to the periphery of the body
  • Only the brain
  • All the nerve cells of the body
  • The brain and spinal cord (correct)

What type of neuron carries impulses from receptors to the spinal cord and brain?

  • Effector neuron
  • Relay neuron
  • Sensory neuron (correct)
  • Motor neuron

What is the function of a relay neuron?

<p>To carry impulses between different parts of the central nervous system (A)</p> Signup and view all the answers

Which neurone carries impulses from the CNS to effectors, such as muscles?

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

Why do reflex actions bypass the brain?

<p>To provide an immediate protective response (D)</p> Signup and view all the answers

In a reflex arc, which of the following is the correct order of events?

<p>Receptor → Sensory neuron → Spinal cord → Motor neuron (B)</p> Signup and view all the answers

What is the role of receptors in a reflex arc?

<p>To detect the stimulus (B)</p> Signup and view all the answers

Which muscle action is associated with pupil constriction in response to bright light?

<p>Contraction of circular muscles (A)</p> Signup and view all the answers

What is the role of the motor neurone in a reflex arc?

<p>To carry the impulse from the CNS to the effector. (D)</p> Signup and view all the answers

What change occurs in the lens when focusing on a near object?

<p>The lens becomes fatter and more curved. (A)</p> Signup and view all the answers

What is the synaptic cleft?

<p>The gap between the presynaptic and postsynaptic neurones. (C)</p> Signup and view all the answers

Which type of photoreceptor cell is primarily responsible for color vision?

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

Where are rod cells primarily located within the retina?

<p>Evenly distributed at the periphery of the retina (C)</p> Signup and view all the answers

How do neurotransmitters transmit impulses across a synapse?

<p>They diffuse across the synaptic cleft and bind to receptors. (C)</p> Signup and view all the answers

When focusing on a distant object, how do the ciliary muscles and suspensory ligaments act?

<p>Ciliary muscles relax, suspensory ligaments contract (A)</p> Signup and view all the answers

Why does an impulse travel only in one direction at a synapse?

<p>Receptors are only present in the postsynaptic neurone, and neurotransmitters in the presynaptic neurone. (D)</p> Signup and view all the answers

What is the function of the radial muscles of the iris during low light intensity?

<p>To contract and cause pupil dilation (D)</p> Signup and view all the answers

Which of the following is not a sense organ?

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

Which part of the eye controls the amount of light entering?

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

How many different types of cone cells are there and what are the colors they are sensitive to?

<p>Three; red, green, and blue (D)</p> Signup and view all the answers

Which statement best explains why the pupil constricts in bright light?

<p>To protect the eye from damage from excessive light. (D)</p> Signup and view all the answers

What is the function of the lens in the eye?

<p>To focus light onto the retina. (C)</p> Signup and view all the answers

Where are the photoreceptor cells located in the eye?

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

Which of the following best describes the primary role of hormones in the body?

<p>To act as chemical messengers, facilitating communication between organs. (B)</p> Signup and view all the answers

Where are hormones primarily produced in the body?

<p>In endocrine glands. (D)</p> Signup and view all the answers

Which of these is NOT a function controlled by the endocrine system?

<p>Muscle Contraction. (C)</p> Signup and view all the answers

During a 'fight or flight' response, which hormone is primarily released?

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

Which of the following best describes the effect of insulin on blood glucose concentration?

<p>Decreases blood glucose concentration. (D)</p> Signup and view all the answers

What is a key difference between nervous impulses and hormones in terms of transmission?

<p>Nervous impulses are transmitted electrically, while hormones travel in the blood. (D)</p> Signup and view all the answers

Which of the following best represents the main role of homeostasis in a biological organism?

<p>To maintain a constant internal environment despite external changes. (C)</p> Signup and view all the answers

How does the duration of hormonal responses typically compare to that of nervous impulses?

<p>Hormonal responses are generally longer lasting than nervous impulses. (C)</p> Signup and view all the answers

What happens to cells when the level of glucose in the blood is too high?

