C3.1  Integration of Body Systems

Theme:  Interaction and Interdependence

Interaction refers to the physical and chemical connections between different physiological systems to coordinate a whole body response.

• In animals, hormones produced in the glands must interact with the blood to be transported. Once at the target tissue, they interact with specific receptors to trigger a change in the organ’s behavior.
• The brainstem interacts with the diaphragm and intercostal muscles via nerves. During exercise, the interaction between rising CO2 levels in the blood and chemoreceptors triggers a faster breathing rate.
• There is a constant bidirectional interaction between the enteric nervous system (in the gut) and the central nervous system, coordinating digestion and emotional state.
• In plants, the hormones transport between cells, interacting with cell walls to promote elongation, leading to photo- and gravitropism.
• When roots sense dry soil, they synthesize Abscisic Acid which travels to the leaves and interacts with guard cells to close stomata, integrating the water-sensing system (roots) with the gas-exchange system (leaves).
• Auxin produced at the shoot apex interacts with lower tissues to inhibit lateral growth. If the tip is removed, cytokinin from the roots  promote growth. 

Interdependence describes how no system can function in a vacuum. A failure in one system creates a "domino effect" across all others.

• In animals, the nervous system is the "integration center," but it depends on the systems that provide it information and execute its commands.
• The hypothalamus (nervous system) depends on the pituitary gland (endocrine system) to translate electrical impulses into hormonal messengers.
• All cells in the body depend on the integrated action of the pancreas, liver and circulatory system to ensure that blood glucose levels remain within narrow homeostasis range.
  
• When the body is too cold, the nervous system triggers the circulatory and muscular system generate and transmit thermal energy through the body.
  
• During exercise, the heart (circulatory) and the diaphragm (respiratory) must increase their rates. This is managed by the brainstem to ensure that increased oxygen demand is met by increased delivery.
  
• Flowering shows the interdependence between the leaves (which sense light) and the shoot apical meristem (where flowers are made).

Guiding Questions:  
Guiding questions help students view the content of the syllabus through the conceptual lenses of both the themes and the levels of biological organization.

• What are the roles of nerves and hormones in integration of body systems? 
• What are the roles of feedback mechanisms in regulation of body systems?

​
​Linking Questions:  
Linking questions strengthen students’ understanding by making connections between topics.  The ideal outcome of the linking questions is networked knowledge.

• What are the consequences of positive feedback in biological systems?
• What are examples of branching (dendritic) and net-like (reticulate) patterns of organization?

Key Terms to Know: * higher level only

Accuracy*
Active Transport*
Adrenal Gland
Apoplast*
Auxin*
Auxin Efflux Carrier*
Balance
Baroreceptor
Blood Pressure
Blood System
Brain
Brainstem
Carbon Dioxide
Cell
Cell Membrane*
Cell Wall*
Cellulose*
Central Nervous System
Cerebral Hemisphere
Cerebellum
Cheetah
Chemoreceptor
Circadian Rhythm
Concentration Gradient*
Conscious Process
Cytokinin*
Development*
Diaphragm
Diffuse*
Digestive System
Diurnal
Effector
Egestion
Elongation*
Emergent Property

Endocrine System
Enteric Nervous System
Epinephrine
Ethylene*
Faeces
Feedback Control
Free Sensory Nerve Ending
Fruit*
Grey Matter
Growth*
Heart Rate
Hierarchy
Hormonal Signaling
Hydrogen Ion*
Hypothalamus
Integration
Intercostal Muscles
Interneuron
Involuntary Response
Lateral Light*
Medulla Oblongata
Melatonin
Motor Neuron
Multicellular
Muscle
Muscle Contraction
Myelinated Nerve Fibre
Nerve
Nerve Fibre
Nerve Impulse
Nerve Sheath
Nervous Signaling
Nervous System
Organ
Organ System

Oxygen
Pain Receptor
Peristalsis
pH
Phytohormones*
Pineal Gland
Pituitary
Positive Phototropism*
Positive Feedback*
Precision*
Predator
Qualitative*
Quantitative*
Receptor Cell
Reflex Arc
Reliability*
Response*
Root (Plant)*
Secretion*
Seedling*
Sensory Neuron
Shoot (Plant)*
Skeletal Muscle
Spinal Cord
Stimulus*
Stroke Volume
System
Tissue
Tissue*
Transverse
Tropic Response*
Unconscious Process
Unmyelinated Nerve Fibre
Ventilation
Voluntary Control

C3.1.1— System integration.

• Define system integration.
• Explain why system integration is needed to perform the functions of life.​

​C3.1.2— Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism.

• Define tissue, organ and organ systems. 
• Outline how integration occurs between and among tissues, organs and organ systems. 
• Define emergent property.
• State an example of an emergent property for each level of biological organization within a multicellular organism.

C3.1.3— Integration of organs in animal bodies by hormonal and nervous signaling and by transport of materials and energy.

• State the two primary mechanisms by which animals integrate organ systems. 
• Compare the type of signal, transmission of signal, effector response, speed and duration of response between hormonal and nervous signals. 
• Outline the role of blood in the transport of material and energy between organs.

C3.1.4— The brain as a central information integration organ.

• State the function of the brain.
• List sources of information input to the brain. ​​

​C3.1.5— The spinal cord as an integrating center for unconscious processes.

