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Brain activity and the senses


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What controls the levels of sleep?
The reticular activating system (RAS)
How do we fall asleep?
Neurons in the RAS releases serotonin, inhibits impulses to arouse brain alowing sleep.
How do we awaken?
Neurons called Norepinephrine, from another part of the brain, inhibits the effects of serotonin and makes us more alert.
How can brain activity be measured?
Brain activity can be measured by reading electrical readings with an electroencephalograms (EEG).
What are the different stages of sleep?
While awake patterns in an EEG show waves that are random small raves.
One phase is: REM (rapid eye movement), at this deep sleep we dream. Heart rate, respiration, and blood flow to the brain increases. Most body muscles go limp. REM at least 6 X a night. At night REM cycles are shorter in the morning they become longer, lasting about 20 minutes.
Why is sleep important?
It has been linked to:
memory consolidation, learning.
If we don't get enough sleep we can become moody, irratable, and depressed, and maybe even hallucinations.
What is the Limbic system?
The limibic system is a collection of neuronal areas near the base of the cerebrum that are involved in emotions(love, anger, fear, or sorrow), basic behaviors, and short-term memory, and also smell goes thru the limbic system. Limibic means "border".
What does the Limbic system consist of?
The Cerebrum, Thalamus, and Hypothalamus.
How many stages does memory consist of? What are they?
2, Short term memory and long term memory.
What is Short term memory?
information retrieved stored within last few minutes or hours. Short term memory is occurs in the limbic system.
What are receptor cells?
Receptor cells are structures specialized to receive certain stimuli, it accepts the stimuli and turns its energy into another form and sends it to the CNS.
What is a sensation?
When the CNS receives an impulse we experience a sensation. A sensation is an awareness of the sensory stimuli. Our brain forms a conscious understanding of sensory data.( We hear thunder)
What is a perception?
a perception is a meaningful interpretation or concious understanding of sensory.(We see thunder clouds so know it is going to rain)
How does the brain catergorize sensory information?
Receptors are classified according to the type of stimulus energy they convert:
-mechanoreceptors: respond to forms of mechanical energy. (hearing, touch)
-thermoreceptors: respond to heat and cold.
-pain receptors: respond to tissue damage or excessive pressure or temperature.
-chemoreceptors: respond to the presence of chemicals in teh nearby area.
-photoreceptors: respond to light.
What are taste buds?
Taste buds convert the presence of a chemical signal to action potentials. A taste bud is a cluster of about 25 taste cells and 25 supporting cells.
What is the function of taste buds?
Taste cells are in the taste buds have taste hairs, at the end of these taste hairs there are sensory receptors called chemoreceptors. Food triggers neurotransmitters that go to sensory receptors. We have aobout 10,000 taste buds.
What are these tasted located?
At the back of the tongue bitter recpeptors, at the tip of the tongue, sweet receptors. However, it is believed all tastes are on the tip, back and sides of tongue, none in the center.
What is the function of the nasal passages?
Nasal passages are line with mucus to protect membranes and help with the smell the smell process.
What type of mechanism begins the electrical impulse in smell?
Chemoreceptor cells.
What are odors detected by?
Odors are detected by olfactory receptor cells in the upper part to the nasal passages. Right under these receptor cells are olfactory hairs embedded in the nasal mucus.
What is the process of smell?
First the odor enters the nasal passages, it gets dissolved in the mucus, than binds to the olfactory hairs causing olfactory receptor cells to generate impulses. Olfactory cells synapse to olfactory neurons, causing a chemical reaction of neurons.
Smell vs Taste
Both taste and smell use chemoreceptors as mechanisms. Sensory receptor (chemorecptors) cells travel via electrical impulse to the CNS.
Difference is that our sense receptors are located on true sensory neurons. There are over 1,000 different odorant chemicals opposed to four in taste. Together we can distinguish over 10,000 smell and taste sensations.
Why do we need 2 ears?
To be able to catch sounds on either side of us.
What are sounds?
Sounds are waves of compressed air. Sound is measured in decibels.
0 is barely can hear sound.
50-60db Normal conversation.
