SUGER Flashcards
How much of cardiac output do the kidneys receive and through which arteries
- about 1/5 of cardiac output
- through the renal arteries that arise directly from the abdominal aorta
What hormones do the kidney produce and what do these hormones do
- erythropoietin for control of red blood cell production
- renin for regulation of water and salt concentration
Describe the cortex and medulla of a kidney
- cortex is pale
- medulla is dark
- kidney contains 10 to 15 medullary pyramids whose apices point towards the hilum of the kidney
- cortex contains all of the glomeruli of the kidney and convoluted (coiled) parts of the proximal and distal tubules, first parts of collecting ducts
- medullary pyramids contains straight portions of the proximal and distal tubules, loops of Henle and distal part of collecting ducts
Describe the blood supply of the kidneys
-abdominal aorta
-renal artery (at L1)
-anterior and posterior division
-interlobar artery
-arcuate arteries (at the cortico-medullary junction)
-interlobular arteries (penetrate and divide cortex into lobules)
-afferent arterioles
-efferent arterioles (renal corpuscle)
-peritubular capillaries
descends into medulla
-vasa recta
-renal veins
-inferior vena cava
Where is blood filtered in the kidney and how
- in the glomerulus
- the glomerulus is made up of fenestrated capillaries ensheathed by podocytes
- the basement membrane between the endothelial cells of the capillaries and the podocytes of the epithelium constitutes the filtration barrier of the kidney
Where are the mesangial cells found
-between the coiled loops of the glomerular tuft
What do mesangial cells do
- they provide structural support for the kidney
- they have smooth muscle which contract and tighten capillaries to reduce the glomerular filtration rate
- produce matrix
- phagocytosis of glomerular breakdown products
Where are macula densa cells found
In the distal convuluted tubules
Where are the renin producing cells of the kidneys found
-the afferent arteriole
What do the macula densa cells do
- they sense low sodium and chloride levels
- stimulate the juxtaglomerular cells in the afferent arterioles of the kidney to release renin
Under how many Daltons do solutes need to be to pass into the urinary space of the kidney as primary filtrate
-50,000 Daltons
Describe the structure of the proximal tubules
- prominent brush border
- complex invaginations on their baso-lateral membrane
- cuboidal epithelium
- eosinophilic cytoplasm
What occurs in the proximal tubules
- re-absorption of filtrate
- sodium and glucose are actively transported
- protein and polypeptide uptake by endocytosis
- contain lysosome that break proteins down
List 2 important proteins that normally pass from the blood into primary filtrate but are recovered (reabsorbed) by the proximal tubule
- albumin
- haemoglobin
- almost any small negatively charged protein
What does the loop of henle consist of
- thick straight descending portion
- thin loop
- thick ascending portion
What does the thin ascending portion of the loop of Henle do
-retains water
-actively re-absorb chloride and sodium
So produces a dilute filtrate (urine) and a hypertonic interstitium (liquid in surroundings)
-vasa recta run alongside these tubules
What is the difference between the permeability of water in the thin descending and ascending loop of Henle and what does this cause
- the thin descending limb has low permeability to ions and urea but is highly permeable to water
- the thin ascending limb is not permeable to water but is permeable to ions
- this creates a concentration gradient within the renal medulla
Describe the distal tubules
- contains macula densa cells
- few short microvilli but no brush border
- cells often appear paler stained than those of proximal tubule
- deep invaginations on basal plasma membrane
- lots of mitochondria
- cuboidal epithelium
What do the distal tubules do
- under influence of aldosterone, sodium ions are reaborbed and potassium ions are excreted
- bicarbonate ions are re-absorbed and hydrogen ions excreted making urine acidic (through cellular carbonic anhydrase)
-acid/base balance and concentrations of urine
Which structures are known as medullary rays
The collecting ducts (and apparently the thin parts of the loop of Henle)
How does anti-duiretic hormone (ADH) affect the collecting duct cells
- increases permeability to water
- more aquaporins insert into its membrane and reabsorb water back
What is special about collecting ducts cells of the kidney
-dark intercalated cells with high concentrations of mitochondria
What structures make up the juxtaglomerular apparatus
-Apparantly just afferent arteriole and distal convoluted tubule but keep the ones below in mind
- afferent arteriole
- efferent arteriole
- macula densa
- lacis cells (specialised cell of the glomerular matrix)
Where in the body is angiotensin 2 produced
Renin secreted by modified muscle cells in the walls of the afferent arterioles of the glomerulus catalyses the conversion of angiotensinogen that is produced by the liver into angiotensin I. This is converted to angiotensin II mainly in the lungs. This goes on to stimulate the release of aldosterone by glomerular cells in the cortex of the suprarenal gland. This in turn promotes the reabsorption of sodium and water from the glomerular filtrate mainly by the cells of the distal tubule and collecting ducts.
