bipn 100 final

starting card 66 is past mt material*

Skin - Variety of Receptors for Touch

Merkel disks - fine texture, ____

_____ corpuscle - fine mechanical sensitivity

Deep subcutaneous tissues:

Pacinian corpuscle - ____; sensitive to ____

Ruffini’s ending - detect ____ of skin when we move fingers or limbs

pressure; Meissners; vibrations; textures; stretching

Type of stimulus WITHIN a modality is coded by:

• ____ _____ - different pathways process different types of stimuli

labelled line

Location mapping

• relative mapping of receptors in ____ SOMETIMES maintained in CNS

periphery

Receptive Fields

• SMALL receptive fields are found in ___ senstive areas (ie fingertip)

• two stimuli activate separate pathways into the ___ → two points are perceived as _____

more; CNS; distinct

Receptive Fields

• Convergence creates ____ receptive fields

• two stimuli fall within a ____ receptive field → two points are received as ____

large; secondary; single

Type of receptor

• _____ respond for the DURATION OF A STIMULUS

  • as long as a signal is there, ap will be triggered → continue to communicate with your brain → constantly aware of what that stimulus is

• ____ ADAPT to a constant stimulus

  • ap stop once the stimulus is ID, typically not harmful stimulus; ex. glasses on face all day

tonic; phasic

Thermal Receptors

• cool receptors: __

• Warm receptors: __

• heat NOCICEPTORS: __

• Cold nociceptors: __

• ____ are for detecting PAIN

Aδ; C; Aδ; C; nociceptors

Thermal Receptors

• have free nerve endings for cool and warm receptors

• ____ ___ - temperature sensitive ion channels

• have ____ cold receptive fields than warm receptive fields

Thermo TRP; MORE

Thermal Receptors

• Aβ

  • ____ aka fast

  • ____ aka touch

  • temperature (___)

• Aδ

  • _____ aka fast

  • ____ aka for pain

  • temperature (___)

  • ___ pain

• C fibers

  • _____ aka slow

  • ____ aka for pain

  • temperature

  • ___ pain, burning pain or itch

myelinated; mechanical; non-pain; myelinated; nociceptor; painful; sharp; unmyelinated; nociceptor; dull

Spinal Cord

• Levels

  • cervical: ____ - ____; affects ____

  • thoracic: ___ - ____; affects _____, ____, ____

  • lumbar: ____ - ____; affects _____

  • sacral ____ - ____

C1; C7; arms; T1; T12; abdomen; trunk; legs; L1; L5 legs; S1; S5

Spinal Cord

• ____ ____

  • light touch, pressure, vibrations, proprioception aka being aware of body’s location

• _____ spinothalamic tract - pain and temperature

• ____ spinothalamic tract- crude touch

dorsal - _____

ventral - ____

RMBR: dorsal fin of orca is the TOP fin, ventral is BOTTO

dorsal column; lateral; anterior; sensory; motor

TOUCH pathway

• __ primary afferent neuron

• the primary afferent neuron comes into the ____ root ganglion

• decussates in the brainstem - _____

• the secondary order neuron ascends _______ (on the same side)

• dorsal column

Aβ; dorsal; medulla; ipsilaterally

PAIN pathway

• __or _ ____receptors (depdends on the stimulus)

• the primary afferent neuron comes into the ___ root ganglion

• decussates in the same segment of the ____ ___

• and the secondary neuron ascends _____ aka on the opposite side

Aδ; C fibers; dorsal; spinal cord; contralateral

Label 1-5

1.

