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Key Concepts. Function Vs. Process Function  why does a system exist, its purpose, what is does for the organism (teleological approach) Process How does a system perform its function, (mechanistic approach)

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Key concepts

Key Concepts

Function Vs. Process

  • Function why does a system exist, its purpose, what is does for the organism (teleological approach)

  • Process How does a system perform its function, (mechanistic approach)

    PHYSIOLOGY integrates both approaches to understand “How” physiological systems work, and “Why” they are there


Key concepts1

Key Concepts

  • Homeostasis Maintaining the internal environment of an organism relatively stable by maintaining certain properties within a normal range

  • E.g. Temperature, blood glucose, blood pressure, salt concentrations, pH


Homeostasis

Homeostasis

  • Keeping these parameters around a set point requires constant monitoring, compensation, and energy input. E.g. Like driving a car straight requires many corrections with the steering wheel

  • Additionally set points may change, either due to biological rhythms or in response to environmental change


Tissue types

Tissue Types


Cell to cell communication

Cell to Cell Communication

Add Red Dye to left cell

Connexon


Cell to cell communication1

Cell to Cell Communication

Paracrine

Target Cell

Cell

Autocrine

Endocrine

Blood


Receptors

Receptors

  • Signalling specificity depends on Receptor Proteins

  • Signalling molecule binds onto a specific receptor found only on target cells transmembrane, cytosolic, or nuclear location

  • Receptor protein is what brings about the response to signal

  • Agonists Binds receptor and activates response

  • Antagonists  Binds receptor and produces no response (inhibitory activity)


Receptors1

Receptors

Biological Signalling Molecule

Foreign “drug” molecule

Foreign “drug” molecule

Antagonist Pathway Without Response

Normal Signal Pathway With Response

Agonist Pathway With Response


Nervous system

Nervous System

  • 1) Receives information  Sensory neurons from external environment (light, sound, pressure etc)

  • 2)Integrates Information  Organizes new information, combines with stored information

  • 3) Transmits Information Sends signals to muscles/glands to carry out action


Neurons

Neurons

Dendrites

Axon Terminal

Node of Ranvier

Soma

Myelin Sheath/ Schwann Cell

Axon

Nucleus

Ref: Wikipedia

http://en.wikipedia.org/wiki/File:Neuron_Hand-tuned.svg


Neurons1

Neurons


Neurons2

Neurons


Nervous system1

Nervous System


Glial cells

Glial Cells

Neurons

Neurons are the VIP’s of the nervous systems! They need other people to help do their laundry, cook food, act as bodyguards, etc etc so they can focus on their jobs


Pns glial cells

PNS Glial Cells

Schwann Cells  form myelin sheath which acts as electrical insulator. Only wrap around 1 cell

  • Structure has many layers of cell membrane with gap junctions connecting layers

-Gap Junctions

Neuron


Pns glial cells1

PNS Glial Cells

  • Satellite Cells  non-myelinating, support nerve cells


Cns glial cells 4 types

CNS Glial Cells-4 Types

  • Oligodendrite Myelinating Cell (like Schwaan) but can wrap around more than one neuron

  • Astroglia  Make contact with blood vessels and neurons; transfer nutrients, maintain microenvironment; Star Shaped.


Cns glial cells

CNS Glial Cells

  • Microglia Small, specialized immune cells -maintain microenvironment like astroglia

    -remove dead cells & foreign invaders, protect neurons

  • Ependymal Cells  Epithelial cells, create semi-permeable barriers between brain compartments

    -produce cerebrospinal fluid


Electrical properties of neurons

Electrical Properties of Neurons

  • Difference between electrical charge on the inside of the cell and the outside environment creates an electrical gradient across the membrane

  • There is also an osmotic gradient due to the differences in concentrations of solutes between the inside & outside of cell


Electrical properties of neurons1

Electrical Properties of Neurons

  • Cell membranes are semi-permeable

    • Allow free diffusion of small, hydrophobic (non-polar) molecules

  • Membranes a impermeable to most molecules, Especially charged ions.

