What’s the function???

Nervous systems contain neural cells and glial cells

Types of neurons

Fig. 28-1b

Sensoryreceptor

12

3

4

Sensory neuron

Brain

Spinalcord

Motorneuron

Quadricepsmuscles

Flexormuscles

Nerve

Interneuron

CNS

PNS

Reflex Arc•Simplest example•Does not send message to brain

Fig. 28-2

Signal direction Dendrites

Cellbody

Nucleus Axon

Schwanncell

Myelin sheath

Signalpathway

Synaptic terminals

NucleusSchwanncell

Layers ofmyelin 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 PotentialA 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 onSignal 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 ofsendingneuron

Vesicles

Synapticterminal

Vesicle fuseswith plasmamembrane

Synapticcleft

Receivingneuron

Receivingneuron

Ion channelsNeurotransmittermolecules

Neurotransmitteris released into synaptic cleft

Neurotransmitterbinds to receptor

Synapse

Actionpotentialarrives

32

1

Fig. 28-7a

Dendrites

Myelinsheath

Axon

Receivingcell body

Inhibitory Excitatory

Synaptic terminals

Fig. 28-7b

Synapticterminals

Botulinum toxin -inhibits release of acetylcholine

Serotonin & dopamine in brain affect sleep/moodAcetylcholine

motor neurons / muscles

5

Neurotransmitter

Ion channel closesIon channel opens

Receptor

Ions

Neurotransmitter brokendown and released

6

Fig. 28-12

Peripheralnervous system

Somaticnervoussystem

Autonomicnervoussystem

Sympatheticdivision

Parasympatheticdivision

Entericdivision

Fig. 28-13

Brain

Parasympathetic division

Constrictspupil

Eye

Stimulatessalivaproduction

LungConstrictsbronchi

Slowsheart

Spinalcord

Stimulatesstomach,pancreas,and intestines

Liver

Stimulatesurination

Promoteserection ofgenitals

Intestines

Genitalia

Bladder

Pancreas

Stomach

Adrenalgland

Heart

Salivaryglands

Sympathetic division

Dilatespupil

Inhibitssalivaproduction

Dilatesbronchi

Acceleratesheart

Stimulatesepinephrineand norepi-nephrine release

Stimulatesglucose release

Inhibitsstomach,pancreas,and intestines

Inhibitsurination

Promotes ejacu-lation and vaginalcontractions

• 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

MidbrainHindbrain

Forebrain

Embryo (one month old)

Cerebralhemisphere Diencephalon

Midbrain

Pons

Cerebellum

Medullaoblongata

Spinal cord

Fetus (three months old)

EmbryonicBrain Regions

Brain StructuresPresent in Adult

Cerebrum (cerebral hemispheres; includescerebral 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

Medullaoblongata

Cerebellum

Cerebralcortex

Spinalcord

Left cerebralhemisphere

Right cerebralhemisphere

Corpuscallosum

Basalganglia

Frontal lobe Parietal lobe

Temporal lobe Occipital lobe

Frontal associationarea

Somatosensoryassociationarea

VisualassociationareaAuditory

associationarea

Speech

Smell

Hearing

Taste

Speech

Reading

Vision

Mot

or c

orte

xS

omat

osen

sory

cor

tex

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

Posteriorpituitary

Anteriorpituitary

Hormone Neuroncell

Bloodvessel

Oxytocin ADH

Kidney tubulesUterine musclesMammary glands

Endocrine cells ofthe anterior pituitary

Pituitary hormones

Releasing hormonesfrom hypothalamus

Neuroncell

Bloodvessel

FSHandLH

TSH ACTH Prolactin(PRL)

Growthhormone

(GH)

Endorphins

Thyroid Adrenalcortex

Testes orovaries

Mammaryglands

(in mammals)

Entirebody

Painreceptors

in the brain

Copyright © 2009 Pearson Education, Inc.

HORMONES AND HOMEOSTASIS

TSH

TRH

Hypothalamus

Anteriorpituitary

Thyroid

Thyroid hormones

Inhibition

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

4Beta cellsof pancreas stimulatedto release insulin intothe blood

Glucoselevel

Homeostasis: Normal blood glucose level(about 90 mg/100 mL)

Glucoselevel

Glucagon

Low bloodglucose level

High bloodglucose level

Bodycellstake up moreglucose

Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes

Liver takesup glucoseand stores it asglycogen

Alphacells ofpancreas stimulatedto release glucagoninto the blood

Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)

Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)

Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes

Liverbreaks downglycogen andreleases glucoseto the blood

7

6

1

2

5

8

3

Insulin

4

Beta cellsof pancreas stimulatedto release insulin intothe blood

Glucoselevel

Homeostasis: Normal blood glucose level(about 90 mg/100 mL)

Glucoselevel

High bloodglucose level

Bodycellstake up moreglucose

Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes

Liver takesup glucoseand stores it asglycogen

Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)

1

2

3

Glucoselevel

Homeostasis: Normal blood glucose level(about 90 mg/100 mL)

Glucoselevel

Glucagon

Low bloodglucoselevel

Alphacells ofpancreas stimulatedto release glucagoninto the blood

Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)

Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes

Liverbreaks downglycogen andreleases glucoseto the blood

7

6

5

8

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