1. Lecture 10c: Control
Systems

2. Nervous System
Signal moves from brain along nerve to
target muscle, which contracts in response
Central nervous system (CNS)- brain and
spinal cord
Peripheral nervous system(PNS)- nerves
outside of CNS
They are connected to each other and work
together

3. Neurons
Remember
neuron
anatomy

4. Neurons
Myelin sheaths- cover axons, they increase the speed at
which nerve impulses travel
3 types of neurons
Sensory: take nerve impulses from sensory organs
to the CNS, may be a simple nerve ending or part of
an organ like the eye
Interneurons: only in the CNS, carry impulses
around the CNS only, what thinks
Motor: take nerve impulses from the CNS to muscles
or glands

5. Nerve Impulse
Nerve impulses are electrical in nature
Nerve impulses are dependent on concentration
gradients
A neuron maintains:
High conc. of K+ inside the cell and a high
conc. of Na+ outside the cell, via membrane
pumps
Inside of cell is negative compared to outside

6. Nerve Impulse
The difference in charge is called an action potential-
the Na+ ions want to go inside the cell, the K+ ions
want to go out
When the neuron is signaled, gated channels open that
allow the Na+ to rush into the cell, making it positive
inside
Then the Na+ channels close and K+ channels open,
and the original gradient is restored
This movement of the charged area is the movement of
the nerve impulse

7. Nerve Impulse
The action potentials are self-propagating along the
length of an axon- as each area changes its charge it
stimulates the next area to do the same
Unmyelinated nerves conduct at about 1m/ sec,
myelinated nerves conduct at about 1oom/ sec
The myelin causes the action potential to jump
along the length of the nerve
Refractory period- a short time in which the gates can
not open- prevents nerve impulse from going
backwards

8. Nerve Impulse

9. Synapse
How does a signal get from one nerve to the next?
The gap between two nerves, or a nerve and a muscle,
is called the synapse
Neurotransmitters- chemicals which carry the
impulse from the first cell to the next across the
synapse
When the impulse gets to the end of the axon,
synaptic vesicles release neurotransmitters into
the synapse, and they are received by the next cell

10. Synapse
There are at least 25 known neurotransmitters, can
either excite or inhibit the receptor cell
Acetylcholine and norepinephrine are two best
known
After release, they are very rapidly either resorbed or
broken down, so as to not constantly stimulate the cell
Each neuron has many dendrites and synapses with
many other cells (1000- 10,000)
If it gets more excited than inhibited, it will send an
impulse

11. Drugs
Cocaine: prevents resorption of dopamine, which then stays
in synapse and continues to stimulate receptor- causes the
rush
Prolonged use- cells become resistant to dopamine
Heroin: binds to endorphin receptors, results in no pain and
good feelings
Prolonged use- body stops making its own endorphins
Marijuana: binds to a receptor for anandamide, which
creates a peaceful and contented feeling
Prolonged use- psychotic symptoms, hallucinations, etc.

12. CNS
Brain- very complex organ, we are learning
more about it all the time
We will discuss:
Cerebrum
Diencephalon
Cerebellum
Brain Stem

13. Cerebrum!!
Communicates with and coordinates the
different parts of the brain
Mostly white matter- made up of long axons
going between brain areas
Has 4 lobes: frontal, parietal, occipital, temporal
Cerebral cortex is outer layer of grey matter,
where higher level thought, voluntary motion,
and interpretation of sensation occur

14. Cerebrum- lobes and
Cerebellum

15. Cerebrum
Each area (lobe) has specific functions
Parietal lobe has primary sensory area, receives
info from skin, muscles, joints
Frontal lobe has primary motor area, makes
decisions about voluntary movement and initiates
this mvmt.
Frontal lobe as prefrontal area, which integrates
information received from other areas and is where
critical thinking and decision making occurs

16. Diencephalon
Located under the cerebrum
Contains the thalamus
receives all sensory info except smell
integrates this info and sends it to the cerebrum
also involved with memory and emotions
And the hypothalamus
helps maintain homeostasis
regulates hunger, thirst, sleep, body temp
link between nervous and endocrine systems

17. Cerebellum
Located in the back of the head
Also receives sensory input
Uses info from joints and skeletal muscles to know
where body is
Uses info from cerebral cortex to know what body
parts should be doing
Sends motor info to the body
Maintains balance and posture
Assists in learning new mechanical skills