Which cells of the kidneys are particularly responsive to aldosterone
Cells of the distal tubule and collecting ducts
-aldosterone promotes re-absorption of sodium ions and water thereby concentrates the urine and conserves body fluid
Which lipid are the membrane plates of the umbrella cells of the bladder rich in
-cerebrosides
Describe the epithelium of the bladder, ureters and urethra
- umbrella cells (can be binucleate)
- pseudostratified squamous epithelium (between 3 to 8 layers)
How are umbrella cells joined together
- thick membranes plates joined by thinner membrane bands
- the thick membrane plates are made of cerebrosides
What shape is the lumen of the ureter
-star shaped
Give the 3 points at which the ureter is sharply constricted and why is this important
- at its origin in the pelvis of the kidney
- as it passes into the true pelvis anterior to the sacro-iliac joint
- as it enters the postero-inferior surface of the bladder
A site where kidney stones are commonly lodged
How many layers of smooth muscle surround the epithelial tube of the ureter
-two helical layers of smooth muscle
Basically opposite to GI tract
-inner longitudinal layer
-outer circular layer
-no serosa
Describe the muscles neck of the bladder
- 3 distinct layers of muscle
- the innermost longitudinal layer projects inferiorly and turns transversely to form a sphincter around the prostatic urethra (male) and the external meatus (female)
Which muscle layer of the bladder forms the sphincter around the urethra
the innermost longitudinal layer projects inferiorly and turns transversely to form a sphincter around the prostatic urethra (male) and the external meatus (female)
How many parts is the male urethra divided into and name them and which epithelium they are covered by
3
prostatic, membranous and penile urethra
-prostatic (urothelium)
-membranous (urothelium)
Both Penile uretha below
- proximal bulbous (psuedostratified)
- distal pendulous (stratified squamous)
How do the epithelium of the male and female urethra differ
The male urethra (20cm) is longer and is covered by urothelium with mucous glands all along its lengths
The female urethra (4 to 5 cm) is covered by stratified squamous epithelium punctuated by areas of mucous glands (paraurethral and periurethral glands open into the urethra)
In both male and female, a striated voluntary muscle sphincter surrounds the membranous part of the urethra (derived from the muscles of the pelvic diaphragm)
What kind of tissue lies under the prostatic urothelium
-dense fibrous connective tissue that will restrict the distension of urothelium
How does the human kidney differ histologically from that of a smaller mammal such as a mouse or rat?
It is a compound kidney rather than a simple kidney which is the case with small mammals. A simple kidney has a single medulla with a single surrounding cortex. A compound kidney is, in effect, many simple kidneys in the same bag, with multiple medullary zones each surrounded by cortex. The human kidney consists of between 15 and 20 simple kidneys fused together with primary and secondary calyces draining into a single renal pelvis.
How is blood flow through the glomerulus regulated?
It is regulated by constriction of the afferent and efferent arterioles.
Contraction of smooth muscle in glomerulus tightens capillaries and reduces the glomerular filtration rate (part of tubular glomerular feedback)
Which do you think is more tightly coiled, the proximal convoluted tubule or the distal convoluted tubule?
