Human Anatomy and Physiology- Control and Coordination- Concept 2: senses-Objectives section

Objectives answered by Anthony Hernandez

obj 1) summarize the general process that all sensory organs/structures use to “sense”

Sensory cells like chemical, electromagnetic and mechanical are translating stimuli and are turned into action potentials that the human human nervous system is receiving. General sensory receptors in the human body are modified nerve endings of sensory neurons.

obj 2) differentiate between general senses and special senses

General senses are somatic, and it relates to our ability to detect pressure, pain, temperature, and tensions through a variety of general sensory receptors. Special senses are hearing, smell, taste and equilibrium. Utilize special sensory receptor cells in sensory organs (ex: ear and eye) and epithelial structures (taste buds and olfactory epithelium) in the head.

obj 3) summarize the pathway that electromagnetic waves take in order to get to our brain to allow us to see

the photoreceptors (vision sensory organ) in our eyes convert electromagnetic waves into electrical energy (action potential) that travels to the brain

obj 4) list and describe each of the surrounding structures that protect and keep the eyeball healthy

• the eye is surrounded by protective fat and the bony orbits inside the skull.

• Eyebrows: keep sweat and sunlight out of eyes

• Eyelids and Eyelashes: trigger reflexive blinking to keep eyes moist

• lacrimal apparatus: consists of the lacrimal gland that makes and secretes tears and the ducts that drain the secretions

• Extrinsic eye muscles: 6 on each eyeball to control the eye’s movement

obj 5a) Distinguish between the three layers of the wall of the eyeball and their unique characteristics. describe the Fibrous Layer

• It is the outermost layer of the eyeball

• Mainly sclera which is the anchoring area for the extrinsic eye muscles

• This layer also includes the cornea which is a window that allows the eye to absorb light.

obj 5b) Distinguish between the three layers of the wall of the eyeball and their unique characteristics. describe the Vascular Layer

• it is the middle layer of the eyeball

Includes:

• choroid and it supplies all the layers of the eye with blood

• Intrinsic eye muscles:

1. Ciliary body= ring of muscle tissue around lens

2. Iris (colored part of the eye) = ring of smooth muscle between the cornea and lens that contracts and expands to change the size of the pupil

• pupil allows light into the eye and the iris controls how much light the eye is allowed to bring in

obj 5c) Distinguish between the three layers of the wall of the eyeball and their unique characteristics. describe the Inner Layer

• it is the Retina

• there are TWO layers:

1. Outer pigmented layer = pigment cells that help absorb light, so it does not scatter

2. Inner neural layer = it has tons of neurons and neuroglia which help create pathways for light

• Millions of photoreceptors that convert light energy into action potentials that travel through the optic nerve to the thalamus and then the visual cortex of the brain

two types:

Rods = register black and white

cones = detect fine detail and color

obj 6) describe the organization of the inside of the eyeball

1. Lens are the convex transparent disc that focused on the allowed amount of light inside the eye and projects that light onto the retina

2. Vitreous humor is the clear gel that fills the posterior segment of the eye behind the lens.

3. aqueous humor is the clear fluid that fills up the anterior segment in front of the lens

obj 7) summarize the pathway and process that molecules take in order to get to our brain to allow us to process smells

• chemoreceptors are used to detect molecules in the air

• molecules hit the olfactory epithelium in the roof of the nasal cavity

• molecules bind to receptors and action potential travels down the olfactory nerve into the ethmoid bone and then to the olfactory bulb that is connected to the brain’

• travels down the olfactory tract to the olfactory cortex and then a signal is sent to the frontal lobe to be identified and then travels to the emotional pathway in our limbic system

obj 8) summarize the pathway and process that molecules take in order to get to our brain to allow us to process tastes

• use gustatory epithelial cells

• these types of cells are made out of a stem cell called basal epithelial cell

• sensory receptor cells turn into action potentials and then they signal to the gustatory cortex of the brain then release digestive enzymes to break down food in order to create energy

obj 9) create a flow chart to summarize the pathway that a sound wave will travel through each part of the ear to get to the brain so that we can actually hear it