1. Sensing and Responding to the Environment

2. Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.
CB 48.3

3.
CB 49.17

4. Neurons: cells specialized for transmitting signals
CB 48.4
Neurons: cells specialized for
transmitting signals

5. In the brain neurons are shorter and highly interconnected
Fig 48.5

6. Signals move through neurons in one direction
Fig 48.4
Axon
Signals

7. Signals move along a neuron via movement of ions across the membrane
Fig 48.4
Axon
Signals

8. Ion movement across the membrane causes the signal to travel from one end to the other
Fig 48.11

9. At rest a neuron is polarized
At rest a neuron is polarized. The electrical signal is a depolarization that moves along the neuron.
Fig 48.11

10. At the synapse the electrical signal is converted to a chemical signal: neurotransmitters
at synapse chemical
electrical
electrical

11. at synapse chemical electrical electrical
at synapse chemical
electrical
electrical

12. Neurons are commonly connected to many other neurons, and the effect of the different incoming signals determines what the neuron will do.
CB 48.14

13. Nervous System Signaling
Stimulus
Integration
Transduction
Transmission
Response

14. Smells are detected by receptor neurons in our nose
Smells are detected by receptor neurons in our nose. Each receptor is sensitive to a different chemical
Fig 50.15

15. Activating more neurons leads to stronger perception
Fig 50.15

16. This stretch sensitive neuron transduces different signals depending on the amplitude of the stimulus
Fig 50.2

17. Light is detected in the eye by receptors on the retina
Fig 50.18

18. Some vision problems arise from misshapen eyeballs
too long
too short
Fig 50.19

19. AAL 42.10

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

21. No light No Signal Inhibitory neuro- transmitter Membrane depolarized
Fig 50.22

22. No inhibitory neuro- transmitter light Signal sent Polar Membrane
Fig 50.22

23. Vertebrate retina structure
Fig 50.23

24. Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.
Fig 46.1
Responses can be release of hormones, change in cell activity, or muscle contraction
Response

25. Next: Consciousness
Reports due Th 4/21