Apart, obviously, of the straight portions of these tubules, the proximal tubule is more tightly coiled than the distal tubule. This results in more transverse and fewer oblique sections through proximal tubules than through distal tubules.
Why do the loops of Henle differ in length from one nephron to another?
This depends on the point of origin of the nephron. Nephrons whose glomeruli originate close to the surface of the kidney (outer cortex) have short loops of Henle that project only as far as the outer reaches of the medulla whereas those nephrons whose glomeruli arise close to the medulla have long loops that project deep into the medulla.
Why is the wall of the ureter composed mainly of smooth muscle rather than of fibrous connective tissue?
The muscular wall or the ureter undergoes peristaltic contraction that helps to conduct the urine to the bladder.
Which nerve tract supplies the muscle in the wall of the urinary bladder and causes it to contract during micturition?
Micturition occurs once the external sphincter of the bladder is relaxed (sympathetic stimulation) and the muscle wall of the bladder (detrusor muscle) contracts (parasympathetic stimulation)
Which glands drain into (a) the prostatic urethra and (b) the penile urethra?
Many of the genital glands drain into the prostatic urethra including the prostate itself, the seminal vesicles and the deferent duct (sperm). The bulbo-urethral glands and other smaller mucous glands drain into the membranous and penile urethra.
What type of epithelium lines the distal end of both the male and female urethra?
The distal ends of both the male and female urethra become lined by a stratified squamous epithelium.
What do mesangial cells do
- phagocytosis of glomerular basement membrane breakdown products
- provide structural support
Give the 3 layers of the glomerular basement membrane
- glomerular capillary wall
- basement membrane
- foot processes of the podocytes
A normal basement membrane has a lamina lucida and a lamina rarer, what does a glomerular basement membrane comprise of
- lamina lucida inturna
- double thickness lamina densa
- lamina lucida externa
- basically to basement membranes back to back
- contains negatively charged heparinsulfate molecules
What does the glomerular basement membrane contain that repulses negatively charges particles
-negatively charged heparinesulfate molecules
Loss of which two proteins in podocytes are associated with glomerular diseases
- defect in gene that produces nephrine causing cogentinal nephrotic syndrome
- defect in gene that produces CD2AP causes focal segmental glomerular sclerosis
What do granular cells do
- located in afferent arteriole
- sense blood pressure changes and secretes renin in response
Describe the epithelium of the thick sections of the loop of Henle
-cuboidal epithelium
Describe the epithelium of the thin sections of the loop of Henle
-simple squamous epithelium
Describe the epithelium of the collecting duct and what it does
- cuboidal epithelium
- contains principal cells that respond to aldosterone and anti-durietic hormone (ADH)
- contains intercalated cells that exchange hydrogen ions (excreted) for carbonate ions (reabsorbed)
Mutation of the aquaporin 2 gene leads to which hereditary disease
-diabetes insipidus
Which part of the kidney is prone to ischemia and why?
-loop of Henle as it is supplied by the vasa recta which is quite far from the glomerulus
Give the layers in the bladder epithelium
- urothelium
- lamina propria
- poorly defined muscularis mucosa
- submucosa
- muscularis propria
- subserosa and serosa
- functional valve to prevent reflux of urine into ureter
What do leydig cells do and where are they found
- produce testosterone
- in between tubules of seminiferous tubules
What do the rete testis do and where are they found
- they transfer sperm to the epididymis
- they connect the seminiferous tubules to the epididymis
What do the seminiferous tubules do and where are they found
- produce sperm
- found in the lobules of the testis
What type of epithelium lines the seminiferous tubules
-stratified epithelium consisting of Sertoli cells and cells of the germ line (developing spermatozoa)
How do sperm develop in the seminiferous tubules
- cells at the periphery of each tubule has germinal epithelium that produces large cells with speckled chromatin within their nuclei know as spermatogonia
- spermatocytes develop from these spermatogonia
- spermatocytes cross the blood-testis barrier created by the Sertoli cells
What do Sertoli cells do and where are they found
- they are supporting cells that nuture the developing sperm
- they are found in the seminiferous tubules
How long does sperm production take
-64 days
What would be the consequence of failure of the blood-testis barrier?
