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
Noradrenaline receptors in the Heart
+ chronotropy - SA node - beta1
+ dromotropy - AV node - beta1
+ inotropy - Atria and ventricles (via increased intracellular Ca) - beta1
Noradrenaline receptors in the Digestive tract
Decreased motility - a1, a2, b2
Inhibited secretions - a2
Contraction of sphincters - a1
Noradrenaline receptors in the liver
Glycogenolysis and gluconeogenesis - a1, b2
Noradrenaline receptors in the gallbladder and ducts
relaxation - b2
Noradrenaline receptors in the pancreas
Inhibits acinar secretion - a
Inhibits b cell insulin secretion - a2, (during alpha blockade b2 increases secretion)
Stimulates a cell glucagon secretion - b2, (during beta blockade a decreases secretion)
Noradrenaline receptors in the bladder
□ Bladder neck, prostate and urethral contraction - a1 Detrusor relaxation (small effect) - b
Noradrenaline receptors in the vas deferens and seminal vesicles
Ejaculation - a1
Noradrenaline receptors in the uterus
Nonpregnant - relaxation - b2
Pregnant - contraction - a1
Noradrenaline receptors in the Large arteries, arterioles, cutaneous and large (not muscular) veins
Vasoconstriction - a1, a2 (a2 present both postjunction, causing vasocontriction but mainly prejunctional with negative feedback on noradrenaline release)
Noradrenaline receptors in brown adipose tissues
Non-shivering Thermogenesis via decoupling of oxidative phosphorylation and production of heat rather than ATP - b1,2 and 3, a1 and 2
Noradrenaline receptors in the immune system
Bone marrow, Thymus, Lymph nodes and Spleen
Modulates immune responses mainly via b2
Noradrenaline receptors in the kidneys
Increased Renin secretion - b1
Decreased renal blood flow - a1
Increased renal tubular sodium absorption - a1
Noradrenaline receptors in the sweat glands
Piloerection - a1
Histamine neurons location
Histaminergic neurons have cell bodies in the tuberomammiliary nucleus in the posterior hypothalamus
Project to cerebral cortex, olfactory bulb, thalamus and spinal cord
Histamine neurotransmitter function
Thought to influence arousal and sleep, learning, sexual behavour, regulation of anterior pituatary hormones, blood pressure, thirst and pain thresholds
Serotonin alt name
5-hydroxytryptamine
Serotonin receptors
7 5-HT receptors
Most metabotropic G-protein coupled
5-HT3 ionotropic
Serotonin functions
Sleep Mood Pain Circadian rhythms Vomiting
Glutamate nature
Most abundant neurotransmitter in the brain and spinal cord (75% of excitatory transmission in the brain)
Excitatory
Glutamate receptors
NMDA
AMPA
Kainate
Metabotropic glutamate receptors
Glutamate functions
learning and memory, particularly in the process oflong-term potentiation (long-term facilitation of transmission) as well as motor co-ordination
GABA (gamma-aminobutyric acid) origin
Synthesized from glutamate
GABA (gamma-aminobutyric acid) nature
Most abundant inhibitory neurotransmitter in brain
GABA (gamma-aminobutyric acid) receptors
GABA A - ionotropic
GABA B - metabotropic
GABA (gamma-aminobutyric acid) functions
regulating neuronal activity, anxiety and sleep
Glycine nature
Used at the majority of inhibitory synapses in the ventral spinal cord and brainstem
Also has an excitatory role within the CNS as it is aco-agonistat glutamatergic NMDA receptors
Glycine receptors
Ionotropic
Glycine functions
motor and sensory functions, such as reciprocal inhibition of antagonistic muscles inspinal reflexes
Aspartate
Excitatory neurotransmitter in the brain
Ionotropic
D-serine
Co-agonist at NMDA receptors
Opioid peptides
enkephalins, endorphins, heptapeptide, octapeptide
Opioid peptides receptors
All metabotropic
mu
kappa
delta
mu opioid receptors functions
Stress responses in the brain . Analgesic . Respiratory depression . Euphoria . Sedation . Increased secretion of prolactin and growth hormone . Miosis Decrease GI motility
kappa opioid receptor functions
Stress responses in the brain . Analgesic . Diuresis . Sedation . Miosis . Dysphoria (unease)
delta opioid receptor functions
Stress responses in the brain
. Analgesic
Somatostatin
In the brain activates a hyperpolarising K+ current and inhibiting Ca2+ influx
Motor activity and cognitive function
Oxytocin function in the brain
Regulation of breast feeding and childbirth
Sexual arousal
Bonding
Maternal behavour
Foetal actions (from maternal circulation) to protect from hypoxic damage at birth
Vasopressin receptors in the brain
V1a
V1b
V2
Function of Vasopressin in the brain
Memory retrieval
Learning
Circadian time keeping
Acetylcholine nature
Acts in the central and peripheral nervous system (main neurotransmitter in the peripheral)
Mostly excitatory
Acetylcholine receptors
Nicotinic receptors - ionotropic
Muscarinic receptors - metabotropic - in PNS is autonomic
Nicotinic receptors
On postsynaptic membrane of the autonomic ganglia (sympathetic and parasympathetic)
On postsynaptic membrane of the neuromuscular junction
In the brain - affect memory
Muscarinic receptors in the brain
Learning
Muscarinic receptors in the eyes
Stimulates contraction of the circular muscle of the pupil
Muscarinic receptors in the salivary gland
Stimulates watery secretion
Muscarinic receptors in the heart
muscle - -ve inotropy
AV and SA nodes - -ve chronotropy and -ve dromotropy
Muscarinic receptors in the lung
Bronchoconstriction
Stimulates secretion
Muscarinic receptors in the digestive tract
Increased motility
Stimulates secretions
Relaxes sphincters
Muscarinic receptors in the liver
Increased glycogen synthesis
Reduced gluconeogenesis
Muscarinic receptors in the gallbladder
Stimulates contraction
Muscarinic receptors in the pancreas
Stimulates secretion of both endocrine and exocrine glands
Muscarinic receptors in the adrenal gland
Stimulate release of Adrenaline as part of the sympathetic nervous system
Muscarinic receptors in the bladder
Contraction of detrusor
Relaxation of sphincter
Muscarinic receptors in the penis
Vasodilation leading to erection
Muscarinic receptors in the Sweat glands
Stimulates secretion (both sympathetic and parasympathetic)
Adenosine receptors
A1, A2A, A2B, A3
Adenosine functions
Brain - Sleep regulating, Modulates hearing
Heart (converted in the interstitium not neuronal)
Coronary vasodilation - Negative chronotrope, Negative dromotrope
Nitric oxide in the brain
Long term depression and potentiation
