Exam #3 W 4/7 in class (bring cheat sheet)

before Exam #3: the nervous system, movement, and the immune system

Fig 45.3Neurons: cells specialized fortransmitting signals

Neurons: signals move through neurons electrically and between neurons chemically

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 48.11

Neurons: signals move through neurons electrically and between neurons chemically

Neurotransmitters can be excitatory or inhibitory

(+)

(–)

(–)

(+)

(+/–)

(–)

tbl 48.1

Fig 48.15

At the end of the neuron, neurotransmitters are released signaling the next neuron to depolarize

electrical electricalat synapse chemical

At the synapse the electrical signal is converted to a chemical signal

Fig 48.14

Neurons are commonly connected to many other neurons, and the effect of the different incoming signals determines what the neuron will do.

Fig 48.16

Neurons are commonly connected to many other neurons, and the effect of the different incoming signals determines what the neuron will do.

Incoming signals move through neurons. Only signals above the threshold are transmitted along the neuron.

Fig 48.12

Sensory and motor neurons are often myelinated

Fig 48.13

Myelination allows faster movement of the action potential

Fig 48.3

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

Response

Nervous System Signaling

Stimulus

Transduction Transmission

Response

Integration

Fig 50.2

This stretch sensitive neuron transduces different signals depending on the amplitude of the stimulus

Smells are detected by receptor neurons in our nose. Each receptor is sensitive to a different chemical

Fig 50.15

Fig 50.18

Light is detected in the eye by receptors on the retina

Fig 50.19

Some vision problems arise from misshapen eyeballs too long

too short

AAL 42.10

Light receptor neurons of the eye:Rods detect black and whiteCones detect colors…one type of cone for each color - red, blue, and green

Fig 50.22

Inhibitoryneuro-transmitter

No light

Membrane depolarized

No Signal

Fig 50.22Polar Membrane

light

Noinhibitoryneuro-transmitter

Signal sent

Fig 50.23

Vertebrate retina structure

Fig 49.4

The brain and the central nervous system integrate the various incoming signals

Fig 48.3

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

Response

Responses can be release of hormones, change in cell activity, or muscle contraction

Muscles allow movement

An earthworm: without something to push against, muscles are not much use.

The skeleton, made of bones, gives support

Fig 50.34

Bones (connective tissue) are alive

Connections between bones and muscles

Fig 50.32

Muscles can only contract. Therefore, two muscles are needed for each range of motion.

2 nerve signals for every movement:excitatory and inhibitory

Fig 50.32

How do muscles contract?

You should watch these animations about neurons:

http://www.youtube.com/watch?v=YwN9aCobCy8

http://www.blackwellpublishing.com/matthews/actionp.html

http://www.blackwellpublishing.com/matthews/nmj.html

And this muscle contraction animation:

http://www.blackwellpublishing.com/matthews/myosin.html