EXP 11 – PITHING THE FROG
Pithing – destroying the central nervous system which consists of the brain and the spinal cord – it renders the frog free from pain – has an anesthetic effect SINGLE Brain or spinal cord
DOUBLE Brain AND spinal cord
Why not use anesthesia? made specifically for humans over dosage can kill the frog can mask physiological effects Signs of successful pithing Frog is less active Head is drooping Partially closed eyes Extended limbs Skin inelasticity EXP 12 – MUSCLE N ERVER PREPARTION
Muscle nerve presentation – representation of motor unit Motor unit involves: Motor nerve – sciatic nerve Muscle: gastrocnemius Connected by: the neuromuscular junction; they do not actually touch due to synaptic gap Muscle is damaged Nerve is damaged – paralysis Muscle itself is damaged Dystrophy Damaged receptors (acetylcholine) (acetylcholine) – butox Muscle dehydration due to slow isolation – should be soaked in amphibian Ringer’s solution
EXP 13 – APPLICATION OF STIMULUS
Mechanical – single Hot – no contraction or single; it must reach threshold stimulus Threshold stimulus – minimum amount of stimulus to produce a reaction Subminimal Stimulus – less the threshold and does not illicit response Maximal stimulus – greater than the threshold and illicit the maximum reaction; least/minimum intensity of stimulus which greater response Supramaximal – stimuli greater intensity than maximal which produces the same greater response Newton per area Greater area, lesser pressure STIMULUS APPLIED Mechanical Thermal Hot Thermal Cold Electrical Direct Electrical Indirect Chemical
Response of Muscle Single Single Single Single Series Series
Example: 5V 6V 7V 8V 9V 10 V 11 V 12 V
Amphibian Ringer’s Solution Mimics extracellular fluid that nourishes the muscle (plasma) Intact muscle is nourished by blood To keep integrity of muscle Muscle oxygen carrier: myoglobin
Oxygen is needed for production of ATP ATP in muscle contraction Maintains resting membrane potential through sodium-potassium ATP pump which pumps out 3 molecules of Na and 2 molecules of K in Hence you only pumped out 1 positive charge Polar – positive outside, negative inside Extracellular – more sodium Intracellular – more potassium
Extracellular & RMP is positive while inside its relatively negative ATP is required for the detachment of cross bridges (attachment of myosin heads to the myosin binding site) Myosin heads carries ADP is more attracted to actin hence when ADP is replaced by ATP it loses affinity to actin, thus detaching No ATP, myosin will not detach from actin causing cramps
5 cm 5 cm 4 cm 4 cm 3 cm 3 cm 3 cm 3 cm
7V – threshold stimulus 5-6V – Subminimal stimulus 9V – Maximal stimulus 10-12V – Supramaximal stimulus EXP 14 – THE SPINAL FROG
Reflex – rapid, involuntary, predictable response to a stimulus center at the spinal cord
Monosynaptic reflex components Sensory receptor – converts stimulus to neural signal Sensory nerve – (mono) body is located in the dorsal root ganglion, dendrites coming from receptor, synapsing into axons towards the motor nerve on the ventral horn of the spinal cord, exiting the ventral root, uniting at dorsal root to form spinal nerve Motor nerve Effector muscle REFLEXES Normal
Reflex RIGHTING uprights the body complex reflex center: brain WITHDRAWAL withdrawal from painful stimulus center: spinal cord CROSS EXTENSOR After pinching, contralateral leg extends while ipsilateral leg flexes CORNEAL center: brain VISION, HEARING, BALANCE & PROPRIOCEPTION
HIGHER HEART RATE Intact Warm Isolated
LOWER HEART RATE Isolated (room temp) Cold Cold
INCREASES HEART RATE Cardiac contractility is directly proportional to: > CD CASET Carbon dioxide Calcium Sympathetic response (fight or flight) Epinephrine (adrenaline) Temperature ∙
Spinal
∙
∙
Dorsal side up
Ventral side up or side up
present
present
present
present
closed its eyes
absent
present
absent
∙
∙
DECREASES HEART RATE Cardiac contractility is indirectly proportional to > Oxygen > Acetylcholine > Potassium
EXP 16 – REFLEX IN HUMANS
EXP 15 – COMPLEX REFLEXES Before strychnine: Withdrawal; stimulates flexor and inhibits extensor by varying the neurotransmitter used Flexor – acetylcholine is used Extensor – glycine, inhibitory Strychnine inhibits the i nhibitor, acetylcholine would increase in the synapse; hence flexor and extensor are stimulated After strychnine: increase in tone muscles, contraction but no movement because antagonistic muscles contract at the same time
COORDINATED Withdrawal reflex Efferent nerves respond in an orderly sequence Purposeful reflex act
EXP 35 – TEMPERATURE & HEART RATE
UNCOORDINATED Stiffening / Spasm Efferent nerves respond in an disorderly sequence Disorderly movements
VISCERAL RELEX accomplished BENEATH the level of consciousness
SOMATIC RELFEX accomplished ABOVE the level of consciousness