1. nucleus

2. dendrites

3. axon hillock

4. cell body

5. axon

Label 6-10

6. myelin

7. presynaptic axon terminal

8. synaptic cleft

9. postsynaptic dendrite

10. postsynaptic neuron

Depolarization

• membrane less ____ → positive ions move ___ → membrane potential goes from negative to positive

Repolarization

• membrane returns to ____ value after signal is complete

Hyperpolarization

• membrane more ____ → positive ions move __ → membrane potential goes from positive to negative

polar; IN: resting; polarized; OUT

Action Potential

• large, fast, long distance spread of ____ ____ ____ that travels along the axon

• same ____ and ____ everytime

• travels in one direction

  • axon hillock to terminal

• rapid reversal of the membrane potential that briefly makes the INSIDE of the neuron _____

• all or nothing effect, you either fire a AP or no

• stronger stimuli lead to multiple __

membrane potential change; magnitude; pattern; positive; aps

Action Potential 5 Steps

1. _____ aka rising phase

• membrane becomes LESS polarized as positive ions move IN (inside the cell becomes more positive);

• membrane potential goes from negative → positive

2. _____ aka falling phase

• membrane returns to resting value after signal is complete

3. _____ aka undershoot

• membrane becomes more polarized as ____ ions move OUT (IC- more negative). Membrane potential goes from positive → negative

depolarization; repolarization; hyperpolarization; positive

Neurotransmitter Release

Signaling Steps

• chemical NT travels across the synaptic gap to the dendrites/cell body of the next cell

• electrical signal aka ___ ____ in the dendrite

• if threshold is met at the ___ ___, an AP is triggered

• AP travels down the axon to the axon terminal

• this triggers the release of NT

  • the elctrical signal reaches the presynaptic axon terminal

  • VG ___ channels open up

  • ____ flows INTO the terminal

  • binds to synaptic vesicles

  • triggers them to dock to the membrane

  • release NT into the ____ ___

  • NT bind to receptors on postsynaptic cell cause a graded potential based on what receptor they bind to

graded potential; axon hillock; Ca2+; Ca2+; synaptic cleft

EPSP

• if ___ ions flow through, the cell becomes slightly DEPOLARIZED and has small ____ postsynaptic potentials

• ____ proabability of AP firing

• ___ influx locally depolarizes dendrite

positive; excitatory; increases; Na+

IPSP

• if ___ ions flow through, the cell becomes slightly HYPERPOLARIZED and has small ___ postsynaptic potentials

• _____ probability of AP firing

• ___ influx locally hyperpolarizes dendrite

negative; inhibitory; decreases; Cl-

• EPSP and IPSPs are ____ and not “all or none” like ap

  • graded potentials that lead to an action potential are called _____ potentials (can be larger or smaller depending on how much NT is released)

  • the amount of NT released depends on amount of ___synaptic ___

  • stronger stimuli, ___ APs, ___ neurotransmission

    • weak stimulus releases little NT

    • strong stimuli causes more ap and releases more nt

graded; synaptic; pre; Ca2+; more; more

Synaptic Potentials to AP

• epsp and ipsp constantly happening on ___ and ____

• an individual epsp generally NOT enough to trigger an ap

• net sum of many EPSP ____ IPSPs must reach threshold

dendrites; soma; minus

TERMINATING Synaptic Transmission

• ____ - transport into axon terminals for reuse or into glial cells

• _____ ____ - enzymes inactivate NT

• ____ - diffuse out of the synaptic cleft

reuptake enzymatic degradation; diffusion

_____ summation - epsps or ipsps arriving NEARER each other (spatially) will summate better

• potentials su if close enough in space

_____ summation - epsps or ipsps arriving closer together in TIME (temporally) will summate better

• potentials sum if close enough in time

spatial; temporal

_____

• fast on/off

• all or non on/off

• ligand-gated ion channels made up of protein subunits that together form an ion-conducting pore in the center of the receptor

ionotropic

_____

• slower off/off

• can amplify or dampen signals

• indirectly linked with ion channels through signal transduction mechanisms, like G proteins

metabotropic

GPCR Effector Pathways

• NT will bind to a ______ receptor → activate the receptor (aka __ ___) → target the ____ protein → target a ____ messenger → target later effector proteins → cellular response

