LAB EXAM 3>

- VISUAL ACUITY - Emmetropia - Myopia - Hyperopia - astigmatisms

"Visual acuity" means visual sharpness. Our visual acuity is our ability to clearly distinguish two closely placed objects. Normal visual acuity (emmetropia) near-sightedness (myopia), far-sightedness (hyperopia), and refracted light (astigmatisms). Myopia can be corrected with concave lenses and hyperopia can be corrected with convex lenses. Astigmatisms result from mis-shaped lens or cornea cause the refraction of light.

1. When you put your hand in cold water, how do you know it is cold? How do you know it is you hand that is cold? 2.Tonic receptors - 3.Phasic Receptors -

1. COLD RECEPTORS SEND ACTION POTENTIALS TO THE BRAIN. ACTION POTENTIALS SEND SIGNALS TO THE HAND REGION OF BRAIN 2.Tonic receptors - FIRE FREQUENCY OF AP CONSTLY FOR AS LONG AS STIMULUS IS APPLIED 3.Phasic Receptors - FIRE A HIGH FREQUENCY OF AP INITALLY AND DECREASE THE FREQUENCY OVER TIME, EVEN WITH A CONSTANT STIMULUS

1. Does each receptor respond to all stimuli? Explain. 2. How is the intensity of a stimulus coded for by our nervous system? How is this interpreted by the brain?

1. Each sensory receptor is responsive to stimuli within a specific region in space, which is known as that receptor's receptive field. 2. FREQUENCY ACTION POTIENTIALS

What types of cells are taste receptor cells? What are the five tastes? Which one is missing and why?

1. GUSTATORY CELL = MODIFIED EPITHELIAL CELL 2. SALTY, SWEET, SOUR, BITTER, UMAMI, SPICY

1. Which conditions produced the most starch digestion? 2. Does cold temperature denature enzymes? How do you know? (Use experimental results).

1. The conditions that produced the most starch digestion were at room temperature, neutral pH level, and high amylase concentration. 2. Cold temperature does not denature enzymes. The experiment shows there was starch breakdown in tube 6 after it was placed on ice and allowed to reach room temperature.

1. Where (specifically) does the perception of touch and temperature occur? Explain exactly what does the map of this region tells us about the density of sensory receptors in different body regions? Provide a specific example.

1.Perception of touch and temperature occurs in the sensory cortex. The map of this region tells us the density of sensory receptors in specific body parts. If a relatively small body part

Visual acuity 20/20 - Near point of vision - Pupillary light reflex - An Ophthalmoscope

20 = when you are 20' away, you see what 20 the average person sees from 20' away Near point of vision is the minimum distance an object can be placed before becoming blurry. It has to do with the amount of elasticity in the lens. bright light causes, the sphincter muscles in the iris surrounding the pupil to constrict making the pupil diameter smaller. This is caused by the parasympathetic division of the autonomic nervous system. An ophthalmoscope is an instrument used clinically to view the posterior parts of the eyeball.

3- Which muscle can produce the stronger contraction? Why? 4- Which muscle can produce more precise movements? Why?

3- . The rectus femoris can produce the stronger contractions because of motor unit recruitment and tetanus. 4- Adductor pollicis can produce more precise movements because it has smaller motor units.

3. Compare the effects of HCl on protein digestion and starch digestion. 4. Explain why frozen food does not grow mold or bacteria for longer than food stored at room temperature.

3. The effects of HCl on protein digestion is that HCl activates pepsin to digest proteins. With starch digestion, HCl denatures the enzyme amylase which inhibits starch digestion. 4. Frozen food does not grow mold or bacteria for longer than food stored at room temperature because enzyme activity is slowed in cold temperatures.

3. Two people the same age may have different near point of vision measurements. How is this possible? 4. In the blind spot demonstration, what did you see in place of the figure that disappeared? Do not answer "nothing" because there is never a hole in our visual fields. Does "seeing" occur in the eyes or in the brain? Use the results of this demonstration to support your answer.

3. Two people of the same age may have different near point of vision measurements because they have different amounts of elasticity in the lens. 4. In the blind spot demonstration, the figure that disappeared from the field of vision is replaced with the blank paper background. Seeing occurs in the brain because the black dot is in front of us but is not perceived.

5- Which muscle can produce continuous contractions? How? 6- Which muscle will fatigue first during continuous moderate strength contraction? Why?

5- The rectus femoris and adductor pollicis can produce continuous contractions through tetanus and motor unit recruitment 6- Adductor pollicis will fatigue first during continuous moderate strength contraction because it has fewer motor units.

5. How does cooking food affect enzyme activity? (This refers to enzymes in the food.) 6. Which conditions produced the most protein digestion?

5. Cooking food affects enzyme activity because it denatures enzymes in high temperatures. 6. The conditions that produced the most protein digestion is tube 2 which is at room temperature and has both HCl and pepsin.

5. Is your visual awareness always an accurate representation of reality? Explain. 6. What abnormalities can be detected by observing the retina with an ophthalmoscope?

