Nervous System Flashcards
CNS consists of:
Brain & spinal chord
Peripheral Nervous system consists of:
Nerves connected to brain and spinal chord
Can be split into Somatic NS and Autonomic NS.
Somatic Nervous System
Interacts with external environment Voluntary control Follows impulse from CNS to end target organ 1 neurone Split into Afferent and Efferent
Autonomic Nervous System
Interacts with internal environment
Involuntary
Follows impulse from CNS to end target organ
2 neurones, synapsing at intermediate ganglion
Split into Parasympathetic and Sympathetic branch
Functions of ANS
Controls involuntary activity and vital functions
Layout of ANS includes
Spinal chord Preganglionic cell body preganglionic axon (myelinated) autonomic ganglion Postganglionic cell body postganglionic axon (unmyelinated) Target tissue
Sympathetic NS
Concerned with emergencies
Fight or Flight
Parasympathetic NS
Concerned with replenishing stores
Rest and Digest
Sympathetic neurones
Close to spinal chord
Acetylcholine in sympathetic ganglion binds to nicotinic receptor
Noradrenaline in target tissue binds to adrenergic receptor
Parasympathetic neurones
Close to target organ
Acetylcholine released binds to nicotinic receptor in parasympathetic ganglion
Acetylcholine released binds to muscarinic receptor in target tissue
Adrenal Medulla
Adrenal gland secretes hormones from an outer cortex and inner medulla
It’s a sympathetic ganglion
releases adrenaline and noradrenaline
Alpha receptors (sympathetic)
Noradrenaline
a1 = dilates pupils
a2= constructs blood vessels
Beta Receptors (sympathetic)
Adrenaline
B1= increases heart rate
B2= dilates some blood vessels
B3= relaxes bladder
Cranial nerves
12 in total
4 carry parasympathetic nerve fibres
Sacral nerves (parasympathetic)
Innervate bladder and lower GI tract