transmembrane; g protein; effector; second

GPCR pathways

___: DECREASES cAMP

___: INCREASES cAMP

G⍺q: increase ___, ____ produciton

βy: ____ ion channels

G⍺i; G⍺s; IP3; DAG; regulates

G⍺i: ____ AC, ____ cAMP

G⍺s: ____ AC, ____ cAMP

inhibits; decreases; activates; increases

GPCR pathway: G⍺i and G⍺s

1. signal molecule binds to G-Protein GPCR, which ____ the G protein

2. G Proteins turns on ____ ___, an amplifier enzyme

3. AC converts ATP to ____

4. cAMP activates protein kinase A

5. Protein kinase A ____ other proteins, leading ultimately to a cellular response

activates; adenylyl cyclase; cyclic amp; phosphorylates

G Proteins: specifically G⍺i, G⍺s

• are coupled to a receptor inside the cell; can be coupled to either Gi, Gs, or Gq proteins

• hormone, drug, NT, or any other ligand bind to a sepcific receptor- going to cause the receptor to CHANGE _____ and that activates the G protein

• G protein has 3 subunits: ___, ____, ____

  • once activated alpha ____ from the other beta and gamma

  • subunit releases GDP and a ___ binds to the alpha subunit

• Alpha + GTP will move together and move to __

• AC takes ATP and converts it to cAMP aka ____ messenger

• cAMP activates PKA - kinases will phosphrylate protein and change their conformation therefore their ____

• cell reponse

conformation; alpha; beta; gamma; separates; GTP; AC; secondary; function

GPCR Pathway for G⍺q:

G⍺q: activates ___, increases ___, ___ production

PLC; IP3, DAG

GPCR Pathway for G⍺q:

1. Signal molecule activates receptor and associated G protein

2. G protein activates phospholipase C, a ____ enzyme

3. PLC converts membrane phospholipids into ___, which remains in the membrane, and ___ which diffuses into the cytoplasm

4. DAG activates protein kinase ___ which phosphorlates proteins

5. IP3 causes release of CA2+ from organelles, creating a Ca2+ signal

amplifier; DAG; IP3; C

Categories of NS

• CNS - ____

  • ____ and ___ ___

• PNS - ____

  • ____ - these are nervous system processes your brain runs automatically and without you thinking about them

  • ___ - these are functions you manage by thinking about them

central; brain; spinal cord; peripheral; autonomic; somatic

____ NS (part of PNS)

• ____ muscles and VOLUNTARY movements

• ___ neuron that goes from the brain directly to the target skeletal muscles

Somatic; skeletal; one

____ NS (part of PNS)

• ___, ____ and -___ muscle, glands

• INVOLUNTARY movements

• need ___ neurons that goe sfrom the brain to ganglion (____ neuron) then ganglion to target organ (____ neuron)

autonomic; organs; smooth; cardiac; two; preganglionic; postganglionic

Autonomic Pathways:

• in total involving ___ neurons that synapse in an autonomic ganglion

CNS → _____ neuron → autonomic ganglion → ____ neuron → target tissue

2; preganglionic; postganglionic

____ Nerves

• rest and digest

• CONSTRICT airway and pupils

• stimulate saliva activity of stomach

• slow heartbeat

____ Nerves

• fight of flight

• RELAX airway

• dilate pupils (letting more light in and processing fight or flight better)

• inhibit activity of stomach

• increase heartbeat

• both target the same organs

parasympathetic; sympathetic

Parasympathetic NS

• cell bodies are in ___ ___ and ___

• preganglionic release NT → _____ → binds to nicotinic acetylcholine receptors on post ganglionic → post ganglionic release NT aka _____ → bind to _____ ____ receptors on target tissue

• RMBR: parasympathetic has ____ preganglionic fibers

spinal cord; brainstem; acetylcholine; acetylcholine; muscarinic acetylcholine; LONG

Sympathetic NS

• cell bodies are in ____ ____ or ____

• preganglionic release NT aka ____ → binds to nicotinic ____ receptors on post ganglionic → post ganglionic releas NT aka ____ → binds to ____ receptors on target tissue

• RMBR: adrenergic receptor have either ____ or ____

• sympathetic has _____ preganglioinic fibers

spinal cord; brainstem; acetylcholine; acetylcholine; norepinephrine; adrenergic; alpha; beta; short