<p>They shrink and eventually die due to water loss. (C)</p> Signup and view all the answers

What is the role of insulin in regulating blood glucose levels?

<p>It causes glucose to be converted to glycogen in the liver. (D)</p> Signup and view all the answers

What is the primary function of glucagon in blood glucose regulation?

<p>To activate an enzyme that converts glycogen to glucose. (A)</p> Signup and view all the answers

Which of the following is NOT a consequence of low blood-glucose levels?

<p>Cells shrinking. (A)</p> Signup and view all the answers

What is the underlying cause of Type 1 diabetes?

<p>An autoimmune response that attacks insulin. (B)</p> Signup and view all the answers

How does glucagon affect cellular respiration?

<p>It decreases the rate of cellular respiration. (D)</p> Signup and view all the answers

What is the most direct consequence of not having enough insulin?

<p>Decreased diffusion of glucose into cells. (B)</p> Signup and view all the answers

What is the ultimate goal of homeostasis in maintaining blood-glucose concentration?

<p>To maintain a constant water potential alongside a reliable source of energy. (C)</p> Signup and view all the answers

What is the primary function of the hypothalamus in terms of regulating body temperature?

<p>To detect temperature changes and initiate responses to maintain an optimum temperature. (B)</p> Signup and view all the answers

If the body temperature drops below 37°C, which physiological response is least likely to occur?

<p>Vasodilation to increase heat loss. (D)</p> Signup and view all the answers

What type of response is a plant's shoot growing towards light?

<p>Positive phototropism. (A)</p> Signup and view all the answers

Which of the following describes how auxins move over long distances in plants?

<p>Via phloem. (A)</p> Signup and view all the answers

Which of the following is a consequence of having a body temperature significantly above 37°C?

<p>Enzymes denaturing and preventing reactions. (C)</p> Signup and view all the answers

If a plant's roots grow away from light, what type of response is that?

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

What is unique about new treatments for disease that include stem cells and artificial pancreases?

<p>They are being developed but are likely very expensive. (A)</p> Signup and view all the answers

Which of the following is a physiological response to an increased body temperature?

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

Flashcards

Synapse

A junction between two neurons where signals are transmitted.

Synaptic Cleft

A gap within a synapse where neurotransmitters are released.

Neurotransmitters

Chemical messengers released by the presynaptic neuron to trigger a response in the postsynaptic neuron.

Presynaptic Neuron

The neuron that releases neurotransmitters into the synaptic cleft.

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Postsynaptic Neuron

The neuron that receives neurotransmitters in the synaptic cleft.

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Cone Cells

Specialized cells in the retina that detect light of different colors, responsible for color vision.

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Rod Cells

Specialized cells in the retina that detect light intensity, responsible for vision in low light.

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Fovea

The central area of the retina with a high concentration of cones, responsible for the clearest visual detail.

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Nervous System: Functions

The nervous system is responsible for coordinating and regulating body functions, including movement and maintaining a stable internal environment (homeostasis). It consists of specialized cells called neurons, which transmit electrical signals called nerve impulses.

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Central Nervous System (CNS)

The central nervous system (CNS) is the control center of the nervous system, processing information and issuing commands. It consists of the brain and spinal cord.

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Peripheral Nervous System (PNS)

The peripheral nervous system (PNS) acts as the communication network, connecting the CNS to the rest of the body. It includes all nerves outside the brain and spinal cord.

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Sensory Neuron

Sensory neurons transmit impulses from receptors (sense organs) to the CNS, providing information about the environment.

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Relay Neuron

Relay neurons, also called interneurons, are found within the CNS and transmit impulses between sensory and motor neurons. They help process and integrate information.

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Motor Neuron

Motor neurons carry impulses from the CNS to effectors (muscles or glands), causing a response.

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Reflexes

Reflexes are rapid, involuntary movements that occur in response to a stimulus. They help protect the body from harm by bypassing the brain, allowing for a quicker response.

