Nervous System Organization

What are the 6 properties of life?

1. organized structure

2. energy processing

3. homeostasis

4. reproduction, growth, & development (individuals)

5. evolution (populations)

6. responses to environment

What are the simplest animals with a nervous system?

cnidarians

Do cnidarians have a central control organ?

no

How is the nervous system organized in cnidarians?

nerve net

nerves

bundles of neurons

What is the central control structure for echinoderms?

nerve ring

radial nerves

connect the nerve ring and muscle

What has the simplest clearly defined central nervous system?

platyhelminthes

How is the nervous system organized in platyhelminthes?

ladder-type nervous system

How is the nervous system organized in arthropods?

• brain = more complex

• ganglia

ganglia

clusters of neuron cell bodies

How is the nervous system organized in vertebrates?

• central nervous system

• peripheral nervous system

What makes up the central nervous system?

brain and spinal cord

What makes up the peripheral nervous system?

nerves and ganglia

What is the role of glial cells?

support for neurons

What glial cells are in embryos?

radial glia

What do radial glia do?

form tracks in the developing embryo

How do neurons use the tracks that are formed by radial glia?

neurons migrate from the neural tube along the tracks

What glial cells are in adults?

• ependymal cells

• astrocytes

• microglia

• oligodendrocytes

• Schwann cells

Where are ependymal cells located?

CNS

Where are astrocytes located?

CNS

Where are microglia located?

CNS

Where are oligodendrocytes located?

CNS

Where are Schwann cells located?

PNS

What are the functions of the ependymal cells?

produces cerebrospinal fluid (CSF)

What are the functions of the astrocytes?

• dilate blood vessels

• regulates CSF

• stimulates formation of the blood/brain barrier

What are the functions of the microglia?

phagocytic; important for cleaning up cellular debris

What are the functions of the oligodendrocytes?

produces myelin

myelin

• lipid in the plasma membrane

• sheath around axons

• electrical insulation

What are the functions of the Schwann cells?

produce myelin sheath

(Gray/white) matter is unmyelinated.

gray

(Gray/white) matter is myelinated.

white

What are ventricles in the brain?

cavities with CSF, nutrients, and hormones;

removes wastes

Where is the spinal cord?

inside the spine

What does the spinal cord do?

links the brain and the rest of the nervous system

What are the four components of the spinal cord?

1. small central canal

2. gray matter

3. white matter

4. CSF

Gray matter surrounds the…

central canal

White matter surrounds the…

gray matter

What are the two functions of the spinal cord?

1. transmits impulses to and from the brain

2. controls reflex actions

What are reflex actions?

• rapid, involuntary response to a specific stimulus

• predictable & automatic

Are reflex actions independent of the brain?

yes

SEQ the knee-jerk reflex

1. sudden stretch in quadriceps muscle

2. detected by a sensory receptor

3. sensory neuron sends a signal to quadriceps

4. motor neuron sends a signal to quadriceps

5. interneuron sends a signal to another motor neuron

6. motor neuron sends a signal to the hamstring

7. quadriceps contract and hamstring releases

What is the function of the peripheral nervous system?

transmits info to and from CNS

What are the two components of the peripheral nervous system?

1. sensory receptors

2. nerves

What do the sensory receptors do in the peripheral nervous system?

detect stimuli

What are the two types of nerves in the peripheral nervous system?

1. cranial nerves

2. spinal nerves

Where do cranial nerves emerge from?

the hind part of the brain

Where do spinal nerves emerge from?

the spinal cord

What do the cranial nerves and spinal nerves innervate?

cranial = head & upper body

spinal = the rest of the body

SEQ the pathway of a signal

stimulus →
sensory receptor →
afferent neuron (sensory) →
CNS →
efferent sensor (motor) →
motor or autonomic nervous system →
effector

Does the efferent motor have effectors?

yes

Does the afferent sensory have effectors?

no

Does the efferent motor have receptors?

no

Does the afferent sensory have receptors?

yes

afferent sensory

arrives at CNS

What are the two parts of afferent sensory?

1. visceral

2. somatic

visceral vs somatic

visceral = not aware of (internal environment)

somatic = aware of (external environment)

efferent motor

exits from CNS

What are the two parts of the efferent motor?

1. motor system

2. autonomic nervous system

What are the effectors of the motor system?

skeletal muscles

What are the effectors of the autonomic system?

glands, heart, & smooth muscles

Motor system is (aware/unaware) of control.

aware

Autonomic system is (aware/unaware) of control.

unaware

The motor system of the efferent motor has a role in…

reflexes involving the spinal cord

What are the three divisions of the autonomic nervous system?

1. enteric

2. sympathetic

3. parasympathetic

enteric division of the autonomic nervous system

• digestive tract

• pancreas

• gall bladder

sympathetic division of the autonomic nervous system

• fight or flight

• prepares for action

How does the sympathetic division of the autonomic nervous system prepare for action?

• increases heart rate, respiration, & metabolic rate

• dilates air passages

• decreased digestion

parasympathetic division of the autonomic nervous system

• rest & digest

• conserve & restore energy

How does the parasympathetic division of the autonomic nervous system conserve & restore energy?

• decreased heart rate & respiration

• increased digestion

What are the main components of the nervous system?

• brain

• spinal cord

• nerves

• sensory organs

What are the main functions of the nervous system?

• coordination of body activities

• detection of stimuli and formulation of responses to them

The CNS and PNS are antagonistic, meaning…

they work in opposition

The forebrain, midbrain, and hindbrain each give rise to…

specific structures of the brain

What region of the brain does the cerebrum develop from?

forebrain

What region of the brain does the diencephalon develop from?

forebrain

What region of the brain does the brainstem develop from?

midbrain & hindbrain

What region of the brain does the cerebellum develop from?

hindbrain

What is the structure of the cerebrum?

divided into left and right hemispheres

corpus callosum

thick band of axons that separates the two hemispheres of the brain

What are the functions of the cerebrum?

• voluntary movement

• learning

• perception

• memory

• emotion

What two parts of the brain does the diencephalon give rise to?

1. thalamus

2. hypothalamus

What are the functions of the thalamus?

main input center for sensory info

What are the functions of the hypothalamus?

• regulates pituitary gland

• homeostasis

• basic drives = hunger, thirst, sex, rage

What serves as the link between the nervous system and the endocrine system?

hypothalamus

What are the three components of the brainstem?

1. midbrain

2. pons

3. medulla oblongata

What are the functions of the midbrain?

integrates sensory info

What are the functions of the pons?

respiratory and sleep centers

What are the functions of the medulla oblongata?

basic life functions;

• respiration

• heartbeat

• blood pressure

• swallowing

• coughing

• vomiting

Where is the medulla oblongata?

on top of and continuous with the spinal cord

What are the functions of the cerebellum?

• gets info from joints, lengths of muscles, eyes, and ears

• motor skills

• coordination

• balance

What does damage to the cerebellum result in?

permanent loss of coordination