Endocrine system

• helps maintain ____

• process is little bit slower BUT they are ___ acting responses

homeostasis; long

Endocrinology

1. Hormones

• chemicals released by an endocrinoe gland into the ____ that regulates ____ target organs/tissues/cells

• targets produce physiological response

2. Endocrine glands

• release hormones into ____ to act on ___ target tissue physiology and function

3. Homeostasis

• maintenance of a constant internal state or environment

bloodstream; specific; bloodstream; distant

Hormone Interactions:

1. _____ - hormone’s can aid in increase intracellular effector proteins to increase the cellular function of the mechanism

permissive

Hormone Interactions:

2. ____ - two or more hormones produce the same effects in a target cell and their results are amplified

synergistic

Hormone Interactions:

3. _____ - two molecules work together to oppose its function and keep homeostasis

antagonistic

Structural Class of Hormones

1. peptide hormones

• made in advance, stored in ____

• string of amino acids; e.g. ____

• released into the plasma to ____

• bind to receptors on transmembrane

• specificity is determined by presence and availability of the receptor

• relatively ____

vesicles; ACTH; dissolve; rapid

Structural Class of Hormones

2. steroid hormones

• derived from cholesterol

• membrane ____

• eg. estradiol, _____

• made on ___, cant be stored by _____

• diffuse out the cell and bind to ___ in the plasma

• bind to receptors the cell

• alters protein production for SLOW but ___-last effects

permeable; cortisol; demand; lipophillic; proteins; long

structural class of hormones

3. amine hormone

• modified single amino acids; e.g. ___, melatonin, thyroxine

• hybrid

• most bind to receptors on target cell membrane

• can act as both long acting and short acting

  • LONG acting act like ____; eg thyroid horones

  • SHORT acting act like ___; eg catecholamines

epinephrine; steroids; peptides

Main source of hormones in the brain come from:

1. ____

• pea-sized gland at base of skull in midline

• 2 anatomically and functionally discrete divisions: ____ and ____

2. _____

• sits above pituitary and under thalamus

• connects to anterior pituitary via stalk

pituitary; anterior; posterior; hypothalamus

POSTERIOR Pituitary System

• posterior pituitary develops as an extension of ____

• releaes hormones, but hormones (are/not?) made in posterior pituitary

• neuroendocrine cells in two hypothalamic regions (PVN, SON) project axons down infundibulum (or pituitary stalk)

• axon terminals in posterior pituitary release 2 hormones in capillary bed

  • 1. _____

  • 2. _____

hypothalamus; NOT; oxytocin; vasopressin

Posterior pituitary system

_______

• peptide hormone

• STIMULATES UTERINE CONTRACTIONS

• triggers milk letdown reflex

• mediates sexual arousal and affection responses

Oxytocin

posterior pituitary system

_____

• antidiuretic and peptide hormone

• increases BP

• conserves water

• strucutrally similar to other one

• monogamy hormone in praire voles

Vasopressin

ANTERIOR Pituitary System:

• hypothalamic neuroendocrine cells produce ____ hormones

• releasing hormoens secreted into “hypothalamus-pituitary portal system” or capillaries

• hormones travel to anterior pituitary and locally affect hormone-producing cells in the anterior pituitary

• anterior pituitary cells then release many ___ hormones into the bloodstream (these stimulate endocrine glands; eg ovaries and thyroids)

  • example of tropic hormone: ___

releasing; tropic; ACTH

Hormones are synthesized in the ____ and stored in the ____ pituitary

hypothalamus; posterior

ADRENAL GLAND- NOT a part of the brain, sits on top of the _____

Two parts:

1. Adrenal ___ - outer part of the adrenal gland

• releases ______:

  • 3 classes:

    • 1. glucocorticoids: eg ____

    • 2. mineralocorticoids: eg aldosterone

    • 3. sex steroids: e.g. androstenedione

2. Adrenal ___ - inner part

• releases ____ and ____ in response to ___ NS activation

kidney; cortex; adrenocorticoids; cortisol; medulla; epinephrine; norepinephrine; Sympathetic

Cortisol

• _____ (what type of andrenocorticoid?)

