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Unformatted text preview: eostasis. Respiratory system: Interface for gas exchange with
the internal environment - obtaining oxygen and
expelling CO2. Lymphatic system: circulates tissue fluid, internal
defense against pathogens. 10. Cardiovascular system: delivers oxygen and nutrients
to all tissues and organs and removes CO2 and other
waste products of metabolism. 11. Endocrine system: produces hormones that activate
and regulate homeostatic functions, growth, and
development. Primary components:
Hypothalmus (nervous and endocrine function
secretes oxytocin and ADH as well as releasing
hormones, which regulate the hormones of the
Pituitary: secretes hormones to regulate the activities
of other endocrine glands.
Parathyroid glands: secrete PTH for regulation of
Pancreatic islets: secrete hormones to regulate
Testes (male) secrete testosterone for maintaining
maleness and for sperm production.
Ovaries secrete estrogen and progesterone to
maintain femaleness, control the menstrual cycle, and
prepare for and maintain pregnancy.
Pineal secretes melatonin to regulate the sleep-wake
Adrenal glands secrete corticosteroids for regulating
aspects of sodium regulation and responses to stress. For Q. 2.-4., more detail is given than may be required.
2. Mechanisms by which responses to stimuli are
brought about and coordinated:
(a) Hormonal response to stimuli: Endocrine glands
respond to a stimulus (e.g. a nerve impulse or
another hormone or metabolite) by producing
hormones which bring about an appropriate
physiological response. For example, nervous
stimulation of the adrenal glands when the
body receives a stressful stimulus causes the
release of epinephrine. This hormone causes
mobilization of glucose in muscle and liver cells,
increases heart rate and directs blood away from
nonessential organs. These responses help the
body react to the stress situation.
(b) Nervous response to stimuli: Direct stimulation
of nerves from a sensory receptor causes a
reaction to the stimulus. This may be a response
requiring interpretation of the message by the
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This document was uploaded on 01/28/2014.
- Winter '13