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Immunology . Quiz!. Covering of the body (skin, mucous membrane) Innate Adaptive (acquired) . What are the three lines of host defenses ?. Skin and mucous membranes . Physical barrier Epidermis, cilia movement, low of air/fluid Chemical pH, enzymes, other antibacterial peptides

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slide2
Quiz!
  • Covering of the body (skin, mucous membrane)
  • Innate
  • Adaptive (acquired)

What are the three lines of host defenses?

skin and mucous membranes
Skin and mucous membranes
  • Physical barrier
    • Epidermis, cilia movement, low of air/fluid
  • Chemical
    • pH, enzymes, other antibacterial peptides
  • Microbiological:
    • Normal flora
slide4
Quiz!
  • Primary
    • bone marrow
    • thymus gland
    • fetal liver and yolk sac
  • Secondary
    • lymph nodes
    • Spleen
    • mucosa-associated lymphoid tissue

What are the organs of the immune system?

innate
Innate
  • NO MEMORY
  • Cellular
    • Phagocytic cells
    • Cells with inflammatory mediators
  • Humoral
    • Acute phase reactant
    • Cytokinins
order of recruitment
Order of recruitment
  • Macrophage
    • Innate immune system
    • Found in all organs/tissues
      • Especially where epithelia are in contact with exterior
      • Pseudopods attracted to bacteria
    • Derived from monocytes
    • Major function: engulf particles
    • Send signals for neutrophil via cytokines (Interferon alpha)
order of recruitment1
Order of recruitment
  • Neutrophils
    • Innate
    • Polymorphonuclear cell family PMNs (with basophils and eosinophils)
    • Found in blood stream
    • Come in massive number
    • Eats the bacteria
    • Then dies
order of recruitment2
Order of recruitment

After macrophage does its job, it returns to regional lymph nodes and calls for

  • Dendritic cells
    • Borderline between innate and adaptive
    • Eats virtually everything
    • Takes in bacteria, carries pieces of it on its surface
    • Gets back to lymph node
how does phagocytic cells recognizes bacteria from self
How does phagocytic cells recognizes bacteria from self?
  • Toll-like receptors
    • PRR – pattern recognition receptors
    • Recognized PAMP – pathogen-associated molecular patterns
    • Type I trans-membrane receptor
      • N-terminal: outside the cell, recognize ligands
      • C-terminal: inside the cell
    • Activate inflammation and kick starts immunity
slide10
Quiz
  • They are PAMP
  • Gram-negative bacteria
  • Peptidoglycan (PGN) are Gram-positive bacteria

What are Lipopolysacchides (LPS)?

adaptive
Adaptive
  • Antigen (and epitope) specific
  • Antigen presenting cells (APC) – (MHC+peptide)
    • Interdigitatingdendritic cell
    • Macrophage
    • B lymphocyte (B cell)
adaptive1
Adaptive

I. Humoral Immunity

RESPOND TO

  • Extracellular pathogens (e.g., bacteria)
  • Antigen presenting cells (APC) MHC II+peptide

PARTICIPANTS

  • TH2 (CD4+)-helper lymphocyte
  • B lymphocyte
  • T cell-B cell interaction (cooperation)
  • Immunoglobulin antibody production
adaptive2
Adaptive

II. Cell-mediated Immunity

  • Antigen presenting cells (APC) MHC+peptide

RESPOND TO

    • Intracellular pathogens (e.g., viruses)

PARTICIPANTS

    • TH1(CD4+)-helper lymphocyte
    • Tc (CD8+)-cytotoxic lymphocyte
    • T cell-Tcell interaction (cooperation)
    • Effector cell is the CD8+ cytotoxic lymphocyte
slide14
Quiz

Side-chain theory

cell under threat grew additional side-chains to bind the toxin, and that these additional side chains broke off to become the antibodies that are circulated through the body

Who is Paul Ehrlich and what was his theory?