85-100 lawn mower
110-130 Live Rock concert Risk of permanent hearing loss.
150 jet plane (can cause permanent hearing loss)
What is a sound wave?
A wave of compressed air. Sound waves come through our ears and starts the process of hearing.
What are the 2 types of sound?
Tone: is the frequency of sound, higher in pitch; more compressed waves of air.
Loudness(intensity): is determined by soundwave amplitude measured in decibel units.
0 decibels = whisper
50-60 = Normal conversation
85-100 = Lawn mower (long time exposed to sound can cause damage)
140 = Shotgun (one time can cause hearing permanent hearing loss)
150 = Jet engine (one time can cause permanent hearing loss.)
What are the parts of the ear?
The Outer(sound chaneled in), Middle(sound amplified) and inner ear(soundwave converted into an electrical impulse).
What is the function of the outer ear?
The outer ear chanels sound into ear. The flaps or earlobes are called Pinna. Sound goes through the auditory canal until it reaches the tympanic membrane (eardrum) causing it to vibrate. The eardrum separates the inner ear from the middle ear.
What is the function of the middle ear?
The middle ear amplifies the sound from the outer ear. The middle ear is within the temporal bone of the skull and an air-filled chamber. It consists of 3 bones, which vibrate when soundwaves hit the eardrum. This vibration causes a small membrane called the oval window to vibrate. The vibration in the middle ear has to be amplified so that the vibrations are strong enough to cause waves into the inner ear.
The eustachian tube. a narrow tube that extends from the middle ear to the throat, which helps keep atmospheric pressure. It opens briefly when swallowing and yawning.
What is the function of the inner ear?
The inner sorts out sounds by tone and vonverts it into an eletrical impulse. The Cochlea (snail like shape). If unrolled the Cochlea is made of three canals. In the middle canal is called the Organ of Corti. Here the sound is turned to electrical impulse. At the very base there is a membrane called the Basilar membrane. The amplified sound goes through the 1st watery channel, through the Organ of corti(middle), causing Basilar membranes to move up and down. The hairs trigger the electrical impulse when they touch the tectorial membrane causing them to bend and release neurotransmitters attaching to the nearest sensory neurons.
What is the Vestibular Apparatus?
Consists of the vestibule and the three semicircular canals filled with water, which have nothing to do with hearing. The vestibular apparatus helps with the sense of balance.
What is light?
Electromagnetic radiation that travels in waves at speed of 186,000 miles per second.
What is the Sclera?
The sclera is the tough white coat that covers and protects the outer surface of the of the eyeball except for the front, where the cornea is.
What is the function of the cornea?
The cornea is the transparent part of the eye that bends incomin light (focuses light) for protecction located in the front of the eye.
What is the process of sight?
First light enters through the cornea and passes the aqueous humor. Then through the pupil, an opening that adjusts in the center of the iris.
Next the light hits a colored, disk shaped muscle lens that determines how much light passes through the pupil, called the iris. Light continues through the water filled eye to the retina. The fovea on the Retina are where images are focused. The optic disk (blind spot) is where the axons exit the eye, there are no photoreceptors here. The optic nerve is connected to the optic disk.
Describe the inner eye.
The inner part of the eye is made of water. Light continues through this area until it reaches the back and side layers of the eye called the retina (helps focus) Two sites on the retina are the fovea a small funnel shaped pit where concentration of photoreceptors is higher than anywhere else in the eye.
What is the function of the iris?
The iris adjusts amount of incoming light with two sets of smooth muscle. Bright light = pupil contracts. Dim light = pupil dilates.
What is the function of the lens?
Lens regulates focus.
What is the function of the aqueous humor?
A fluid filled space that cushions and nourishes the cornea and lens.
What is the function of the pupil?
The pupil is an opening, in the center of the iris, that adjusts.
How does the eye focus?
Lens focus light onto the retina by bending light rays. The lens is stationary, the fatter the lens the more it can bend light. Objects that are close muscles in the eye contract and ligaments slacken making lens thinner.
Objects that are distant: Muscle relaxes, and stretches out ligaments making lens thicker.
What happens to lens as we get older?
The lens begins to stiffen and is not as flexible, not allowing objects to seen as easily.