- the individual might recognise his sperm as “non-self’ and raise antibodies against them
- antibodies would then destroy his sperm rendering him infertile
At what stage in development of sperm does the reduction division take place?
The first meiotic division during which the developing sperm go from being 2n (number of chromosomes) to 1n occurs when the primary spermatocytes become secondary spermatocytes.
Where in relation to the blood-testis barrier does this reduction division take place?
- it occurs on the luminal side of the blood-testis barrier where the developing spermatids are not in direct contact with the blood stream and they are therefore not detected by the individual creating them.
- this prevents the production of auto- antibodies that may well destroy the developing sperm.
What epithelium line the efferent ducts
- cuboidal epithelium (basal cells)
- ciliated and non ciliated columnar epithelium
What does the epididymis do and how long is it
- 5m long
- serves as a storage and maturation site for sperm
What epithelium lines the epididymis
- pseudo-stratified columnar epithelium
- also contains a thin layer of smooth muscle that becomes thicker as it approaches the vas deferens
What do the small basal cells in the epididymis do
- they support the stereocilia (tall columnar cells with long microvilli)
- re-absorb excess testicular fluid
- phagocytose damaged sperm and cell debris
- provide nutrients for waiting sperm
Describe the stereo-cilia of the epididymis? Why are they inappropriately named?
- they help to provide nutrients to the sperm stored in the epididymis.
- unlike true cilia they are not motile nor do they have a core of microtubules as true cilia do.
What is the epithelium of the vas deferens
- pseudo-stratified columnar epithelium
- has 3 layers of smooth muscle
During ejaculation, how is sperm transported in the vas deferens
- sudden and rhythmical contraction of its smooth thick muscle wall help to expel the sperm during ejaculation
- has microvilli too
At vasectomy, how would you differentiate between the vas deferens and other vessels running in the cord, (a) by gross appearance and (b) histologically?
- the thick muscular wall of the vas deferens provides more resistance to the touch (feels cord-like) and unlike the testicular artery is difficult to compress and has no pulse!
- histologically the two tubes can be differentiated by the thickness of the smooth muscle wall, which is much thicker in the vas deferens and composed of 2 distinct layers, and by the nature of the epithelial lining which is a pseudostratified one in the vas deferens but a simple squamous one (endothelium) in the artery
What does the seminal vesicles do
- when stimulated by testosterone
- the cells of the seminal vesicles enlarge and secrete a creamy opalescent fluid
- this fluid has an acid pH, rich in globulin, vitamin C, amino acids and sugars, notable fructose all nutrients for the sperm
- comprises 70% of the ejaculate
What hormone causes the cells of the seminal vesicles to enlarge
-testosterone
Contraction of the double layered capsule of the smooth muscle of the seminal vesicles at ejaculation expels fluid into the
-ejaculatory duct where it mixes with spermatozoa
What is the epithelium of the seminal vesicles
-pseudo-stratified columnar epithelium
What are the 3 layers of glands within the prostatic gland and where do they discharge into
- mucosal
- submucosal
- main
All discharge seperately into different part of the prostatic urethra
How does testosterone affect the prostate gland
- the cells of the prostate gland increase in height and secrete different digestive enzymes into urethra forming seminal fluid
- a digestive enzyme secreted is acid phosphatase
Which glands in a male secrete a watery galactose-rich secretion into the membranous urethra that precedes the main ejaculate
-bulbo-urethra glands
What do the bulbo-urethra glands in a male do?
-secrete a watery galactose-rich secretion into the membranous urethra that precedes the main ejaculate
Extreme resistance may be felt when trying to insert a catheter trans-urethrally into the bladder of a man. What histological structures may be the cause of this resistance?
- sometimes the tip of the catheter can be diverted into the blind‐ ended bulbo‐ urethral glands that discharge into the membranous part of the male urethra.
- the shorter and straighter female urethra does not normally pose the same problem.
