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BIOLOGY 30 NERVOUS & ENDOCRINE SYSTEM
What does the nervous system consist of? =brain, spinal cord, peripheral nervous system and the
endocrine system
two divisions of the nervous system =central nervous system and peripheral nervous system
what does the central nervous system consist of =brain and spinal chord
two divisions of the peripheral system =sensory and motor pathways
two divisions for motor pathways =somatic and autonomic
two divisions of autonomic =sympathetic and parasympathetic
basic impulse transmission pathway =reflex arc
cells of the nervous system =glial cells and neurons
glial cells =support and nourish neurons
neurons =basic unit of the nervous system, formed from nerves
3 types of neurons =sensory, inter neurons, motor
sensory =receive stimuli
interneurons =integrate information
motor =send instructions to effectors
reflex arc =sensory neuron, interneuron, motor neuron, effector
neuron structure =dendrites, cell body and axon
dendrite =receives information from sensory receptors or other neurons and sends the signal to the cell
body
cell body =integrates and generates signals in and out
axon =conducts signals from the cell body to an effector or another neuron
nodes of ranvier =areas between the myelin sheath; where action potentials take place
myelin sheath =fatty protein that covers the axon (as schwann cells) to speed the rate a which impulses
are travelling in
neurilemma =thin membrain that allows damaged cells to repair after an injury
white matter =contains neurilemma and myeline
grey matter =no neurilemma and myeline
homeostasis =`a state of relative stability within the body

membrane potential =generate a voltage difference across the inside and outside of the cell membrane,
this generates a nerve impulse
resting membrane potential =potential difference across the membrane in a resting neuron; -70mV
...
this provides energy for the nerve impulse (preparations)
polarization =generating a resting potential of -70mV
how to achieve polarization =large protein molecules and small ions are negatively charged inside the
axon and the sodium-potassium exchange pump
sodium-potassium exchange pump =uses atp to transport 3 sodium ions out and 2 potassium ions into
the cell
location of action potentials =nodes of ranvier
what are nerve impulses made of =series of action potentials
action potential =nerve cells get excited and open sodium gates which lead to depolarization and the
inside of the cell becomes more positive; -55mV
threshold potential =once the voltage difference reaches -55mV an action potential will occur, once it
reaches +35mV sodium gates close
repolarization =potassium gates open carrying out positive charges out of the cell and return to its
previous polarization
hyperpolarization =membrane potential overshoots and reaches -90mV, at this point the potassium
gates close
refractory period =brief time that action potentials cannot occur
how does one action potential stimulate another =sodium ions diffuse both directions and reach
neighbouring nodes of ranvier causing it be more positive, depolarized to threshold
synapse =connection between a neuron and another neuron or an effector
neuromuscular junction synapse =synapse between a motor neuron and a muscle cell
neurotransmitters =chemical messengers that carry neural signals from one neuron to another, effector,
gland or muscle
acetylcholine =a neurotransmitter that excites a muscle cell membrane causing depolarization and the
muscle fibres to contract
cholinesterase =breaks down acetylcholine allowing ion gates to close repolarize
spinal cord =nerve issue that extends out of the skull from the brain, vital communication link with the
brain and peripheral nervous system
3 protections for the brain and spinal cord =vertebrae, cerebrospinal fluid, meninges
cerebrospinal fluid =shock absorber and transports material

meninges =encloses the brain and spinal cord
3 layers of meninges =dura, arachnoid, pia
blood brain barriers =separates blood and the central nervous system
...

thalamus =provides connections between various parts of the brain; relays information from senses to
parts of the brain
hypothalamus =helps regulate the internal environment
cerebrum =largest part of the brain, divided into right and left hemisphere
...
lets the other half know what
the other half is doing
...
sensory neurons send information about the environment to the
central nervous system
autonomic system =involuntary control
...
releases norepinephrine which has
an excitatory effect on its target muscles
...
consist of rods and cones that absorb light and allow us to
sense different levels of lights and shades of color
chemoreceptors =stimulated by chemicals
...
touch, hearing, balance
thermoreceptors =temperature
adaptation =adjust the size of the pupil based on light conditions
...
involves utricles and saccule
proprioceptors =mechanoreceptors found in joints, tendons and muscle
papillae =bumps on the tongue that detect taste
sound to electrical impulses =sound waves, vibrations, nerve impulse
sound to brain =auditory nerve, brain stem, thalamus, temporal lobe
olfactory cells =chemoreceptors for the nlose
hearing loss =damaged hair cells
endocrine system =endocrine glands and the hormones they secrete
...
ex estrogen
anterior pituitary =produces 6 major hormones (hGH, TSH, ACTH, FSH, LH, PRL)
posterior pituitary =stores 2 hormones, produced by the hypothalamus (ADH, OCT)
Pancreas hormones =insulin and glucagon
insulin (beta) =lowers blood sugar converts glucose into glycogen (stored by liver)
glucagon (alpha) =increase blood sugar by converting glycogen to glucose in the liver
What is T4 and T3 made of? =Iodine
How do you treat Graves Disease? =Destroy the thyroid, then treat for hyperthyroidism with
supplements
Calcitonin =Lowers blood calcium levels
parathyroid hormone (PTH) =increases blood calcium levels
What do Calcitonin and PTH act on? =Intestines, kidneys and bones



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