  • Specific protein transporters move these molecules across the membrane


Resting membrane potential

Resting Membrane Potential

  • Resting Membrane Potential for a neuron is around -70 mV to -90 mV  Negative charge compared to environment; mostly due to phosphate (HPO42- ,H2PO4-), and negatively charged proteins & DNA

+

+

+

-

+

-

-

-

+

+

-

-

-70 mV

-

+

+

+

-

-

+

-


Resting membrane potential1

Resting Membrane Potential

  • Know the relative ion concentrations for the neuron at rest:

  • Na+, Cl-, and Ca2+ have concentrations higher in the extracellular fluid (outside cell)

  • K+ has a higher concentration inside the cell

Na+

Cl-

-70 mV

Ca2+

K+


Na k atpase

Na+/K+ ATPase

  • Active transport of 3 Na+ out of the cell and 2 K+ into the cell powered by ATP

  • Pumps ions against gradient (by consuming energy) to maintain cellular concentrations of K+ and Na+

  • Compensates for ions leaking into/out of cell along their concentration gradient


Nernst equation

Nernst Equation

  • Equilibrium Potential (Eion) is the electrical potential of the Cell needed to generate an equilibrium state for a KNOWN concentration gradient  The electrical gradient needed to balance the concentration gradient

  • Compare this to known cell potential to predict where ions are likely to flow


Nernst equation1

Nernst Equation

  • Know that K+ is found at higher concentrations inside of the cell  Concentration gradient dictates K+ would flow out of the cell

  • Calculated Equilibrium Potential for Potassium is -90 mV.

Neuron with membrane potential of -70 mV

Neuron with membrane potential of -90 mV

-

-

-

-

-

-70 mV

-90 mV

-

K+

K+

K+ will flow (leak) out of cell

Negative charges not enough to attract Positive K+to remain in the cell

No NET K+ movement

Negative charges attract Positive K+ to balance concentration gradient


Nernst equation2

Nernst Equation

  • Know that Na+ is found at higher concentrations outside of the cell  Concentration gradient dictates Na+ would flow into the cell

  • Calculated Equilibrium Potential for Na+ is +60 mV.

Neuron with membrane potential of -70 mV

Neuron with membrane potential of +60 mV

-

+

+

-

Na+

Na+

+

-70 mV

+60 mV

+

+

Na+ will leak into the cell

Negative charges not enough to repel Positive Na+to prevent movement into cell

No NET Na+ movement

Positive charges repel Positive Na+ to balance concentration gradient


Resting membrane potential ion permeability

Resting Membrane Potential & Ion Permeability

  • The relative permeability of these ions dictate how important its contribution to the resting membrane potential is

  • Ions that can move more easily through the membrane contribute greater to the RMP

  • RMP can be calculated using the Goldman Equation which takes into account the relative permeability of ions

  • Permeability can be increased by:

    1)opening gated protein channels for transport

    2) increasing the # of transport proteins


Gated channels

Gated Channels

Stretch

+

+

+ +

Channel Closed

Channel Open

Channel Closed

Channel Open

Channel Closed

Channel Open

Voltage Gated

- Respond to membrane potential changes

- Involved in initiation and conduction of electrical signals

Chemically Gated

- Respond to ligand binding (neurotransmitters, neuromodulators)

- “most important” for neurons (located in synapses)

Mechanically Gated

- Respond to physical forces

- Found in Sensory neurons


Changes in membrane potential

Changes in Membrane Potential

Repolarizationis any change in membrane potential which returns it to the Resting Membrane Potential


Graded action potentials

Graded & Action Potentials


Action potential

Action Potential

3

4

2

0

-55 mV

1

6

-70 mV

5


Action potential voltage gates

Action Potential-Voltage Gates

Na+

+

+

+

Activation Gate

Inactivation Gate

Sodium (Na+) Channel with Activation Gate (opens at -55 mV), and Inactivation Gate (voltage activated but time delayed)