What kinds of focus problems are there?
Normal eyes: focus point is directly on the fovea.
Nearsighted(myopia): Hardtime focusing on objects far away. The lens is thinner in the middle.
Farsighted (Hyperopia): Can see objects far away. Eye is shorter and light is focusing after retina. Lens is thicker in the middle.
Astigmatism: "Limp eye" light is scattered all over the eye, there is no focus point. The cornea and lens have abnormal shapes or curvature.
How does the brain convert visual stimuli into electrical impulse?
When the light reaches the fovea (retina)we have photoreceptors. There are 2 types:
Cones: provide color vision.
Rods: provide vision in dim light (grays). Rods are located throughout the eye but there are more rods near focal point (fovea) and diminishes toward front eye.
How do rods and cones detect light?
They have pigments that capture light. In the rods they are called rhodopsin. In the cones the pigments are called photopsin. There are 3 types of cones/rods:
red, green, and blue.
In color blindness you can be missing one the color cones/rods.
What chemical change happens in the retina?
Chemical change happens in the rods and cones (photoreceptors). Electrical impulses are sent to figure out if they are rods or cones.
What is the function of bones and skeleton?
Support of soft tissues, Movement (bones and muscles work together), flexibility, proteccion of organs (heart), blood cell production, mineral storage such as calcium (our body uses this calcium as last resort).
What are bones, ligaments, and cartilage made of?
They are made up of connective tissues.
What are the characteristics of bones?
Are durable adn flexible.
What are the characteristics of ligaments?
Connects bones, provides flexibility.
What are the characteristics of cartilage?
Helps movement of bones, provides cushioning between bones (i.e. vertebrae)
What are the parts of the bone?
The fibrous connective tissue helps our bone repair itself. On each side of bone there is a cartilage creating cushioning. Bone cells: secrete flexible fibers of collagen protein embedded hard calcium salts called matrix.
Collagen: Provides flexibility in the bones (which we can get through excercise). Calcium provides durability outside of bone.(consumed) Matrix of fibers is most dense part of bone. In the middle their is bone marrow, where red blood cells are made. There are blood vessels connected to bone.
What special functions do bones have?
Bones are constantly remodeling and repairing continuously, they break down and rebuild. 10% of bone mass of young adults is replaced a year.
What is the process of how bones break?
1- Blood vessels bleed into area creating a hematoma.
which causes:
2- inflammation, swelling pain.
3- Natural body begins repairs within days:
-creating cartilage between 2 broken parts (called callus)
-Broken bone and blood clot removes any broken pieces, hematoma, body will break down and get rid of.
-New bone made and cartilage.
-Takes weeks to months to heal.
What makes bones stronger?
Taking calcium (1000-1500mg/day) and weight bearing exercise. All this will help prevent Osteroporosis.
What bone disorders are there? What are the risk factors?
Osteoporosis is an experience, of bone loss (because bones are spongy)
Many women get hip fractures.
Risk factors: Sedentary lifestyles, low calcium intake, being underweight.
Back Pain: Weak skeletal parts in system. Soft organs are in front and our back has to work to balance us out. (causing lower back pain)
Arthritis: Inflammation of the joints. There are 2 types:
1-Osteroarthritis: imflammation of the joints, degenerate condition (because of age). Degenerate wear and tear of joints because of age.
2- Rheumatoid arthritis: (attacks joints). Autoimmune disease = body's immune system attacks joint tissue.
What is a sprain?
A stretched (body can heal) or torn ligament, such as ankle. Torn ligaments: can't heal itself, surgery may be needed.
Sprains happen because there are not many cells in ligaments. and there is poor circulation to ligaments.
What is the main function of muscles?
1-Movement and generation of 3/4 of our body's heat, 1/2 of our body mass include muscles.
Name and explain the three muscles.
1-Skeletal muscles (attach to bones)
2-Cardiac muscle.
3-Smooth muscles (digestive tracts helps in peristalisis)internal movement of uterous, blood vessels.
How does muscles attach to skeleton?
muscles attach to bones via tendons. Main function is to contract or shorten to move in our arm for example.

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