Nervous
Control
Nervous Response
Detect a stimulus.
Impulses are transmitted by a neuron.
Impulses are interpreted and analyzed in
the brain or spinal cord.
The response is carried out by an effector,
such as a muscle or gland.
Nervous Tissue
Sensory neuron- transmit incoming impulses
from sense organs to brain or spinal cord.
Motor neuron- transmit outgoing messages
from brain or spinal cord to effector.
Interneuron- pathway between sensory &
motor neurons.
Nerves- many neurons grouped together.
Neuron structure
Cell body- cytoplasm & nucleus.
Axon- transmit impulses away from cell body.
Dendrites- transmit impulses toward cell
body.
Myelin sheath- outer layer that allows impulse
to travel more quickly.
Neuron Junctions
Synapse- small, fluid-filled space between
neurons through which the impulse has to cross.
Neurotransmitter- chemicals that are released
by axon of a neuron; they transmit impulses across the synapse .
Drugs and the Nervous System
Depressants decrease nerve transmission;
results in impaired coordination, slowed reaction time, & impaired
judgement.
Stimulants such as caffeine increase nerve
transmission causing increased heartbeat rate, blood pressure, & mental
alertness.
Nervous Systems
Unicellular organisms
Examples: Bacteria, Protozoan (Euglena,
Paramecium)
taxis- movement of an organism toward or
away from a stimulus
contain specialized cell parts ( eye spots
& flagella) to help respond to the environment
Porifera: none.
Cnidaria: nerve net.
Platyhelminthes: eye spots; central ganglion.
Nematoda: nerve ring; dorsal and ventral
nerve cords.
Annelida: anterior ganglion; ventral nerve
cord.
Gastropoda: six pair of ganglion; nerve
cord.
Bivalvia: ganglia above mouth and foot.
Cephalopoda: complex brain and eyes.
Echinodermata: nerve ring around mouth.
Crustacea: ganglia connected to ventral
nerve cord.
Arachnida: two large ganglia; six to eight
simple eyes.
Insecta: chain of ganglia on ventral nerve
cord. Hearing, smelling; two compound eyes, up to three simple eyes.
Chondrichthyes: dorsal nerve cord, anterior
brain; acute sense of smell.
Osteichthyes: dorsal nerve cord, anterior
brain; acute sense of smell; lateral line system.
Amphibia: dorsal nerve cord; anterior brain.
Reptilia: dorsal nerve cord, anterior brain;
Jacobsen’s organs used for smell.
Aves: dorsal nerve cord; large brain; color
vision; well-developed hearing.
Mammalia: dorsal nerve cord; highly developed
brain; most have good vision.
Human Nervous System
Central Nervous System (CNS)
brain and one or more nerve cords (spinal
cord) which serve as control centers
Peripheral Nervous System (PNS)
sensory and motor neurons connected to the
CNS
Central Nervous System
Brain
Protected by the skull and meninges
(3 layers of membranes)
Fluid fills the cavities of the brain
3 major parts: (forebrain, midbrain,
& hindbrain)
Cerebrum
Sensory perception: touch, pressure,
temperature, and body position.
Motor transmission.
Integration of information.
Consciousness.
Language.
Emotions.
Memory.
Cerebellum
Produces skilled movement by coordinating
activities of muscle groups.
Helps control posture.
Maintains equilibrium by controlling
skeletal muscles.
Brain Stem
Medulla oblongata: vital reflexes
and non-vital reflexes.
Pons: regulation of reflexes; cranial nerve
reflexes.
Spinal Cord: connects the brain with the PNS.
Surrounded and protected by an extension
of the meninges that cover the brain and by a series of bony vertebrate.
Contains a fluid-filled central canal.
Spinal nerves serve as the communication
link between the spinal cord and the rest of the body.
Peripheral Nervous System
Sensory- Somatic System
controls responses that are under
conscious control
reflexes: involuntary or automatic responses
to stimuli
Autonomic System
controls cardiac and smooth muscle
consists of two groups of nerves
sympathetic nerves: prepares body
for stress. “fight-or-flight.”
parasympathetic nerves: returns body to
normal state. “rest-and-repair.”
Sensory Systems
Ear: senses of hearing and equilibrium.
Ear canal: sends sound waves to ear drum.
Tympanic membrane: ear drum attached to
three small bones.
Cochlea: fluid-filled snail-shaped organ
used to transmit sound waves.
Semi-circular canals: fluid-filled tubes
used in balance.
Eye: sense of sight.
Cornea: clear covering over the eye.
Pupil: opening in the eye that allows light
to the retina.
Iris: circular muscle that regulates the
size of the pupil.
Lens: disk that focuses light on the retina.
Retina: membrane of photoreceptors at the
back of the eye.
Nose: detects chemicals dissolved in mucus
membranes.
Seven basic odors: camphorous, musky, floral,
ethereal, pungent, putrid, pepperminty.
Tongue: detects chemicals dissolved in saliva.
Four basic tastes.
Sweet: tip of the tongue.
Sour: sides of tongue.
Bitter: back of the tongue.
Salty: sides of the tongue.
Taste buds: taste cells in papilla that
detect chemicals.
Skin: contains touch and pressure receptors.
Touch receptors are more concentrated in
fingertips, palms, soles of the feet, lips (areas of skin with no hair).
Chemical
Control
Hormone: a chemical messenger sent to a specific
target cell.
Glands
Endocrine glands: Secrete products directly
into the blood.
Examples include the thyroid, pancreatic
islets, and gonads.
Exocrine glands: Secrete products into ducts.
Examples include tear ducts, gastric glands,
and sweat glands.
Plant
Hormones
Auxin: Plays various roles in plant development.
Gibberellins: Elongation of stem cells.
Stimulation of leaf growth.
Inhibitors: inhibits effects of other hormones.
Cytokinins: Stimulate seed production.
Endocrine
Glands
Hypothalamus: region of the brain that controls
the release of hormones.
Anterior Pituitary: the master gland made
of endocrine tissue. Secretes hormones to signal endocrine glands to produce
hormones.
Posterior Pituitary: organ made of nervous
tissue that secretes hormones made by the hypothalamus.
Animal
Hormones
Insulin: Produced in the pancreas. Regulates
glucose uptake by cells from the blood stream.
Glucagon: Produced in the pancreas. Increases
blood sugar levels by stimulating breakdown of glycogen.
Thyroxin: Produced by the thyroid gland.
Affects the metabolic rate of every cell in the body.
Adrenaline: Produced by the adrenal glands
located on top of the kidneys. Dilates blood vessels, increases blood pressure,
increases blood sugar.
Feedback
Mechanisms
Negative feedback: Change in a condition
causes a change in activity to bring the situation back to the average.
Example: a thermostat that controls room
temperature.
Positive feedback: Change in a condition
causes more of the same activity to continue.
Example: a bully who makes someone cry;
reaction causes bully to continue bullying.
back
to tech biology!