Action potential voltage gates1

Action Potential-Voltage Gates

+

+

K+

Potassium (K+) Channel with Voltage Gate which opens later than Na+ channels (fully open at +30 mV)


Action potential1

Action Potential

0

MP = Less than -55 mV

+

+

1

MP = -55 mV

+

+


Action potential2

Action Potential

Na+

2

+

MP = Between -55 mV and +30 mV

+

3 &4

+

+

MP = +30 mV to -70 mV

K+


Action potential3

Action Potential

ABSOLUTE REFRACTORY

5

+

MP = Less than -70 mV

+

K+

5.5

RELATIVE REFRACTORY

+

MP = Less than -70 mV

+

K+


Refractory periods

Refractory Periods

  • Set directionality of Signal  cannot activate membrane regions which have recently fired

Na+

+

+

+

Na+

Na+

Na+


Action potential4

Action Potential


Action potential5

Action Potential


Synapses

Synapses

  • Electrical Synapses Gap junctions connect 2 cells allowing direct electrical signalling

    - CNS; between 2 neurons, or neuron and glial cell

    - Nervous system development and transmission in adult brain

Action Potential Depolarization wave

Action Potential Depolarization wave


Chemical synapse

Chemical Synapse

Synaptic Cleft

Presynaptic cell

Postsynaptic cell

Action Potential Depolarization wave

Ions

Neurotransmitter Receptors can either open ion channel directly, or cause another (long lasting) signal cascade  coupled to G proteins etc

AP causes Ca+2 entry  vesicles release neurotransmitter

Ca2+


Types of neurotransmitters

Types of Neurotransmitters


Types of neurotransmitters1

Types of Neurotransmitters


Peripheral nervous system

Peripheral Nervous System


Key concepts

CNS

Somatic neuron Always excitatory

ACh

Nicotinic ACh receptors

Muscle Cell


Key concepts

CNS

Parasympathetic 2 Neuron chain

Sympathetic 2 Neuron Chain

Swollen Terminals Varicosity; stores a lot of neurotransmitter

Ganglion

Target Cell

Target Cell


Adrenergic receptors

Adrenergic Receptors


Cholinergic receptors

Cholinergic Receptors


Muscles

Muscles

  • Tissues specialized to convert biochemical reactions into mechanical work

  • Generate force, motion, & heat

  • Skeletal attached to skeleton, responsible for movement; has striations

  • Smooth  internal organs; influences movement of materials through body  no striations

  • Cardiac  Heart muscles; pumps blood; has striations


Skeletal muscles

Skeletal Muscles

  • Attach to bones via tendons at 2 points;

    - Origin at “least” moveable part of body

    -Insertion at “most” moveable part of body

  • Flexor Muscles contraction brings bones closer together

  • Extensor Muscles  contractions moves bones away from another

  • Flexor & Extensor are antagonistic pairs


Muscle structure

Muscle Structure

Epimysium- outer connective tissue

Perimysium- contains Nerves & blood vessels surround fascicles

Fascicles- Bundles of individual Muscle Fiberseach wrapped in a connective tissue sheath (Endomysium)


Muscle fibres

Muscle Fibres

  • Muscle Fibres = Muscle Cells

  • Contain mostly Myofibrils Functional unit of muscle

  • Energy from mitochondria (oxidative phosphorylation  ATP synthesis) and glycogen granules (glucose storage)

  • Cell membrane  Sarcolemma

    Cytoplasm  Sarcoplasm

    Modified Endoplasmic Reticulum  Sarcoplasmic Reticulum  Sequester Ca2+ for rapid release into cell