• stress hormone induced by psychological stress, hypoglycemia, infection

• increases ___ production

• suppresses immune system

glucocorticoid; glucose

Anterior Pituitary Hormone Pathway: CORTISOL

Hypothalamus releases ___ → travels down to ____ pituitary to produce ___ → which travels down to the adrenal cortex to produce _____

• this can all negatively feedback and could ____ the hypothalamus and anterior pituitary once enough cortisol is produced

CRH; anterior; ACTH; cortisol; inhibit

Too LOW of cortisol

• ___ ACTH

• ____ disease

• autoimmunity

• hypotension

• take synthetic steroids

low; addison’s

Too HIGH cortisol

• ___ ACTH

• ____ syndrome

• chronic stress

• hypertension

• impairs memory formation

• drugs, surgery

high; Cushing’s

PRIMARY PATHOLOGY

• affects the ___ gland or the ___ hormone (specifically ____ cortex)

• affects ____ production

• have a problem with the final hormone - can either have over or under production

  • for OVER production:

    • LOW ___ and ___ levels and HIGH ____ levels

    • this can feedback negatively onto the anterior pituitary and should decrease amounts of cortisol

    • solution is for surgery to remove tumor

  • for ____ production:

    • ____ ACTH and CRH levels and ___ cortisol levels

    • ____ feedback negatively if cortisol levels low

endocrine; final; adrenal; cortisol; ACTH; CRH; cortisol; under; high; low; CANNOT

SECONDARY PATHOLOGY

• have a problem wit the ____ or ____ pituitary

• affects ____ production

• OVERproduction:

  • ___ CRH and ACTH levels, ___ cortisol levels

  • since this increases cortisol, it will negatively feedback on the hypothalamus and AP → hypothalamus will respond, but AP will keep producing ___ since there is a tumor

• UNDERproduction:

  • HIGH ___, LOW ____ and _____ levels

  • if levels of ACTH are low, adrenal cortex will not be stimulated and can’t produce cortisol, will tell hypothalamus to make CRH to increate those levels→ NO negative feedback

hypothalamus; anterior; ACTH; low; high; CRH; ACTH; cortisol

Cushings Syndrome

• Primary pathology

  • pathology in the ____ ___ - they make too MUCH ____

    • suppresses ACTH and CRH

• Secondary pathology

  • tumor in the ___ ____ - make too MUCH ___

    • increases ____ production and lowers ___

• symptoms

  • emotional distrubance, osteoporosis; obesity; skin ulcers

adrenal cortex; cortisol; anterior pituitary; ACTH; cortisol; CRH

Addisons Disease

• Primary Pathology

  • pathology in the ___ ___ - too LITTLE ____

  • low cortisol does not suppress ACTH and CRH, therefore ___ ACTH and CRH

  • failure in feedback loop

adrenal cortex; cortisol; high

Between the two: does Addisons/Cushings have ONLY primary pathology

Addisons

Upper Motor Neurons (UMN)

• these are the motor neurons whose cell bodies lie in the ____ ___ or _____ and they activate the lower motor neuron

• connects brain to spinal cord

Lower Motor Neurons (LMN)

• these are the motor neurons of the ___ ___ (AHC) and brain stem motor nuclei of the cranial nerves that innervates skeletal muscle directly

• connects spinal cord to muscle

motor cortex; brainstem; spinal cord

Label 1-6

1. motor cortex

2. muscle

3. upper motor neuron

4. lower motor neuron

5. peripheral nervves

6. spinal cord

LMN cell bodies are organized in the ___ horn of the spinal cord:

• lower motor neuron are arranged _____:

  • ____ ventral horn → proximal muscles

    • muscles closer to the middle, like trunk, shoulder

  • ____ ventral horn → distal muscles

    • muscles further away from body like hands

  • flexors and extensors are also grouped into separate layers/regions

RMBR Like: M = Medial = Middle (of the body & L = Lateral = Limb-end muscles

ventral; topographically; medial; lateral

Driving Force eqtn

Vm - Eion

vm = membrane potential

Eion= equilibrium potential

If Vm is LESS than Eion, current is _____ for POSITIVE ions

If Vm is MORE than Eion, current is ____ for POSITIVE ions

THINK: if membrane is negative, the ion wants the membrane to be more positive so to make it less negative, positive charge must enter