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Reflex Arc

The reflex arc is the pathway of a reflex action, involving a receptor, sensory neuron, relay neuron, motor neuron, and effector. Information travels rapidly through the arc.

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What is accommodation?

The process of adjusting the lens shape to focus on objects at different distances.

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What are suspensory ligaments?

These are muscles that connect to the lens; they relax when focusing on distant objects, and contract when focusing on near objects.

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What are ciliary muscles?

These muscles contract when focusing on near objects, and relax when focusing on distant objects.

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What are cones in the eye?

These cells are responsible for color vision in bright light.

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What are rods in the eye?

These cells are responsible for night vision and sensitivity to low light.

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How do pupils control light?

The circular muscles contract to constrict the pupil in bright light, and relax to dilate it in low light. The radial muscles do the opposite.

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What is the pupil reflex?

The ability of the pupil to expand and contract to control the amount of light entering the eye.

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What is the endocrine system?

A system of glands that produce and secrete hormones, which act as chemical messengers within the body.

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Hormones

Chemical messengers produced by glands, transported via the bloodstream to target organs, triggering cellular changes.

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Endocrine system

A network of hormone-producing glands regulating growth, metabolism, and maintaining internal balance.

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Endocrine gland

A type of gland that secretes hormones directly into the bloodstream.

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Adrenaline

The hormone secreted by the adrenal glands during stress or excitement. It increases heart rate, breathing, and blood glucose levels.

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Homeostasis

The balance of the body's internal environment, despite external changes to maintain optimal cell function.

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Nervous system

A system that uses electrical signals along specialized nerve cells for rapid communication.

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Insulin

The hormone secreted by the pancreas that lowers blood glucose levels.

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Glucagon

The hormone secreted by the pancreas that raises blood glucose levels.

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Blood Glucose

The sugar that cells use for energy. Its level in the blood must be tightly controlled.

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Diabetes

A condition where the pancreas does not produce enough insulin, or the body's cells do not respond to insulin properly, resulting in high blood glucose levels.

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Type 1 Diabetes

Diabetes caused by an autoimmune response where the body's immune system attacks insulin-producing cells in the pancreas.

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Type 2 Diabetes

Diabetes caused by either insufficient insulin production by the pancreas or by the body's cells not responding properly to insulin.

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Glycogen

A complex carbohydrate stored in the liver and muscles. It is the storage form of glucose.

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Body Temperature

The optimal temperature for enzyme reactions in humans, allowing for efficient metabolism.

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Hypothalamus

The part of the brain responsible for regulating body temperature, detecting changes in temperature using thermoreceptors.

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Shivering

A physiological response to low internal temperature where muscles contract involuntarily to generate heat.

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Vasoconstriction

A physiological response to high internal temperature where blood vessels narrow, reducing blood flow to the skin surface and minimizing heat loss.

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Sweating (Perspiration)

A physiological response to high internal temperature where sweat is released from the skin, cooling the body as it evaporates.

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Vasodilation

A physiological response to high internal temperature where blood vessels widen, increasing blood flow to the skin surface and allowing heat loss to the environment.

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Tropism

Growth responses in plants caused by external stimuli, like light or gravity.

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Phototropism

A plant's response to light, typically seen as shoots growing towards light sources for photosynthesis.

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Study Notes

Coordination and Response

  • The nervous system coordinates and regulates body functions via electrical signals (nerve impulses) along specialized nerve cells (neurons).
  • This maintains homeostasis (a constant internal environment).
  • The nervous system has two main parts:
    • The central nervous system (CNS): Composed of the brain and spinal cord.
    • The peripheral nervous system (PNS): Contains nerves outside the brain and spinal cord, carrying impulses to and from the CNS.
  • Types of Neurons:
    • Sensory neurons: Carry impulses from receptors to the spinal cord and brain.
    • Relay neurons: Carry impulses between different parts of the central nervous system.
    • Motor neurons: Carry impulses from the central nervous system to effectors (e.g., muscles).

