Download The Endocrine System

The Endocrine System
Chapter 2.1
Biological level of analysis
The endocrine system
• Another way of transmitting information in the body is via the
endocrine system. The vehicle used to transmit information
through the endocrine system is provided by hormones.
• Hormones are chemicals that are carried by the blood from
one location to another, more distant location.
These chemical messengers take longer to transmit their
information than the nervous system, but their effects are
usually longer lasting.
What is the endocrine system?
http://www.youtube.com/watch?v=kIPYVV4aThM
Learning outcome: explain, using
examples, functions of two hormones
on human behaviour
• The glands produce the hormones
• Two Examples of hormones and their
functions:
• Adrenaline (adrenals gland) flight or fight
response, arousal
• Melatonin (pineal gland) regulation of sleep
Functions
of the human
endocrine system
Melatonin
• Melatonin is a hormone secreted by the
pineal gland in the brain.
• It helps regulate other hormones and
maintains the body's circadian rhythm. The
circadian rhythm is an internal 24-hour “clock”
that plays a critical role in when we fall asleep
and when we wake up.
Melatonin
• When it is dark, your body produces more
melatonin; when it is light, the production of
melatonin drops.
• Being exposed to bright lights in the evening
or too little light during the day can disrupt
the body' s normal melatonin cycles.
• For example, jet lag, shift work,
and poor vision can disrupt
melatonin cycles.
Melatonin
• By taking melatonin in the early evening may
improve one’s ability to fall asleep.
• However, higher levels of melatonin has been
shown in research to contribute to SAD
(seasonal affective disorder) – a subcatory of
depression that is characterized by sleepiness
and lethargy and cravings for carbohydrates.
• Higher rates of SAD in Scandinavia
Adrenaline
also called Epinephrine
• Adrenaline is produced in the adrenals gland
flight or fight response, arousal
Adrenaline
• http://www.youtube.com/watch?v=06jbq3bx
KE0
• When it is produced in the body it stimulates
the heart-rate, dilates blood vessels and air
passages, and has a number of more minor
effects.
• Adrenaline is naturally produced in high-stress
(psychological stress) or physically exhilarating
situations (hard labor)
“Fight or flight”
• The term "fight or flight" is often used to
characterize the circumstances under which
adrenaline is released into the body.
• It is an early evolutionary adaptation to allow
better coping with dangerous and unexpected
situations.
• With dilated blood vessels and air passages, the
body is able to pass more blood to the muscles
and get more oxygen into the lungs in a timely
manner, increasing physical performance for
short bursts of time.
1.
2.
3.
4.
5.
Within seconds of any situation which causes you to become
upset, which is fight-or-flight, the primitive amygdala (trauma
center in your mid-brain) automatically sounds a general alarm.
The adrenal system promptly floods the body with adrenaline
and stress hormone (cortisol).
Non-essential physiological (body) processes switch off.
Digestion stops, skin cools, and blood is diverted from viscera and
small muscles into the outer, large muscles in preparation for a
burst of emergency action (fight/flee/freeze).
Breathing quickens and becomes shallow, the heart races, and
blood pressure skyrockets, infusing the body with oxygen while
the liver releases glucose for quick fuel.
The entire body is suddenly in a state of high alert, ready for
fight-or-flight.
Adrenaline
• One example is ; When there is fire, a person
can suddenly carry heavy stuff that he/she
cannot usually carry in normal condition. It is
the adrenalin hormone that is responsible in
that sudden strength.
Fight-or-flight is designed only for emergencies:
not for everyday living!
• Our culture today places so many demands on us,
that we live in this state too often for good health
and well-being.
• We experience this response on a regular basis
through pressure at work, traffic jams,
anticipating the future or stewing about a past
event, family and relationship challenges, the
intensity of school, and many more situations
that are not life-threatening.
• But some seek it too: adrenaline junkies!
Used in the treatment of:
• Severe allergic reactions
• To restore the heartbeat of patients suffering
cardiac arrest
• To treat severe asthma, adrenaline relaxes the
muscles in the bronchi (the large air passages
into the lungs).