Physiology Flashcards
Cell membrane
Phospholipid bilayer with embedded proteins
Selectively permeable to ions
Can anchor cytoskeleton
Acid base balance - buffers
Bicarbinate
Proteins - 2/3 of the buffering in the blood and most within cells
Phosphate
Organs of acid base balance
Brain: sense elevation of CO2 via pH sensation at the respiratory centre in the brainstem
Lungs: ensure removal of carbonic acid (as CO2)
Kidneys: removal of H+ ions and regeneration of HCO3- due to presence of carbonic anhydrase
Henderson-Hasselbach equation
pH= 6.1 + log (HCO3/H2CO3)
Anabolism
constructive metabolic process in which a cell uses energy to construct molecules such as enzymes and nucleic acids
Catabolism
The purpose of catabolic reactions is to provide the energy and components needed by anabolic reactions
Standard processes of Aerobic respiration
Glycolysis Pyruvate oxidation Citric acid cycle Oxidative phosphorylation via electron transport chain Production of 38ATP from 1 glucose
Glycolysis
In the cytosol of cells
Substrates: Glucose, NAD, ADP and O2
Products: Pyruvate, NADH, ATP
Pyruvate oxidation
Cytosol of cells
Substrates: Pyruvate, CoA and NAD
Products: Acetyl-CoA, NADH and CO2
Citric acid cycle
Mitochondrial
Substrates: Acetyl-CoA, NAD, FAD, H2O and ADP
Products: CoA, NADH, FADH2, H, ATP, CO2
Oxidative phosphorylation
Mitochondrial via electron transport chain
Substrates: ADP, NADH FADH2 and O2
Products: ATP, NAD, FAD and H2O
Substrates for aerobic respiration
Fatty acids
Amino acids
Fatty acid metabolism
Lipolysis - triglycerides to free fatty acids and glycerol
Fatty acids in metabolising cells via beta oxidation to Acetyl-CoA
Glycerol in liver converted to glucose via gluconeogenesis
Amino acids
Converted to different substrates in the citric acid cycle or pyruvate and acetyl-CoA
Anaerobic respiration
Lactic acid fermentation in cell cytoplasm
Anoxic regeneration of NAD+ as a source of energy
Pyruvate to lactate producing ATP and regenerating NAD for glycolysis
Production of 2 ATP from 1 glucose
Mechanisms of capillary exchange
Diffusion
Transcytosis
Bulk flow
Diffusion
Passage of molecules from high concentration to low concentration
Transcytosis
Large lipid insoluble substances are endocytosed, cross the membrane and then exocytosed
Bulk flow
Movement dependent on pressure and the four Starling forces
Starling forces
Oncotic or colloid osmotic pressure in the capillary
Oncotic or colloid osmotic pressure in the interstitium
Hydrostatic pressure in the capillary
Hydrostatic pressure in the interstitium
Oncotic pressure
A form of osmotic pressure exerted by proteins either in the blood plasma or interstitial fluid
Hydrostatic pressure
A force generated by the pressure of fluid on the capillary walls either by the blood plasma or interstitial fluid
Osmolarity
Essentially the amount of solute in the solvent (water)
The higher the osmolarity, the more solute there is and the relative “concentration” of the water is low. The water mores from high concentration to low (area of low osmolarity to low)
Lymphatic system
Series of vessels andnodes that collect and filter excess tissue fluid (lymph), beforereturning it to the venous circulation
Functions of the spleen
Malpighian corpuscles
§ Periarteriolar lymphoid sheaths rich in T-lymphocytes and macrophages
§ Lymphoid follicles rich in naïve B-lymphocytes
Cords
§ Removal of old, damaged and dead red cells, antigens and opsonised microorganisms which are phagocytosed by macrophages
§ Sequestration of platelets
§ Storage of red cells
Normal values of CSF
Protein § 15-45 Glucose § 5-8 (2/3 Blood glucose) Mononuclear cells § 0-5 Opening pressure § 7-18 cmH2O
Normal value of pleural fluid
Protein
Fluid/serum <0.5
<30 g/l
LDH
Fluid/serum <0.6
Pleural fluid volume, production and absorption
- Small volume (0.3ml/kg with turnover 0.15ml/kg/h)
- Produced by the parietal pleura in less dependent areas and absorbed by the parietal pleural lymphatics in the more dependant areas, on the diaphragmatic surface and the mediastinal regions
- The pleural mesothelial cells have oligolamellar surfactant molecules of a negative charge and so repulse each other assuring lubrication
- Pleural fluid acts to both lubricate and the negative pressure allows the chest wall and lungs to move in synchrony
Pericardium
• Serosal cavity
• Two anatomical structures closely connected
○ external sac of fibrous pericardium
○ Internal sac of serous pericardium
• Product of ultrafiltration
• Drained by lymphatic capillary bed mainly and mesothelial cells lining the membrane may also have a role
• It provides lubrication during heart beating by
oligolamellar surface-active phospholipid surfactant molecules of a negative charge and so repulse each other assuring lubrication
Peritoneal fluid
- An ultrafiltrate of plasma
- A lubricant around abdominal organs and allows the diffusion of electrolytes and other substances to and from the serosal surfaces of the abdominal cavity
- Produced by mesothelial cells in the membrane
- Absorbed by capillary absorption
Neurotransmitters
Endogenous chemicals that enable communication within the nervous system and between the nervous system and the rest of the body
Dopamine
Monoamine
D1, D2-like and TAAR receptors (all metabotropic G-protein)
Excitatory or inhibitory
Roles in exectutive function, motor control, motivation, arousal, reinforcement, reward, lactation, sexual gratification and nausea
Noradrenaline class
Catecholamine
Noradrenaline in the brain
attentiveness, emotions, sleeping, dreaming, and learning
Noradrenaline receptors
alpha1 alpha2 beta1 beta2 beta3
Noradrenaline receptors in the eye
Dilator pupillae - alpha1
Superior tarsal muscle (smooth muscle attached to levator palpebrae superioris) - alpha1
Ciliary epithelium - alpha2 - decreases aqueous humor production, beta2 - increases aqueous humor production
Noradrenaline receptors in the Salivary glands
Stimulates mucus secretion - alpha1
Noradrenaline receptors in the lungs
Bronchial muscle - relaxation - beta2