Muscle fibres proteins

Muscle Fibres- Proteins


Myofibril structure

Myofibril Structure

Sarcomere

A Band

Half of I Band

Half of I Band

H Zone

Z Disk

M Line

Tintin

Thin Filament-Actin, troponin, tropomyosin

Myosin Thick Filament


Myofibril structure1

Myofibril Structure

Contraction: Thick Filaments remain same size, but thin filaments have slid closer to M line Z Discs closer together


Sliding filament theory

Sliding Filament Theory

F-Actin

1

2

3

4

5

6

1

2

3

4

5

6

Myosin Head

ATP

Step 1:

Crossbridge 45°

Myosin tightly bound

Step 2:

ATP binds to myosin head; Myosin dissociates from actin


Sliding filament theory1

Sliding Filament Theory

1

2

3

4

5

6

1

2

3

4

5

6

ADP

Pi

ADP

Pi

Step 3:

ATP Hydrolyzes to ADP + Pi

Step 4:

Myosin Head rotates, binds weakly to new actin molecule


Sliding filament theory2

Sliding Filament Theory

1

2

3

4

5

6

1

2

3

4

5

6

ADP

ADP

Pi

Step 5:

Pi is released; Myosin head rotates 45° dragging actin filament with it; POWER STROKE; Still weakly bound

Step 6:

ADP dissociates from myosin Tight binding of Myosin to Actin


Sliding filament theory3

Sliding Filament Theory

  • Overall

1

2

3

4

5

6

Myosin has not moved;

Thin Filament (actin) has

BEFORE

1

2

3

4

5

6

AFTER


Regulation of contraction

Regulation of Contraction

Troponin- 3 Subunits

Relaxed Muscles have myosin heads mainly in step 4

Tropomyosin position allows for weak binding of myosin to actin, but prohibits the ability to perform the “Power Stroke”

1

2

3

4

5

6

ADP

Pi

Tropomyosin


Regulation of contraction1

Regulation of Contraction

Troponin- 3 Subunits

Contracting Muscles troponin C subunit binds to Ca2+ which shifts the tropomysosin position allowing the myosin head to carry out the power stroke & bind tightly to actin

1

2

3

4

5

6

Calcium ; Ca2+

ADP

Tropomyosin


Excitation contraction coupling

Excitation Contraction Coupling

Cholinergic ReceptorsNa+/ K+ channels

T Tubule

Ryanodine Receptor

Sarcoplasmic Reticulum

+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Dihydropyridine Receptor (DHP)


Excitation contraction coupling1

Excitation Contraction Coupling

+

Ca2+

ACh

Ca2+

Ca2+

Na+

K+

Ca2+

Ca2+

Na+

Na+

Ca2+

Ca2+

Na+

Na+


Excitation contraction coupling2

Excitation Contraction Coupling

  • Ca2+ is pumped back into the SR by Ca2+-ATPase How fast calcium is removed dictates how fast muscle relaxes

  • Twitch  Single contraction-relaxation cycle

    -Dependant on ATPase rate and Ca2+ removal rate


Muscle fibre classification

Muscle Fibre Classification


Motor unit

Motor Unit

  • Composed of a single motor neuron and all the fibres that it controls (can be branched multiple times)

  • All muscle fibres in Motor Unit are the same type (e.g. all slow twitch)

  • # of muscle fibres associated with a neuron determines if it is “fine” control (few) or “coarse” (many muscle fibres)


Practice questions

Practice Questions


Practice questions1

Practice Questions

  • The teleological approach to physiology:

    a) Explains “how” a process occurs

    b) Examines how an organism maintains a stable internal environment

    c) Describes the “Function” of a system

    d) Describes the “Process” of a system


Practice questions2

Practice Questions

  • Which of the following is NOT an example of homeostatis?

    a) Maintaining a blood pH level of ~7

    b) Keeping blood [Na+] within a normal range

    c) A snakes body temperature matching that of its environment

    d) Negative feedback controlling blood pressure

    e) All of the above are homeostatic


Practice questions3

Practice Questions

  • Which of the following are types of connective tissue?