INWARD; OUTWARD

Glial Cells: SEAMOS

1. _____

2. _____

3. _____

4. _____

5. _____

6. _____

Schwann; ependymal; astrocytes; microglia; oligodendrocytes; satellite cells

___ channels are OPEN during depolarization

___ channels are OPEN during resting and repolarization

Na+; K+

Explain the logic behind diagram

Electrostatic force - blue

Concentration gradient - green

• The concentration gradient pushes an ion from where it is more concentrated to where it is less concentrated (i.e. Na+ higher outside so pushed inside)

• The ion goes to the side “Opposite charged” side (i.e. cations go inside the cell (intracellular aka negative)))

• Inhibiting Na/K/ATPase prevents ___ from exiting cell. This _____ intracellular Na+ and ____ intracellular K+

• Bc intracellular N+ is now higher, the Na+ gradient becomes ____

  • the Na+/Ca2+ exchanger aka NCX needs that Na+ gradient to bring Na+ in and push Ca2+ out. if the Na+ gradient is weaker, NCX works less aka ___

  • this results in less ____ that leaves the cell and there an increase inside

• ____ heart contraction

Na+; increases; decreaes ; weaker; slows; Ca2+; stronger

Label 1 and 2

lateral corticospinal tract; anterior corticospinal tract

Lateral corticospianl tract

• f(x)- ____ movement

• decussates in the ____(pyramids, aka brainstem)

limb; medulla

Anterior corticospinal tract

• f(x) - ____ movement (axial muscles)

• decussates _____ the segment

trunk; within

Skeletal Muscle:

______ reflex aka stretch

• bc it’s a reflex it stays within the ______ - does not have to go up to the brain in order to execute a movement; the spinal cord works as an integrating center

• RMBR somatic motor neuron is _____ therefore will release acetylcholine onto nicotinic receptors

monosynaptic; spinal cord; excitatory

Skeletal Muscle:

_____ Reflex aka stretch

• will make the motor neuron fire ___ aps - if you stop firing ap decrease contractions therefore ___

• the interneuron creates ____ within the motor neuron to stop firing ap

polysynaptic; fewer; IPSPs

Patellar Tendon Reflex aka Knee Jerk

• monosynaptic stretch reflex and polysynaptic reciprocal inhibition of the ___ muscle

• will need to activate BOTH in order to contract the quadricep muscle and relax the hamstring muscle in order to see the reflex occur

• when we have a ____ this is typically to inhibit an AP in the post synaptic neuron and therefore RELAX a muscle

antagonistic; interneuron

Three Types of Muscles

1. ___ muscle - large, multinucleated cells, appear striated voluntary

2. ___ muscle - striated but smaller, branched, uninucleate. cells join by intercalated disks. involuntary

3. ___ muscle - small, lack striations, uninucleate, involuntary

skeletal; cardiac; smooth

Muscles Work in _____ pairs

• muscle contraction can pull on a bone but CANNOT push a bone away

• antagonistic muscle groups move bones in opposite directions

• axons leave the spinal cord via the ____ root; this is an _____ signal ONLY (aka releases acetylcholine)

antagonistic; ventral; excitatory

___ ___ - one motor neuron and all the muscle fibers it innervates; a muscle may have many motor units of different types; all the motor units that innervate a muscle are the motor ___

motor unit; pool

Muscles are Bundles of Cells that Work Together

1. ______ Reticulum - essentially like the endoplasmic reticulum (BUT specific for the muscles) store Ca2+

2. ___ - allow the AP to travel deeper into the muscle cell

3. Contractile proteins

   1. THICK filmanet - ____

   2. THIN filament - ___

4. Regulatory Proteins

   1. ____

   2. ____

Sarcroplasmic; T-tubules; myosin; actin; tropomyosin; troponin

The Sarcomere ____ during Contraction

• filaments DON’T shorten - they ____ - and this is how the muscle contracts. their size does NOT change at all

