4.4 PNS and Endocrine System

Question 1

PNS: Somatic NS

Answer 1

contains nerves that carry sensory signals from body to CNS

nerves that carry signals from CNS to skeletal muscles

associated w voluntary movement, e.g. pressing a button: signal from BRAIN to finger via SNS

Question 2

PNS: Autonomic NS

Answer 2

regulates internal enviro of the body
=> involuntary movement

signals from internal organs to CNS, from CNS to internal organs

e.g. digestion and heartbeat

Nerve fibers:
- Sympathetic
- Parasympathetic

Question 3

PNS
ANS

Sympathetic NS (fight or flight responses) vs Parasympathetic NS (rest and digest responses)

Answer 3

increases energy by stimulating and mobilizing VS conserves energy

SNS - Fight or flight: increase heart rate, stimulate sweat glands

PNS - Eating a meal: stimulate digestion, slow heart rate

=> these two are “competing interests” than run the Autonomic Nervous System

Question 4

where do the fibers of the systems originate?

Answer 4

sympathetic fibers: thoracolumbar - originate around the ribs area
=> so they can coordinate the functions of many major organs AT ONCE.

parasympathetic fibers: above and below the SF
=> craniosacral: sprout from base of the brain
=> and sacral spinal cord

Question 5

Ganglia differences

Answer 5

Ganglia (ganglion)
- both parts of the ANS require 2 neurons to work!
- they meet in ganglia: clusters of neuron cell bodies that house millions of synapses

where the ganglia appear relate to their function and which division of the ANS they are serving
- sympathetic ganglia (SG) is closer to the spinal cord (fight or flight high excitement movement send signal far and wide)
- PG: way out of the spine, even inside their effector organs
occurs only when u hv the time and energy to do it, so more specific strategic signals

Question 6

Neuron differences

Answer 6

• different forms (length of axon)

SS: pre-fibers = much shorter than post-fibers because SG are close to the spinal cord, but they need a lot more to cover on the post-side to reach effectors

PG: opposite.
Most Pganglia are close or inside the effector organs, so the pre are longer, so post ganglions are shorter

Question 7

preganglionic cell/fibers

Answer 7

neurons BEFORE the ganglion

Question 8

postganglionic cell/fibers

Answer 8

neurons AFTER the ganglion

Question 9

Enteric Nervous System

Answer 9

nervous system acts autonomously inside the stomach and intestines

=> reflex circuits within the ENS, does not require instructions from the brain to work

Question 10

Functions of the ENS

Answer 10

• communicates with the endocrine system to ensure release of chemicals needed in digestion
• communciates with the vagus nerve: transmits info on gut’s microbiome to the brain
• hunger, satiety (conscious perceptions)
• source of 95% of the body’s serotonin!

Question 11

Endocrine system

Answer 11

• made up of glands that release hormones (chemical messengers) into our bloodstream
• ES responds to input from the NS and hypothalamus
• involved in arousal, growth and metabolism

Question 12

Most important glands

Answer 12

in the brain
- pineal gland
- pituitary gland

• thyroid gland (throat)
• adrenal gland (above the kidney)
• islets of Langerhands (pancreas)
• ovaries and testes

Question 13

Pituitary gland

Answer 13

• above roof of mouth
• many of the hormones it releases activates other glands
• regulated by hypothalamus (above it)

Question 14

Pituitary hormones

Answer 14

• oxytocin
• vasopressin
• human growth hormone