Nervous and Endocrine Systems

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Transcript Nervous and Endocrine Systems

HUMAN REGULATION
Nervous & Endocrine Systems
REGULATION
Integration of nervous & endocrine
systems
Similarities
Secrete chemicals
Major role in homeostasis
Differences
Nerve response – more rapid &
shorter duration
FUNCTIONAL DEFINITIONS
Regulation: All the activities that help to
maintain homeostasis in an organism
Impulse: Message carried by the nerve
cells
Stimulus (stimuli) – Change in external
or internal environment which initiates
(starts) an impulse
T YPES OF RECEPTORS
FUNCTIONAL DEFINITIONS
Receptors – Structures specialized to
detect certain stimuli
Effectors: Muscles and glands that
respond to the stimulus
Response: Change based on stimulus
FUNCTIONAL ORGANIZATION OF
THE NERVOUS SYSTEM
Neurons
Basic cellular unit
Specialized for transmission impulse
NEURON
ACTUAL NEURONS IN BODY
NEURONS
THE NEURON
Composed of:
1) Dendrites – fibers detect the stimulus
& generate impulses toward the cyton
2) Cyton – cell body containing nucleus &
most organelles
THE NEURON
3) Axon – single long fiber that
transmits impulse away from cyton to
the terminal branches
4) Terminal branches – ends of axon –
synaptic knobs secrete chemicals
(neurotransmitters)
THE NEURON
5) Synapse – space between adjacent
neurons or between neuron & effector
6) Neurotransmitters – chemicals
secreted to aid in transmission of
impulse across synapse
FUNCTIONAL ORGANIZATION OF
NERVOUS SYSTEM
Three types of neurons:
1) Sensory Neurons
From receptors to
central nervous
system
(brain & spinal cord)
2) Interneurons
Inside CNS
FUNCTIONAL ORGANIZATION OF
NERVOUS SYSTEM
3) Motor Neurons
Transmit from
CNS to
effectors
(muscles and
glands)
FUNCTIONAL ORGANIZATION OF
NERVOUS SYSTEM
Nerves – bundles of neurons
Can be sensory, motor, or mixed
Specialized for
impulse transmission
over long distances
CENTRAL NERVOUS SYSTEM
1) Brain
Large mass of neurons
Protected by skull
Three major
divisions:
CENTRAL NERVOUS SYSTEM
1a) Cerebrum
Largest part of brain
Voluntary activity,
memory, thinking,
reasoning
CENTRAL NERVOUS SYSTEM
1b) Cerebellum
Coordination of motor activities
 Maintaining balance
1c) Medulla
Involuntary activities – breathing,
heartbeat, blood pressure,
peristalsis
Lowest part of brain
Continuous with the
spinal cord
CENTRAL NERVOUS SYSTEM
2) Spinal Cord
Lies within, & protected by, vertebrae
of spinal column
Coordinates activities between brain
& other body structures
 Reflex actions
PERIPHERAL NERVOUS
SYSTEM



1)
Outside CNS
Nerves extending throughout body
Two parts:
Somatic NS – control
voluntary
muscles
PERIPHERAL NERVOUS
SYSTEM
2) Autonomic NS – two sets of nerves
control involuntary muscles
 One set stimulates activity
(sympathetic)
 Other slows down activity
(parasympathetic)
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Somatic
Autonomic
Sympathetic
Parasympathetic
NERVOUS SYSTEM
MALFUNCTIONS
Cerebral palsy – congenital diseases
- motor function disturbance
Meningitis – inflammation of
membranes surrounding brain &
spinal cord
NERVOUS SYSTEM
MALFUNCTIONS
Stroke – cerebral hemorrhage (blood
clot) in vessels - can result in brain
damage
Polio – viral disease of CNS; may
result in paralysis; preventable
through immunization
TYPES OF BEHAVIOR
Behavior – responses of living
things to stimuli
Reflex – inborn, involuntary
response
Involves a pathway (reflex arc)
Impulse travels from receptor
sensory neuron  spinal cord
(interneuron)  motor neuron 
effector
TYPES OF BEHAVIOR
Habit – conditioned behavior acquired by
repetition
Repetition establishes pathways for
nerve impulse transmission
Permits automatic responses to various
stimuli
THE ENDOCRINE SYSTEM
Made up of ductless glands
located throughout the body &
their hormones
Hormones released directly into
the bloodstream - affect various
tissues or organs (target tissue)
Hormones coordinate responses
to various conditions
HYPOTHALAMUS
Small region of
brain
Produces
hormones which
influence
pituitary gland
PITUITARY GLAND
Base of brain
Secretes:
1) Growth Stimulating Hormone (GSH)
Elongation of bones
Affects metabolic
activities for growth
Problems with GSH
Oversecretion in child:
Giantism
Oversecretion in adult: Acromegaly
(enlarged bones of face, feet, hands)
Undersecretion: Dwarfism
2) Thyroid Stimulating Hormone (TSH)
Tells thyroid to produce thyroxin
3) Follicle Stimulating Hormone (FSH)
Stimulates egg development in ovary
& sperm development in testes
THYROID GLAND
In the neck
Produces thyroxin,
which contains iodine
Thyroxin regulates
metabolic rate –
essential for proper
development
Problems with thyroid
Oversecretion: nervous, weight loss
Undersecretion: cretinism (mental
retardation, small size)
Deficiency of iodine – goiter
(enlarged gland)
PARATHYROID GLAND
Embedded in thyroid gland
Produces & secretes parathormone,
which controls calcium metabolism
Necessary for nerve function, blood
clotting, proper growth of teeth &
bones
Problems with parathyroid
Undersecretion: nerve disorders,
brittle bones, clotting problems
ADRENAL GLANDS
Two – one on top of
each kidney
Each has two regions
Outer portion – adrenal cortex
Inner portion – adrenal medulla
ADRENAL CORTEX
 Secretes two steroid hormones
1) Cortisone – regulates metabolism of
organic molecules & promotes
conversion of body fat & protein to
glucose
2) Aldosterone – promotes reabsorption
of sodium & chlorine ions by kidney
into bloodstream – affects water
balance & maintenance of blood
pressure
Problems with cortisone
Oversecretion – Cushing’s disease
(high glucose, excess fat)
Undersecretion – Addison’s disease
(low glucose, weight loss)
ADRENAL MEDULLA
Secretes adrenaline
Increases blood sugar levels &
accelerates heart & breathing rate
ISLETS OF LANGERHANS
Located in pancreas
Secretes insulin & glucagon
Insulin – allows glucose to enter
cells from blood – lowers blood
sugar levels
Glucagon –stimulates release of
sugar into blood – raises blood
sugar levels
Problems with pancreas
Oversecretion of insulin – low blood
sugar
Undersecretion – diabetes (high
blood sugar)
GONADS
Male – testes secrete testosterone –
influences development of secondary
sex characteristics
Female – ovaries secrete several
hormones, including estrogen –
development of female secondary sex
characteristics
NEGATIVE FEEDBACK
MECHANISM
Type of self-regulation
Level of one hormone in blood
inhibits (slows) production of
another hormone
Keep everything in homeostasis
TSH & thyroxin; insulin & glucagon
Negative Feedback Mechanism
POSITIVE FEEDBACK
MECHANISM
• Positive feedback – one promotes
production of the other
• Ex: snowball rolling down a hill