Autonomic Nervous System Flashcards
Vertebral column (Spine)
• Houses and protects spinal cord
• Muscle attachment
• Locomotion
• Series of irregular bones with regional variations
• Regions of the vertebral column • Cervical / thoracic / lumbar / sacral /
caudal or coccygeal
• Vertebral formula (dog) • C7T13L7S3CCvariable
Thoracic spine
Corresponds with number of ribs (13 in dog and cat)
• Limited movement in this region (due to articulation with ribs at
costal fovea)
• Protects thoracic viscera
• Provides attachment for thoracic limb • Short vertebral body
• Long dorsal spinous process
• Small transverse process
Lumbar Spine
Stouter vertebral bodies • Forward sloping dorsal spinous processes • Long flat transverse processes Ligaments 1. Supraspinousligament; 2. spinous process; 3. interspinous ligament; 4. arch of vertebra; 5. interarcuate ligament; 6. Intervertebral foramen; 7. dorsal longitudinal ligament; 8. ventral longitudinal ligament; 9. intervertebral disc
Sacral spine
The sacrum is a single bone formed by three fused vertebrae
• The sacrum articulates with the pelvic girdle • Reduced dorsal spinous processes
Coccygeal spine
- AKA caudal spine
- Number varies
- Processes are reduced
Divisions of the autonomic nervous system
- Sympathetic
- Fight and flight response (4Fs) • Thoracolumbar outflow
- Parasympathetic
- Maintains homeostasis • Relaxed state
- Rest and digest
- Craniosacral outflow
Anatomy of the autonomic nervous system
- Motor and sensory component
- Motor component consists of pre and post ganglionic fibres • Dual innervation of organs
- All pre-ganglionic fibres cholinergic, are myelinated (fast)
- Post ganglionic fibres are unmyelinated (slower but efficient) • Parasympathetic are cholinergic
- Sympathetic mostly adrenergic
Anatomy of the autonomic nervous system
Sympathetic
- Pre-ganglionic fibres in lateral horn of thoracolumbar spinal cord
- Sympathetic – one pre-ganglionic fibre synapses with 20 post-ganglionic fibres
- Sympathetic ganglia near spine (short neurons for speed of response)
- No cranial nerves contain sympathetic fibres (thoracolumbar outflow only)
Anatomy of the autonomic nervous system
Parasympathetic
- Parasympathetic ganglia in or near target (except for those of the head)
- Parasympathetic – one pre-ganglionic fibre synapses with four post-ganglionic fibres
- Cranial nerves containing parasympathetic fibres • Occulomotor
- Facial
- Glossopharyngeal
- Vagus
Sympathetic response
Fight or flight Muscles tense Increase heart rate Pupils dilate (let more light in) Decrease salivation (dry mouth) Adrenalin released from adrenal glands Glycogen converted to glucose Shorter neurons allows a faster response time
Parasympathetic response
Maintains homeostasis Rest and digest Pupils contract Increase salivation (for digestion) Longer neurons respectively leading to slower responses
Pharmacological regulation of the autonomic nervous system
• Pharmacology will be covered fully at a later stage of the course
• Here are some common examples of drugs you may have come across
that act on the ANS
Salbutamol– inhibits bronchospasm
Propanolol – slows heart rate, reduces blood pressure