TYPES OF REFLEX Monosynaptic – one synapse between two neurons Polysynaptic – several neurons communication communication with each other COMPONENTS OF A REFLEX A monosynaptic reflex would have: a. Sensory receptor – present where the stimulus is received, it converts stimulus to a neural signal b. Sensory nerve – 1 connection between 2 neurons c. Motor nerve – conveys signal from sensory nerve to muscle d. Effector muscle – muscle which moves *All components must be present to illicit reflex Polysynaptic reflex would have: Several interneurons which can ascend up to the brain and the response would be modified by several motor neurons EXP 10 – ISOTONIC & ISOMETRIC CONTRACTIONS
ISOMETRIC – pinned leg, same length of gastrocnemius, increase tone or tension, tension directly proportional to cross bridges ISOTONIC – free leg, change in length of muscle, same number of cross bridges COCENTRIC – muscle shortening ECCENTRIC – length increases, tone is same
Results ISOTONIC (frog) ISOMETRIC (frog) ISOMETRIC (human)
EXP 9 – SUMMATION
Flexing of leg Stiffening of leg No change in length, more tension
Stimulate at relative refractory period
ISOTONIC Shortened Lesser amount Greater amount Lesser amount
Muscle length Muscle tension Inertia Force
ISOMETRIC No change Greater amount Lesser amount Greater amount
EXP 8 – SIMPLE CONTRACTION
A. Lag phase AP reaches axon terminal and causes reversal of charges (depolarized), (depolarized), AP opens voltage gated calcium channels, calcium will go in. Increase in calcium will cause synaptic vesicles containing ach will fuse with premembranes. Ach will be r eleased, diffuses in synaptic cleft, binding to receptors and lig and gated channels. Ach then opens sodium channels and sodium goes and depolarizes. Calcium in SR, will release calcium and goe s out and binds with troponin C. Troponin will take myosin out of binding site B. Contraction phase starts when myosin binding site is exposed cross bridge cycling happens C. Relaxation phase calcium will be brought back by calsequestrin calcium will detach and cover troponin binding site
Single Muscle Contraction
A AB BC CD C
– application of stimulus – lag / latent phase – contraction phase – relaxation phase – peak
Refractory period – no action potential can be generated Absolute refractory – Point 0 to positive, to resting membrane potential Relative r efractory – can be stimulated again, threshold potential is farther from RMP; need higher intensity of stimulus Threshold potential should be r eached to open sodium voltage gated channels, rush of sodium, to turn to positive Potassium voltage gate channels remains open during repolarization
Summation
A AB BC C CD DE E EF
– application of stimulus – lag / latent phase – 1st contraction phase – 1ST peak – 1st relaxation phase – 2nd contraction phase – 2nd peak – 2nd relaxation phase
Reflexes Corneal/Conjunctiva Blink Photopupillary Direct Photopupillary Consensual Pupillary Skin
Sensory receptor Mechanoreceptors Rods & Cones Rods & Cones
EYE REFLEXES Sensory nerve Motor nerve
CN 5 Div 1 CN 2 CN 2
CN 7 CN 7 CN 3
Effector muscle Orbicularis oculi Orbicularis oculi Circular muscle of iris
Rods & Cones
CN 2
CN 3
Circular muscle of iris
Pain receptors
CN 5
CN 3
Radial muscles of iris
Accommodation Far to near Accommodation Near to far
Retinal ganglion cells Retinal ganglion cells
CN 2
CN 3
Medial rectus
CN 2
CN 3
Lateral rectus
convergence
Photoreceptors
CN 2
CN 3
Medial rectus muscle
DIVERGENCE
Photoreceptors
CN 2
CN 6
Lateral rectus muscle
Patellar
Golgi tendon receptor
Biceps Triceps Ankle Wrist
Golgi tendon receptor
Stretch Receptors Golgi tendon receptor Golgi tendon receptor
DEEP TENDON REFLEXES L3 L4
C5 C6 S1 C6
C6 C7 S2 C7
Quadriceps femoris, hamstring Biceps brachii Triceps brachii Gastrocnemius Extensor digitorium
Action Blinking of eyes Blinking of eyes Constricting of pupils
Constricting of contralateral pupil Dilation – sympathetic response Dilation of pupils to have clearer view, lens relaxes Constriction of pupils increases amt of light, increase focus, lens bulge (Nearer) Medial deviation of iris (Farther) Lateral deviation of iris Extend Flex Extend Dorsiflex Flex
OTHER REFLEXES REFLEX Sneezing Palmar Abdominal Pharyngeal Plantar Axon Babinski Palatal Epigastric Cremasteric Gluteal
EFFECTOR EFFECTO R MUSCLE Chest muscles Tendons of fingers Rectus abdominis Middle constrictor of pharynx Gastrocnemius, soleus, flexor digitorium longus Vessel dilator Toe extensors Palatal muscle Rectus abdominis Cremaster muscle Gluteus maximus
ACTION sneezing flexes fingers contraction of abdomen dilation followed immediately by constriction plantar flexion of all toes flexes the fingers dorsiflexion of big toe and abduction of 4 other toes uvula deviates to ipsilateral side contraction of ipsilateral abdominal wall elevation of ipsilateral testicles contraction of gluteus maximus
