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diffusion of water through a selectively permeable membrane

Selective permeability

only certain chemicals can pass through the membrane


spontaneous movement of a substance from high to low concentration


a specific type of transmembrane protein channel, lets water molecules pass in and out of the cell

Concentration gradient

There needs to be two solutions of different concentrations on either side of a membrane. ie. A difference in the concentration of a substance across a distance.

Passive transport does not expend metabolic energy, and the flow of materials is down the concentration gradient. With passive transport, materials move to reach an equilibrium. Active transport uses metabolic energy, and material flow is against the concentration gradient.


A unit of measure which describes the degree of acidity of alkalinity of a solution. It is measured on a scale of 0-14.


The H+concentration is greater than OH- and the pH value will be less than 7.


The OH- concentration is greater than H+ and the pH value will be more than 7


Equal amounts of H+ and OH- ions are present and it will have a pH of 7

Stomach Acid pH



Neutralize stomach acid.


An aqueous solution that has a highly stable pH.

If you add acid or base to a buffered solution, its pH will not change significantly. Similarly adding water to a buffer or allowing water to evaporate will not change the pH of a buffer.

What is the most important way that blood pH is kept relatively constant?

buffers dissolved in the blood

How do you know that distilled water is not buffered?

There is no resistance to change of its pH.


A protein serving as a catalyst; a chemical agent that speeds up the rate of reaction without being consumed by the reaction by reducing the activation energy required for the reaction to proceed.

An enzyme that has lost its shape as a result of extreme heat and extreme pH swings is said to be _______.


What effect does temperature have on enzyme activity?

lower temperatures slow down enzymatic activity...higher temperatures raise enzymatic activity.

But biological enzymes can also be denatured (i.e rendered inactive) when heated past their denaturation point.

Were your results with the boiled rennin different from the results of the non-boiled rennin? Why?

The results of the boiled and non-boiled rennin were different. The boiled rennin had no reaction with the milk. The boiling of the rennin most likely denatured the enzyme.

Where in the cell does the exchange of ions, gases, nutrients and wastes take place?

cell's surface

What does a cell need to perform this function efficiently?

Adequate ratio between the cell's volume and its surface area.

As a cell volume increases its surface area _________.


If you continue to increase a cells volume what would happen?

It would soon be unable to efficiently exchange materials and the cell would die.

What is the relationship between the rate of ion exchange and the surface-to volume ratio?

As the surface to volume decreases so does the rate ion exchange.

Why is it important for a cell to have a large surface-to-volume ratio?

If the SA:V is too small then then rate of ion exchange will decrease, if this rate of ion exchange is too low then the cell will no longer be viable.

Which is more efficient at exchanging materials, a small or a large cell? Explain

A small cell would be more efficient at exchange of materials from its surrounding environment as once material enters the cell it would be more evenly distributed internally. In bigger cells the concentration of materials near the periphery would be greater than near the center thus the cell would have to even out the concentration gradient to allow more material to enter.

How does cell growth affect the cell's surface-to-volume ratio?

As the cell grows the SA:V decreases, until a point is reached where any further increase in size would make the cell nonviable.

In order for a cell to continue being efficient at exchanging materials, what must it do to maintain its surface-to-volume ratio as it grows larger?

For the cell to continue growing and maintain a viable SA:V it would have to adapt its shape so as to be wide and thin as in the case of the nerve cells or develop a more "textured" surface, i.e develop microvillus

Your lab partner argues with you that if you add acid to a solution, the hydrogen ion concentration should increase and therefore the pH should increase. Is he correct? What do you tell him?

I would tell him that he is incorrect because pH decreases as something becomes more acidic.

What is the normal pH range of human blood?


Which buffer system in the body maintains the blood pH within this range?

bicarbonate ion (HCO3-)

What happens if the buffer systems are overwhelmed and the blood becomes excessively basic (high pH) (a condition known as alkalosis)?

Neurons become hyper-excitable firing action potentials at the slightest signal. This condition shows up first as sensory changes, such as numbness or tingling then as muscle twitches. If this condition is severe muscle twitches turn into sustained contractions (tetanus) that paralyze respiratory muscles.

What happens if the buffer systems are overwhelmed and the blood becomes excessively acidic (low pH) (called acidosis)?

Neurons become less excitable and CNS depression results. Patients become confused and disoriented, then slip into a coma. If CNS depression progresses, the respiratory centers cease to function, causing death.

What are the major components of a reflex arc?

1. sensory receptor
2. the sensory (afferent neuron)
3. the integration center
4. the motor (efferent neuron
5. the effector

What are the two classes of reflexes?

autonomic & somatic

Autonomic (or visceral) reflexes

Are not subject to conscious control.