    a) Adipose

    b) Bone

    c) Blood

    d) Skeletal muscle

    e) Loose, elastic


Practice questions4

Practice Questions

  • _______, and ______ are associated with local communication, while ______ are a component of long distance communication

    a) Paracrines, Autocrines, Acetylcholine

    b) Paracrines, Autocrines, Endocrines

    c) Neurotransmitters, Connexons, Endocrines

    d) Endocrines, Paracrines, Autocrines

    e) None of the Above


Practice questions5

Practice Questions

  • The type of signalling molecule determines the response that occurs in the cell

    a) True

    b) False


Practice questions6

Practice Questions

  • Which of the following pairs are analogous in the CNS and PNS

    a)Nuclei; Ganglia

    b) Tracts; Nerves

    c) Oligodendria; Schwann cells

    d) All of the Above

    e) None of the Above


Practice questions7

Practice Questions

  • Efferent Neurons

    a) Are a part of the sympathetic nervous system

    b) Are the main component of the CNS

    c) Carry information to the CNS

    d) Have cell bodies within the CNS

    e) Include auditory nerve cells which sense sound


Practice questions8

Practice Questions

  • Which is NOT true of Glial Cells

    a) They outnumber neurons

    b) They do not carry electrical signals

    c) They Insulate neurons for better signal conduction

    d) They can remove dead/foreign cells

    e) All of the above are true


Practice questions9

Practice Questions

  • A new element is discovered at high concentrations in the extracellular fluid of neural tissue in an ionic form. The ion, J-2 has a negative charge and the cell membrane is completely impermeable to this ion. Which of the following are true statements:

    a) The ion has a significant impact on the resting membrane potential of neurons

    b) If J-2 were allowed to enter the cell it would be hyperpolarizing

    c) If J-2 were allowed to enter the cell as part of a graded potential, it would help trigger an Action Potential

    d) Osmotically speaking, the concentration gradient forces the ion out of the neuron.

    e) None of the above


Practice questions10

Practice Questions

  • Which of the following is found at relatively low concentrations in the resting neural cell

    a) K+

    b) Phosphate

    c) Ca2+

    d)Na+

    e) B, C, D

    f) C, D


Practice questions11

Practice Questions

  • A Positive ion is calculated to have an equilibrium potential of -20 mV. The ion will have a tendency to leak out of the cell:

    a) At resting membrane potential

    b) At the peak of an action potential

    c) During the refractory period

    d) None of the above


Practice questions12

Practice Questions

  • Graded Potentials

    a) Always cause depolarization

    b) Can be summer temporally and spatially

    c) Can travel long distances

    d) Can only be caused by Na+ transport

    e) None of the above


Practice questions13

Practice Questions

  • During the rising (depolarization) phase of an action potential

    a) The sodium channel is open

    b) The Na+/K+ATPase is inactive

    c) The cell is undergoing a positive feedback loop

    d) The Potassium channel is pumping K+ into the cell

    e) A and C


Practice questions14

Practice Questions

  • What determines the threshold potential of a neuron?

    a) The properties of the voltage gated potassium channel

    b) The resting membrane potential

    c) The properties of the voltage gated sodium channel

    d) Excitatory Post Synaptic Potentials

    e) None of the above


Practice questions15

Practice Questions

  • The absolute refractory period:

    a) Last ~ 1 msec

    b) Prevents an action potential from occurring unless a suprathreshold stimulus is applied

    c) Occurs because the potassium channel is closed

    d) Ensures action potentials move in one direction

    e) A and D


Practice questions16

Practice Questions

  • Which of the following is NOT a method to reduce resistance in nerves?