major histocompatibility complex
Major Histocompatibility Complex
  • Two molecular system
    • MHC I
      • present in almost all nucleated cell
    • MHC II
      • Present in APC (macrophage, dendritic, B-cell)

In each class, molecules have two chains

- alpha and beta

slide16
Quiz

How many alpha chain does MHC I has?

lymphocytes
Lymphocytes
  • All starts in the bone marrow – stem lymphocytes
  • Some will go to Thymus
    • T-cells
    • Specialized in that microenvironment
    • Becomes either CD4 or CD8
  • Some will remain in the Bone marrow
    • B-cells
  • Migration to lymph nodes
maturation
Maturation
  • TCR (T-cell surface receptors) and slg (B-cells – Specific Ig) are formed randomly
  • Early T-cells are double positive (both CD4 and CD8)
    • CD4 – TH1, and TH2, recognizes MHC II
    • CD8 – Cytotoxic T-cells, recognizes MHC I
  • 95% of all T-cells are deleted in the thymus
    • If they don’t recognize MHC or recognize it too well
slide20
QUIZ

False, it is a life long phenomenon

(T/F) Deletion of T-cells (selection for reactivity to MHC-peptide tolerance) stops at the age of 6 month

quizzzzz
Quizzzzz

Cytotoxic T-cell

CD 4 becomes helper T-cell: target for HIV

CD 8 becomes what cell?

quizzz
Quizzz

Then you have dendritic cells that moves in between B and T cells

Interacts with both

T cells are found in the superficial cortex of the lymph nodes

continuing the sequence
Continuing the sequence…

1st specific reaction

Binding of MHCII (dendritic cell) to T-cell

Genetically programmed to recognizes one epitope

slide24
Quiz
  • On dentritic cell: B7
  • CD-80, CD-86
  • On the T-cell: CD 28
  • Confirms that it is not attacking self
  • Intracellular: costimulating factor giving the signal to attack

What make sure that T-cell are not attacking “self”?

slide25

B-cell recruited: ligande CD40L (T-cell) with CD40 (B-cell)

  • B-cell receptor surface immunoglobuline recognizes the surface of the bacteria
slide26
Quiz!!!
  • What does IL 4, 5, 6 do?
  • Interleukins that causes the maturation and proliferation of B-cell
    • Produces more antibody
slide27
Quiz!!
  • False!!!
  • B-cells proliferate (under influence of interleukins) and makes antibody
  • When it becomes a plasma cell, it no longer makes antibody, only secrets it

(T/F) B-cell becomes a plasma cell and start to make antibodies

antibodies
Antibodies

Humoral immunity

Ig

Structure

4 chains

2 identical light chains

2 identical heavy chains

slide29
Quiz

(T/F) Both intra and inter chains are held together by disulfide bound

slide30

Five (5) Classes

– determined by the Heavy (H)

  • Two (2) Types

– determined by the Light (L)

    • κ kappa, λ lambda
  • Fab = antigen binding fragment
    • “hypervariable region”
  • Fc = crystalizable fragment
    • “Tail”
    • determines the biological actvity of the Ig Class
classes of ig
Classes of Ig
  • IgM – class mu
    • First activated
    • Recognizes A or B antigen on RBC
  • IgG – class gamma
    • Only one that can pass through placenta
    • Bacteria, virus, fungi, etc.
  • IgA – class alpha
    • Mucosal immunity
    • Found in saliva, tear, other secretion
  • IgE – class epsilon
    • Allergies
slide32
QUIZ

Which Ig is monomeric?

after antibody binds
After antibody binds…

Antibody can’t do anything until it borrows complements from the innate system

what to remember
What to remember?