These reflexes activate smooth muscles, cardiac muscle and the glands of the body and regulate bodily functions such as digestion and blood pressure.

Somatic reflexes

Include all reflexes that stimulate skeletal muscles.

ex. rapid withdrawal of your foot from a piece of glass you have just stepped on.

stretch reflex

Important in maintaining posture and equilibrium and are initiated when a muscle is stretched.

ex. the patellar or knee jerk reflex is the simplest of these.

plantar reflex

Is elicited by stimulating the cutaneous receptors in the sole of the foot. In adults, stimulating these receptors causes the toes to flex and move closer together.

Special Sensory

(afferent) signals originating from eyes, nose, ears, and mouth. Includes vision, smell, hearing, equilibrium and taste. Example: someone eating, you smell their food

Visceral Motor

Regulates the contraction of smooth and cardiac muscle and the secretion of the body's many glands. Makes up the ANS also referred to as the involuntary nervous system.

Branchial motor

Information is from motor activity of muscles of the larynx, pharynx, jaw and face- also salivation; muscles of neck and hand

General Sensory

Receptors react to touch, pressure pain, heat, cold, and changes in space; are distributed throughout the body.

What are the 12 pairs of cranial nerves?

1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducens
7. Facial
8. Vestibulocochlear
9. Glossopharyngeal
10. Vagus
11. Accessory Nerve/Spinal Accessory Nerve
12. Hypoglossal

On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How

Olfactory Nerve

Order: I
Modality: Special Sensory
Function: Smell

Optic Nerve

Order: II
Modality: Special Sensory
Function: Vision

Oculomotor Nerve

Order: III
Modality: Somatic Motor & Visceral Motor
Function: Levator palpebrae, superioris, median & inferior recti muscles
Parasympathetic to ciliary and puillary constrictor muscles

Trochlear Nerve

Order: IV (4)
Modality: Somatic Motor
Function: Superior oblique muscle

Trigeminal Nerve

Order V (5)

Modality: Brachial Motor and Function: Muscles of Mastication

Modality: Sensory Motor and Function: Sensory for head/neck, sinuses, meninges and external surfaces of tympanic membrane

Abducens Nerve

Order: VI (6)
Modality: Somatic Motor
Function: Lateral rectus muscle

Facial Nerve

Order: VII (7)
Modality & Function
Brachial Motor--Muscles of facial expression
Visceral Motor--Parasympathic to all glands of head except the parotid
General Sensory--Sensory for ear and tympanic membrane
Special Sensory--Taste anterior two-thirds of tongue

Vestibulocochlear Nerve

Order: VIII (8)
Modality: Special Sensory
Function: Hearing and Balance

Glossopharyngeal Nerve

Order: IX (9)
Modality & Function
Branchial Motor: Stylopharyngeus muscle
Visceral Motor: Parotid gland
Visceral Sensory: Carotid body
General Sensory: Sensation posterior one-third tongue & internal surface of tympanic membrane
Special Sensory: Taste posterior ine-third tongue

Vagus Nerve

Order: X (10)
Modality & Function
Branchial Motor: Muscles pharynx & larynx
Visceral Motor: Parasympathetic to neck, thorax & abdomen
Visceral Sensory: Sensory for pharynx, larynx & viscera
Special Sensory: Sensory for external ear

Spinal Accessory Nerve

Order: XI (11)
Modality: Branchial Motor
Function: Trapezius & sternocleidomastoid muscle

Hypoglossal Nerve

Order: XII (12)
Modality: Somatic Motor
Function: Tongue muscles except palatoglossal

What test would allow you to asses the function of the Olfactory nerve?

Test each nostril with essence bottles of coffee, vanilla, peppermint.

What test would allow you to asses the function of the optic nerve?

Use an eye chart to check their vision.

What test would allow you to asses the function of the Oculomotor, Trochlear, Abducens nerves?

1. Shine light in from the side to gauge pupil's light reaction.
2. Follow finger with eyes without moving head and draw a Z and a H.

What test would allow you to asses the function of the Trigeminal nerve?

Have the patient close their eyes and clench their teeth.

What test would allow you to asses the function of the facial nerve?

Have the patient smile, frown, raise eyebrows and puff cheeks.

What test would allow you to asses the function of the Vestibulocochlear nerve?

Hold a tuning fork on top of the patients head and tap it with a rubber mallet ask the patient if they hear the vibration in one ear better than the other.

What test would allow you to asses the function of the Glossopharyngeal & vagus nerves?

Have patient swallow and cough.

What test would allow you to asses the function of the spinal accessory?

Have your patient elevate and depress his or her shoulders and turn his or her head to the right and to the left.

What test would allow you to asses the function of the hypoglossal nerve?

Have your patient protrude his or her tongue and check for abnormal deviation or movement.

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