    a) Lowering the surface area: volume ratio of a nerve

    b) Having giant axons

    c) Wrap cells in myelin sheath

    d) Increasing ionic leaking through the cell membrane


Practice questions17

Practice Questions

  • When Ca2+ channels in the axon terminal open

    a) The axon terminal was recently depolarized by an action potential

    b) Neurotransmitter will be released

    c) Calcium flows out of the cell into the synaptic cleft

    d) A and B

    e) All of the above


Practice questions18

Practice Questions

  • Nitric Oxide

    a) Is a stable gas

    b) Is synthesized by Nitric Oxide Synthase

    c) Is stored in neurotransmitter vesicles

    d) Is a biogenic amine type neurotransmitter

    e) All of the above


Practice questions19

Practice Questions

  • Acetlycholine

    a) Is synthesized from acetate and choline

    b) Is degraded in the synapse by acetylcholinesterase

    c) Is released by neurons of the parasympathetic pathway, but not the sympathetic

    d) Will not bind to muscarinic receptors

    e) None of the above


Practice questions20

Practice Questions

  • Which of the following is true with regards to nicotinic receptors?

    a) They bind nicotine as an antagonist

    b) They act via ion channels

    c) They are a slow synaptic potential using G proteins

    d) They are found on tissues of the parasympathetic pathway

    e) None of the Above


Practice questions21

Practice Questions

  • Somatic neurons:

    a) Have a single neuron between the CNS and muscle fibre

    b) Each control a distinct motor unit

    c) Release ACh which binds adrenergic receptors

    d) Are afferent neurons

    e)A and B


Practice questions22

Practice Questions

  • Which is true of skeletal muscles?

    a) They can only contract

    b) They generate both motion and force

    c) They do not control the contractions of the heart

    d) They appear striated under a microscope

    e) All of the above


Practice questions23

Practice Questions

  • The role of Troponin

    a) Involves the binding of calcium ions

    b) Involves the interaction with nebulin

    c) Activates contraction in the absence of Ca+2

    d) Involves a direct interaction with ryanodine receptors

    e) None of the above


Practice questions24

Practice Questions

  • The Thin Filament is:

    a) Composed of G Actin

    b) Composed of F Actin

    c) Composed of Myosin

    d) Makes up the M Line

    e) Is the only component of the H zone


Practice questions25

Practice Questions

  • The “Power Stroke” of a myosin molecule:

    a) Involves the release of ADP

    b) Requires Ca2+ to be bound to tropomyosin

    c) Moves consecutive Z discs further apart

    d) Requires the release of inorganic phosphate


Practice questions26

Practice Questions

  • At the motor end plate:

    a) ACh is bound nicotinic andrenergic receptors

    b) K+ efflux exceeds Na+ influx when Na+/K+ channels are open

    c) Curare can block receptors

    d) DHP receptors bind ACh


Practice questions27

Practice Questions

  • Muscles can use energy from:

    a) Oxidative phosphorylation

    b) ATP

    c) Glycolysis

    d) Creatine-Phosphate

    e) All of the above


Practice questions28

Practice Questions

  • Which is true of Slow-twitch oxidative muscle fibres?

    a) They have a lower threshold for recruitment then fast-twitch glycolytic

    b) They are easily fatigued

    c) They are Red in colour

    d) The have a fast myosin ATPase

    e) A and C

    f)B and D


Practice questions29

Practice Questions

  • Isometric muscle contraction:

    a) Moves the body

    b) Does not create force

    c) Has muscle length change

    d) Has sarcomeres shorten

    e) None of the above


Practice questions30

Practice Questions

  • β1 type receptors are:

    a) Cholinergic receptors

    b) Are responsive more to norepinephrine than epinephrine

    c) Increase cAMP production when active

    d) Increase cytosolic Ca+2 levels


Practice answers

Practice Answers


Practice questions31

Practice Questions

  • The teleological approach to physiology:

    a) Explains “how” a process occurs

    b) Examines how an organism maintains a stable internal environment

    c) Describes the “Function” of a system

    d) Describes the “Process” of a system


Practice questions32

Practice Questions

  • Which of the following is NOT an example of homeostatis?

