Transcript nervous system - gloriousbiology

 The Endocrine system and the Nervous
system.
 Local Regulators
 The Hypothalamus and Pituitary
 Nonpituitary hormones
 Invertebrate Regulatory Systems
 The nervous system conveys high-speed
electrical signals along specialized cells
called neurons.
 These rapid messages control the movement
of the body parts in response to sudden
environmental changes.
Jerk your hand away from a hot pan
Pupils dilate when you enter a dark room
 Collectively, all of an animal’s hormone
secreting cells constitute its endocrine
system.
 Hormone-secreting organs, called endocrine
glands, are referred to as ductless glands
because they secrete their chemical
messengers directly into extracellular fluid.
 Certain specialized nerve cells known as
neurosecretory cells release hormones into
the blood via the extracellular fluid.
 These hormones are called neurohormones
to avoid confusion with normal hormones.
 A few chemicals serve both as hormones in
the endocrine system and as chemical
signals in the nervous system.
Epinephrine, functions as the “fight or flight” hormone
and as a neurotransmitter.
 In addition, the nervous system plays a role
in certain sustained responses— for example,
controlling day/night cycles and
reproductive cycles in many animals— often
by increasing or decreasing secretion from
endocrine glands.
A biologist was interested in studying how far bullfrogs can jump.
He brought a bullfrog into his laboratory, set it down, and
commanded, "Jump, frog, jump!"
The frog jumped across the room.
The biologist measured the distance, then noted in his journal,
"Frog with four legs jumped eight feet."Then he cut the frog's
front legs off. Again he ordered, "Jump, frog, jump!"
The frog struggled a moment, then jumped a few feet.
After measuring the distance, the biologist noted in his journal,
"Frog with two legs jumped four feet."
 Next, the biologist cut off the frog's back legs. Once more, he
shouted, "Jump, frog, jump!"
The frog just lay there.
"Jump, frog, jump!" the biologist repeated.
Nothing.
The biologist noted in his journal, "Frog with no legs goes deaf."

 Receptor, sensor— detects a stimulus
a change in blood calcium level
 … send information to the control center
 … after, the control center sends out an
effecter to respond
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 In contrast to long-distance endocrine signaling
by hormones, local regulators convey messages
between neighboring cells— a process referred
to as paracrine signaling.
 Once secreted by the cells that make them,
local regulators act on nearby target cells within
seconds or even milliseconds, eliciting cell
responses more quickly than hormones can
 Some local regulators have cell-surface
receptors; others have intracellular receptors.
 Cytokines - play a role in immune responses
 Growth factors – stimulate cell proliferation
and differentiation
 Nitric oxide (NO) – improves blood flow to
tissues when blood oxygen level falls; nitric
oxide also plays a role in male sexual
function
 Prostaglandins (PGs) – modified fatty acids,
often derived from lipids in the plasma
membrane
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Major
Human
Endocrine
Glands
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The hypothalamus and pituitary integrate many functions of
the vertebrate endocrine system
The hypothalamus plays an important role in integrating the
vertebrate endocrine and nervous systems
 Receives information from nerves throughout the body
 Initiates endocrine signals appropriate to environmental
conditions
 E.g.: Seasonal changes triggering release of
reproductive hormones required for breeding.
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The hypothalamus contains two sets of neurosecretory cells
whose hormonal secretions are stored in or regulate the
activity of the pituitary gland, a lima bean-sized organ
located at the base of the hypothalamus.
Posterior Pituitary (neurohypophysis): extension of the
hypothalamus that grows downward toward the mouth
during embryonic development.
Anterior Pituitary (adenohypophysis): develops from a fold of
tissue at the roof of the embryonic mouth; this tissue grows up
toward the brain and eventually loses its connection to the
mouth.
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In humans and other mammals, the thyroid gland consists of
two lobes located on the ventral surface of the trachea.
 Produces triiodothyronine (T3 ) and thyroxine (T4)
 Secretion controlled by hypothalamus and pituitary
 Plays a crucial role in vertebrate development and
maturation
 E.g.: Metamorphosis of frog (tissue reorganization)
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When blood Ca2+ levels fall below a set point, parathyroid
hormone (PTH) is released.
PTH is produced by the parathyroid glands, embedded on
the surface of the thyroid.
The dual functioning pancreas functions in both the
endocrine and digestive systems.
 Produces glucagon and insulin
 Produces bicarbonate and digestive enzymes
Reactions to danger are part of the fight-or-flight response
stimulated by hormones of the adrenal glands.
 The adrenal medulla of the adrenal glands releases these
hormones
 Adrenaline and non Adrenaline
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Involve endocrine and nervous system reactions
 Function in reproduction and development
In insect hormonal regulation, three hormones play major
roles in molting and metamorphosis into the adult form.
 Brain hormone: produced by neurosecretory cells;
stimulates release of ecdysone
 Ecdysone: Promotes molting and development of adult
characteristics
 Juvenile hormone: secreted by glands behind the brain;
promotes retention of larva characteristics