• List organs of the central nervous system. 
• ​Compare and contrast conscious and unconscious processing.
• State that the spinal cord can only coordinate unconscious processes.​​​

​C3.1.6- Input to the spinal cord and cerebral hemispheres through sensory neurons.

• List types of sensory receptors.
• Outline the function of sensory neurons.

C3.1.7- Output from the cerebral hemispheres to muscles through motor neurons.

• State the location and function of the cerebral hemispheres, primary motor cortex and skeletal muscles. 
• Outline the function of motor neurons.

​C3.1.8- Nerves as bundles of nerve fibers of both sensory and motor neurons.

• Define nerve.
• Describe the structures visible in a nerve transverse cross section. 
• State that nerves can contain either or both sensory and motor neurons.

C3.1.9- Pain reflex arcs as an example of involuntary responses with skeletal muscle as the effector.

• Define reflex and reflex arc.
• Outline the input, processing and output of the pain reflex arc, including the role of receptors, sensory neurons, interneurons, motor neurons and effectors.

​C3.1.10- Role of the cerebellum in coordinating skeletal muscle contraction and balance.

• Identify the cerebellum on a diagram of the human brain.
• State the functions of the cerebellum. 

C3.1.11- Modulation of sleep patterns by melatonin secretion as a part of circadian rhythms.

• Define circadian rhythm.
• State the role of suprachiasmatic nuclei cells in the circadian rhythm. 
• Outline how suprachiasmatic nuclei cells sense and respond to changes in light.
• State that melatonin is secreted by the pineal gland glands in preparation sleep. 
• Outline the mechanism of action of melatonin as a signaling molecule. 
• Outline the effects of melatonin on the body.

​​​C3.1.12- Epinephrine (adrenaline) secretion by the adrenal glands to prepare the body for vigorous activity.

• State that epinephrine is secreted by adrenal glands in preparation for vigorous activity.
• Outline the mechanism of action of epinephrine as a signaling molecule. 
• Outline the effects of epinephrine on the body, including:  skeletal muscles, liver, bronchi and bronchioles, ventilation and heart rate, cardiac output, and vessel dilation.

C3.1.13- Control of the endocrine system by the hypothalamus and pituitary gland.

• Outline the role of the hypothalamus as a link between nervous and endocrine systems.
• List body processes that are monitored by the hypothalamus.
• Draw a diagram to illustrate the structural relationship between the hypothalamus and pituitary.

C3.1.14- Feedback control of heart rate following sensory input from baroreceptors and chemoreceptors.

• State that the myogenic heart rate can be adjusted by neural and endocrine feedback mechanisms. 
• Described the structures and functions of nervous tissue that can regulate heart rate, including the role of the medulla oblongata, sympathetic nerve, vagus nerve, baroreceptors and chemoreceptors. 
• Outline the source and effect of epinephrine on heart rate. 
• Outline factors that will increase heart rate.
• Outline factors that will decrease heart rate.

C3.1.15- Feedback control of ventilation rate following sensory input from chemoreceptors.

• State the effect of exercise on CO2 production.
• Outline the relationship between CO2 production and blood pH.
• Outline the feedback loop that regulates the rate of ventilation, including the role of chemoreceptors, brainstem, diaphragm and intercostal muscles. 
• Explain how and why hyperventilation occurs in response to exercise.​

C3.1.16- Control of peristalsis in the digestive system by the central nervous system and enteric nervous system.

• Outline the role of the central and enteric nervous systems in movement of material into, through and out of the gut.
• List components of the movement of material into, through and out of the gut that are under voluntary and involuntary control. ​

AHL ​​​​C3.1.17- Observations of tropic responses in seedlings.

• Contrast positive and negative tropism. 
• Outline phototropism and gravitropism in roots and stems.​

AHL ​​​​C3.1.18- Positive phototropism as a directional growth response to lateral light in plant shoots.

• Outline the cause and consequence of positive phototropism in a plant shoot.​

AHL ​​​​C3.1.19- Phytohormones as signaling chemicals controlling growth, development and response to stimuli in plants.

• Define phytohormone.
• List examples of chemicals that function as phytohormones.
• Outline role of phytohormones in plant growth, development and response to stimuli. ​

AHL ​​​​C3.1.20- Auxin efflux carriers as an example of maintaining concentration gradients of phytohormones.

• State two roles of the hormone auxin.
• Describe the mechanism of movement of auxin into and between plant cells. ​

AHL ​​​​C3.1.21- Promotion of cell growth by auxin.

• Explain how auxin concentrations allow for phototropism.
• Describe the mechanism of action of auxin in the phototropic response, including the role of H+ ions and cellulose crosslinks. ​

AHL ​​​​C3.1.22- Interactions between auxin and cytokinin as a means of regulating root and shoot growth.

• Outline the source and transport of auxin and cytokinin in plants.
• Explain how root and shoot growth are regulated by the interaction of auxin and cytokinin. ​

AHL ​​​​C3.1.23- Positive feedback in fruit ripening and ethylene production.

• State the function of fruits.
• List changes that occur to a fruit as it ripens.
• Describe the positive feedback mechanism of fruit ripening. 
• Outline why fruit ripening has evolved to be rapid and synchronized.​