Book 2 Flashcards
Definition of pain?
Pain is an unpleasant emotional and sensory experience associated with actual or potential tissue damage, or described in terms of such damage
Pain cant always be linked to actual tissue damage
Describe the basic flow of pain in the pain pathway?
- pain stimulus
- transduction (nociception) conversion of pain stimuli to nerve impulses by pain receptors
- transmission of pain impulses to spinal cord by sensory neurones
- spinal cord processing
- transmission of pain information via ascending tracts in spinal cord to the brain
- processing of pain information in the brain
What are pain receptors called?
What are the two types of pain receptors??
Nociceptors, free nerve endings sensory neurones
Found in somatic and visceral structures
High threshold mechanoreceptor - responds to intense mechanical stimulation
Polymodal nociceptor - responds to unpleasant mechanical, chemical and thermal stimuli
What two types of pain stimuli are there?
Physical- thermal /mechanical stimuli
Chemical - released due to a damaged tissue can also cause pain
What are the 4 basic processes in nociception?
Transduction, transmission, perception, modulation
What happens in the transduction of pain in nociception?
When painful stimuli, mast cells release histamine.
Histamines stimulates neurochemicals to be released from nociceptor ending. Eg substance P.
These neurochemicals further stimulate mast cells and nociceptors.
This stimulation leads to ion channels, sodium ions in fluxing in and a nerve impulse action potential being created along nerve fibres to spinal cord
Ischaemia or hypoxia will cause pain as accumulation of pain stimulating chemicals, certain chemicals may lower pain threshold so becomes sensitised
What are the two types of sensory fibres involved with pain?
A delta fibres - a fast conducting, myelinated fibre from high threshold mechanoreceptor, that is the first pain that is sharp and felt in a defined area. Larger diameter of 2 to 5ym.
C fibres are slow conducting, unmyelinated fibres that signal a later, more chronic that is a more dull, long lasting aching pain. From polymodal nociceptors. Smaller diameter of 0.2-1.5ym
What are the structures of the urinary system???
Kidneys- remove urea from the blood and expel it in urine, waste product of protein metabolism. Help to maintain a balance of fluids, salts and other substances. Produces erthropoietim.
Ureter - narrow tubes that take urine from kidney to bladder. Smooth muscle contracts and relaxa to force urine down.
Bladder -muscular walls contract and relax and stretch to store urine. And contract to flattern and empty of urine
Urethra - tube allows urine to exit body
What are the 3 areas of the kidney??
Outer cortex, inner medulla and renal pelvis (where urine is collected and drains in to the ureter.
What is a nephron?
Microscopic functional units of the kidney that is responsible for purification and filtration of blood.
Consists of two parts, renal corpuscle which filters blood, and renal tubule where reabsorption and secretion occurs
What two parts is the renal corpuscle made from??
Bowmans corpuscle and glomerulus
What happens when blood is filtrated in the kidneys??
At renal corpuscle with bowmans corpuscle and glomerulus.
Bowmans corpuscle encloses glomerulus with capillaries, afferent aterieole brings blood at high pressure which pushes it out of the capillaries of the glomerulus. This makes a filtrate (glomerular filtrate) which contains water, electrolytes, urea, amino acids and glucose. This is then sent along the renal tubule
Describe the process as glomerular filtrate goes through the renal tubule in nephrons in kidney??
Begins are proximal convoluted tubule. (PCT) where reabsorption begins as glucose, amino acids and electrolytes are reabsorbed, attracting 80% of water. By active transport
Loop of henle next U shape. Sodium and water is reabsorbed which concentrates the filtrate
Distal convoluted tubule next where electrolytes like h plus, toxins and nitrogenous wasteare actively transported from plasma filtrate into urine which then flows to collecting ducts.
Final water reabsorption is in collecting ducts which have water pores in epithelial, work under influence of ADH.
Explain ADH within kidney
Anti- duiretic hormone
Produced in hypothalamus, stored in pituitary gland, released into bloodstream
osmoreceptors in hypothalamus detect changes in concentration of solutes in blood.
Angiotensin effects release of ADH too.
ADH has two functions - water retention by re absorption in distal tubule and collecting ducts by changing their permeability.
Vasoconstriction so increasing peripheral resistance increasing blood pressure (hormonal regulation) as ADH increases volume of water in blood, increasing blood pressure
What is the main function of renal corpuscle, pct, loop of henle, dct and collecting ducts??
