1. Bellwork: How does an animal respond to it’s environment
Bellwork: How does an animal respond to it’s environment? Give at least three examples of how humans respond to their surroundings

2. Chapter 28: Animal Systems II
Response
Chapter 28: Animal Systems II

3. How quickly does an animal respond to an event around itself?
Almost instantaneously!
How?
Often through the use of a specialized nervous system
Composed of neurons
Together neurons collect information, interpret it and decide what to do with it

4. What is a stimulus? Anything that causes an organism to react
Can be chemicals, light, heat,
Ability to detect stimuli depends on sensory neurons
Each sensory neuron is responds to a particular stimulus
What examples can you think of?
Humans share a number of sensory organs with other animals
Some animals can responds to stimuli that humans can’t
Eg. Electric currents or the Earth’s magnetic field

5. How is the information from a sensory neuron passed around the body?
Interneurons – process information and determine how an organism responds to a stimuli
The more complex an organisms the more interneurons
The brain is essentially a mass of many interneurons

6. What examples of sensory responses can you think of?
A response is a specific reaction to a stimulus
When responding to a stimulus, often numerous body systems have to work together – often nervous and muscular system
Motor neurons carry directions from interneurons to muscles

7. How have nervous systems evolved through time?
Animal nervous systems exhibit differing degrees of cephalization and specialization
Invertebrates – large amount of diversity
Nerve nets, Nerve cords and Ganglia

8. Are heads common in invertebrates?
Bilaterally symmetrical animals often exhibit cephalization
Even some flatworms and roundworms display some form of cephalization
Certain molluscs and arthropods show higher degrees of cephalization
Ganglia form in several places, but largest in the head region (Cerebral Ganglia)
Cerebral Ganglia can be further organized into a brain

9. What is a chordate? What are their nervous systems like?
Higher degree of cephalization
Highly developed nervous system
Brains formed from many interneurons within the skull
Human brain has more than 100 billion nerve cells!
Signals sent to over 1000 nerve cells
Signals received from 10,000 more

10. How does a brain work?
A brain is divided into a series of different regions
Cerebrum, Cerebellum, Medulla Oblongata, Optic lobes, and Olfactory bulbs
Cerebrum: Thinking part of brain – memory, learning and conscious thought
Cerebellum: Coordinates movement and controls balance
Medulla Oblongata: Controls functioning of internal organs
Optic Lobe: Vision
Olfactory bulb: Sense of smell

11. Vertebrate Brains
Brain evolution involves increasing size and complexity as you move to the right of a cladogram

12. What sense organs do invertebrates have?
Many have sense organs that can detect light, sound, vibrations, movement, body orientation or chemicals in air/water
Invertebrate sense organs vary widely in complexity
Flatworms have tiny slits to detect presence and direction of light
Some Cephalopods and arthropods have complex eyes that detect motion and color, can form images

13. How do vertebrates differ in their ability to hear?
The hearing range of vertebrates spans from 50 Hz (tree frog) to 150,000 Hz (bottlenose dolphin)
Most vertebrates have highly evolved sense organs
Particularly for taste, smell and hearing
Some sharks can sense 1 drop of blood in 100 liters of water
Most vertebrates have color vision as good, or better than humans
Some species can even (such as duckbill platypus) detect weak electrical currents in water
Sharks will use ability to sense Earth’s magnetic field to navigate
Similar idea to how many birds navigate
Some fish generate electric current to communicate

14. Key point questions What does a motor neuron do?
How can nervous systems vary between animal groups
What is cephalization? How does it vary between animal groups?
How could you tell which has a better sense of smell: Amphibians or Reptiles?
What would you look for when assesing how capable an animal is of learning?
What is the general relationship between the complexity of an animal’s nervous system and that of it’s sensory system