5. Visual awareness is not always an accurate representation of reality. This is demonstrated by the binocular rivalry test when there appeared there was a hole in the hand when it did not exist. 6. Abnormalities such as burst blood vessels, floaters, and a torn retina can be detected in the retina with an ophthalmoscope

6. Review the structures of sweet-tasting molecules. Note glucose and fructose are made of the same number and types of atoms. Why do they taste different?

6. Even though fructose and glucose have the same number and types of atoms, they tastedifferent because they have different three dimensional structures. This allows for differentbinding to the sweet receptors which stimulates the receptors to send different frequencies ofaction potentials

7- What are the causes of fatigue? 8-What happens to strength of contraction as fatigue occurs? Why does this change in strength occur?

7- The causes of fatigue are relative lack of ATP, ionic imbalances, and buildup of acidic compounds. 8- As fatigue occurs, strength of contraction decreases because of relative lack of ATP, ionic imbalances, and buildup of acidic compounds.

7. Aspartame is made of two amino acids. Why is it sweet tasting if it is not even a carbohydrate?

7. Aspartame is sweet tasting even though it is not a carbohydrate because its molecular shapeallows it to bind to sweet receptors. The sweet receptors then send action potentials to the brainso aspartame is perceived as sweet.

7. Why are vision and hearing tests given as part of a regular physical exam to young children before starting school? 8. How is sound located? Why are we often inaccurate locating sound that originates in the midsagittal plane? 9. Predict the results of Rinne's and Weber's test in someone with conductive hearing loss in one ear and another person with sensory loss in one ear.

7. Vision and hearing tests are given as part of regular physical exams to young children before starting school to detect if there is an impairment and accommodate accordingly. 8. Sound is localized by the difference in loudness of sound reaching two ears and the difference in time of arrival of sound reaching two ears. We often inaccurately locate sounds that originate in the midsagittal plane because the loudness is about the same and it reaches both ears at about the same. 9. In the Rinne's test someone with conductive hearing loss in one ear will hear the tuning fork on the bone and will not hear the tuning fork when placed in front of their ear canal. In the Weber's test they will hear the tuning fork sound louder in the deaf ear because there is no ambient noise. Someone who has sensory deafness in one ear will hear nothing in both tests.

8. Physicians advise some people to cut down on table salt (NaCl) and use the substitute (KCl). Based on your results, explain why these people tend to use too much salt substitute. 9. How would the death of receptors effect perception? Explain.

8. People tend to use too much salt substitute because salty receptors send a higher frequencyof action potentials when stimulated by NaCl compared to KCI. Thus, people use more KCI tosimulate the taste of NaCl. 9.The depth of receptors would decrease transduction which would decrease perception.

9- After an injury, some of the motor neurons to a muscle are dead. The surviving motor neurons may form new branches that extend to more muscle cells. How exactly would this affect movement and strength?

9- After an injury when motor neurons to a muscle are dead, there are less motor units causing strength to decrease. Motor neurons form new branches, increasing size of motor units, which causes less precise movements.

Precised Movements -LARGE MOVEMENTS -SMALL MOTOR UNITS? -LARGE MOTOR UNITS? -TENSION

If a muscle contains small motor units (1 motor neuron:23 muscle fibers) are present Precised movements are made. If a muscle contains large motor units (1:2000) _Large movements are made. Where in the body might you find large and small motor units? Give one example of each. EYES,_SMALL MOTOR UNITS , LEG LARGE = TENSION - when a muscle is relaxed, but random asynchronous motor unit contractions cause a constant low tension.

Compare the rectus femoris muscle with the adductor pollicis muscles for the following features: -2 Which muscle can produce contractions of different strengths (weaker or stronger)? How?

In comparison, the rectus femoris has many muscle cells, and many cells per motor unit while the adductor pollicis has fewer muscle cells, and fewer cells per motor unit -.2 Rectus femoris and adductor pollicis can produce contractions of different strengths through motor unit recruitment.

- Motor Units -Recrutment -Less -More -The size of motor unit affects

Motor Units - groups of muscle cells that are innervated by one motor neuron and contracted together and stimulated by that motor neuron. - Motor Unit Recrutment - when the brain estimates the strength of contraction needed to lift an object and activates motor units. When more strength is needed More - motor units are recruited. When less strength is needed _-less motor units are recruited. The size of a motor unit affects the precision or grossness of muscle movements.

-Pancreatic Juice -IKI - Benedicts

Pancreatic juice has all manner of food digesting enzymes that humans have. This includes pancreatic amylase for the continued breakdown of starch as well as various lipases (enzymes that break down lipids) and proteases (enzymes that breakdown proteins). IKI is an amber colored liquid looks for starch. When starch is present, IKI will turn dark (up to black). Benedict's is a light blue reagent that looks for the presence of simple sugars. Benedict's will be positive (turn burnt, milky orange) if boiled in the presence of simple sugars. Simple sugar is only present if starch is broken down..