Renal corpuscle - filtration
Pct - reabsorption
Loop of henle - adjust ts water conc of water
Dct - secretion in to urine
Collecting ducts - AHD water re absorption
What does DNA stand for? And its structure?
What are AG and TC??
Deoxyribonucleic acid.
Double helix as double stranded, with nucleotides consisting of a bases (GC, AT) sugar deoxyribose, and phosphate group.
AG purines
CT pyrimidines
What is RNA and its structure?
Ribonucleic acid 2 types- messenger and transfer Sugar is ribose AU, GC Uracil!!!
What is chromatin??
What is genome?
What is gene??
Chromatin is DNA tightly wrapped around histones.
Genome is all the genes in a cell
Gene is an area on a chromosome that codes for a particular protein
What are the 3 stages of protein synthesis??
Transcription - where DNA sequence copied into similar single stranded molecule MRNA . Enzyme breaks hydrogen bonds on DNA and free nucleotides align with DNA bases to form a complementary strand.
Slicing - introns out that don’t code for proteins
Translation- amino acid chains are made on ribosomes with assistance of TRNa. mRNA attaches to ribosome in cytoplasm or RER. Ribosome moves along MRNA and TRNA brings amino acid. 3 bases for 1 amino acid - triplet code is a codon.
What is pharmo cogenetics??
Look at DNA and see what meds someone will best respond to, as everyones diff dna
What are the two types of fluids in the body that are separated by a cell membrane?
Extracellular fluid -
Blood plasma and interstitial fluid also other fluids like gasto-intestinal secretions, CSF 40% of fluid in body
Intracellular fluid - cytosol 60% of fluids is found within the cell membrane
What does insensible loss of water mean?
Loss of water, normally by diffusion through the skin and evaporation from the respiratory tract
Why is water important in the body??
Transport, temperature regulation, blood pressure, lubricant, chemical reagent, universal solvent
What factors determine blood volume (water)
Amount of water and sodium ingested and excreted by kidney
Water lost through gi tract, skin and lungs
What two receptors detect changes in blood volume/ blood pressure ??
What is the controller and effector?
Osmoreceptors as part of ADH in hypothamalus
Baro receptors in heart in aortic arch and carotid arteries signify vasomotor centre and cardiac centre
Controller - ADH
Effector - distal convoluted tube and collecting ducts
What does RAAS stand for?
Renin- angiotensin - aldosterone- system hormonal system
What are the main aims of RAAS
Renin angiotensin aldosterone system regulates blood pressure by the blood volume by regulating the fluid balance in the body, sustain balance of sodium and water
How does RAAS work?
When blood volume is low, specialised cells called juxtaglomerular cells in the kidneys secrete renin.
Renin causes angiotensinogen produced in liver to convert to angiotensin 1
Angiotensin 1 travels in circulation to lungs where it is converted to angiotensin 2 by enzyme ACE angiotensin converting enzyme
Angiotensin 2 causes vasoconstriction increasing peripheral resistance
Angiotensin 2 also stimulates adrenal glands to stimulate kidney to produce aldosterone which decreases urine output by faciliatating pottasium exchange for sodium in DVC. Which allows sodium reabsorption increasing BP.
Angiotensin 2 stimulates ADH secretion too.
Stimulates thirst sensation too.
Pharmocology for fluid balance… How to treat hypertension?
Duiretics. Which cause excess water and sodium ions to be excreted from kidneys to lower blood pressure.
Commonly used directics
ACE inhibitors (angiotensin converting enzyme) causes vasodilation by inhibiting the formation of angiotensin 2 at the lungs.
Loop diuretics- inhibit re absopbtion of sodium ions in the loop of henle, so sodium is passed on to collecting ducts where it attracts lots of water to be excreted. Can be toxic tho
Thiazides - inhibit sodium reabsorption at the start of DVC most commonly used.
Which to hormones /processes are responsible for the hormonal control of BP
ADH
rAAS
What are the two funciojs of the urinary bladder?)
Storage and eliminating urine
What is micturition? In bladder
Release of urine from the urinary bladder into the urethra so that it can be eliminated via the urethral meatus.
How does urine move from the kidney down to the bladder via the ureters?
By waves of peristalsis into the bladder.
Smooth muscle in their middle coat allows peristaltic waves.
Ureters enter the bladder at an acute angle to prevent reflux and infection
What is the bladder wall like?
