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?

To carry impulses between different parts of the central nervous system Signup and view all the answers

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

Motor neuron Signup and view all the answers

Why do reflex actions bypass the brain?

To provide an immediate protective response Signup and view all the answers

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

Receptor → Sensory neuron → Spinal cord → Motor neuron Signup and view all the answers

What is the role of receptors in a reflex arc?

To detect the stimulus Signup and view all the answers

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

Contraction of circular muscles Signup and view all the answers

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

To carry the impulse from the CNS to the effector. Signup and view all the answers

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

The lens becomes fatter and more curved. Signup and view all the answers

What is the synaptic cleft?

The gap between the presynaptic and postsynaptic neurones. Signup and view all the answers

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

Cone cells Signup and view all the answers

Where are rod cells primarily located within the retina?

Evenly distributed at the periphery of the retina Signup and view all the answers

How do neurotransmitters transmit impulses across a synapse?

They diffuse across the synaptic cleft and bind to receptors. Signup and view all the answers

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

Ciliary muscles relax, suspensory ligaments contract Signup and view all the answers

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

Receptors are only present in the postsynaptic neurone, and neurotransmitters in the presynaptic neurone. Signup and view all the answers

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

To contract and cause pupil dilation Signup and view all the answers

Which of the following is not a sense organ?

Brain Signup and view all the answers

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

Iris Signup and view all the answers

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

Three; red, green, and blue Signup and view all the answers

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

To protect the eye from damage from excessive light. Signup and view all the answers

What is the function of the lens in the eye?

To focus light onto the retina. Signup and view all the answers

Where are the photoreceptor cells located in the eye?

Retina Signup and view all the answers

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

To act as chemical messengers, facilitating communication between organs. Signup and view all the answers

Where are hormones primarily produced in the body?

In endocrine glands. Signup and view all the answers

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

Muscle Contraction. Signup and view all the answers

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

Adrenaline. Signup and view all the answers

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

Decreases blood glucose concentration. Signup and view all the answers

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

Nervous impulses are transmitted electrically, while hormones travel in the blood. Signup and view all the answers

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

To maintain a constant internal environment despite external changes. Signup and view all the answers

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

Hormonal responses are generally longer lasting than nervous impulses. Signup and view all the answers

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

They shrink and eventually die due to water loss. Signup and view all the answers

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

It causes glucose to be converted to glycogen in the liver. Signup and view all the answers

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

To activate an enzyme that converts glycogen to glucose. Signup and view all the answers

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

Cells shrinking. Signup and view all the answers

What is the underlying cause of Type 1 diabetes?

An autoimmune response that attacks insulin. Signup and view all the answers

How does glucagon affect cellular respiration?

It decreases the rate of cellular respiration. Signup and view all the answers

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

Decreased diffusion of glucose into cells. Signup and view all the answers

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

To maintain a constant water potential alongside a reliable source of energy. Signup and view all the answers

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

To detect temperature changes and initiate responses to maintain an optimum temperature. Signup and view all the answers

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

Vasodilation to increase heat loss. Signup and view all the answers

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

Positive phototropism. Signup and view all the answers

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

Via phloem. Signup and view all the answers

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

Enzymes denaturing and preventing reactions. Signup and view all the answers

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

Negative phototropism Signup and view all the answers

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

They are being developed but are likely very expensive. Signup and view all the answers

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

Sweating Signup and view all the answers

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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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.