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HUMAN ORGAN SYSTEMS II
REGULATION
NERVE AND CHEMICAL CONTROL
Nervous System
Main organs:
brain
nerves
neuron
nerve cord
Functions:
To pick up stimulus from
the body and the environment
and respond appropriately.
Maintain homeostasis by controlling and
coordinating functions throughout
the body.
Neurons: the main functional unit of nervous system
Cell body-largest part of the neuron
Dendrites-carry impulses towards cell body
Axons-long fibers that carry impulse away from cell body
Synapse-small gap where impulses cross from one neuron to the next
How an impulse travels along a neuron:
the dendrite is the input site
the axon is the output site
neurotransmitters are chemicals that allow
the impulse to move across a
synapse. These are released by the
axon types and picked up by the
dendrites, like puzzle pieces.
Axon=output
signal or
impulse
Dendrite=input
stimulus
Electrical signal is caused by movement of sodium and potassium ions. Both are
positive ions, but there are always more sodium ions outside of the cell than there
is potassium ions inside. This makes the inside of the cell less positive or ‘negative’
than outside. When this is the case, the neuron is at ‘rest’.
When Mario’s hammer hits Luigi’s foot an impulse is sent to the neuron, specifically
the dendrite-the input site. The neuron will no longer be at the resting potential. It will
have the potential to respond and this is called the action potential. The response
comes as an electrical impulse along the Axon. The axon, through the use of protein
channels and gates, will allow more sodium ions into the cell. This shifts the charge
from negative to positive. This shift will continue all the way down the axon until it
reaches the synapse.
Interneuron
Motor neuron
During the resting potential, the protein gates allow three sodium ions out of the
Cell while keeping only 2 potassium ions inside=more positive outside. The reverse
Happens during the action potential-allowing more sodium in while letting fewer
Potassium out.
As the sodium and potassium ions change locations all the way down
the axon, three things happen
1. the impulse travels closer and closer to the synapse.
2. the resting potential returns to the neuron once the impulse
passes.
3. the action potential is transferred to the next neuron
A synapse is a microscopic gap between one neuron and another neuron
And where the impulse will be transferred to another neuron. The
Impulse is transferred through the secretion of neurotransmitters.
Neurotransmitters are amino acids that move
Across the gap and fit into shape specific
Receptors on the dendrites of the next neuron.
This activates the next neuron and the impulse.
Vesicle releasing neurotransmitters into synapse
Vesicle containing neurotransmitters
Receptor sites for neurotransmitters on next neuron
Direction of impulse
Central Nervous System:
a. brain 100 billion neurons
1. cerebrum-largest
left and right sides
intelligence, learning, judgment
2. cerebellum-coordinates and controls
muscle activity
balance
3. brain stem-connects brain to spinal cord
involuntary life dependent
actions
b. spinal cord connects brain to body
1. spinal nerves
i. Reflex automatic reaction
Peripheral Nervous System:
a. nerves and cell that are found outside brain
and spinal cord.
1. sensory-impulses from sensory organs
to CNS
** sight, hearing, taste, touch, smell**
2. motor-impulses from CNS to muscles
and/or glands
3. somatic – controls voluntary activities
such as voluntary muscles
4. autonomic – involuntary activities
Organ system: Skeletal
Main organ: BONE=living cells + protein fibers + Ca
a. cartilage
b. spongy
c. compact
d. ligament
e. marrow
Function: support and movement
protection
production of blood cells
store
Strength – arches
less dense
Strength, more dense, storage of
Ca, Mg, and P, blood vessels
Connective tissue, produces
red blood cells, stores fat,
removes old blood cells
Supplies
Blood to
Living cells
Provides protection,
nourishment
and sensation
Joints: where two bones meet.
a. moveable – hinge
pivot
gliding (saddle)
ball and socket
b. immoveable – ribs
skull
: ligaments- hold bones together
strong connective tissue
: cartilage-connective tissue that cushions,
supports, provides nutrients for
bone growth
Organ System: Muscular
Main organ:
Muscle
smooth
striated (skeletal)
cardiac
tendons
Human body has more than 600
Muscles – over 400 are skeletal
Function: Movement of bones
Protection of organs
Composition of organs
Striated or Skeletal Muscle: Muscle that is attached to bone
Muscle that can contract and relax
Muscle that is made of bands of tissue
Muscle that will tire over time
Muscle is voluntary
Contracted muscle: shortened
pulls bone
Relaxed muscle: longer
Muscle fiber=muscle cell: some
of the largest cells in the body
Muscle cells contain many
nuclei.
