1. Integration and Control: Nervous System
Chapter 37
Integration and Control: Nervous System

2. Communication Lines Stimulus (input) Receptors (sensory neurons)
Integrators
(interneurons)
motor neurons
Effectors
(muscles, glands)
Response
(output)

3. Invertebrate Nervous Systems
All animals except sponges have some sort of nervous system
Nerve cells are oriented relative to one another in signal-conducting and information-processing highways

4. Vertebrate Nervous Systems
Vertebrate nervous system divisions

5. Central and Peripheral Nervous Systems
Central nervous system (CNS)
Brain
Spinal cord
Peripheral nervous system (PNS)
Nerves that thread through the body

6. Central nervous Peripheral nervous system (CNS) system (PNS) Brain
Cranial
nerves
Spinal cord
Ganglia
outside
CNS
Spinal
nerves
Figure 38.4 The vertebrate nervous system 6

7. Peripheral Nervous System
Afferent
sensory
ends in the brain
Efferent
Somatic nerves
motor functions
Autonomic nerves
visceral functions
controls
smooth, cardiac muscles
glands

8. (information processing)
Central Nervous
System
(information processing)
Peripheral Nervous
System
Afferent neurons
Efferent neurons
Autonomic
nervous system
Motor
system
Sensory
receptors
Control of
skeletal muscle
Figure 38.5 Functional hierarchy of the vertebrate peripheral nervous system
Internal
and external
stimuli
Sympathetic
division
Parasympathetic
division
Enteric
division
Control of smooth muscles,
cardiac muscles, glands 8

9. Peripheral Nervous System
3 Divisions
Sympathethic Divsion
Originate in the thoracic and lumbar regions of the spinal cord
Ganglia are near the spinal cord
cluster of neurons
Energy expending
Promote responses that prepare the body for stress or physical activity
fight-or-flight response

10. Peripheral Nervous System
Parasympathetic Division
Originate in the brain and the sacral region of the spinal cord
Ganglia are in walls of organs
promotes calming and a return to “rest and digest” functions
Energy conserving
Enteric Division
controls activity of the digestive tract, pancreas, and gallbladder

11. Sympathetic and Parasympathetic Nerves
Autonomic nerves

12. Central nervous system (CNS)
Peripheral nervous system (PNS)
Brain and spinal cord
Cranial nerves and spinal nerves
Integrative and control centers
Communication lines between the
CNS and the rest of the body
Sensory (afferent) division
Motor (efferent) division
Somatic and visceral sensory
nerve fibers
Motor nerve fibers
Conducts impulses from the CNS
to effectors (muscles and glands)
Conducts impulses from
receptors to the CNS
Somatic sensory
fiber
Somatic nervous
system
Autonomic nervous
system (ANS)
Skin
Somatic motor
(voluntary)
Visceral motor
(involuntary)
Conducts impulses
from the CNS to
skeletal muscles
Conducts impulses
from the CNS to
cardiac muscles,
smooth muscles,
and glands
Visceral sensory fiber
Stomach
Skeletal
muscle
Motor fiber of somatic nervous system
Sympathetic division
Parasympathetic
division
Mobilizes body
systems during activity
Conserves energy
Promotes house-
keeping functions
during rest
Sympathetic motor fiber of ANS
Heart
Structure
Function
Sensory (afferent)
division of PNS
Parasympathetic motor fiber of ANS
Bladder
Motor (efferent)
division of PNS

13. Vertebrate Brains 3 areas of the brain Hindbrain
regulates organs below level of consciousness
coordinates motor activity
Midbrain
reflex response to sight and sound
Forebrain
receives sensory input from midbrain and hindbrain
regulates their output
optic lobes
coordinating reflex responses

