Three major structures of the brain
What does the cerebrum do?
Seat of consciousness and higher mental functions. Also processes memory, and some involuntary somatic functions.
What does the cerebellum do?
Fine tunes motor control and balance.
What does the brainstem do?
Processing centre to/from the spinal cord, cranial nerves and cerebrum/cerebellum.
What does the midbrain do?
Processes visual and auditory info, and deals with involuntary somatic responses. Also the main seat of the RAS.
What does the hypothalamus do?
Endocrine function, kidney function. Hunger, thirst, nausea, temperature control, emotions.
What does the thalamus do?
Switching centre between the pons and cerebrum, relaying sensory info.
What is the RAS?
Reticular activating system - determines and controls consciousness.
What does the pons do?
Interchange point for info from/to other regions of the brain, particularly for sensory info to the thalamus and cerebellum.
What does the medulla oblongata do?
Controls respiration, cardioascular system and vasomotor systems. Also relays sensory info to thalamus and cerebellum.
Cerebral perfusion pressure
Pressure actually moving blood through the brain.
Autoregulation of cerebral perfusion pressure
Process of changing blood pressure to ensure adequate CPP.
Four major arteries providing blood to the brain
Internal carotid arteries and vertebral arteries.
Fluid in the posterior chamber of the eye
Fluid in the anterior chamber of the eye
List the four major blood vessels that transverse the neck
- Internal/external/common carotid arteries
- Internal/external jugular veins
- Subclavian arteries/veins
Six major parts of the brain
- Diencephalon (hypothalamus, thalamus, pituitary)
- Mesencephalon (midbrain)
- Medulla oblongata
What does the pituitary do?
Releases hormones under control of the hypothalamus.
What area of the brain controls speech?
What area of the brain controls vision?
What area of the brain controls personality?
What area of the brain controls balance/coordination?
What area of the brain controls higher sensory processing?
What area of the brain controls higher motor control?
What area of the brain controls the RAS?
The lateral medulla and pons, but especially the midbrain.
Two system the supply blood flow to the brain
- Vertebrobasilar system (posterior)
- Carotid system (anterior)
What parts of the body are controlled by the cervical brachial plexus?
Diaphragm, shoulders and arms
What nerve(s) are controlled by the plexus at C1-C5 (cervical plexus)?
Prenic nerve (diaphragm)
What nerve(s) are controlled by the plexus at C5-T1 (cervical plexus)?
Axillary, radial, median, musculocutaneous and ulnar nerves.
What nerve(s) are controlled by the plexus at T12-L4? (lumbar plexus)?
Femoral and obturator nerves (lower abdomen, thighs, glutes).
What nerve(s) are controlled by the plexus at L4-S3 (sacral plexus)?
Sciatic nerve (legs).
What region of spinal nerves is involved in the sympathetic nervous system?
Thoracic and lumbar nerves
What region of spinal nerves is involved in the parasympathetic nervous system?
Sacral and cranial nerves
Processing centre where nerves of the autonomic nervous system interact with other nerves.
Ganglia located in the abdominal cavity that is stimulated as part of the sympathetic nervous system.
Process of sympathetic nervous system stimulation
Ganglia located near spine. Pre-ganglionic neurons release ACh to postganglionic neurons. These send nerve fibres to target organs where NE is released.
Process of parasympathetic nervous system stimulation
Ganglia located near target organs. Preganglionic neurons release ACh to postganglionic neurons. These send nerve fibres to target organs where ACh is released.
Other effects of sympathetic nervous system stimulation
Tissues not directly innervated by sympathetic nervous system can be affected by NE or epinephrine released by adrenal medulla in response to sympathetic direction.
Types of sympathetic nervous system receptors
- Adrenergic (most), including alpha1, alpha2, beta1 and beta2 receptors.
- Dopaminergic, cause dilation of specific arteries.
What do alpha1 receptors do?
Cause vasoconstriction, bronchoconstriction, and increased metabolism.
What do alpha2 receptors do?
Inhibit over-release of NE in a synapse. Located on presynaptic membrane.
What do beta1 receptors do?
Increase heartrate, cardiac contractility and cardiac conduction.
What do beta2 receptors do?
Vasodilation, bronchodilation, lower metabolism (opposite of alpha1 receptors).