CNS and Afferent PNS

What is in the CNS?

• brain

• spinal cord

what is in the PNS?

• afferent division

• efferent division

what goes into afferent division?

• sensory stimuli

• visceral stimuli

what is in the efferent division?

• somatic nervous system

• automatic nervous system

what is in the somatic nervous system?

• motor neurons (skeletal muscle)

what is in the automatic nervous system?

• sympathetic nervous system

• parasympathetic nervous system

  • smooth muscle

  • cardiac muscle

  • exocrine glands

  • some endocrine glands

what is plasticity of the brain?

•When you learn, new connections between neurons are made, not new nerve cells.

how is homeostasis maintained in the brain?

•The blood-brain barrier helps to keep the environment in the brain in a steady state

what does the blood brain barrier prevent?

•fluctuations in electrolyte concentrations within the brain

•circulating hormones from reaching the brain

•harmful blood-born substances from reaching the brain

does the flow of blood and blood pressure fluctuate?

• False

  • because A constant supply of  oxygen and glucose are needed to supply the ATP needed

what are the cerebral cortex major functions?

1. Sensory perception

2. Voluntary control of movement

3. Language

4. Personality traits

5. Sophisticated mental events, such as thinking memory,

    decision making, creativity, and self-consciousness

what is the basal nuclei major functions?

1. Inhibition of muscle tone

2. Coordination of slow, sustained movements

3. Suppression of useless patterns of movements

what is the thalamus major functions?

1. Relay station for all synaptic input

2. Crude awareness of sensation

3. Some degree of consciousness

4. Role in motor control

what is the hypothalamus major functions?

1. Regualtion of many homeostatic functions, such as temperature

    control, thirst, urine output, and food intake

2. Important link between nervous and endocrine systems

3. Extensive involvement with emotion and basic behavioral patterns

what is the cerebellum major functions?

1. Maintenance of balance

2. Enhancement of muscle tone

3. Coordination and planning of skilled voluntary muscle activity

what is the brainstem major functions?

1. Origin of majority of peripheral cranial nerves

2. Cardiovascular, repiratory, and digestive control centers

3. Regulation of muscle reflexes involved with equilibrium and posture

4. Reception and intergration of all synaptic input from spinal cord;

    arousal and activation of cerebral cortex

5. Role in sleep-wake cycle

what is the function of the afferent pathways?

•carry information from receptors to the central nervous system

what are the efferent pathways?

•carry information from the central nervous system to tissues and organs

does input about homeostatic conditions reach a conscious awareness level?

False

what are the conscious somatic sensations?

• touch

• pressure

• heat

• cold

• pain

what are the conscious specialized senses?

• vision

• hearing

• taste

what are sensory receptors?

specialized ending of a neuron or a separate cell
that is closely associated
with neuron                                                                        

what is transduction?

stimulus must be converted into electrical energy

what is the process of transduction?

stimulation → Receptor membrane permeability is altered (the stronger the stimulus, the more change in permeability) → Na+ influx → graded potential (weak stimulus) OR actional potential (if threshold is reached)

what are chemoreceptors?

detect chemicals dissoved in solution like O₂ or CO₂,  glucose, electrolytes, etc. (also the senses of smell and taste)

what are thermoreceptors?

heat and cold

what are photorecptors?

light

what are mechanoreceptors?

respond to touch, pressure, vibration and stretch

what are baroreceptors?

monitor changes pressure within organs (blood pressure in blood vessels)

what are nociceptors?

pain

what is sensory adaption?

•Receptor adapts to sustained stimulus by not responding to it to the same degree

what are phasic receptors?

adapt rapidly to sustained stimulus

what are tonic receptors?

–do not adapt or if they do, very slowly

what is sensory acuity?

The area around a sensory receptor = the receptive field

The more dense the receptors

→

the smaller the receptive field

→

the higher the acuity

…and vis versa