Flashcard set 1
(35 cards)
What is the homeostasis control process?
stimulus -> sensor -> controller -> effector -> response
and negative feedback regulation = effector leads to reduction in stimulus
What is the organisation of the ANS?
- sensory afferent nerve fibres
- control centres: hypothalamus, brain stem, spinal cord
- efferent pathways: sympathetic nervous system, parasympathetic nervous system
What are the common features of the efferent pathway?
- 2 neurons in series
- preganglionic neuron originate in CNS
- postganglionic neuron originate in autonomic ganglia
- 1 preganglionic neuron can synapse with many postganglionic neurons (8-9)
What is the flight or fight pathway?
sight, sound, smell -> amygdala centre -> osteoblasts -> osteocalcin -> inhibits parasympathetic neuron
Organisation of the sympathetic nervous system?
- preganglionic origin = thoracic 1, Lumbar 2/3
- postganglionic origin = autonomic ganglia
- preganglionic neuron is short
- postganglionic neuron is long
Organisation of the parasympathetic nervous system?
- preganglionic origin = cranial nerve III (eye), VII (facial), IX (parotid), X (vagus)
- postganglionic origin = autonomic ganglia
- preganglionic neuron is long
- postganglionic neuron is short
Neurotransmitters of ANS and their synapses
Neurotransmitters:
- Acetylcholine (Ach)
- Noradrenaline (NAdr)
- Adrenaline (Adr)
- Non-adrenergic non-cholinergic (NANC)
Synapses:
- Cholinergic = nicotinic or muscarinic
- Adrenergic = alpha or beta
What is the organisation of the muscarinic receptor?
- target organ in PNS (parasympathetic nervous system)
- exception is sweat glands in SNS (sympathetic nervous system)
- blocked by ATROPINE
What is the organisation of the nicotinic receptor?
- ganglia in SNS and PNS
- located at neuromuscular junction
- blocked by CURARE
What is the organisation of adrenoreceptor Alpha 1?
- postsynaptic
- releases NAdr > Adr
- vasoconstrictor and smooth muscle contraction
What is the organisation of adrenoreceptor Alpha 2?
- presynaptic
- releases Nadr > Adr
- reduction in adrenergic and cholinergic transmission
- blocked by PHENTOLAMINE
What is the organisation of adrenoreceptor Beta 1?
- receptor in the heart
- releases Adr = NAdr
- increase in heart rate and force of contraction
What is the organisation of adrenoreceptor Beta 2?
- releases Adr > NAdr
- vasodilation and smooth muscle relaxation
- blocked by PROPANOL
What are small and large red blood cells called and where are they found?
- small RBCs = microcytic -> found in iron deficiency anaemia
- large RBCs = macrocytic -> found in folate (vitamin B9) deficiency anaemia
What happens to ages RBCs after 120 days?
- phagocytized in liver and spleen
- haemoglobin decomposed into heme and globin
- heme components are recycled e.g heme = bilirubin, iron = stored in liver
Structure of haemoglobin molecule
- globin = made up of 4 protein chains (alpha, beta, gamma, delta)
- 4 iron containing haem groups = consists of porphyrin ring with 1 Fe atom
What are the types of haemoglobin/globin forms?
HbA = 2 alpha, 2 beta HbA2 = 2 alpha, 2 delta HbF = 2 alpha, 2 gamma HbS = sickle cell anaemia HbH = alpha thalassemia
What are the 2 forms of Hb and what are their characteristics?
- r form (relaxed) = high O2 affinity = firmly binds O2
- t form (taught) = low O2 affinity = releases O2
What is sickle cell anemia?
genetic disease = mutation in beta globin gene -> glutamic acid residue is replaced by valine = sticky patches
Hb polymerises at low PO2 forming long crystals of HbS
What is alpha thalassaemia?
- production of alpha globin is reduced = leads to excess of beta chain
- unstable tetramer of 4 beta chains = HbH
- reduced oxygen carrying
What is beta thalassemia?
- results in iron overload = organ damage
- excess of alpha chains
- bind to and damage RBC membranes
How is thalassemia diagnosed?
Diagnosed by electrophoresis
- alpha thalassemia = reduced HbA, presence of HbH
- beta thalassemia = decreased HbA, beta globin reduced or absent
What is haemostasis?
arrest of bleeding from a broken blood vessel
Where are platelets stored and how are they released?
stored in the spleen and released by contraction of the spleen activated by SNS