Remember: action of muscles will require ATP for energy
Muscle fibers slide over each other CONTRACT – shorten and pull bone
Muscle fiber return to RELAXED position
Muscles work in pairs: when one relaxes the other contracts.
Contracted muscle pulls lower arm up
Tendon-bone
to muscle
Relaxed muscle
Relaxed muscle
Relaxed muscle: forearm is down
Contracted muscle: forearm is pulled up
Smooth muscle: Muscle that composes major organs
Muscle that can contract and relax
Muscle that is composed of continuous sections of cells-look
smooth
Muscle that does not tire over time
Muscle cell contains only one nucleus
Muscle is involuntary
Cardiac Muscle: Muscle that is found in the heart
Muscle that can contract and relax
Muscle that looks like striated but functions like smooth
Muscle that does not tire over time
Single nucleus
Muscle is involuntary
0RGAN SYSTEM: INTEGUMENTARY
MAIN ORGAN: SKIN
EPIDERMIS
DERMIS
NERVES
MELANOCYTES
HAIR FOLLICLES
SWEAT GLANDS
THICKNESS OF SKIN WILL RANGE
BETWEEN .55MM (EYELIDS) TO 4MM (SOLES OF FEET/PALMS OF HANDS
.1 INCH
1 INCH
THERE IS APPROXIMATELY
22 square feet of skin on the average adult human
FUNCTION: PROTECTION-BARRIER
HOMEOSTASIS – TEMPERATURE
RESPONSE TO ENVIRONMENT
EXCRETORY
ENDOCRINE SYSTEM: system of glands that
produce and secrete hormones that connect
nervous system to brain
Hormones activate the production
Of enzymes w/in the nucleus
Functional units
glands
hormones-steroid
nonsteroid
target cells
Exocrine glands secrete through ducts
Endocrine glands secrete into bloodstream
Glands of the endocrine system
Hypothalamus-found within the brain-cerebral cortex
controls pituitary gland
Pituitary – controls most of the endocrine glands
produces large number of different hormones
Thyroid – controls metabolism
Parathyroid – controls levels and absorption of calcium
Adrenal gland – regulate water balance, and as a result BP
increases metabolism, heart rate, breathing
helps to convert complex fat and protein into
simpler glucose molecules
Islets of Langerhans – produce insulin and glucagon=storage
nonsteroid
of sugar
Gonads – testes=testosterone
ovaries=estrogen and progesterone
steroid
How do endocrine glands work? Negative feed back
Example: Mary Lou eats 5 donuts for breakfast.
Her stomach and small intestine breakdown the
sugars in those donuts and the bloodstream absorbs
the smaller molecules, raising blood sugar levels.
The pancreas monitors blood sugar levels and if
Mary Lou’s levels exceed 140mg/dl, the Islets of
Langerhans will produce and secrete insulin. The
insulin will gather all the excess glucose from the
bloodstream and send it to the liver for storage.
Four hours later, Mary Lou feels tired. The pancreas
monitors lower levels of glucose and stimulates the
Islets of Langerhans to produce and secrete glucagon
that will stimulate the liver to release glucose.
Example #2: from the text
The levels of calcium are controlled by the parathyroid glands
thyroid gland, kidneys, and the small intestine.
If calcium levels are too high, the thyroid and parathyroid
glands will produce and secrete hormones that will trigger
the kidneys to absorb more calcium in the filtrate to be
excreted with the urine. This hormone will also stimulate the
bones to absorb and store more calcium
If calcium levels are too low, the parathyroid will secrete
PTH that will trigger the intestine to absorb more calcium,
the kidneys to allow reabsorption of calcium from the neuron
and the bones to release some of the calcium stored in them.
Example #3: from last year
Walking alone down a dark street
www.abpischools.org.uk/page/modules/hormones
Reproduction:
Female
Male
Fertilization:
Sperm + egg = zygote
23
+
23
=
Diploid number
returns
46