PHASE 1 - LATENT PERIOD PHASSE 2 - CONTRACTION PERIOD PHASE 3 RELAXATION PERIOD

Phase 1 = Latent Period, which occurs immediately after the stimulus is given. Depolarization of the sarcolemma occurs, and excitation-contraction coupling occurs, but there is not visible shortening of sarcomeres and thus, no force. Phase 2 = Contraction Period, which is when cross bridge cycling causes sarcomeres to shorten and force increases to maximum Phase 3 = Relaxation Period, which is when calcium ions are actively transported back into the sarcoplasmic reticulum, crossbridge cycling decreases and ends, thus force declines, and muscle returns to original length.

Sensory Adaptation = 2. How does sensory adaptation occur? 3. Which senses adapt rapidly? Which senses do not adapt quickly?

SENSORY ADAPATION - BRAINS WAY ON IGNORING CONSTANT STIMULUS 2. PHASE RECEPTORS THAT FIRE A HIGH FREQUENCY OF AP INITALLY AND THE FREQUENCY OF AP OVER TIME, EVEN WITH A CONSTANT STIMULUS 3. Phasic receptors adapt rapidly and inform, therefore, about the rate of change of a stimulus. Tonic receptors adapt slowly and inform about the presence and strength of a stimulus.

Sound localization depends on the brain's perception of two differences.

Sound localization depends on the brain's perception of two differences. -1. The difference in the loudness of the sound reaching the two ears. -2. The difference in the time of arrival of the sound at each ear.

-TEMPORAL WAVE SUMMATION -INCOMPLETE TETANUS - COMPLETE TETANUS - FATIGUE

TEMPORAL (WAVE) SUMMATION when a second stimulus of the same intensity is applied to a muscle before the completion of the relaxation period of the first stimulus resulting in increased muscle tension. - INCOMPLETE TETANUS - If continuous and increasingly rapid stimuli are applied to a muscle the summation continues, and the contraction becomes jerky but sustained. This is called - If an even faster frequency of stimulation occurs, the contraction strength becomes maximal, smooth, and sustained. This is called - FATIGUE - If the stimulation continues, over time, the contraction will become weaker. This weakening of muscle strength is called

-TENSION -THREE PHASES TO TWITCH -LATENT PERIOD

TENSION = a muscle contraction in response to a single stimulus of adequate strength. There are three phases to a twitch, which begin after stimulation:LATENT PERIOD, CONTRACTION PHASE, RELAXATION PHASE

-Amylose -Pepsinogen (pepsin)

The chemical digestion of starch (amylose) begins in the mouth when salivary amylase is released and mixed with food as we chew. In the stomach, there is no further enzymatic breakdown of starch (because the amylase is denatured) In the stomach, a different enzyme is released called pepsinogen. Pepsinogen must be in an acidic environment to become the active form of a protein digesting enzyme called pepsin.

-optic disc -conduction deafness - sensory deafness

The optic disc of the retina is called the "blind spot" because is it where the axons of ganglion cell converge and become the optic nerve. conduction deafness results from an inability to transmit sound to an intact and functioning inner ear. Sensory deafness results from an inability to transduce or perceive sound. This can result from the death of hair cells in the cochlea, detachment of CN VIII (Vestibulocochlear nerve), damage to the temporal lobe of the brain.

- THREE MAIN CAUSES OF MUSCLE FATIGUE - EMG

The three main causes of muscle fatigue include: 1. Relative lack of ATP 2. Ionic imbalances 3. Buildup of acidic compounds -The electrical activity in the motor units during a muscle contraction can be recorded as bursts of muscle action potentials that are collectively known as an electromyogram (EMG).

TRANSDUCTION OF SALTY AND SOUR WORK IN THE SAME WAY The transduction of sweet and umami occur the same, TRANSDUCTION FOR BITTER

Transduction of salty and sour work in the same way, but the salty pathway uses Na+ and the sour pathway uses H+. • Ion enters cell via open channel, which causes depolarization. • Depolarization opens voltage gated Ca2+ channels, allowing Ca2+ to diffuse into cell. Ca2+ diffusing into the cell causes • neurotransmitter release onto sensory neuron • Sensory neuron sends action potentials to the brain. The transduction of sweet and umami occur the same, but each receptor type responds to different molecules. ● Molecule binds cell surface receptor and activates G-coupled protein cascade. ● G-coupled protein cascade closes K+ channels, which causes depolarization. ● Depolarization causes release of neurotransmitter onto a sensory neuron. ● Sensory neuron sends action potentials to the brain

- TWO POINT THRESHOLD

Two-point threshold is an indication of the tactile acuity (sharpness of touch perception). It is dependent on the density of touch receptors in a given receptive field (area of skin). When skin has a high density of receptors present, the two-point threshold is small. Conversely, when skin has a low density of receptors present, the two-point threshold is larger. Two-point threshold is measured as the minimum distance at which two distinct points can be felt

1. What is transduction and where does it occur? 2. What is perception and where does it occur?

What is transduction and where does it occur?- PROCESS OF SENSORY RECEPTORS TAKING IN INFORMATION FROM THE OUTSIDE WORLD AND CHANGING IT A FOR THE NERVOUS SYSTEM UNDERSTANDS 2. BRAINS INTERPRETATION OF THE TRANSDUCED INFORMATION