Plastic Movie:M 4/13 at 7pm in Welch 1.308

Today:Intro to Animals and theNervous System

Fig 1.9

Life as we know it…the animals

Protostomes DeuterostomesFig32.8

Animal Development

One important consideration of structure and function…surface area

Nalca leaveshttp://www.celebratebig.com/chile/index3.htm

One important consideration of structure and function…surface area

See fig's 41.9+.13

Why is surface area so critical?

Animals (and plants) must exchange various components with the environment

Organisms are organized:

atoms

molecules

organelles

cells

tissues

organs

systems

organisms

Fig 41.8

Four major tissue types in animals:

epithelial, connective, muscle, and nervous

Fig 41.8

Fig 41.6

Epithelieal tissue:Covers and lines body and/or parts. Tightly packed cells.

Connective tissue:Holds and supports. Few cells with an extensive extracellular matrix.

Fig 41.3

Fig 41.5Muscle tissue:Movement. Long muscle fibers cells.

Nerve tissue:Signaling. Generally long cells, neurons.

Fig 41.4

Different tissues that comprise the stomach, an organ.

Homeostasis:

Maintaining a steady-state

internalcondition

Fig 41.14

Sensing and reacting to the environment is critical

Failure to properly sense and react to the environment can be fatal

Fig 45.18

Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.

Fig 45.3Neurons: cells specialized fortransmitting signals

Axon

Parts of a neuron

Signals

Fig 45.3

Fig 45.3

In the brain neurons are shorter and highly interconnected

Neurons: signals move through neurons electrically and between neurons chemically

Nervous System Signaling

Stimulus

Transduction Transduction

Response

Na+/K+

pump

plasma membrane

Na+

K+

ATP–>ADP

Fig 45.4

Ionic gradients in neurons

Fig 45.11

At rest, the Na+/K+

gradient is maintained

Depolarization occurs with the opening of Na+ channels

Fig 45.11

An action potential starts when the local depolarization causes other Na+ channels to open

Fig 45.11

Action potentials only occur when the initial depolarization is above the threshold

Fig 45.11An action potential starts when the local depolarization causes other Na+ channels to open

Fig 45.6

Repolarization is achieved via

closing Na+ and opening K+ channels

Fig 45.11

the Na+/K+ pump reestablishes the resting state

Depolarization of one part of the membrane opens Na+ channels further along so the signal travels from one end to the other

Fig 45.11

Neurons: signals move through neurons electrically and between neurons chemically

Plastic Movie:M 4/13 at 7pm in Welch 1.308

Coming up:Nervous systemandImmune system