Flashcards in Physiology Deck (219)
What are the two phases of the gait cycle?
Stance phase (60% of cycle)
Swing phase (40% of cycle)
What are the different sections of the stance phase in the gait cycle?
1- Heel strike (heel hits ground)
2- Mid stance (tibia parallel to ground)
3- Toe-off (knee flexion has begun, toe leaves ground)
(Stance phase is 60% of gait cycle)
What are the different sections of the swing phase in the gait cycle?
1- Early swing (hip flexion begins, knee stays in flexion)
2- Late swing (max hip flexion, full knee extension)
Connective tissue is mainly made up of what?
What is the function of Cap Z and tropomodulin?
Cap Z- Caps +ve end of actin filament at z-disc
Tropomodulin- Caps -ve end of actin filament
What is the function of nebulin?
Binds actin monomers (around 200) so therefore regulates then length of actin
What is the role of A-Actinin?
Cross linkings actin filaments at z-disks
a) A typical muscle is controlled by how many motor neurons?
b) Each motor neuron controls how many fibres?
a) Around 100
b) Around 100-1000
What is a muscle unit?
Muscle fibres innervated by a single motor neuron
What is a motor unit?
Muscle unit + motor neuron
What is a motor neuron pool?
Collection of neurons innervating a single muscle (found in ventral horn of spinal cord)
What is a positive allosteric modulator (PAM), aka allosteric enhancer?
Amplifies an agonist effect at a receptor
What is the definition of awareness?
Continuous awareness of the external and internal environment, both past and present, together with the emotions arising from it
What are the results of higher than normal or lower than normal CO2 on the blood vessels of the brain?
High CO2: Vasodilator
Low CO2: Vasoconstrictor (Reduces blood flow to brain, hence hyperventilating- lowering of CO2 in patients with cerebral oedema)
How is arousal (waking from sleep) regulated?
By the reticular activating system (in reticular system running from the brain stem to the thalamus and then out to the whole cortex). Simulation of RAS stimulates activation of the cortex
How can you be awakened from sleep?
Any stimulation of the RAS strong enough to activate it (light, sound, touch), after this +ve feedback from area's of the cortex (motor/ sensory) keeps the RAS activated
What happens when the RAS becomes less responsive to stimulation?
RAS becomes less responsive after being activated for many hours, this leads to lethargy and decreased alertness
Which neurotransmitters are involved with sleep/ wake cycles?
Noradrenaline (stimulates RAS)
Serotonin (inhibits RAS)
Amphetamines stimulate the release of which neurotransmitter?
Drugs which increase serotonin levels well beyond normal would do what?
Heighten perception of sensory information and cause possible hallucinations
What are the three stages of memory?
Perception, storage and retrieval
What is normal intercranial pressure for a supine adult?
How could seizures raise intercranial pressure?
Increased oxygen/ blood demands to the brain (raising BP and causing vasodilation)
Which neurotransmitters act at each synapse in the autonomic system?
All preganglionic: ACh
Parasympathetic postganglionic: ACh
Sympathetic postganglionic: Noradrenaline
What is the pathophysiolgy of post traumatic epilepsy?
Of a few days glial and macrophage reactions result in scarring (hemosiderin stained depressions) on the cortex, often leading to PTE (More severe or penetrating injuries most like to lead to PTE)
What is the effect of light on melatonin levels?
Melatonin increases as light decreases (so raised melatonin makes you sleepy)
What is the raphe nuclei and what is its role in sleep?
In pons and medulla
Secretes serotonin and has been shown to induce sleep
Discharge of noradrenergic neurons in which two brain areas stimulates wakefulness?
Locus ceruleus and serotonergic neurones
(Found in midbrain raphe nucleus)
What are the functions of sleep spindles and k-complexes? In what sleep phase are they found?
Found in deep sleep phase N2
Sleep spindles: Inhibit thalamus activity to maintain sleep
K-Complex's: Block cortical arousal due to non harmful stimuli (eg light touch) and aids memory consolidation