ELC2
What is the name of the catecholamine-secreting tumour of the adrenal medulla
pheochromocytoma
Ethanol is metabolised in two steps by two enzymes, Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Which enzyme is the rate limiting step and which is associated with 'oriental flush'
ADH --> rate limiting - enzyme saturated after one drink
ALDH --> 'Oriental flush' - dominant negative genetic variants are common in East Asians
Plantar flexed + inverted
Name the layers of the scalp
Skin
Connective tissue
Aponeurosis
Loose areolar tissue
Periosteum
Chromaffin cells derive from which cells in the developing embryo
Neural crest cells
What is the artery that runs deep to the pterion?
medial meningeal artery
What are the contents of the popliteal fossa?
Tibial nerve, popliteal vein, popliteal artery
What is secreted by the posterior pituitary gland?
ADH & oxytocin
Long feedback pathway
Cortisol --> anterior pituitary inhibiting ACTH release, hypothalamus inhibiting CRH release
Short feedback pathway
ACTH --> hypothalamus --> inhibits CRH release
Describe the natural history of T2DM
Visceral adiposity --> insulin resistance --> hypertrophy of beta cells --> beta cell failure (decrease in mass and function of beta cells) --> T2DM
What is titin?
Name the branches of the facial nerve
Zygomatic
Buccal
Marginal mandibular
Cervical
We learnt about two forms of congenital adrenal hyperplasia (CAH), 11B hydroxylase deficiency and 21a hydroxylase deficiency, how do each manifest and why?
11B hydroxylase deficiency
- increased androgen (common precursor to androgens and cortisol can still go down the androgen pathway)
- HTN (cortisol precursor has mineralocorticoid properties)
21a hydroxylase deficiency
- low cortisol
- high ACTH (less -ve feedback)
- high androgens
Blood supply to the scalp comes from 3 branches of the external carotid and 2 branches of the internal carotid, name one of each
External carotid
- superficial temporal
- posterior auricular
- occipital
Internal carotid
- supra orbital
- supratrochlear
Match the muscles with the compartment, action and nerve supply
- Anterior, Posterior, Lateral
- Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, Fibularis tertius
- Fibularis longus, Fibularis brevis
- Gastrocnemius, Plantaris, Soleus
- Popliteus, Tibialis posterior, Flexor digitorum longus, Flexor hallucis longus
- Plantar flexion, Dorsi flexion, Eversion
- Superficial fibular nerve, Deep fibular nerve, Tibial nerve
- Anterior --> Dorsi flexion --> Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, Fibularis tertius --> Deep fibular nerve
- Posterior --> Plantar flexion --> (Superficial) Gastrocnemius, Plantaris, Soleus, (Deep) Popliteus, Tibialis posterior, Flexor digitorum longus, Flexor hallucis longus --> Tibial nerve
- Lateral --> Eversion --> Fibularis longus, Fibularis brevis --> Superficial fibular nerve
In GDM insulin resistance is triggered by which hormones released by the placenta
Human placental lactogen and placental growth hormone
Name the hormones synthesised in the adrenal gland, where they are synthesised and what stimulates the production of each hormone
Sympathetic stimulation, ACTH and cortisol from adrenal cortex --> Adrenal medulla --> Catecholamines
Angiotensin II --> Zona glomerulosa --> Mineralocorticoids (Aldosterone)
ACTH --> Zona fasciculata --> Glucocorticoids (cortisol)
ACTH --> Zona reticularis --> Androgens (DHEA)
Which muscles of facial expression are involved in the "trumpet playing" facial expression?
Buccinator (resists distension during blowing action) + Orbicularis oris (tonic contraction resists opening of the oral cavity)
What influences muscle tension?
Frequency of stimulation, length of the fibre at onset of contraction
- Muscle fibre number
Finer controlled movements have fewer fibres per motor unit, courser controlled movements have more fibres per unit
- Muscle cross sectional area
Greater cross sectional area can produce more tension
Explain excitation-contraction coupling and muscle relaxation
Sliding filament model
ATP hydrolyses to activate myosin head. Increase in calcium exposes binding sites on actin. Cross bridges form and power stroke occurs. Thin filament slides inwards over thick filament (Z lines appear closer). Sarcomere shortens causing muscle contraction.
Muscle relaxation
Active process dependent on calcium reuptake into SR - calcium moves back into the SR when generation of local action potential decreases.
Acetylcholine release triggers calcium release. Acetylcholine is broken down by acetylcholinesterase at the neuromuscular junction.