How does an erection occur
- the erectile compartments are fed by the helicine branches of the pudendal artery
- in a flaccid state, arterio-venous shunts direct the blood away from these arteries
- parasympathetic stimulation closes the arterio-venous shunts diverting blood into the erectile compartments which become turgid with blood causing an erection
Describe the skin covering the penis
- most of the penis is covered in hairy keratinising stratified squamous epithelium
- except the prepuce (foreskin) and glans penis which are covered in lightly keratinising stratified squamous epithelium
In what way does the epithelium inside the prepuce (foreskin) differ from that of the rest of the penis and what consequence does this have for disease processes?
- the epithelium on the inside of the prepuce is nominally a stratified squamous (keratinized) epithelium. It is however very thin and very lightly keratinized.
- it is therefore rather prone to the ingress of invading organisms.
- it is a prime site for the uptake of HIV and it has been shown that circumcision greatly decreases the entry of this virus mainly because the remaining and exposed epithelium becomes much more heavily keratinized.
Erection and ejaculation are separate but interlinked processes. How are these processes controlled neuronally and which anatomical nerves are involved?
- parasympathetic nerve (pelvic splanchnic nerves) = erection
- sympathetic autonomic nerve (hypogastric plexus from the terminal part of the sympathetic chain) = ejaculation
Think “Point and Shoot”
Which erectile compartment/s is/are the least rigid during an erection, and why?
- the two corpora cavernosa usually become more rigid than the corpus spongiosum. (As the name suggests the corpus spongiosum is spongier).
- the penile urethra passes through this compartment and therefore is less liable to be compressed than if it were to pass through the more rigid compartments, thus ensuring the passage of seminal fluid during ejaculation.
Give the average weight of the testis
15-19g
Give the 3 layers of the capsule surrounding the testis
- tunica vaginalis (flattened layer of mesothelial cells)
- tunica albuginea (collagen fibre with fibroblasts, myocytes and nerve fibres)
- tunica vasculosa (loose connective tissue containing blood vessels and lymph)
Give the 3 types of spermatogonia
- Type A (dark staining stem cells (Ad) and pale staining stem cells (Ap))
- Type B
Describe the parts of a spermatozoa (sperm)
- head (acrosomal cap and nucleus)
- midpiece (spiral mitochondria)
- tail (neck - centrioles, axoneme and plasma membrane)
What is special about the histology of Leydig cells
- they contain Reinke’s Crystalloids
- which are not seen before puberty and become more common with increasing age
What epithelium lines rete testis
-ciliated simple columnar epithelium
Give the lobes of prostate gland
- anterior
- middle
- posterior
- 2 lateral lobes
Which part of the prostate gland is a common site for cancer and which part is commo to increase in age
- peripheral zone is a common site for prostate cancer
- central zone increases with age
What do the secretory cells located on in the luminal side of the acini glands in the prostate secrete
-PSA prostate specific antigen (an enzyme used to liquidify semen after ejaculation) and PAP into the seminal fluid
What does the stroma of the prostate contain and why is it important
- contains smooth muscle, blood vessels, fibroelastic fibres and nerves
- it is important because it usually undergos hyperplasia with increasing age (common in a condition called benign prostatic hyperplasia)
Give the steps of differentiation into the male reproductive system
- XY chromosomes
- encodes the SRY gene
- promotes testis-determining factor
- genital ridge develops into testis
- leydig cells secrete testosterone
- mesonephric duct development
- sertoli cells secrete mullerian-inhibiting factor
- degeneration of the paramesonephric ducts
Give the steps that lead to the development of female reproductive system
- XX chromosomes
- no gonadal hormone influence
- genital ridge develops into ovarian tissue by default
- abscene of testosterone
- mesonephric ducts degenerate
- absence of mullerian-inhibiting factor
- paramesonephric ducts develop
Describe the major complications of chronic renal failure
- anaemia
- Gout
- Heart failure
- Stroke
- Hyperkalemia (high potassium)
- Metabolic disorder like osteodystrophy (slow bone growth or weak bones due to low calcium and phosphorus levels in the blood), inflammation and dyslipidemia (abnormal levels of lipid in the blood)
List the common causes of chronic renal failure
- diabetes (high blood sugar damages the blood vessels of the kidney)
- high blood pressure (damages blood vessels in the kidney)
- polycystic kidney disease (genetic condition that causes growth of cysts in the kidneys)
- lupus (lupus nephritis) leading to glomerulonephritis (inflammation of glomeruli and nephrons)
- recurrent kidney infections
- Good pasture syndrome (damages the kidney membranes)
List the causes of acute kidney injury and classify as pre-renal, renal or post-renal.
