C3.1 Integration of body systems Flashcards
(from the study guide)
Comparing hormonal and nervous signalling
Hormone signalling: GDRCCCM
- God do repreat can’s country mice
Nervous signalling: CCCS
- can cooks clean sinks
What is crucial to integrate systems
communication between the different components
The difference between unconscious processes and conscious processes
Unconscious processes:
- can happen when asleep
- involunatary
- controlled by the brain and the spinal cord
- glands and smooth muscle are controlled involuntarily
- e.g.: peristalsis (though this is controlled by the enteric nervous system)
Conscious processes
- only happen when awake
- volunatry
- controlled by the cerebral hemispheres of the brain
- striated muscle is controlled voluntarily
- example: chewing food
What acts as the integrating centre for unconscious processes?
- the grey matter of the spinal cord
The pathway how unconscious actions occur
- neurons bring information to the grey matter of the spinal cord and from the sense organs
- interneurons pass impulses via synapses between neurons in the grey matter
- decides the appropriate action for the stimuli
- motor neurons convey signals from grey matter -> muscles and glands
sense organs/receptors -> sense neurons -> interneurons (spinal cord) -> motor neurons -> effectors (for the response)
Why does the spinal cord coordinate unconscious processes
Quicker than conveying signals to the brain
- useful especially in dangerous situations
How does the sensory neuron convey messages from the receptors to the CNS?
- receptor cell detect a change in the external/internal environment*
- receptor cells sends a signal to sensory neurons*
- the sensory neurons convey the impulses to the CNS via the spinal nerves or the cranial nerves (axon)
spinal or cranial depending on where the signal is coming from
- note: for sensory neurons, they have nerve endings that already act as receptors for touch and heat. so in that case, then no need for a receptor cell
Where are the receptor cells located?
- in the skin and sense organs
What do receptor cells do?
Detect changes in the external environment
- e.g. the rod and cone cells in the retina of the eye detect light
From which source does the spinal cord attain sensory information?
- signals from other organs of the body (skin, muscles)
From where does the brain attain sensory information?
- all the signals come from the sense organs on the head: the eyes, ears, nose and tongue
- sensory inputs to the brain are received by specialized areas in the cerebral hemispheres
- for example, the visual cortex receives signals from rod and cone cells
Parts of the spinal cord
Two main tissues:
1.) The white matter
- transmission centre.
- contains axons
- carry impulses to and from the brain
2.) The grey matter
- contains cell bodies of neurons and many synapses
- processing centre for unconscious movements
- decides on the appropriate reaction for the stimuli
Describe the cerebral hemisphere
- part of the brain that plays a major role in conscious movements
- conscious movements -> control of striated muscles
- specifically the motor cortex sends the signals
Striated muscle where is it attached?
To the bone
Wh
What is striated muscle used for?
- to maintain posture
- for locomotion (e.g. standing up)
Overall, how is information conveyed from receptors to the CNS?
How do motor neurons convey messages from the CNS to the muscles?
- the motor neurons receive signals from interneurons from their many dendrites
- one axon leads from the cells body of the motor neuron out of the brain and down the spinal cord
- there, synapse is formed with a second motor neuron whose axon leads to one specific muscle
- the second motor neuron’s axon leads to a specific straited muscle
- then contraction is stimulated once the nerve impulse reaches the end
summary: interneuron -> first motor neuron which has the axon leading out of the brain and down the spinal cord -> the second motor neuron receives the signal via synaptic transmission -> signal sent to the effector for response
Define what a nerve is
- bundle of nerve fibres enclosed in a protective sheath
Which nerve is the widest?
- ## the sciatic nerve is the widest (20 mm across)
Optic nerve
contains up to 1.7 million nerve fibres
How many fibres would small nerves contain
- fewer than a hundred
How many nerves do the organs of the body have
- one or two nerves