What’s the function???

Nervous systems contain neural cells and glial cells

Types of neurons Sensory neurons Interneurons Motor neurons

Fig. 28-1b Sensory receptor Sensory neuron Brain Spinal cord Motor neuron Quadriceps muscles Flexor muscles Nerve Interneuron CNS PNS Reflex Arc Simplest example Does not send message to brain

Fig Signal direction Dendrites Cell body Nucleus Axon Schwann cell Myelin sheath Signal pathway Synaptic terminals Nucleus Schwann cell Layers of myelin sheaths Cell Body

Neurons work by sending an electrical impulse (action potential) from one end of the neuron (cell body) to the other (synaptic terminal) -works in ONE DIRECTION only

There is a difference in the distribution of charges inside the cell compared to outside -inside is negative; outside is positive There is a difference in the concentration of certain ions inside compared to outside outside high concentration of Na+ inside high K+ Resting Potential Animation link

Action Potential A stimulus to a neuron causes Na+ gates to open (Na+ rushes into the cell) reversing the charge cell is DEPOLARIZED Charge distribution is reestablished when K+ is allowed to leave the cell Cell is Repolarized Na+/K+ pump reestablishes the ion concentrations (expends the most energy in your body)

Sending the message on Signal reaches synaptic terminal causing vesicles containing neurotransmitters to be released into synapse Neurotransmitters diffuse across the synapse and bind to receptors on receiving cell These receptors are also gated channels -may be Na+  effect? -may be K+  effect?

Sending neuron 4 Axon of sending neuron Vesicles Synaptic terminal Vesicle fuses with plasma membrane Synaptic cleft Receiving neuron Receiving neuron Ion channels Neurotransmitter molecules Neurotransmitter is released into synaptic cleft Neurotransmitter binds to receptor Synapse Action potential arrives 3 2 1

Fig. 28-7a Dendrites Myelin sheath Axon Receiving cell body Inhibitory Excitatory Synaptic terminals

Fig. 28-7b Synaptic terminals

Botulinum toxin -inhibits release of acetylcholine Serotonin & dopamine in brain affect sleep/mood Acetylcholine motor neurons / muscles

5 Neurotransmitter Ion channel closes Ion channel opens Receptor Ions Neurotransmitter broken down and released 6

Fig Peripheral nervous system Somatic nervous system Autonomic nervous system Sympathetic division Parasympathetic division Enteric division

Fig Brain Parasympathetic division Constricts pupil Eye Stimulates saliva production Lung Constricts bronchi Slows heart Spinal cord Stimulates stomach, pancreas, and intestines Liver Stimulates urination Promotes erection of genitals Intestines Genitalia Bladder Pancreas Stomach Adrenal gland Heart Salivary glands Sympathetic division Dilates pupil Inhibits saliva production Dilates bronchi Accelerates heart Stimulates epinephrine and norepi- nephrine release Stimulates glucose release Inhibits stomach, pancreas, and intestines Inhibits urination Promotes ejacu- lation and vaginal contractions

Sensory receptors –Specialized cells or neurons that detect stimuli

Copyright © 2009 Pearson Education, Inc. All senses trigger the same type of action potential The brain distinguishes the type of stimulus Perception is the brain’s integration of sensations

Midbrain Hindbrain Forebrain Embryo (one month old) Cerebral hemisphere Diencephalon Midbrain Pons Cerebellum Medulla oblongata Spinal cord Fetus (three months old)

Embryonic Brain Regions Brain Structures Present in Adult Cerebrum (cerebral hemispheres; includes cerebral cortex, white matter, basal ganglia) Diencephalon (thalamus, hypothalamus, posterior pituitary, pineal gland) Midbrain (part of brainstem) Pons (part of brainstem), cerebellum Medulla oblongata (part of brainstem) Forebrain Midbrain Hindbrain

Midbrain Hindbrain Forebrain Cerebrum Thalamus Hypothalamus Pituitary gland Pons Medulla oblongata Cerebellum Cerebral cortex Spinal cord

Left cerebral hemisphere Right cerebral hemisphere Corpus callosum Basal ganglia

Frontal lobe Parietal lobe Temporal lobeOccipital lobe Frontal association area Somatosensory association area Visual association area Auditory association area Speech Smell Hearing Taste Speech Reading Vision Motor cortex Somatosensory cortex

Copyright © 2009 Pearson Education, Inc. The hypothalamus “master controller” influences many hormones The hypothalamus –Links the endocrine and nervous systems –Receives input from nerves about body conditions –Responds by sending out appropriate nervous or endocrine signals –Uses the pituitary gland to exert master control over the endocrine system

Brain Hypothalamus Posterior pituitary Anterior pituitary (Bone)

Hypothalamus Posterior pituitary Anterior pituitary Hormone Neuron cell Blood vessel Oxytocin ADH Kidney tubules Uterine muscles Mammary glands

Endocrine cells of the anterior pituitary Pituitary hormones Releasing hormones from hypothalamus Neuron cell Blood vessel FSH and LH TSH ACTH Prolactin (PRL) Growth hormone (GH) Endorphins Thyroid Adrenal cortex Testes or ovaries Mammary glands (in mammals) Entire body Pain receptors in the brain

Copyright © 2009 Pearson Education, Inc. HORMONES AND HOMEOSTASIS

TSH TRH Hypothalamus Anterior pituitary Thyroid Thyroid hormones Inhibition Thyroid hormones -regulate metabolism

Copyright © 2009 Pearson Education, Inc. The pancreas secretes two hormones that control blood glucose –Insulin—signals cells to use and liver to store glucose –Glucagon—causes liver to release stored glucose into the blood

Insulin 4 Beta cells of pancreas stimulated to release insulin into the blood Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Glucagon Low blood glucose level High blood glucose level Body cells take up more glucose Blood glucose level declines to a set point; stimulus for insulin release diminishes Liver takes up glucose and stores it as glycogen Alpha cells of pancreas stimulated to release glucagon into the blood Stimulus: Declining blood glucose level (e.g., after skipping a meal) Stimulus: Rising blood glucose level (e.g., after eating a carbohydrate-rich meal) Blood glucose level rises to set point; stimulus for glucagon release diminishes Liver breaks down glycogen and releases glucose to the blood

Insulin 4 Beta cells of pancreas stimulated to release insulin into the blood Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level High blood glucose level Body cells take up more glucose Blood glucose level declines to a set point; stimulus for insulin release diminishes Liver takes up glucose and stores it as glycogen Stimulus: Rising blood glucose level (e.g., after eating a carbohydrate-rich meal) 1 2 3

Glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 mL) Glucose level Glucagon Low blood glucose level Alpha cells of pancreas stimulated to release glucagon into the blood Stimulus: Declining blood glucose level (e.g., after skipping a meal) Blood glucose level rises to set point; stimulus for glucagon release diminishes Liver breaks down glycogen and releases glucose to the blood

Reproductive hormones Testosterone –Supports sperm formation –Promotes development of secondary sex characteristics Estrogen –Promotes female secondary sex characteristics FHS (folicle stimulating hormone) –Stimulates production of eggs and sperm Progesterone –Promotes growth of the uterine lining