-acute kidney failure is where the kidneys suddenly stop working properly, can range from minor loss of kidney function to complete kidney failure
Pre-renal (when the blood flow to the kidney is impaired)
- low blood volume (blood loss, excessive vomiting, diarrhoea or severe dehydration)
- heart disease (heart pumping out less blood)
- liver failure (heart pumping out less blood)
- sepsis (heart pumping out less blood)
- medication like aspirin and ibuprofen
- overuse of non steroidal antiinflammatory drugs (NSAIDs)
Renal (damage to the kidney)
- blood clot in the kidney
- Kidney infections
- Chemotherapy drugs and antibioics
- Hemolyic uremic syndrome
- Glomerulonephritis (inflammation of the glomeruli -the kidney filters)
- Blood vessel inflammation or vasculitis
Post-renal (urinary obstruction)
- colon cancer
- prostate cancer
- cervical cancer
- blood clots
Presentation and management of atopic eczema
- Atopic dermatitis is a chronic, itchy skin condition
- common in children but may occur at any age
- also known as eczema and atopic eczema and was formerly known as Besnier prurigo
- the most common form of dermatitis.
- usually occurs in people who have an ‘atopic tendency’ so may develop any or all of three closely linked conditions; atopic dermatitis, asthma and hay fever (allergic rhinitis)
- these conditions run within families with a parent, child or sibling also affected. A family history of asthma, eczema or hay fever is particularly useful in diagnosing atopic dermatitis in infants.
-Atopic dermatitis arises because of a complex interaction of genetic and environmental factors including defects in skin barrier function making the skin more susceptible to irritation by soap and other contact irritants, the weather, temperature and non-specific triggers
Presentation
- inflamed red, blistered weepy patches of skin
- in between flare ups, skin can look normal or have dry thickened and itchy areas
- common in folds of skin of the elbow and knees but can be anywher on the body
Management
- reduction of exposure to trigger factors where possible
- regular emollients (moisturisers)
- intermittent topical steroids
Common triggers for skin conditions
- harsh soaps and detergents
- coarse fibres (wool and synthetic) and seams in undergarments
- cosmetics and perfumes
- dusty environments
- prescribed and over the counter treatment crems
- stress
- cold and dampclimate
What are the ethical issues around self-prescribing/prescribing for friends and family
What does the GMC say about self prescribing
18 - you must not prescribe a controlled medication for yourself or someone close to you unless;
a. no other person with the legal rights is there to prescribe where a delay could put your life or patients life’s at risk or cause unacceptable pain
b. the treatment is immediately necessary to save a life, avoid deterioration in health or alleviate uncontrollable pain or distress
19 if you prescribe for yourself or someone close to you, you must
a. Make a clear record at the same time or as soon as possible giving relationship to patient and reasons you prescribes
b. tell you GP what medicines you prescribe (unless the patient objects)
What forms the filtration barrier of a nephron and how does it work
- formed by the basement membrane that has a charge that repels proteins and molecules larger than 50,000 Daltons
- the podocyte foot processes create physical pores
More than 3 grams of albumin a day in the urine is indicative of
-something wrong in the glomerulus
What does the alpha intercalated cells of the collecting ducts do
-secrete acid
What does the beta intercalated cells of the collecting ducts do
-secrete bicarbonate
what is an elderly primigravida
The elderly primigravida is defined as a woman who goes into pregnancy for the first time at the age of 35 years or older.