• muscle contraction - sliding filament theory → ______ actin and myosin filaments of fixed length slide past one another in a process that requires energy

• the _____ shortens and that causes the muscle to contract

shortens; contract; overlapping; sarcomere

_____ ____ aka NMJ

• the whole ____

• the motor end is comprised of a series of juncitonal folds (with ___ ____ receptors aka nACh)

• NMJ contains a ___ density of nACh receptors

Neuromuscular Junction; synapse; nicotinic acetylcholine; high

The Relaxed State

• myosin head is cocked

• tropomyosin partially ___ binding site on actin

• myosin is weakly bound to actin

• tropomyocin is ____ myosin from strongly interacting with the actin

• troponin is NOT bound by _____

blocks; preventing; calcium

Initiation of Contraction

• Ca2+ levels ____ in cytosol

• Ca2+ binds to troponin aka TN

• Troponin-Ca2+ complex pulls tropomyosin ___ from actin’s myosin binding site

• Myosin binds strongly to actin and completes power ____

• actin filament moves towrads center of ___

*** this is Calcium is important

increase; away; stroke; sacromere

The contraction cycle

• in order to have a contraction - the myosin head needs to ___ strongly to actin to perform the ____

• during resting state - NO ___ is present so the actin binding site is blocked by tropomyosin

  • tropomyosin has ____ bound to it - ““ is what has a binding site for ____

• to initiate a contraction - Ca2+ levels must increase so they can bind to troponin - once bound this will pull on the tropomyosin and move it away from its original site - no longer blocks the binding site on actin where the myosin head need to bind to ___ the muscle = contraction

For contraction itself-

1. the active site on ___ is exposed to Ca2+ binds to troponin

2. the myosin head forms a cross bridge with actin

3. during the power stroke, the myosin head bends and ___ and ___ are relased

4. A new molecule of ATP attaches to the myosin head, causing the cross bridge to detach

5. ATP _____ to ADP and phosphate, which returns the myosin to the “____” position

bind; powerstroke; Ca2+; troponin; Ca2+; shorten; actin; ADP; phosphate; hydrolyzes; cocked

____ ___ - when you die → no longer make ATP → myosin head doesn’t unbind → muscle stays contracted

rigor mortis

Initiation of Muscle AP

1. motor neuron releases ___ at the neuromusular junction (the presynaptic cell releases NT into the synaptic cleft)

2. NT is going to cross the synaptic cleft and bind to receptors on the post synaptic celll - in this case we refer to it as a the motor end plate

3. ACh is always ____ so when they bind - Na+ will flow in - ____ - initiate muscle AP

4. The AP ( or depolarization) will travel down the tubule and open DHP channel which is a VG calcium channel - lets Ca2+ in

5. DHP channel is physically linked to the RyR channel (mechanically gated Ca2+ channel on the SR)

6. When DHP open, the RyR opens and Ca2+ flows ____ the SR and bind to ____

Relaxation Phase : Clearing Ca2+

7. the Sarcoplasmic Ca2+ pump uses ATP to pump Ca2+ back into the SR

8. ____ in free cytosolic [CA2+] causes Ca2+ to unbind from troponin

9. tropomyosin recovers binding site. when myosin head releases, elastic elements pull filaments back to their replaced position

ACh; excitatory; depolarize; out; troponin; decrease

Smooth Muscle

• small, lack striations, uninucleate, _____ (depends on communication from sympathetic and parasympathetic branches to help control smooth muscle)

involuntary

Smooth muslce communication with neighboring cells

• Single-unit smooth muscle cells: connected by ___ ____, when one cell depolarizes, all connected cells contract as a single unit (ie uterus, GI, bladder)

• Multi-unit smooth muscle cells: NOT electrically linked, each cell must be stimulated ____ (ie large airways, most arteries, iris, ciliary body)

gap junctions; independently