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Control and Coordination
All the activities of multicellular organisms require coordinating, some very
rapidly and some more slowly. The nervous system and the endocrine system
provide coordination in mammals. Coordination systems also exist in plants.
Learning Outcomes:
1. Describe the features of the endocrine system with reference to the
hormones ADH, glucagon and insulin.
2. Compare the features of the nervous system and the endocrine system.
3. Describe the structure and function of a sensory neurone and a motor
neurone and state that intermediate neurones connect sensory neurones
and motor neurones.
4. Outline the roles of sensory receptor cells in detecting stimuli and
stimulating the transmission of impulses in sensory neurones.
5. Describe the sequence of events that results in an action potential in a
sensory neurone, using a chemoreceptor cells in a human taste bud as an
example.
6. Describe and explain changes to the membrane potential of neurones,
including: how the resting potential is maintained, the events that occur
during an action potential, how the resting potential is restored during the
refractory period.
7. Describe and explain the rapid transmission of an impulse in a myelinated
neurone with reference to saltatory conduction.
8. Explain the importance of the refractory period in determining the
frequency of impulses
9. Describe the structure of a cholinergic synapse and explain how it
functions, including the role of calcium ions..
Starting points:
Control and Coordination 1
, the endocrine system is a slower system that controls long-term changes
The nervous system provides fast communication between receptors and
effectors.
Transmission between neurones takes place at synapses
Control and Coordination in Mammals
The need for communication systems
The ability to detect change and to make responses essential for the survival of
living things. It is a feature of single-celled organisms as well as flowering
plants and mammals - for example, Amoeba detects a suitable food organism
and captures it by phagocytosis.
Large and complex organisms detect changes in the external environment and
changes within the body. They need to communicate this information to parts
of the body where appropriate responses will be made.
Changes that bring response = stimuli
The stimuli is detected by = receptor
What brings the response = effector
Since response often occurs in a different part of the body, efficient internal
communication is also essential!
In mammals, internal communication involves:
The Endocrine system (hormone producing)
The nervous system
Introducing the endocrine system
Hormones = chemical messengers. They are produced and secreted from the
cells in glands known as ductless or endocrine glands. These contain capillary
networks and specialised secretory cells that make and release hormones.
Hormones are released from the cells of the ductless gland, directly into the
blood stream, when stimulated to circulation system, but they act only at
specific sites, appropriately called target organs. Cells of the target organ
possess specific receptor molecules on the external surface of their cell
surface membrane to which the hormone molecules bind. A hormone typically
works by triggering changes to specific metabolic reactions in their target
Control and Coordination 2
, organs. Although present in small quantities, hormones are extremely effective
in the control and co-ordination of several body activities.
Hormones circulate in the bloodstream only briefly because in the liver they are
continually being broken down. Any breakdown products no longer of use to
the body are excreted in the kidneys. So, long-acting hormones must be
secreted into the bloodstream continuously to be effective - and they are.
Antidiuretic hormone (ADH) is involved in osmoregulation; it is produced in the
hypothalamus and released into the capillary network in the posterior pituitary
gland.
Glucagon and insulin are hormones involved in the control of blood glucose
concentration; they are secreted by alpha and beta cells of the islets of
Langerhans in the pancreas.
The structure of endocrine glands can be contrasted with that of other glands
in our body which deliver their secretions through tubular ducts, such as the
salivary glands in the mouth and sweat glands in the skin. These ducted glands
are called exocrine glands. Their secretions pass out of the gland via ducts and
they have altogether different roles in the body.
Hormonal control of body function mostly works by causing specific changes
in metabolism or development, often over an extended period of time. The
nervous system, on the other hand, is concerned with quick, precise
Control and Coordination 3
Control and Coordination
All the activities of multicellular organisms require coordinating, some very
rapidly and some more slowly. The nervous system and the endocrine system
provide coordination in mammals. Coordination systems also exist in plants.
Learning Outcomes:
1. Describe the features of the endocrine system with reference to the
hormones ADH, glucagon and insulin.
2. Compare the features of the nervous system and the endocrine system.
3. Describe the structure and function of a sensory neurone and a motor
neurone and state that intermediate neurones connect sensory neurones
and motor neurones.
4. Outline the roles of sensory receptor cells in detecting stimuli and
stimulating the transmission of impulses in sensory neurones.
5. Describe the sequence of events that results in an action potential in a
sensory neurone, using a chemoreceptor cells in a human taste bud as an
example.
6. Describe and explain changes to the membrane potential of neurones,
including: how the resting potential is maintained, the events that occur
during an action potential, how the resting potential is restored during the
refractory period.
7. Describe and explain the rapid transmission of an impulse in a myelinated
neurone with reference to saltatory conduction.
8. Explain the importance of the refractory period in determining the
frequency of impulses
9. Describe the structure of a cholinergic synapse and explain how it
functions, including the role of calcium ions..
Starting points:
Control and Coordination 1
, the endocrine system is a slower system that controls long-term changes
The nervous system provides fast communication between receptors and
effectors.
Transmission between neurones takes place at synapses
Control and Coordination in Mammals
The need for communication systems
The ability to detect change and to make responses essential for the survival of
living things. It is a feature of single-celled organisms as well as flowering
plants and mammals - for example, Amoeba detects a suitable food organism
and captures it by phagocytosis.
Large and complex organisms detect changes in the external environment and
changes within the body. They need to communicate this information to parts
of the body where appropriate responses will be made.
Changes that bring response = stimuli
The stimuli is detected by = receptor
What brings the response = effector
Since response often occurs in a different part of the body, efficient internal
communication is also essential!
In mammals, internal communication involves:
The Endocrine system (hormone producing)
The nervous system
Introducing the endocrine system
Hormones = chemical messengers. They are produced and secreted from the
cells in glands known as ductless or endocrine glands. These contain capillary
networks and specialised secretory cells that make and release hormones.
Hormones are released from the cells of the ductless gland, directly into the
blood stream, when stimulated to circulation system, but they act only at
specific sites, appropriately called target organs. Cells of the target organ
possess specific receptor molecules on the external surface of their cell
surface membrane to which the hormone molecules bind. A hormone typically
works by triggering changes to specific metabolic reactions in their target
Control and Coordination 2
, organs. Although present in small quantities, hormones are extremely effective
in the control and co-ordination of several body activities.
Hormones circulate in the bloodstream only briefly because in the liver they are
continually being broken down. Any breakdown products no longer of use to
the body are excreted in the kidneys. So, long-acting hormones must be
secreted into the bloodstream continuously to be effective - and they are.
Antidiuretic hormone (ADH) is involved in osmoregulation; it is produced in the
hypothalamus and released into the capillary network in the posterior pituitary
gland.
Glucagon and insulin are hormones involved in the control of blood glucose
concentration; they are secreted by alpha and beta cells of the islets of
Langerhans in the pancreas.
The structure of endocrine glands can be contrasted with that of other glands
in our body which deliver their secretions through tubular ducts, such as the
salivary glands in the mouth and sweat glands in the skin. These ducted glands
are called exocrine glands. Their secretions pass out of the gland via ducts and
they have altogether different roles in the body.
Hormonal control of body function mostly works by causing specific changes
in metabolism or development, often over an extended period of time. The
nervous system, on the other hand, is concerned with quick, precise
Control and Coordination 3
