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Biology 212 2nd exam


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Glial cell:Neuron Ratio
Glial Functions (6)
Creates Myelin Sheath
Creates a matrix that connects neurons
Helps guide development of neural pathways
Blood-brain-barrier (tight junctions)
Provides metabolic support for neurons
NEW: appear to communicate chemically with other
What is "membrane potential"
Charge difference between the inside and outside of the membrane
An "Electrical signal" of the nervous system is a change in the membrane potential
What determines the value of the membrane potential at any time?
Chemical gradients
Electrical gradients
Selective permeability of the membrane

Why is the resting membrane potential negative?
At rest, the membrane is 25X more permeable to K+ than Na+, resulting in the interior of the cell to become more negative because positive charges are leaving the cell.
What is Action potential?
A rapid, transient change in the membrane potential from negative to positive and back again.
What allows the charges in membrane potential to occur during an AP? (2)
Changes in MEMBRANE PERMEABILITY due to opening and closing of VOLTAGE-GATED channels
Resultant movement of ions along their chemical and electrical gradients
What cell makes up the Myelin Sheath?
Schwann cell
What is Saltatory conduction?
Ions jumping from node of ranvier to node of ranvier
What do neurotransmitters prevent?
the intake of sodium into the cell.
What is a sensation?
Electircal impulses that reach the brain via sensory neurons
what is a perception?
Interpretation of electrical impulses by the brain
Mechanoreceptors stimulated by...
Physical deformation (touch)
Nociceptors stimulated by...
Inflamed/Damaged tissue
Thermoreceptors stimulated by....
Chemoreceptors stimulated by....
specific molecule types
(ex. osmoreceptors-detect chenges in solutes, Gustatory (taste) Olfactory (smell))
Electromagnetic receptors stimulated by...
Electromagnetic energy (Light energy)
Light detection eyes detect...
Light intensity/directionally
Compound Eyes detect....
Movement, consists of multiple ommatidia
Single-lens eye detects.....
movement, one enlarged ommatidia.
Functions of the Cornea (2)
allows light into eye
Funtion of pupil
Regulates amount of light entering eye
Function of lens
Focuses image onto back of eye
Funtion of Rhodopsin
(light absorbing pigment) triggers signal-transduction pathway
What are components of a Hydrostatic Skeleton (3)
Fluid-filled compartments provide support
Movement by circular and longitudinal muscles
Ideal for aquatic life (can't support body vertically)
Components of an Exoskeleton (3)
Rigid encasement deposited on surface of organism
(Made of Chitin/Calcium carbonate)
Muscles attach from outer "shell" to interior body
must be periodically shed
Components of endoskeleton (2)
Rigid internal skeleton supporting body
Can grow with organism; relatively lightweight
Functions of Muscle (5)
Maintain posture
Support soft tissue
Guard entrance/exit
Maintain body temperature
Connective tissue layers of Muscle (3)
Name the Triad of Muscle Fibers (3)
Transverse Tubules
Sacroplasmic reticulum
Name the two myofilaments (2)
Sarcomere are...
repeating units of myofilaments
List the events in muscle contrations (6)
1. Acetylcholine released from synaptic knob
2. ACh binds to receptor on motor end plate; generates AP
3. Action potential conducted along Sarcolemma
4. AP descends into muscle fiber via T-tubles
5. AP trigger
List the events in Cross Bridging events (6)
1. Ca++ binds with proponin; exposes active sites on actin
2. Myosin head (cocked) binds with active site
3. Myosin head pivots-pulls actin forward
4. ATP binds to myosin head; head detaches and re-cocks
5. Myosin head binds to active
Skeletal Muscle
1. Filament Organization
2. Control Mechanism
3. Calcium Source
4. Contraction
5. Energy Source

1. Sarcomeres along myofibrils
2. Neural
3. Sarcoplasmic reticulum
4. Rapid onset: tetanus can occur:rapid fatigue
5. Aerobic/Anaerobic
Cardiac Muscle
1. Filament Organization
2. Control Mechanism
3. Calcium Source
4. Contraction
5. Energy Source

1. Sarcomeres along myofibrils
2. Automaticity (pacemaker cells)
3. SR/across sarcolemma
4. Slower onset: no tetanus; fatigue-resistant
5. Aerobic
Smooth Muscle
1. Filament Organization
2. Control Mechanism
3. Calcium Source
4. Contraction
5. Energy Source

1. Scattered in sarcoplasm
2. Automaticity, neural, hormonal
3. Across sarcolemma
4. Slow onset: tetanus can occur, fatigue-resistant
5. Aerobic
What is a motor unit?
A single motor neuron and all the muscle fibers innervated by it (all-or-none)
What is recruitment and its purpose?
addition of motor units to produce smooth, steady muscle tension
what is a Twitch?
Single stimulus-contration-relaxation sequence
What is homeostasis?
the process of maintaining a relatively stable internal environment
What are the three different classes of hormones (3)
1. Amino Acid Derivatives (ex Epinephrine)
2. Peptide Hormones (ex Insulin)
3. Lipid Derivatives (ex. Testosterone)

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