14. Embryonic brain regions Brain structures in child and adult
Cerebrum (includes cerebral cortex,
white matter, basal nuclei)
Telencephalon
Forebrain
Diencephalon (thalamus,
hypothalamus, epithalamus)
Diencephalon
Midbrain
Mesencephalon
Midbrain (part of brainstem)
Metencephalon
Pons (part of brainstem), cerebellum
Hindbrain
Myelencephalon
Medulla oblongata (part of brainstem)
Mesencephalon
Cerebrum
Diencephalon
Metencephalon
Midbrain
Diencephalon
Myelencephalon
Hindbrain
Figure 38.6b Exploring the organization of the human brain (part 2: brain development)
Midbrain
Pons
Medulla
oblongata
Spinal
cord
Forebrain
Telencephalon
Cerebellum
Spinal cord
Embryo at 1 month
Embryo at 5 weeks
Child 14

15. What is a Neuron? Carries an action potential Amitotic
Wrapped in myelin
insulates
speeds up transmission
3 components
cell body
1 or more dendrites
axon

16. 2 Functions of a Neuron Excitability respond to a stimulus
Conductivity
ability to transmit a stimulus

17. Three Classes of Neurons
1.) Motor neurons
efferent
take impulses from CNS to muscles and glands
have many dendrites and a single axon (multi- polar)
2.) Sensory neurons
afferent
take info to the CNS
unipolar

18. Neurons

19. Motor Neuron dendrites Input Zone cell body Trigger Zone axon endings
Conducting Zone
axon
Output Zone
axon endings

20. Three Classes of Neurons
3.) Inter-neurons
occur within the CNS
multi-polar
account for complex pathways that account for
thinking
memory
language

22. Neuroglia 2 types of Neuroglia microglia immune cells
remove bacterial and debris
astrocytes
provide metabolic and structural support
form tight junctions
blood-brain barrier

23. Function of the Spinal Cord
Expressway for signals between brain and peripheral nerves
Sensory and motor neurons make direct reflex connections in the spinal cord
Spinal reflexes do not involve the brain

24. Organization of the spinal cord

25. Stretch Reflex
Stretch reflex

26. Transmission of Nerve Impulses
Voltage is a measure of the electrical potential difference between 2 points
one placed inside and another placed outside the axon
Resting potential
axon isn’t conducting an impulse
directly related to Na and K present
normally higher concentration of K within axon
due to active transport
sodium / potassium pump

27. Ion Concentrations: Resting Potential
Potassium (K+)
higher inside than outside
Sodium (Na+)
higher outside than inside

28. Animation: Resting Potential
Right click slide / Select play

29. Transmission of Nerve Impulses
Action Potential
rapid change in polarity
gated ion channels open / close in response to stimuli
during depolarization many more Na ion gates open
change in polarity causes Na channels to close and K channels to open
hyperpolarization

30. All or Nothing All action potentials are the same size
If stimulation is below threshold level, no action potential occurs

31. Action potential propagation

32. Summarizing Action Potentials
Response to a stimulus
Membranes become permeable to Na+
Na+ rapidly enter cell
depolarizes the membrane
continued Na+ diffusion causes reverse polarization
membrane becomes impermeable to Na+ and permeable to K+
K+ diffuses out to repolarize the membrane
hyperpolarization

33. Synaptic Transmission
Synapse
axon terminal is in close proximity to the dendrite of another neuron
synaptic cleft
small gap between neurons
nerve impulse must be carried across the synaptic cleft via a neurotransmitter
stored in synaptic vesicles

34. Synaptic Transmission
Action potential in axon ending of pre-synaptic cell causes voltage-gated calcium channels to open
Flow of calcium into pre-synaptic cell causes release of neurotransmitter into synaptic cleft

35. Synaptic Transmission
Neurotransmitter diffuses across cleft and binds to receptors on membrane of postsynaptic cell
ligand-gated ion channels
binding of neurotransmitter opens ion channels in the membrane of postsynaptic cell
generating a postsynaptic potential

