3 - Controlling Organ System Flashcards
What is the main role of the brain in the CNS
It acts as the main switching unit of the central nervous system (CNS)
What is the function of the spinal cord
Links the brain to the rest of the body and acts as a minor coordinating centre for simple reflexes
Where is afferent sensory information processed
In the somatic sensory nuclei
How are efferent motor signals delivered to muscles and glands
Through the ventral root from the somatic motor nuclei
What does the ANS regulate
Muscles in the skin, around blood vessels, in the eye, stomach, and heart, as well as glands
How is the ANS controlled
By the hypothalamus and medulla; it functions in an involuntary, reflexive manner
What are the two main types of acetylcholine receptors
Nicotinic receptors (excitatory, fast depolarisation) and muscarinic receptors (either excitatory or inhibitory, slow responses)
What type of synapses use noradrenaline and what are its effects
Adrenergic synapses; can be excitatory or inhibitory depending on the receptor type
Where are alpha1 receptors located and what do they do
On blood vessels to the skin, mucosa, and abdominal viscera
Vasoconstriction (excitatory)
Where are beta1 receptors located and what is their effect
In the heart; increase heart rate (excitatory)
Where are beta2 receptors located and what is their effect
On respiratory airways and blood vessels to skeletal muscle and the heart
Cause relaxation (inhibitory)
What is dopamine’s role in the CNS
Controls movement (excitatory or inhibitory); dopamine deficiency leads to Parkinson’s symptoms
How does cocaine affect dopamine
Inhibits its reuptake, increasing its presence in the synapse and causing feelings of intense pleasure
How does nicotine affect the ANS
It activates both the sympathetic and parasympathetic systems equally
What is the structure of sympathetic nerves
Short preganglionic fibres, long postganglionic fibres; ganglia are close to the spinal cord
What is divergence in the sympathetic system
One preganglionic fibre can influence many ganglia, allowing widespread, complex responses
What neurotransmitters are used in the sympathetic division
Preganglionic fibres release acetylcholine
Most postganglionic fibres release noradrenaline
Some release acetylcholine or nitric oxide
When is the sympathetic system most active
During stress, exertion, or emergencies (“fight or flight” response)
How are parasympathetic fibres organised
Less divergent; preganglionic fibres synapse on neurons in the same ganglia, targeting specific organs
What type of receptors do ganglionic neurons have in the parasympathetic system
Nicotinic receptors (respond to acetylcholine)
What receptors are found on parasympathetic effector tissues
Muscarinic receptors, which can produce high or low responses depending on the signalling pathway
What is the structural difference between the sympathetic and parasympathetic systems
The sympathetic system has widespread effects; the parasympathetic system has more targeted, local effects
How do visceral reflexes compare to somatic reflexes
They share similar components but are always polysynaptic and can be short or long reflexes
What is autocrine signalling
A hormone acts on the same cell that secreted it