Reflexes

  • Reflex actions are involuntary responses to a stimulus to quickly remove the organism from a danger.
  • The nervous impulse does not travel to the brain in a reflex action, as these reactions need to occur almost instantly.
  • A reflex arc is the pathway followed by a nerve impulse during a reflex action:
    • Stimulus detected by receptors.
    • Sensory neuron carries impulse to the spinal cord.
    • Relay neuron in the CNS passes the impulse to the motor neuron.
    • Motor neuron carries the impulse to an effector (e.g., muscle), causing a response.

Synapses

  • Synapses are junctions between neurons, forming a gap called the synaptic cleft.
  • When an impulse arrives at a presynaptic neuron, neurotransmitters are released into the synaptic cleft.
  • Neurotransmitters diffuse across the synapse, binding to receptors on the postsynaptic neuron.
  • This triggers a nervous impulse in the postsynaptic neuron, transmitting the signal.
  • Synapses ensure unidirectional transmission of impulses; neurotransmitters are present only in the presynaptic neuron, while receptors are only present in the postsynaptic neuron.

Sense Organs

  • Sense organs are groups of receptor cells that respond to specific stimuli (e.g., light, temperature, touch, sound, chemicals).
  • The eye is a sense organ that responds to light:
    • Cornea: Refracts light into the eye.
    • Iris: Controls the amount of light entering the eye.
    • Pupil: Allows light into the eye.
    • Lens: Focuses light onto the retina.
    • Retina: Contains photoreceptor cells (rods and cones) sensitive to light.
    • Fovea: Area in the retina with the highest concentration of cones, providing the clearest image.
    • Optic nerve: Carries impulses to the brain.

Pupil Reflex

  • The pupil of the eye adjusts to control the amount of light entering.
  • Circular muscles and radial muscles work antagonistically to adjust pupil size based on light intensity.

Accommodation

  • The eye can focus on both near and far objects by changing the shape of the lens.
  • Ciliary muscles and suspensory ligaments work together to achieve this.

Rods and Cones

  • Rods: Used for monochromatic night vision.
  • Cones: Used for color vision in bright light.

Hormones

  • The endocrine system uses hormones (chemical messengers) transported in the blood to regulate body functions.
  • Hormones are secreted by glands and travel to target organs/cells to induce a response.
  • Examples of endocrine glands and associated functions
    • Adrenal gland: Produces adrenaline, involved in the "fight or flight" response.
    • Pancreas: Produces insulin and glucagon, which regulate blood glucose levels.
    • Testes: Produce testosterone, regulating male reproductive functions.
    • Ovaries: Produce estrogen, regulating female reproductive functions.

Endocrine vs Nervous System

  • Nervous impulses travel along neurons, while hormones travel in the blood.
  • Nervous impulses are much quicker than hormones, while hormonal responses can be longer-lasting.
  • The nervous system uses electrical signals, while the endocrine system uses chemical signals (hormones).

Homeostasis

  • Homeostasis is the maintenance of a relatively stable internal environment despite external changes.
  • This process is crucial for optimal cellular function.

Regulating Blood Glucose

  • The body maintains blood glucose levels within a narrow range through the action of insulin and glucagon.
  • Insulin lowers blood glucose by promoting glucose uptake by cells and glycogen synthesis.
  • Glucagon raises blood glucose by stimulating glycogen breakdown.

Regulating Temperature

  • Humans maintain a core body temperature of 37°C for optimal enzyme function.
  • To maintain temperature, the body uses responses such as shivering, vasoconstriction, sweating, and vasodilation.

Tropic Responses

  • Tropisms are directional growth responses by plants in reaction to stimuli,
  • Examples:
    • Phototropism : plants growing toward or away from light.
    • Gravitropism : plants growing toward or away from gravity.

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Coordination and Response IGCSE Biology Notes PDF

Description

Explore the fascinating mechanisms of the nervous system in this quiz on coordination and response. Understand the roles of different types of neurons and how reflex actions work to protect the body. Test your knowledge on central and peripheral nervous systems and their importance in maintaining homeostasis.

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