2. Hormones Are:
• Produced in one part of the organism and
pass through a transport system to target
tissue
• Specific
– stimulus only affects certain hormone
secreting cells
– only certain cells can respond
• Relatively slow
3. Endocrine Glands
• Organs that produce and release
hormones directly into the circulatory
system
• Fig 15.2 page 280
4. For a list of the glands and
what they do see Table 15.1
page 281 of your text
Note:
Endocrine glands
release
hormones
directly into the
_____________
system
7. Pituitary Gland
• Central role in overall endocrine regulation
• Growth, lactation, reproductive state, skin
pigmentation, fat tissue, kidney function &
activity of thyroid and adrenal glands
• Connected to the hypothalamus
– Hypothalamus -collects info about the body’s state
(water, food, pain, emotions) and releases releasing
hormones to the pituitary
– Pituitary- receives this info and releases hormones to
regulate the body’s response
• Fig 15.4 page 283
9. Anterior Pituitary Gland
Thyroid Stimulating Hormone
Thyroid Gland
Thyroxine
Target Cells (most cells in the body)
via blood vessels
Stimulates an increase
in metabolic rate in cell
Thyroid stimulating hormone
releasing hormone
Hypothalamus
via blood
vessels
releases
releases
via blood vessels
10. Nervous Systems
• More direct pathway of communication
• Extremely rapid responses are possible
• Functional unit is the neuron
• Neurons communicate between
– Sensory cells that detect a disturbance
– Effector cells that produce the response
• Specific receptors bring about highly
precise responses
• Expensive, require a lot of energy to run
11. Nervous Systems – Evolution
Note development of a bundle of
nerves at the front of the animal
12. Knee-Jerk Response – Simplest of all
Stretch Receptor
Effector Muscle
Count the nerves!
15. Interneurons
• Neurons that transmit information from
one neuron to another
• Allow more co-ordinated responses
– Withdrawal reflex in hand
• Triceps stay relaxed
– Withdrawal reflex in foot
• Opposing foot braces itself
• Task try balancing on one foot.
16. The Reflex Response
• A reflex is a rapid, unconscious response
– hand on a stove
– Stand on a pin
• Brain registers the ‘pain’ but doesn’t facilitate the
response (spinal cord does)
• Knee-jerk response involves only 2 neurons!
17. Reflexes in Homeostasis
• Baroreceptor-heart rate reflex maintains
blood pressure
• Also see Fig 15.10 page 287
18.
19. Task
• Draw a stimulus response model to
represent the control of blood pressure
24. Mammalian Nervous Systems
• Central nervous system (CNS) – ‘co-
ordinating centre’
– Brain
– Spinal cord
• Peripheral Nervous System – ‘sensing and
responding’
– Motor (muscular) neurons
– Sensory neurons
25.
26. Human Nervous System
• See Fig 15.3 page 282
• Note location and function of:
– Cerebral cortex
– Hypothalamus
– Cerebellum
– Brainstem
27. Human Nervous System
Central Nervous System (brain & spinal cord)
Peripheral Nervous System
Voluntary (somatic) -skeletal muscles
Involuntary (autonomic)
-unconscious responses
See Table 15.2 page 288
Sensory (info to the CNS)
Motor (signals to effector-organs)
28. Autonomic Nervous System
(unconscious responses)
• Sympathetic division
– Increases energy use
– Prepares body for action
• Parasympathetic division
– Conserves energy
– Slows heart rate
• Enteric division
– Nerves specific to gut
29. Major Sense Organs
Types of Receptors
• Photoreceptors
– Visible light, infrared radiation
• Chemoreceptors
– Taste, smell, communication
– Oxygen, CO2, pH, water, salts etc
• Mechanoreceptors
– Hearing, balance, pressure, touch
• Thermoreceptors
– Heat and cold
30. Vision
• Photoreceptor cells contain light-sensitive
pigments that
• The interaction of light with the pigment
creates an electrical signal in a sensory
nerve
• Types of eyes
– Simple
– Compound (see fig 15.11 p 289)
31. Neurons
• Cell body
– Nucleus
– Usual cell functions
• Dentrites
– Carry impulses towards cell body
• Axons
– Carry impulses away from cell body to next neuron
• Synapse
– Space across which one neuron makes contact with another
• Myelin
– Like insulation tape around a neuron (fatty)
34. Neurons
• Signals travel quickly along neurons an
electrical impulses
• The signals that travel between neurons,
across the synapse are chemical
35. Nerve Bundles
• See fig 15.12 p 291
• Many neurons group together forming a
single nerve
36. Action Potentials
“When a nerve is stimulated its cell membrane is
depolarised so that the inside of the cell becomes less
negative. The potential is conducted along the axon to
the axon terminal. At the dendrite it stimulates the
realease of a chemical transmitter, which diffuses
across a synapse. The transmitter binds to receptor
sites on the postsynaptic cell membrane to stimulate
the generation of another impulse.”
• My advice
– carefully read and re-read page 291-293 when you have a quite
period at home
