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BASIM ZWAIN LECTURESMEDICAL PHYSIOLOGYCELL PHYSIOLOGY - 1
Professor Dr. Basim Zwain
Faculty of Medicine
Jabir ibn Hayyan Medical University
CELL PHYSIOLOGY
Plasma MembraneThe fluid mosaic modelIntegral and peripheral proteins
CELL PHYSIOLOGY
Proteins act as:ReceptorsEnzymesCarriersChannels
ChannelsUngated (leak)Voltage gatedLigand gated
-Direct receptor channel complex-Intracellular second messenger–gated channel-NMDA (voltage and ligand gated)
Mechanically gated
CELL PHYSIOLOGY
Clinical considerationsCystic fibrosis is an autosomal recessive disease of a direct effect on ion channels caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene, which codes for the chloride channel gated by cAMP. Deletion of single phenylalanine molecule prevents the channel protein from reaching the plasma membrane. Reduction in chloride channels results in thick mucous secretions that block airways.
CELL PHYSIOLOGY
CYSTIC FIBROSIS
CYSTIC FIBROSIS
Clinical considerationsMyasthenia gravis is an indirect ion channel disease produced by an autoimmune disorder. Autoantibodies against the AChRs lower the receptor concentration, causing lysis of the motor endplate. The decreased number of nicotinic AChRs results in smaller postsynaptic responses and a tendency to block neuromuscular transmission. Individuals with this disease experience weakness of skeletal muscles.
CELL PHYSIOLOGY
MYASTHENIA GRAVIS
BLEPHAROPTOSIS
Clinical considerationsMalignant hyperthermia is an autosomal dominant condition occurs due to mutations in the ryanodine receptor leading to an overactive receptor to halothane and muscle relaxants such as carbachol. It results in increased Ca2+ release, sustained muscle contraction, extensive necrosis of muscle cells, release of large amounts of K+, cardiac arrhythmias, and ventricular fibrillation. High Ca2+ levels leads to increased heat production. Treated with dantrolene, inhibits the receptor.
CELL PHYSIOLOGY
Clinical considerationsBrody disease is an autosomal recessive mutation in the ER Ca2+-ATPase, which leads to exercise induced impairment of skeletal muscle relaxation.Darier disease is an autosomal dominant skin disorder (dyskeratosis follicularis) due to mutations in the ER Ca2+-ATPase, leads to loss of cell adhesion.
CELL PHYSIOLOGY
BRODY DISEASE
DYSKERATOSIS FOLLICULARIS
Clinical considerationsX-linked congenital stationary night blindness is a recessive disease of human retina due to mutations in a voltage-gated Ca2+ channel, defective glutamate release and neurotransmission. Patients have difficulty adapting to low light situations, reduced visual acuity, myopia, nystagmus, and strabismusLambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease characterized by an increased number of LEMS antibodies against voltage-gated Ca2+ channels, leads to defective neurotransmission and weakness of proximal muscles.
CELL PHYSIOLOGY
VOLTAGE-GATED CA2+ CHANNEL
CELL PHYSIOLOGY
Transport processes across plasma membrane:
Passive transport
Active transport
Passive transportDiffusion
Simple diffusionFacilitated diffusionOsmosis
Osmolality, osmolarity, isotonic, hypotonic and
hypertonic solutions.
Filtration
CELL PHYSIOLOGY
CELL PHYSIOLOGY
Active transportPrimary activeSecondary active
Symport (cotransport)Antiport (exchange)
CELL PHYSIOLOGY
CARDIAC STIMULANTSThe natural wild flower Digitalis purpurea (foxglove) and synthetic cardiac glycosides, including ouabain and digitalis, inhibit the Na+/K+-ATPase pump.