Has smooth muscle called the detrusor muscle
Folds in the lining due to stretchy transitional epithelium, and mucous membranes that allows for stretching as the bladder fills.
What two structures do you have in the kidney to allow urination and preventing urinary leakage??
Bare sensory ending neurones of parasympathetic nervous system
Numerous nerve endings between urinary orifices and bladder neck known as trigone
Bladder closure mechanism at the base supports the urethra allowing automatic closure and conscious override when we need to micturate.
Internal urethral sphincter which is under automatic control smooth circular muscle
External urethral sphincter which is voluntary control striated skeletal muscle
We also have muscles of pelvic floor to help support urethra and bladder when sudden intra-abdominal pressure from laughing, sneezing
What are the 4 micturition centres involved in the storage and voiding of urine?
Spinal micturition centre (SMC) in spinal cord between s2 and s4. Relay centre that organises incoming sensory info from bladder and outgoijg motor neurones to PMC. That inhibits micturition reflex, or cerebral cotext to give sense lf fullness.
Pontine micturition centre (PMC) in brain stem as a neural switch between storage and voiding in bladder. Inhibits descending signals to SMC during filling and releases to SMC to allow emptying.
Cerebral cortex allows voluntary inhibition of the micturition reflex
Hypothalamus - integrates micturition centres but is hormonal control not neural
What is the process of normal voiding?
As bladder fills, sensory nerve endings in bladder (stretch receptors)
Afferent signals to sacral segments in SMC via pelvic nerves
Intergration of signals in spinal cord
Efferent signals from spinal cord to bladder (parasympathetic allows voiding)
Dfferent impulses cause detrusor muscle in bladder to contract and inner and external urinary sphincter to relax.
Voluntary delay of normal voiding process??
Bladder fills 200-300ml person aware they need to void by sensory nerve endings
Afferent signals to sacral segments in spinal cord via pelvic nerves
Integration of signals in spinal cord
Efferent signals from spinal cord to pons (pontine )
Pontine MC sends descending signals via spinal cord to reduct intensity of bladder contractions and stimulate efferent neurones that keep external urinary sphincter contracted
When convenient to urinate higher brain centres send impulses via pons to spinal cord toinhibit urinary sphincter
This desire initiates mixturition relfexes, as streched bladder stimulates ascending fibres in spinal cord signalling higher centres
Pons swtiches off signals that decrease bladder contractions allowing efferent signals to create bladder contraction and sphincters to relax
What 3 things is urinary continence dependant on?
Relaxation of the bladder as it fills
Higher pressure in urethra than in bladder
Inhibition of bladder contractions during filling
What is the pelvic floor and its 2 functions?
Muscles - superficial a d deep muscle layers, ligaments and fibrous connective tissue.
Punctured around the urethra, vagina and rectum
It provides support for the contents of abdominal cavity
Contributes to maintaining continence by supporting closure of the urthra and anus
What two hormones are though to have a role in lower utinary tract?
Oestrogen and progesterone
Respnsible for urinary symptoms during menstruation and pregnancy - incontinence
Receptors found in brain, bladder, urethra and pelvic floor
What is gasto-colic reflex ??
What is rectal distension?
Gasto-coloc reflex is when slow peristaltic waves are replaces by mass peristaltic waves and the faeces propels into the rectum giving a sense of fullness
Rectal distension - relaxation of interal anal sphincter which allows contents to move to upper part of the anus
What are the two processes im cell division?
Mitosis - production of genetically identical cells for growth and repair. 46 chromosomes
Meosis- genetic variable gametes 23
What is interphase and its steps?
Interphase is the phase which happens between cell divisions.
G1 - cell grows and organelles duplicated
S phase - chromosomes replicated by dna replication, dna polymerase keeps two strands separate and links news nucleotides
G2- cell grows and produces further organelles
What are the 4 stages of mitosis?
Prophase - chromatin condenses into chromosomes (two sister chromatids joined by a centromere attached to centriole spindles from poles of cell) . Nuclear envelops disappear
Metaphase - align pulled by spindles
Anaphase - centromeres break apart and chromatids pulled opposite sides
Telophase - new nuclear membranes around each of the two chromosome sets
What is the third step of mitotis
Cytokinesis - cytoplasm divides and two seperate cells form
What are the two processes that crest genetic variation?
Independent assortment - homologous chromosomes align at equator either side, so what chromosome is pulled im each direction alters, anaphase1
Crossing over during prophase 1- fragments of chromosomes containing genes are exchanged between chromatids
