How Organisms Respond to Their Environment

This set of flashcards covers key concepts related to how organisms respond to their environment, focusing on the nervous system's structure, function, and the processes of transduction, action potentials, and neurotransmission.

What is sensitivity in living organisms?

The ability to respond to a stimulus.

What system imparts the ability to respond to stimuli in organisms?

The nervous system.

What is the nerve net in coelenterates?

A simple network of nerves that sends electrical impulses according to the type of stimulus.

What role do receptors play in higher organisms?

They receive stimuli from the environment and convert them to electrical impulses.

What is the process called when stimuli are converted to electrical impulses?

Transduction.

What are effectors in the nervous system?

Cells, tissues, or organs that respond to stimuli.

What composes the central nervous system?

The brain and spinal cord.

What is the function of the peripheral nervous system?

To connect tissues with the CNS and transmit instructions.

What are the two portions of the peripheral nervous system?

The afferent and efferent portions.

What do afferent pathways carry?

Information from sensory cells to the CNS.

What is the role of efferent pathways?

To carry information from the CNS to muscles and glands.

How are sensory neurons distinguished?

They conduct impulses towards the CNS.

What is the function of interneurons?

To connect sensory and motor neurons and integrate information.

What is a synapse?

The gap between neurons where neurotransmitters travel to transmit impulses.

What is the function of glial cells?

To support and maintain neurons, provide nutrients, and aid in ionic balance.

What is the resting potential of a neuron?

The charge difference across the membrane of an unstimulated neuron, typically about -70mV.

What initiates an action potential in a neuron?

A stimulus that causes enough change to reach the threshold potential.

What occurs during depolarization in an action potential?

The membrane potential becomes positive as Na+ channels open and Na+ enters the cell.

What is hyperpolarization?

A phase where the membrane potential becomes more negative than the resting potential.

What is the all-or-nothing law in action potentials?

An action potential occurs at maximum intensity or not at all, with frequency signaling stimulus strength.

How do nerve impulses propagate along a neuron?

As action potentials moving as a wave of depolarization, triggered by entry of Na+.