18. Brain Stem
Connects the brain to the spinal cord
Contains midbrain
Visual and auditory reflex centers/ startle
Medulla oblongata
reflex centers regulate heartbeat, breathing, blood pressure
Reflex centers for vomiting, sneezing, swallowing,
hiccuping
Internal organ control as well
Pons- links medulla with midbrain, vital for breathing

19. How does the brain combine
different stimuli?
Limbic system- blends higher mental
functions with more primitive emotions
Includes the diencephalon parts of the
cerebrum
Binds memory to reasoning
Binds memory, emotion, and reasoning
Why we don’t always act on strong
emotions

20. Memory
Short term memory stored in the prefrontal
area, but long term memory is different
Mixture of semantic and episodic memory
Semantic- the words or numbers
Episodic- association with people, places,
etc.
In order to learn, both types must be
activated

21. Peripheral Nervous System
Outside of the CNS- contains nerves, which
are bundles of axons
Cell bodies are either within the CNS (spinal
cord, mostly) or are stored in ganglia-
collections of cell bodies within the PNS
Sensory neurons have their cell bodies in
what is called the dorsal root ganglion- a
ganglia that is next to the spinal cord

22. Somatic System
The part of the PNS that takes sensory
info from receptors/ sense organs to the
CNS, and takes motor commands from
the CNS to the skeletal muscles
In a reflex, the command to move comes
from the spinal cord, not the brain
However, the brain is told about the
stimulus that caused the reflex as well

23. Autonomic System
Automatically and involuntarily
controls cardiac and smooth muscle,
and gland activity
Parasympathetic- promotes the relaxed or
normal state
Sympathetic- promotes ‘fight or flight’,
used in emergency situations

24. Endocrine Systems
Now, we will talk about the other control
system in the body
This system consists of glands and
tissues that secrete hormones
Hormones are secreted directly into
the blood, where they have effects on
many different bodily functions

25. Hormones
Hormones bind to receptors on cells that can
respond to them, and then the cell undergoes a
metabolic change
Steroid hormones cause the cell to make a
protein
Peptide hormones bind to membrane receptor,
then start a cascade of events inside the cell-
just one binding can have a huge impact

26. Hypothalamus and Pituitary
Gland
Hypothalamus- helps regulate the
internal environment
Communicates with medulla
oblongata
Controls secretions of pituitary
gland, which is connected to the brain

27. Anterior Pituitary
Hypothalamus causes the AP to release
hormones that stimulate other glands
Involved in stimulating gonads to produce
gametes and sex hormones, and in production
of milk
Involved in growth via growth hormone
Involved in carbohydrate and fat metabolism
More, too, involving thyroid, etc.

28. Posterior Pituitary
Antidiuretic hormone- released when bld
is too concentrated, causes water to be
reabsorbed in the kidney
Oxytocin- causes uterine contractions
and also milk release during nursing

29. Thyroid and Parathyroid
Glands
Thyroid- gland in the neck, hormones it
produces increase the metabolic rate
Stimulate all cells to work at a faster rate
Thyroid and the parathyroid also involve in
Ca+ regulation in the body
Ca+ important to muscle and nerve
function, blood clotting

30. Adrenal Glands
Sit on top of the kidneys
Have inner and outer portion
Adrenal cortex (outer) and adrenal
medulla (inner)
Stimulated by the hypothalamus to
produce its hormones

31. Adrenal Medulla
Produce epinephrine and norepinephrine
Helps the sympathetic nervous
system in response to an emergency
Short-acting

32. Adrenal Cortex
Produce mineralocorticoids
Ex. aldosterone, regulates salt and
water volume
and glucocorticoids
Ex. cortisol, regulates carb, protein,
and fat metabolism

33. Pancreas
Two types of tissue, exocrine discussed in
digestion
Other type is endocrine, discusses here
Produces insulin and glucagon
Glucagon- secreted between meals, when
bld glucose is low- stimulates liver to
break down glycogen to glucose- it raises
bld glucose levels

34. Pancreas
Insulin secreted when blood glucose is high, stimulates
uptake of glucose by cells-- so insulin lowers bld glucose level
Diabetes Mellitus- Body cells do not take up or metabolize
glucose- cells need glucose even though there is plenty in the
blood
Type I- the pancreas does not produce insulin- must take
insulin injections
Type II- liver and other cells become resistant to insulin
due to poor health and eating habits
End results of both types can be the same: blindness,
kidney disease, circulatory disorders, death