1. The master controlling and communicating system of the body
Nervous System
The master controlling and communicating system of the body
Receives, integrates, and responds to information
Functions
Sensory input – monitoring stimuli (see water)
Integration – process and interpretation of sensory input (I’m thirsty)
Motor output – response to stimuli (pick up the glass and drink)

2. Nervous System
Figure 11.1

3. Histology of Nerve Tissue
The two principal cell types of the nervous system are:
Supporting cells –
cells that surround and wrap neurons
Back-up singers and the band
Neurons –
excitable cells that that respond to stimuli and transmit electrical signals
The lead singer

4. Nervous Tissue
Figure 4.10

5. Neurons (Nerve Cells)
Figure 11.4b

6. Dentrites: Structure and Function
Short, tapering, and diffusely branched processes
They are the receptive, or input, regions of the neuron
(the “listeners”)

7. Axons: Structure and Function
Long axons are called nerve fibers
Axonal terminal – branched terminus of an axon
(the “talkers”)
Generate and transmit action potentials
Secrete neurotransmitters (such as Acetylcholine (ACh)) from the axonal terminals

8. Stunning Brain Map--National Geographic

9. Chunk and Chew Partner A: Partner B:
Please explain to your partner the components of nervous tissue. What are the two main “types” of cells?
Partner B:
Please describe the structure of neurons and how they actually send messages through synapses.

10. Eye and Associated Structures
70% of all sensory receptors are in the eye
Most of the eye is protected by a cushion of fat and the bony orbit
The eye is about 1 inch in diameter and only 1/6 is visible

11. Transparent membrane that:
Conjunctiva
Transparent membrane that:
Lines the eyelids
Covers the whites of the eyes
Lubricates and protects the eye
The space between the conjunctiva and the eyelid is where contact lenses reside
Conjunctival infection = pinkeye

12. Consists of the lacrimal gland and associated ducts
Lacrimal Apparatus
Consists of the lacrimal gland and associated ducts
Lacrimal glands secrete tears
Tears
Contain mucus, antibodies, and lysozyme (enzyme that destroys bacteria)
Cleanses, protects, moistens, and lubricates the eye
Drain into the nasolacrimal duct and causes the “sniffles”

13. Lacrimal Apparatus
Figure 15.2

14. Structure of the Eyeball
Figure 15.4a

15. Structure of the Eyeball
A slightly irregular hollow sphere with anterior and posterior poles
The wall is composed of three tunics – fibrous, vascular, and sensory
The internal cavity is filled with fluids called humors to help maintain its shape
The lens separates the internal cavity into anterior and posterior segments

16. Forms the outermost coat of the eye and is composed of:
Fibrous Tunic
Forms the outermost coat of the eye and is composed of:
Opaque sclera (posteriorly)
Clear cornea (anteriorly)
The sclera protects the eye and anchors muscles
The cornea (window) lets light enter the eye

17. The colored part of the eye (really only brown pigment from melanin)
Vascular Tunic: Iris
The colored part of the eye (really only brown pigment from melanin)
Presence of a lot of pigment = eyes appear brown or black
Small amount of pigment present = eyes appear blue, green, or gray
Shorter wavelengths of light are scattered from the unpigmented parts

18. Pupil – central opening of the iris
Vascular Tunic: Iris
Pupil – central opening of the iris
Regulates the amount of light entering the eye during:
Close vision and bright light – pupils constrict
Distant vision and dim light – pupils dilate
Changes in emotional state – pupils dilate when the subject matter is appealing or requires problem-solving skills (try it!!!)

19. A delicate two-layered membrane
Sensory Tunic: Retina
A delicate two-layered membrane
Pigmented layer – the outer layer that absorbs light and prevents it from scattering
Neural layer, which contains:
Photoreceptors that transduce light energy
Rods and cones

20. The Retina: Neurons called Photoreceptors
Rods:
Respond to dim light
Are used for peripheral vision
Lack sharp images and color vision
Cones:
Respond to bright light
Have high-acuity color vision

21. Internal chambers and fluids
The posterior cavity is filled with vitreous humor
Clear, watery gel
Transmits light
Supports the posterior surface of the lens and holds the retina in place
Contributes intraocular pressure—counteracts pulling forces from eye muscles

22. Internal chambers and fluids
The anterior cavity is filled with aqueous humor.
Clear fluid similar in composition to blood plasma
Constantly flows and drains
Supplies nutrients and oxygen to the lens and cornea and carries away wastes

23. A biconvex, transparent, flexible, avascular structure that:
Lens
A biconvex, transparent, flexible, avascular structure that:
Allows precise focusing of light onto the retina
Is composed of epithelium and lens fibers

24. Partners A and B: Anatomy of the eye
Chunk and Chew:
Partners A and B: Anatomy of the eye
Please turn to your partner and discuss the three different tunics of the eyeball and what functions they hold (take turns with each tunic).
Please compare and contrast aqueous and vitreous humors

25. Light
Electromagnetic radiation – all energy waves from short gamma rays to long radio waves
Our eyes respond to a small portion of this spectrum called the visible spectrum

26. Light
Figure 15.10

27. Refraction and Lenses
When light passes from one transparent medium to another its speed changes and it refracts (bends)
Light passing through a convex lens (as in the eye) is bent so that the rays converge to a focal point
When a convex lens forms an image, the image is upside down and reversed right to left

28. Refraction and Lenses
Figure 15.12a, b

29. Focusing Light on the Retina
Pathway of light entering the eye: cornea, aqueous humor, lens, vitreous humor, and the neural layer of the retina to the photoreceptors
Light is refracted:
At the cornea
Entering the lens
Leaving the lens
The lens curvature and shape allow for fine focusing of an image

30. Problems of Refraction
Emmetropic eye – normal eye with light focused properly
Myopic eye (nearsighted) – the focal point is in front of the retina
Corrected with a concave lens
Hyperopic eye (farsighted) – the focal point is behind the retina
Corrected with a convex lens

31. Problems of Refraction
Figure 15.14a, b

32. Chunk and Chew: Partners A and B:
Please turn to your partner and explain the pathway of light as it enters the eye and travels through.