It’s a cascade, each amplifies the “waterfall”

C3 and C5 calls for neutrophilphagocytosis

Later molecules in the sequence – C9 – punches a hole in the bacterial membrane

slide38

In genome, 200 genes code for immunoglobulins

  • DNA from these genes cut, then rearranged and rejoined
  • Accounts for millions of possibilities
  • The last one C – determines the class (IgM, IgG, IgE, IgA)
slide39
Quiz

True: Class switch can occur in the apical light zone

IgM often switches class

(T/F) B-cell can change the class of Ig it produces

memory
Memory
  • After exposure, B cells differentiate into plasma cells that secrete antibodies
  • A small minority survives as memory cellsthat can recognize the same epitope
  • With each cycle, the number of surviving memory cells increases. Increase is accompanied by affinity maturation – survival of B cells that bind to the particular antigen with high affinity
  • secondary immune response
slide42
Quiz

(T/F) B-cells need T-cell to activate and produce antigens.

  • False!
  • B-cell can produce and secrete antigen without T-cell
  • T-cell causes B-cell to proliferate and render them much more efficient
major divisions
Major Divisions

Afferent

  • Cranial Nerves
  • Spinal Nerves
    • Touch
    • Pain
    • Temperature
  • Visceral

Efferent

  • Cranial Nerves
  • Spinal Nerves
    • Somatic (voluntary)
    • Involuntary
  • Enteric
slide46
Quiz!
  • What structure connects the two hemispheres?
  • Corpus Callosum
slide47
Quiz
  • T/F
  • The dorsal root carries motor neurons
  • False!
  • Ventral root carries motor neurons
slide48
Quiz
  • By which week of gestation do the neural plate start to form?
  • 3rd!
neural tube
Neural tube
  • Ectoderm starts to fold and forms the neural groove
  • Neural groove eventually becomes neural tube (4 weeks)
  • Neural tube becomes CNS
  • Bits and pieces of ectoderm forms neural crest
  • Neural crest forms PNS
cerebrospinal fluid csf
Cerebrospinal Fluid (CSF)
  • Produced by Choroid Plexus @ rate of 500 ml/day
    • Ventricle can only contain 150mL
  • Function is SNoW
    • Support and cushion the brain
    • NOurishment
    • Waste removal – arachnoidvilli
csf circulation
CSF Circulation

Chroid plexus

Lateral ventricle

Foramen of Monro

3rd ventricle

Cerebral aqueduct

4th ventricle

Foramens of Lushka & Magendie

Subarachnoid space

Dural sinus

Venous blood

Heart

problem with circulation
Problem with circulation
  • Communicating Hydrocephalus
    • Problem with CSF removal

 arachnoidvilli inflammation

    • Pressure starts to build up outside the ventricles
    • Eventually a global increase in pressure
  • Non-communicating Hydrocephalus
    • Pressure build-up inside the ventricles
    • Not necessarily affect all the ventricles
    • Localized
slide53
Quiz!
  • Glycogen is the only substrate metabolized by the brain
  • False!
  • Glucose
  • The brain need a continuous supply of glucose and O2
brain blood supply
Brain Blood Supply

Basilar artery

Internal carotid artery

External carotid artery

slide56
BBB
  • Pass
    • H2O
    • Co2
    • O2
    • Lipid soluble
    • Na+
    • K+
    • Cl+
    • Active transport of GLUCOSE and AMINO ACID
  • Blocked
    • Large molecules
slide57
Quiz!
  • What are the function of astrocytes?
  • Phagocytosis of debris
  • Reuptake of neurotransmitters (such as Glutamate)
  • Regulation of ion concentration
    • i.e. reuptake of K+
  • Structural support
  • Induce tight junction (BBB)
perception
Perception
  • Law of specific energy
  • MODALITY!
  • Regardless of the type of energy that stimulate a nerve, the sensation felt correspond to nerve type
  • Rubbing eyes
  • Law of projection
  • LOCATION!
  • Regardless of where you stimulate a sensory nerve, the sensation is always felt at the sensory receptor location
  • Phantom limb pain
adaptation of afferent
Adaptation of afferent
  • Non-adapting
    • Constant discharge even if there is no change in stimulus
    • You constantly feels the sensation
  • Slowly-adapting
    • Discharge stops slowly if there is no change in stimulus
    • You still feel the sensation but less and less
  • Rapidly-adapting
    • Discharge stops if there is no change in stimulus
    • You stop feeling the sensation after a while
    • i.e. do you feel your underwear all day long?
receptive field
Receptive field