36. Generation of Postsynaptic Potentials
Postsynaptic potentials fall into two categories
Excitatory postsynaptic potentials (EPSPs)
depolarizations that bring the membrane potential toward threshold
continues the action potential
Inhibitory postsynaptic potentials (IPSPs)
hyperpolarizations that move the membrane potential farther from threshold
stops the action potential 36

37. Generation of Postsynaptic Potentials
Duration of postsynaptic potential is limited by rapidly clearing neurotransmitter molecules from the synaptic cleft
neurotransmitters can be
recaptured into presynaptic neurons to be repackaged into synaptic vesicles
recaptured into glia to be used as fuel or recycled to neurons
removed by simple diffusion or hydrolysis of the neurotransmitter 37

38. K Ca2 Na Presynaptic cell Postsynaptic cell Axon Synaptic vesicle
containing neurotransmitter 1
Synaptic
cleft
Postsynaptic
membrane
Presynaptic
membrane 3 4
Figure A chemical synapse K
Ca2 2
Ligand-gated
ion channels
Voltage-gated
Ca2 channel
Na 38

39. Dendrites Stimulus Axon hillock Nucleus Cell body Presynaptic cell
Signal
direction
Synapse
Synaptic terminals
Figure 37.2 Neuron structure
Synaptic
terminals
Postsynaptic cell
Neurotransmitter 39

40. Types of Neurotransmitters
Acetylcholine (Ach)
excites skeletal muscle
inhibits cardiac muscle
Norepinephrine (NE)
important in dreaming, waking, mood, respond to stress
Epinephrine
adrenalin
Dopamine
emotions, learning, attention, fine motor skills

41. Types of Neurotransmitters
Serotonin
thermoregulation, sleeping, emotions, perception
GABA
gamma amino acid butyric acid
inhibitor of neurotransmitters released by other neurons
Acetycholinesterase (Ache)
enzymes that rapidly inactivate the neurotransmitter

42. Nervous System Controls Muscle Contraction
Signals from nervous system travel along spinal cord, down a motor neuron
Endings of motor neuron synapse on a muscle cell at a neuromuscular junction

44. Neuromuscular Junction
Axon terminal fits into depression in sarcolemma
Nerve impulse travels down axon to axon terminal
ACH is released into synaptic cleft and binds with receptor sites
Travels into T-tubules which cause Ca to be released from sarcoplasmic reticulum
Ca alters the configuration of actin and causes a change in binding site on actin

45. Troponin and Tropomyosin
lie in groove in actin filament
when muscle is relaxed, tropomyosin blocks myosin binding site
myosin
binding site
blocked
troponin
actin

46. Troponin and Tropomyosin
when troponin binds calcium ions, it changes shape and moves tropomyosin
cross-bridge formation and contraction can now proceed
myosin head
actin

47. Troponin and Tropomyosin

48. Neuromuscular Junction
Ach
contraction
activates release of Ca
Ache
relaxation
recyles Ach
causes Ca to be reabsorbed into sarcoplasmic reticulum

50. Sliding filament model
Muscle Contraction
Sliding filament model

52. Muscle Contractions
Types of contractions

53. Neurotransmitter Imbalances
Stimulants
increase alertness and body activity, then cause depression
caffeine
nicotine
mimics acetylcholine
affects skeletal muscle activity
cocaine / Heroin
blocks neurotransmitters reuptake
affects dopamine levels

54. PET Scan
Cocaine's long term effect

55. Neurotransmitter Imbalances
amphetamines & Ecstasy
induce dopamine release
Depressants
lower activity of nerves and parts of the brain
low level of serotonin
Parkinson’s
lack of dopamine
Alzheimer’s
lack of acetylcholine

56. Fig a, p.582

59. Neurotransmitter Imbalances
Hallucinogens and Marijuana
skew sensory perception by interfering with action of neurotransmitters
LSD affects action of serotonin
marijuana is a depressant at low dose
it can also cause disorientation, anxiety, delusion, and hallucinations