Human Nervous System Overview

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Questions and Answers

What is the general purpose of the sympathetic nervous system?

Its primary purpose is to stimulate the body's fight-flight-or-freeze response and maintain homeostasis.

Where are sympathetic preganglionic cell bodies located?

In the spine.

Where are sympathetic postganglionic cell bodies located?

In a sympathetic ganglion, next to the spinal cord.

How does the sympathetic nervous system affect the cardiovascular and respiratory systems?

It accelerates heart rate, widens bronchial passages, constricts blood vessels, increases peristalsis, causes pupillary dilation, piloerection, perspiration, and raises blood pressure. Signup and view all the answers

How does the sympathetic nervous system affect the digestive system?

It inhibits gastrointestinal secretion and motor activity. Signup and view all the answers

What is the general purpose of the parasympathetic nervous system?

It conserves energy by slowing the heart rate and increasing intestinal and gland activity. Signup and view all the answers

Where are parasympathetic preganglionic cell bodies located?

In the brain stem or sacral spinal cord. Signup and view all the answers

Where are parasympathetic postganglionic cell bodies located?

In a ganglion near the target organ. Signup and view all the answers

How does the parasympathetic nervous system affect the cardiovascular and respiratory systems?

It conserves energy by slowing the heart rate and respiratory rate. Signup and view all the answers

How does the parasympathetic nervous system affect the digestive system?

It increases intestinal and gland activity, relaxing sphincter muscles. Signup and view all the answers

Describe how light activates photoreceptors.

Photoreceptor proteins absorb photons, changing the cell's membrane potential. Signup and view all the answers

Explain how the optical system of the eye creates an image on the retina.

Light rays converge at the cornea and lens, forming an inverted real image on the retina. Signup and view all the answers

What are the functions of rods?

Rods are responsible for vision at low light levels and do not process color vision. Signup and view all the answers

What are the functions of cones?

Cones are responsible for color vision and high spatial acuity. Signup and view all the answers

Trace the path of light as it passes through the eye to the retina.

Light passes through the cornea to the lens, focuses on the retina, and converts to electrochemical impulses. Signup and view all the answers

Explain the process of light adaptation.

Rods regenerate rhodopsin in low light; in high light, rhodopsin is bleached. Signup and view all the answers

Study Notes

Sympathetic Nervous System

Stimulates the body's fight-flight-or-freeze response; constantly active to maintain homeostasis
Preganglionic cell bodies located in the spine
Postganglionic cell bodies found in sympathetic ganglia next to the spinal cord
Affects cardiovascular and respiratory systems: increases heart rate, dilates bronchial passages, constricts blood vessels, enhances peristalsis, and raises blood pressure
Inhibits gastrointestinal secretion and motor activity; causes contraction of sphincters and blood vessels

Parasympathetic Nervous System

Conserves energy; slows heart rate and increases intestinal and gland activity
Preganglionic cell bodies found in brain stem or sacral spinal cord
Postganglionic cell bodies located in ganglia near target organs
Affects cardiovascular and respiratory systems by slowing both heart and respiratory rates
Increases intestinal and gland activity, relaxing sphincter muscles

Photoreceptors and Vision

Light activates photoreceptors by absorbing photons, which changes the cell's membrane potential
Rods and cones release neurotransmitters when depolarized in the dark; hyperpolarizes bipolar cells, preventing signal transmission to ganglion cells
Image formation on the retina occurs as light rays converge at the cornea and lens, creating an inverted image

Functions of Rods and Cones

Rods function in low light; do not process color and have low spatial acuity
Cones function in bright light; enable color vision (blue, green, red) and high spatial acuity

Visual Processing Pathway

Light travels through the cornea and lens to focus on the retina
Retina converts light to electrochemical impulses sent via the optic nerve to the brain
Output from retina passes through optic chiasm, optic tract to LGN, and then to the primary visual cortex

Light Adaptation Process

In low light, rods regenerate rhodopsin quickly, maintaining sensitivity to light
In high light, rhodopsin is rapidly bleached, making some rods nonfunctional; cones then take over
Automatic adjustment of retinal sensitivity occurs according to light intensity

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Description

Explore the key functions and components of the sympathetic and parasympathetic nervous systems. This quiz covers their roles in maintaining homeostasis, effects on the cardiovascular and respiratory systems, and energy conservation. Test your knowledge on how these systems interact and influence the body's response.