Strongest in the middle

Smaller RF = increase acuity

Overlapping receptive fields: the one that respond the loudest determines location

Lateral inhibition further sharpens acuity

slide62
Quiz

T/F

Signal from the brain can decrease the pain from a paper cut

True

Sensation is shaped by both:

Bottom up – mechanical stimulation on the skin

Top down – CNS signals

  • Top down inhibition/excitation can be presynaptic or postsynaptic
slide63
Quiz!
  • Mechanoreceptors are activated by what?
  • By mechanical deformation!
  • Stretch of the skin that opens channels
quizzzzzzz
Quizzzzzzz

T/F

Cutaneousmecanoreceptor nerve ending are all the same, the only difference is the types of tissue surrounding them and there they are located

True!

  • End organ allows only selective mechanical information to activate nerve terminal
  • Meissner and Merkle (M&M): superficial

- light touch, texture

  • Pacinian and Ruffini: deeper

- stronger deformations of the skin  deep pressure, shape

other sensation
Other sensation!
  • Thermoreceptors
    • Cold: 0-35 C
    • Warm: 30-50 C
    • >50C  PAIN!
  • Nociceptors
    • Mechanical deformation
    • Temperature
    • Chemicals
slide66
Quiz!

T/F

Inflammatory molecules increase the threshold of nociceptors, causing hyperalgesia

false
FALSE

Hyperalgesia: sensitive to pain

Increase threshold: more AP to actually cause pain

Hyperalgesia is associated with decrease threshold – less AP to cause pain

another one
Another one!

T/F

Histamin

Bradykinin

5-HT

Prostaglandin

K+

Activates nociceptors

This leads to release of substance P at both spinal cord and the site of injury

this one is true
This one is TRUE

Activation of nociceptors leads to release of substance P (for pain) in the spinal cord and afferent feedback onto mast cells

Mast cells then secrete histamine, further sensitize the nerve ending

pathways
Pathways
  • Touch and Proprioception
    • Ipsilateral
    • Dorsal column
    • Synapses @ medulla (x-over), thalamus
  • Pain and Temperature
    • Contralateral
    • Anterolateral column
    • Synapses @ dorsal horn of spinal cord, thatlamus
cns analgesia
CNS Analgesia

PAG – periaqueductal gray matter

Reticular formation

Both are from medulla

Decends in dorsalateralfuniculus

Presynaptic or post synaptic inhibition

slide72
Quiz!

T/F

The foviacentralis is where all optic nerves are leaving the retina, therefore it has the highest visual acuity

False

Optic disk is where the optic nerve are exiting the eye

Foviacentralis is the highest visual acuity area, that is true

slide73
Quiz!

T/F

The cornia refracts light more than the lens

True

slide74
Quiz!

T/F

If the eye is myopic, then the image is formed behind the retina

This condition can be corrected with concave lens

First part is false – myopic = nearsighted, image is formed before the retina

Second part is true – myopia is corrected with concave lens

slide75

Retina circuitry may prevent light from getting to rods and cones

In fovea centralis, the circuitry is shifted out of the way

Nourishes rods and cone – detached retina: separation of retinal from pigmented epithelium

Bipolar / Amacrine /

Horizontal cells : process, compress, converge raw data from rods and cones

send info to brain

phototransduction
Phototransduction

In the dark, the cell is depolarizing, transmitter always released by the inner segment

