Nervous Systems

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The sympathetic and parasympathetic divisions have antagonistic effects on target organs.

Slide 27

The sympathetic division correlates with the “fight-or-flight” response.

The parasympathetic division promotes a return to “rest and digest.”

The enteric division controls activity of the digestive tract, pancreas, and gallbladder.

Slide 28

PNS:

autonomic nervous system

Stimulates glucose

release from liver;

inhibits gallbladder

Dilates pupil

of eye

Parasympathetic division

Sympathetic division

Action on target organs:

Inhibits salivary

gland secretion

Accelerates heart

Relaxes bronchi

in lungs

Inhibits activity

of stomach and

intestines

Inhibits activity

of pancreas

Stimulates

adrenal medulla

Inhibits emptying

of bladder

Promotes ejaculation and

vaginal contractions

Constricts pupil

of eye

Stimulates salivary

gland secretion

Constricts

bronchi in lungs

Slows heart

Stimulates activity

of stomach and

intestines

Stimulates activity

of pancreas

Stimulates

gallbladder

Promotes emptying

of bladder

Promotes erection

of genitals

Action on target organs:

Cervical

Sympathetic

ganglia

Thoracic

Lumbar

Synapse

Sacral

Slide 29

Slide 30

The vertebrate brain is regionally specialized

All vertebrate brains develop from three embryonic regions: forebrain, midbrain, and hindbrain.

By the fifth week of human embryonic development, five brain regions have formed from the three embryonic regions.

Slide 31

Development of the human brain

Pons (part of brainstem), cerebellum

Forebrain

Midbrain

Hindbrain

Midbrain

Forebrain

Hindbrain

Telencephalon

Telencephalon

Diencephalon

Diencephalon

Mesencephalon

Mesencephalon

Metencephalon

Metencephalon

Myelencephalon

Myelencephalon

Spinal cord

Spinal cord

Cerebrum (includes cerebral cortex, white matter,

basal nuclei)

Diencephalon (thalamus, hypothalamus, epithalamus)

Midbrain (part of brainstem)

Medulla oblongata (part of brainstem)

Pituitary

gland

Cerebrum

Cerebellum

Central canal

Diencephalon:

Hypothalamus

Thalamus

Pineal gland

(part of epithalamus)

Brainstem:

Midbrain

Pons

Medulla

oblongata

(c) Adult

(b) Embryo at 5 weeks

(a) Embryo at 1 month

Slide 32