Warm-Up Draw and label the parts of a neuron. Describe saltatory conduction. Explain how a nerve impulse is transmitted across a neuron.

Warm-Up What happens at the synapse? Choose 1 neurotransmitter. Describe its action. What is the role of the following structures in the human brain? Brainstem Cerebellum Cerebrum Corpus callosum

Nervous Systems Chapter 38

You must know Different sensory receptors respond to various types of input. The brain serves as a master neurological center for processing information and directing responses. Different regions of the brain have different functions. Structures and associated function for animal brains are products of evolution, and increasing complexity follow evolutionary lines. How the vertebrate brain integrates information, which leads to an appropriate response.

Evolution of Nervous Systems

Vertebrate Nervous System Central nervous system (CNS): brain + spinal cord Peripheral nervous system (PNS): transmits info to/from the CNS Ganglia: clusters of neurons that act as relay points to transmit info

Connecting the CNS and PNS

Peripheral Nervous System Somatic nervous system Autonomic nervous system Sympathetic division Parasympathetic division Enteric division

Sensory vs. Motor Division

Sensory Receptors Mechanoreceptors: physical stimuli – pressure, touch, stretch, motion, sound Thermoreceptors: detect heat/cold Chemoreceptors: transmit solute conc. info – taste (gustatory), smell (olfactory) Electromagnetic receptors: detect EM energy – light (photoreceptors), electricity, magnetism Pain receptors: respond to excess heat, pressure, chemicals

This rattlesnake and other pit vipers have a pair of infrared receptors, one between each eye and nostril. The organs are sensitive enough to detect the infrared radiation emitted by a warm mouse a meter away. Eye Infrared receptor Some migrating animals, such as these beluga whales, apparently sense Earth’s magnetic field and use the information, along with other cues, for orientation. Chemoreceptors: antennae of male silkworm moth have hairs sensitive to sex phermones released by the female

Stimulus – Response

STIMULUS   RESPONSE Sensory receptors Sensory neurons Interneurons Effector organ (muscles, glands) Motor neurons  RESPONSE

Reflexes Simple, automatic nerve circuit in response to a stimulus Conscious thought NOT required Reflex arc: Stimulus detected by receptor Sensory neuron Interneuron (spinal cord or brain stem) Motor neuron Response by effector organ (muscles, glands)

Knee-jerk reflex

The Vertebrate Brain

Vertebrate brain is regionally specialized Major Regions: forebrain, midbrain, hindbrain

Brain Development

Human Brain Structure Function Brainstem Cerebrum Cerebellum

Human Brain Structure Function Brainstem Cerebrum Cerebellum *Oldest evolutionary part* Basic, autonomic survival behaviors Medulla oblongata: breathing, heart & blood vessel activity, digestion, swallowing, vomiting Conducts sensory and motor signals between spinal cord and higher brain centers Cerebrum Cerebellum

Brainstem

Human Brain Structure Function Brainstem Cerebrum Cerebellum *Oldest evolutionary part* Basic, autonomic survival behaviors Medulla oblongata: breathing, heart & blood vessel activity, digestion, swallowing, vomiting Conducts sensory and motor signals between spinal cord and higher brain centers Cerebrum Information processing (learning, emotion, memory, perception, voluntary movement) Right & Left cerebral hemispheres Corpus callosum: connect hemispheres Cerebellum

Grey matter: neuron cell bodies, unmyelinated axons White matter: fatty, myelinated axons Cerebrum

Thalamus: main center sensory/motor info passes to and from cerebrum Hypothalamus regulates homeostasis feeding, fighting, fleeing, reproducing, thermostat, thirst, appetite, circadian rhythms Releases hormones that affect pituitary

Human Brain Structure Function Brainstem Cerebrum Cerebellum *Oldest evolutionary part* Basic, autonomic survival behaviors Medulla oblongata: breathing, heart & blood vessel activity, digestion, swallowing, vomiting Conducts sensory and motor signals between spinal cord and higher brain centers Cerebrum Information processing (learning, emotion, memory, perception, voluntary movement) Right & Left cerebral hemispheres Corpus callosum: connect hemispheres Cerebellum Coordinate movement & balance Motor skill learning

Cerebellum

Cerebral cortex controls voluntary movement and cognitive functions