Light hits rhodopsin/opsin molecule (outer segment)  change in configuration

Reaction via G-protein cascade

cGMP is converted to GMP

Closes the cGMP gated channel

Na+ can no longer flow in

Hyperpolarization– stops release of transmitter by the inner segment

many quizzzzes
Many quizzzzes
  • Day vision
  • Slow response time
  • Sensitive to scattered light
  • Low amplification
  • Single photon closes many Na+ channels
  • High acuity
  • Less convergent
  • Cones
  • Rods
  • Rods
  • Cones
  • Rods
  • Cones
  • Cones
center surround theory
Center surround theory
  • Retina ganglion cells
  • Help to detect the RELATIVE difference of light across their receptive field
  • The same processing can be applied to color
  • Red, blue, green
while crossing dr penfield a car is coming full speed from the right will bobby see it
While crossing Dr. Penfield, a car is coming FULL speed from the right… will Bobby see it?
  • Yup, R visual field of R eye will spot the car
  • Yup, R visual field of the L eye is okay
  • Yup, R visual field of both eye would be okay
  • Yup, intact R visual field of R eye
  • Noooooooooooooooo
slide80

Deflection of basilar membrane produces shearing of hair cell stereocilia

  • As they move, tip link that connect each sterocilia pulls open gated ion channel and causes depolarization
  • It’s a fast, direct channel activation
slide81
Quiz

T/F

Auditory information is carried by the 8th cranial nerve, it synapses with a 2nd order neuron in the medulla, crosses over, and is sent to the contralateral Primary auditory cortex

  • False! – its bilateral
  • Bilateral pathway allows for sound localization (base on time difference of signals from each ear)
semicircular canals
Semicircular Canals

Detects angular acceleration

semicircular canals1
Semicircular Canals
  • No angular acceleration
  • Clockwise acceleration
    • inertia causes endolymph to lag behind - cupula deflects toward counterclockwise
  • Perceived sensation: clockwise
semicircular canals2
Semicircular Canals
  • Constant clockwise motion – cupula not deflected
  • Canal stopped
  • Momentum keeps endolymph moving – cupula moves with endolymph in the clockwise direction
  • Perceived sensation: counterclockwise
utricle and saccule
Utricle and Saccule

Utricle

HORIZONTAL acceleration

Saccule

VERTICAL acceleration

Mechanism:

Otoliths lags behind and pulls on the hair cells

gustatory
Gustatory
  • Salty: Na+

- direct effect on sodium channel

  • Sour: H-

- direct effect on sodium channel, can interfere with Na+

  • Bitter: G-protein cascade
    • A lot of way to transduce bitterness
  • Sweet: G-protein cascade
olfactory
Olfactory

Molecules dissolved in mucus, detected by olfactory receptor cells

G-protein cascade leading to opening of ion channel

Synapse at the olfactory bulb

The only sensory modality that does not have synapse at medulla or thalamus

Olfactory bulb has direct connection with the limbic system –strong effect on emotion and memory

cognition
Cognition
  • Alpha rhythm
    • Relaxed state
    • Low frequency
    • High amplitude
  • Beta rhythm
    • Alert state
    • High frequency
    • Low amplitude
slide89
Quiz

T/F

As you fall deeper asleep (stage 1-4) amplitude increases and frequency decreases

  • True!
slide90
Quiz

Circadian rhythm is controlled by what structures of the brain (3)

  • Preoptic area (hypothalamus)
  • Suprachiasmatic nucleus (hypothalamus)
  • Reticular activating system

(reticular formation)

state of conciousness
State of conciousness
  • Factors to consider

Reticular activating system

    • Aminergic neuron and Serotonin
    • Cholinergic neuron

Hypothalamus

    • GABA
    • Histamine
  • Tricks to help to remember
    • Serotonin makes you happy and excited – anything that makes serotonin go up will be associated with alertness
    • The two –nergic systems goes against each other
    • GABA always associated with decrease in activity
slide92
Quiz

Dopamine is produced

  • Olfactory bulb
  • Midbrain
  • Prefrontal cortex
  • Locus Ceruleus
  • Hippocampus
  • Amygdala
  • Midbrain

D

Dopamine – reward pathway (Locus ceruleus, midbrain, prefrontal cortex)

case study 1
Case study 1

Mrs. D has undergone an aggressive surgery to treat glioma (tumor). A large part of her hippocampus and basal ganglia are removed. What type of memory deficit do you anticipate for Mrs D?

