23/06/2021
Course BBS2051
Pluis, CMH
Pluis, CMH 1
Introduction to homeostatic
mechanisms (Lecture 1)
• Homeostasis is the ability to maintain a (relatively)
constant internal environment (despite external and
internal changes)
• Internal changes causes a loss of homeostasis
• The body attempts to compensate this change
• If it succeeds, there is wellness
• If it fails, there is disease or death
• Maintaining homeostasis is key to maintain the body’s
overall functioning
Pluis, CMH 2
1
, 23/06/2021
Introduction to homeostatic
mechanisms (Lecture 1)
• Standard layout:
• A stimulus is detected by a sensor
• Sensor compares and communicates with control
• Control senses the effector to respond
Pluis, CMH 3
Introduction to homeostatic
mechanisms (Lecture 1)
• Example
• A decrease in blood glucose
levels stimulates the release
of glucagon by the pancreas
(alpha cells). Glucagon
breaks (stored) glycogen in
the liver (and a bit in
skeletal muscle) tissue down
into glucose
• An increase in blood glucose
levels stimulates the release
of insulin by the pancreas
(beta cells). Insulin converts
glucose into glycogen to be
stored
Pluis, CMH 4
2
, 23/06/2021
Introduction to homeostatic
mechanisms (Lecture 1)
• However, not all physiological pathways need a
stimulus (e.g. a decrease or increase in blood
glucose levels).
• Some hormones are secreted continuously during
the day: they rise and fall in concentration
• These physiological functions that change over a
time are examples of biological rhythms
• The circadian rhythm is an example of a biological
rhythm
• It is composed of a central peacemaker in the
hypothalamus and peripheral clocks in the brain
and other body tissues. There is a communication
between these clocks.
Pluis, CMH 5
Introduction to homeostatic
mechanisms (Lecture 1)
• There are two ways for communication and regulation:
• 1. Neuronal: the nervous system monitors, responds
and regulates
• 2. Hormonal: the endocrine system regulates and
maintains by synthesizing and releasing chemical
messengers: hormones
• In addition to input and output signals, biological
homeostasis is also influenced by our environment, our
behaviour and the decisions that we make on a daily
basis.
Pluis, CMH 6
3
, 23/06/2021
Introduction to regulation and feedback
mechanisms in homeostasis (Lecture 2)
• There is a neuro-endocrine control of
homeostasis
• Of which, the interaction between the
hypothalamus with the cortex and the
brainstem can be highlighted
• Control systems: autonomic nervous system
(ANS) and endocrine system
• Systems involved in maintaining
homeostasis: autonomic nervous system
(ANS), endocrine system, cardiovascular,
pulmonary etc.
Pluis, CMH 7
Introduction to regulation and feedback
mechanisms in homeostasis (Lecture 2)
• Pain (sensory input (feedback from body))
• Parasympathetic and sympathetic nervous system play a role
Pluis, CMH 8
4
Course BBS2051
Pluis, CMH
Pluis, CMH 1
Introduction to homeostatic
mechanisms (Lecture 1)
• Homeostasis is the ability to maintain a (relatively)
constant internal environment (despite external and
internal changes)
• Internal changes causes a loss of homeostasis
• The body attempts to compensate this change
• If it succeeds, there is wellness
• If it fails, there is disease or death
• Maintaining homeostasis is key to maintain the body’s
overall functioning
Pluis, CMH 2
1
, 23/06/2021
Introduction to homeostatic
mechanisms (Lecture 1)
• Standard layout:
• A stimulus is detected by a sensor
• Sensor compares and communicates with control
• Control senses the effector to respond
Pluis, CMH 3
Introduction to homeostatic
mechanisms (Lecture 1)
• Example
• A decrease in blood glucose
levels stimulates the release
of glucagon by the pancreas
(alpha cells). Glucagon
breaks (stored) glycogen in
the liver (and a bit in
skeletal muscle) tissue down
into glucose
• An increase in blood glucose
levels stimulates the release
of insulin by the pancreas
(beta cells). Insulin converts
glucose into glycogen to be
stored
Pluis, CMH 4
2
, 23/06/2021
Introduction to homeostatic
mechanisms (Lecture 1)
• However, not all physiological pathways need a
stimulus (e.g. a decrease or increase in blood
glucose levels).
• Some hormones are secreted continuously during
the day: they rise and fall in concentration
• These physiological functions that change over a
time are examples of biological rhythms
• The circadian rhythm is an example of a biological
rhythm
• It is composed of a central peacemaker in the
hypothalamus and peripheral clocks in the brain
and other body tissues. There is a communication
between these clocks.
Pluis, CMH 5
Introduction to homeostatic
mechanisms (Lecture 1)
• There are two ways for communication and regulation:
• 1. Neuronal: the nervous system monitors, responds
and regulates
• 2. Hormonal: the endocrine system regulates and
maintains by synthesizing and releasing chemical
messengers: hormones
• In addition to input and output signals, biological
homeostasis is also influenced by our environment, our
behaviour and the decisions that we make on a daily
basis.
Pluis, CMH 6
3
, 23/06/2021
Introduction to regulation and feedback
mechanisms in homeostasis (Lecture 2)
• There is a neuro-endocrine control of
homeostasis
• Of which, the interaction between the
hypothalamus with the cortex and the
brainstem can be highlighted
• Control systems: autonomic nervous system
(ANS) and endocrine system
• Systems involved in maintaining
homeostasis: autonomic nervous system
(ANS), endocrine system, cardiovascular,
pulmonary etc.
Pluis, CMH 7
Introduction to regulation and feedback
mechanisms in homeostasis (Lecture 2)
• Pain (sensory input (feedback from body))
• Parasympathetic and sympathetic nervous system play a role
Pluis, CMH 8
4