    a) Maintaining a blood pH level of ~7

    b) Keeping blood [Na+] within a normal range

    c) A snakes body temperature matching that of its environment

    d) Negative feedback controlling blood pressure

    e) All of the above are homeostatic


Practice questions33

Practice Questions

  • Which of the following are types of connective tissue?

    a) Adipose

    b) Bone

    c) Blood

    d) Skeletal muscle

    e) Loose, elastic


Practice questions34

Practice Questions

  • _______, and ______ are associated with local communication, while ______ are a component of long distance communication

    a) Paracrines, Autocrines, Acetylcholine

    b) Paracrines, Autocrines, Endocrines

    c) Neurotransmitters, Connexons, Endocrines

    d) Endocrines, Paracrines, Autocrines

    e) None of the Above


Practice questions35

Practice Questions

  • The type of signalling molecule determines the response that occurs in the cell

    a) True

    b) False


Practice questions36

Practice Questions

  • Which of the following pairs are analogous in the CNS and PNS

    a)Nuclei; Ganglia

    b) Tracts; Nerves

    c) Oligodendria; Schwann cells

    d) All of the Above

    e) None of the Above


Practice questions37

Practice Questions

  • Efferent Neurons

    a) Are a part of the sympathetic nervous system

    b) Are the main component of the CNS

    c) Carry information to the CNS

    d) Have cell bodies within the CNS

    e) Include auditory nerve cells which sense sound


Practice questions38

Practice Questions

  • Which is NOT true of Glial Cells

    a) They outnumber neurons

    b) They do not carry electrical signals (they do over short distances)

    c) They Insulate neurons for better signal conduction

    d) They can remove dead/foreign cells

    e) All of the above are true


Practice questions39

Practice Questions

  • A new element is discovered at high concentrations in the extracellular fluid of neural tissue in an ionic form. The ion, J-2 has a negative charge and the cell membrane is completely impermeable to this ion. Which of the following are true statements:

    a) The ion has a significant impact on the resting membrane potential of neurons

    b) If J-2 were allowed to enter the cell it would be hyperpolarizing

    c) If J-2 were allowed to enter the cell as part of a graded potential, it would help trigger an Action Potential

    d) Osmotically speaking, the concentration gradient forces the ion out of the neuron.

    e) None of the above


Practice questions40

Practice Questions

  • Which of the following is found at relatively low concentrations in the resting neural cell

    a) K+

    b) Phosphate

    c) Ca2+

    d)Na+

    e) B, C, D

    f) C, D


Practice questions41

Practice Questions

  • A Positive ion is calculated to have an equilibrium potential of -20 mV. The ion will have a tendency to leak out of the cell:

    a) At resting membrane potential

    b) At the peak of an action potential (+30 mV is greater than -20 mV)

    c) During the refractory period

    d) None of the above


Practice questions42

Practice Questions

  • Graded Potentials

    a) Always cause depolarization

    b) Can be summer temporally and spatially

    c) Can travel long distances

    d) Can only be caused by Na+ transport

    e) None of the above


Practice questions43

Practice Questions

  • During the rising (depolarization) phase of an action potential

    a) The sodium channel is open

    b) The Na+/K+ATPase is inactive

    c) The cell is undergoing a postive feedback loop

    d) The Potassium channel is pumping K+ into the cell

    e) A and C


Practice questions44

Practice Questions

  • What determines the threshold potential of a neuron?

    a) The properties of the voltage gated potassium channel

    b) The resting membrane potential

    c) The properties of the voltage gated sodium channel

    d) Excitatory Post Synaptic Potentials

    e) None of the above


Practice questions45

Practice Questions

  • The absolute refractory period:

    a) Last ~ 1 msec

    b) Prevents an action potential from occurring unless a suprathreshold stimulus is applied

    c) Occurs because the potassium channel is closed

    d) Ensures action potentials move in one direction

    e) A and D


Practice questions46

Practice Questions

  • Which of the following is NOT a method to reduce resistance in nerves?