  • Basal ganglia – long term procedural memory (i.e. how to play tennis)
  • Hippocampus – short term declarative memory (i.e. what she had for breakfast this morning)
case study 2
Case study 2

Mr. W had a left middle cerebral artery stroke 2 m.o. ago. When asked how he is doing he responds

“Well I eat grasshoppers and boy does that shin look chipy bog”

Which area is affected? Broca or Wernicke?

  • Wernicke: comprehension
  • Broca’s area is more just articulation. They understand fine and can formulate sentence that makes sense
motor
Motor

Extension

Flexion

Agonist

Antagonist

monosynaptic stretch reflex
Monosynaptic stretch reflex

Agonist excitation: THERE IS NO INTERNEURONS!!

motor cheat sheat
Motor cheat sheat
  • Corticospinal – voluntary movement
    • Pyramidal
    • Contralateral
    • Synapse with ALPHA motor neuron in the VENTRAL horn (via interneuron most likely)
  • Extrapyramidal – posture, trunk
    • Extrapyramidal
    • Ipsilateral
  • Alpha motor neuron: skeletal muscle (extrafusal)
  • Gamma motor neuron: intrafusal, monitor muscle length
flexion withdrawal
Flexion withdrawal

Touch something hot

Sensory fiber transmit pain

Activate ipsilateral flexors (via excitatory interneuron)

Inhibit ipsilateral extensors (via inhibitory interneuron)

Result in removal of arm from the stove – whole process does not require cortical input

cross extensor reflex
Cross extensor reflex

Just remember: the interneuron that crosses to the contralateral side is always excitative.

Therefore to inhibit contralateral side, you need a 2nd interneuron to do this

slide100
Quiz
  • What is irridation?

Increase in rate and magnitude of withdrawal response with increased stimulus strength

The more it hurts, the stronger your reaction is going to be

parallel system
Parallel system
  • Ia(Nuclear bag fibers)
    • Dynamic change in muscle length
    • Takes into consideration the relative length of the muscle
  • IIa (Nuclear chain fibers)
    • Static muscle length
    • Only mind the absolute length of the muscle

When a muscle is lengthened, there is no problem

When a muscle is in shortened position, muscle spindle collapse and sensitivity is reduced

 Decrease in force production

parallel system1
Parallel system
  • Solution: Gamma motor neuron
  • Activate and cause contraction of muscle spindle
  • Tension is put on the spindle and sensitivity is maintained
  • Able to apply further force and continue contraction

ALPHA GAMMA CO-ACTIVATION

series system
Series system

Golgi Tendon Organs

  • Ib afferent
  • Reports muscle tension
  • Prevent muscle injury by inhibition of the same muscle when too much stretch is put onto it
  • Underlies inverse stretch reflex (polysynaptic)
slide105

There is also an excitation of antagonist muscle (not on the picture)

GTO is the main underlying mechanism for stretch reflex

N.B: The stretch reflex (knee jerk) is usually considered to be the same thing as GTO reflex.

motor control
Motor Control
  • Premotor: planning and initiation
  • Primary motor: encode motor command
  • Fine tuning of motor command
    • Basal ganglia – sequence
    • Cerebellum – amplitude modification, timing of movement
    • Brain stem – posture, balance
time for quiz
Time for… Quiz!
  • Spasticity results in what?
  • It is associated with damage to motor neuron or higher level motor pathway?
  • Spasticity: high muscle tone, overactive motor reflexes
  • It is a upper motor disease – damage to CNS
  • Without any input from the brain, gamma motor neuron (reflex) takes over
basal ganglia
Basal Ganglia

Parkinson disease

  • REDUCED dopamine
  • Akinesia
  • Bradykinesia
  • Rigidity
  • Resting tremor

Huntington disease

  • TOO MUCH dopamine
  • Hyperkinetic
  • Choreiform movement
cerebellum disorders
Cerebellum disorders

Asynergia

Dysmetria

Ataxia

Intention tremor

Paralysis and weakness (?)

slide111

Describe the three different types of muscle.

  • Define the terms muscle fiber, tendon, myofibril, sarcomere, I band, A band, Z line, thick filament, thin filament, actin, myosin.
  • Explain the sliding filament model of muscle contraction.
  • Describe the actin-myosin cross-bridge cycle. Understand why muscle contraction requires hydrolysis of ATP.
  • Define the terms motor neuron, motor unit, neuromuscular junction, motor end-plate, acetylcholine, nicotinic acetylcholine receptors, end plate potential.
  • Explain synaptic transmission at the neuromuscular junction
  • Explain excitation-contraction coupling.
  • Explain the difference between slow oxidative, fast oxidative and fast glycolytic muscle fibers.
  • Understand the length-tension relationship of muscle fibers.
  • Define the terms twitch, summation, tetanus and recruitment.
  • Explain how summation and recruitment contribute to generation of muscle force.
  • Explain the factors that contribute to muscle fatigue.
  • Know the characteristics of neurogenic, myopathic and upper motor neuron disorders.
describe the three types of muscle
Describe the three types of muscle
  • Skeletal – stripped
    • Posture
    • Locomotion
    • Voluntary
  • Cardiac
    • Heart muscle
  • Smooth
    • Organs
    • Blood vessels
muscle fiber
Muscle fiber

Made of multiple precursors called myoblast

Multinucleated

Stripped

slide114

Muscle fiber

Myofibril

Skeletal muscle fibers consist of cylindrical bundles called myofibrils.

Myofibril

slide115

Myofibril

I band

A band

Z line

Sarcomere

The striations within each myofibril are caused by alternating light I-bands and dark A-bands. In the center of each light band is a dark line called the Z-line. These structures delineate the sarcomere, the contractile unit of skeletal muscle.

slide116

Thick filaments

Z line

Z line

Thin filaments

Sarcomere

Each sarcomere consists of two sets of parallel and partially overlapping protein filaments: thick filaments extending from one end of the A band to the other, and thin filaments, attached to the Z lines and extending across the I band and part way into the A band.

Crossbridges

slide117
Quiz
  • What makes up the thin filament?
  • Actin
  • Thick filament is made of Myosin
slide120

The cross-bridge cycle is driven by ATP binding and hydrolosys by the myosin head groups.

ADP + Pi

ADP + Pi

Myosin

Myosin binds

to actin

ATP

hydrolysis

Power stroke

Myosin dissociation

ADP + Pi

ATP

slide121
Quiz!

What is included in a motor unit?

(2)

  • Motor neuron
  • Group of muscle it innervates
  • Synapse are usually located at the middle of the muscle belly
slide122
Quiz
  • What neurotransmitter is release at the neuromuscular junction?
  • ACh
  • Activating NICOTINIC receptors
slide123

AP travels down T-tubules

  • Opens the voltage gated Ca+ channels in the T-tubules
  • This is coupled with activation of Ca+ channels in Sarcoplasmic reticulum
  • Ca+ released from SR cause muscle contraction

Muscle fiber surface

T-tubule

myofibril

Sarcoplasmic reticulum

slide124
Quiz

T/F

Muscle contraction is possible even if T-tubules are blocked

True

Ability of muscle to contract is coupled with Ca release by SR

T-tubules are more signal detectors, not very important for contraction of skeletal muscles