    a) Lowering the surface area: volume ratio of a nerve

    b) Having giant axons

    c) Wrap cells in myelin sheath

    d) Increasing ionic leaking through the cell membrane


Practice questions47

Practice Questions

  • When Ca2+ channels in the axon terminal open

    a) The axon terminal was recently depolarized by an action potential

    b) Neurotransmitter will be released

    c) Calcium flows out of the cell into the synaptic cleft

    d) A and B

    e) All of the above


Practice questions48

Practice Questions

  • Nitric Oxide

    a) Is a stable gas

    b) Is synthesized by Nitric Oxide Synthase

    c) Is stored in neurotransmitter vesicles

    d) Is a biogenic amine type neurotransmitter

    e) All of the above


Practice questions49

Practice Questions

  • Acetlycholine

    a) Is synthesized from acetate and choline

    b) Is degraded in the synapse by cholineacetyltransferase

    c) Is released by neurons of the parasympathetic pathway, but not the sympathetic

    d) Will not bind to muscarinic receptors

    e) None of the above


Practice questions50

Practice Questions

  • Which of the following is true with regards to nicotinic receptors?

    a) They bind nicotine as an antagonist

    b) They act via ion channels

    c) They are a slow synaptic potential using G proteins

    d) They are found on tissues of the parasympathetic pathway

    e) None of the Above


Practice questions51

Practice Questions

  • Somatic neurons:

    a) Have a single neuron between the CNS and muscle fibre

    b) Each control a distinct motor unit

    c) Release ACh which binds adrenergic receptors

    d) Are afferent neurons

    e)A and B


Practice questions52

Practice Questions

  • Which is true of skeletal muscles?

    a) They can only contract

    b) They generate both motion and force

    c) They do not control the contractions of the heart

    d) They appear striated under a microscope

    e) All of the above


Practice questions53

Practice Questions

  • The role of Troponin

    a) Involves the binding of calcium ions

    b) Involves the interaction with nebulin

    c) Activates contraction in the absence of Ca+2

    d) Involves a direct interaction with ryanodine receptors

    e) None of the above


Practice questions54

Practice Questions

  • The Thin Filament is:

    a) Composed of G Actin

    b) Composed of F Actin

    c) Composed of Myosin

    d) Makes up the M Line

    e)Makes up the I Band

    f)B and E


Practice questions55

Practice Questions

  • The “Power Stroke” of a myosin molecule:

    a) Involves the release of ADP

    b) Requires Ca2+ to be bound to tropomyosin

    c) Moves consecutive Z discs further apart

    d) Requires the release of inorganic phosphate


Practice questions56

Practice Questions

  • At the motor end plate:

    a) ACh is bound nicotinic andrenergic receptors

    b) K+ efflux exceeds Na+ influx when Na+/K+ channels are open

    c) Curare can block receptors

    d) DHP receptors bind ACh


Practice questions57

Practice Questions

  • Muscles can use energy from:

    a) Oxidative phosphorylation

    b) ATP

    c) Glycolysis

    d) Creatine-Phosphate

    e) All of the above


Practice questions58

Practice Questions

  • Which is true of Slow-twitch oxidative muscle fibres?

    a) They have a lower threshold for recruitment then fast-twitch glycolytic

    b) They are easily fatigued

    c) They are Red in colour

    d) The have a fast myosin ATPase

    e) A and C

    f)B and D


Practice questions59

Practice Questions

  • Isometric muscle contraction:

    a) Moves the body

    b) Does not create force

    c) Has muscle length change

    d) Has sarcomeres shorten

    e) None of the above


Practice questions60

Practice Questions

  • β1 type receptors are:

    a) Cholinergic receptors

    b) Are responsive more to norepinephrine than epinephrine

    c) Increase cAMP production when active

    d) Increase cytosolic Ca+2 levels


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