Cadmium – Ca+ blocker

slide125

Ca2+ binding site

Troponin

Actin

Tropomyosin

  • Ca+ cause conformation change in troponin – moves the tropomyosin out of the way
  • Free the binding site for myosin head
muscle types
Muscle types
  • Runners
  • Springers
  • Soccer players
  • Slow oxidative
    • Low ATPase
    • Red – O2 transport
    • Endurance
  • Fast glycolytic
    • High ATPase
    • No myoglobin
    • Power
  • Combined
muscle contraction
Muscle contraction
  • All or nothing
  • Delay in excitation-contraction coupling
  • Duration of contraction – time it takes to pump out Ca+
  • Twitch – 1AP
  • Summation – closely packed twiches
  • Tetanus – sustained contraction, summation of very fast, successive twiches
what is another way to control muscle force
What is another way to control muscle force?

Summation

Order?

  • Weaker units are recruited first
  • Slow oxidative
  • Fast glycolytic
  • Fast oxidative
slide129
Quiz
  • What are the three factors of muscle fatigue?
  • Build-up of potassium in the t-tubules – loss of chemical gradient needed for depolarization
  • Lactic acid build-up – change in pH, alteration in protein structure
  • ADP-Pi build-up in the muscle fiber– inhibition of cross-bridge
disease of motor unit
Disease of motor unit

Spinal cord injury after an accident on Dr. Penfield

  • Upper motor neuron
  • Spasticity
  • Overactive reflex
disease of motor unit1
Disease of motor unit

Duchene Muscular Dystrophy

  • Myopathic – mutation in muscle cytoskeleton protein Dytrophin
  • Muscle weakness
  • Myoglobinurea
  • Fasciculation (?)
  • Increase in sarcoplasmic enzyme
disease of motor unit2
Disease of motor unit

Carpal Tunnel syndrom

  • Neurogenic: change in motor neuron cell axons (peripheral nerve)
  • Muscle atrophy
  • Fasciculation
  • Decreased muscle tone
minute quiz
Minute Quiz

Is autonomic system sensory or motor?

Both

What is main purpose of autonomic system?

Homeostasis

What are the divisions of autonomic system?

Sympathetic, parasympathetic, enteric

Where are automatic motor neuron located?

Outside the spinal cord, in groups called autonomic ganglia

comparison
Comparison

Sympathetic

Parasympathetic

  • Fight or flight
  • Increase heart beat and contraction
  • Presynaptic:

Ach  Nicotinic receptor

  • Postsynaptic:

NE  alpha/beta adrenergic

  • Rest and digest
  • Decrease heart beat and contraction
  • Presynaptic:

Ach  Nicotinic receptor

  • Postsynaptic:

Ach  Muscarinicreceptor

sensory input
Sensory input
  • Vagus
    • Most visceral information
  • Glossopharyngeal
  • Facial
    • Both synapses in the brain stem in nucleus of solitary tract
slide137

Limbic cortex

Amygdala

Hypothalamus

Nucleus of the solitary tract

Visceral organs

The nucleus of the solitary tract integrates visceral sensory inputs and autonomic outputs and project to higher brain centers involved in homeostasis.

another minute quiz
Another minute quiz

Homeostasis is maintained through what type of feedback?

Negative feedback

What is a Nucleus?

Collection of neuron body in CNS

What is equivalent of nucleus in the PNS?

Ganglion

Enteric system depends on sympathetic and parasympathetic system to function

No, it receives input from them but can function alone

last one
Last one!
  • Which CNS structures gives input to the autonomic system?
  • Hypothalamus
    • BP and body temperature
    • Electrolyte balance (thirst)
    • Energy metabolish (hunger)
    • Reproduction
    • Response to stress
  • Limbic system
    • Visceral response to emotion
    • Amygdala
    • Cingulate cortex