what three layers make up the skin
epidermis, dermis and fatty subcutis layer
when does the breast become fully functional
during pregnancy
is the breast a sweat gland
yes
what is the mucosa of the epidermis
stratified squamous keratinising epithelium
list the 4 main layers of the epidermis
- layer of dead keratinised squames (stratum corneum)
- granular layer with cells containing keratohyaline granules (stratum granulosum)
- spinous layer (thickest layer) (stratum spinosum)
- germinative layer (stratum basale)
list the 2 parts of the dermis layer
the fibrous layer (rich in collagen and elastic fibres)
-papillary dermis few in collagen fibres
-reticular dermis rich in collagen fibres
the adipose layer (fatty layer)
which part of skin contains the root of hairs cell, sweat glands and sensory nerve endings
the dermis of the skin
where is the epithelium that forms the epidermis of the skin thickest and thinnest
thickest at the palms of the hands and the soles of the feet
thinnest on the some parts of the abdomen, thorax, lips, eyelids and external genitalia
is the skin on the palm of the hand and the sole of the feet hairless
yes
what are the keratohyaline granules a precursor for
keratin
what cells make up the majority of the epidermis
keratinocytes
where are keratinocytes derived from
germ cells within the germinal layer of the epidermis
apart from keratinocytes, what other cells are within the epidermis layer of the skin
melanocytes
where are melanocytes derived from
- the neural crest of the embryo
- they migrate into the epidermis during development
to which layers in the epidermis does the melanin from the melanocytes migrate to
the basal and prickle layer in the epidermis
does the number of melanocytes determine the colour of skin
no, all races have the same number of melanocytes
what determines the colour of skin
the amount of melanin stored in the keratinocytes is proportional to the colour of the skin
what prevents the skin from splitting when stretched
the desmosomes between the cells of the spinous (prickle) cells
what do the langerhan cells of the epidermis do
- they act as the antigen detecting cells as part of the immune response of the skin
- they increase with inflammation
what is the clinical significance of Merkels cells
they can give rise to a rare form of skin cancer
what do Merkels cells do and where can they be found
- in the basal cells of the epidermis
- they relay sensory information of fine touch
- they form nerve synapses with nerve fibres in the dermis
are hair cells from the dermis or epidermis
they are epidermal in origin
what is the glassy membrane
a thickened version of the basement membrane where hair root arises from
how does sympathetic innervation affect the erector pilli (smooth muscle)
causes it contract and stand on end
what are fingernails and toe nails made from
compacted keratin
how are fingernails and toenails produced
-they arise from nail matrix cells from the eponychium (cuticle)and can be seen through the lunula (pale crescent of cells)
the fold of skin under the distal edge of the nail is called
hyponychium
destruction of the nail matrix cells will result in permanent loss of
the nail
which sweat glands are most common
the eccrine sweat gland
how do the myoepithelial cells help with sweat glands
-the contractile cells help to expel the sweat
where are pheromone apocrine sweat glands found
in the armpits, around the anus and external genitalia
give a sensory nerve endings that is commonly found in the dermal papillae
meissner’s corpuscle
which dye is used on nerve fibres and stains black
osmium tetroxide
give two olaces that a pacinian corpuscle can be found
in the dermis of the skin
in the pancreas
give a sensory nerve endings that is commonly found in the dermis
pacinian corpuscle
give the mucosa of the conjunctiva
- two layers of cells
- stratified columnar epithelium cells
give an example of a large sebaceous gland of the eyelid
the meibomian gland
give an example of 4 smaller sweat glands of the eyelid
moll sweat gland
zeis (sebaceous) sweat gland
kraus and wolfring (accessory lacrimal) sweat glands
when do milk producing alveolar cells develop
during pregnancy
when do breast tissue develop
1 or 2 years before period starts at about 9 to 11 years old
what attach the breast to the chest wall and skin
suspensory ligaments of Cooper (thick fibrous strands)
how does milk travel from the breast tothe nipple
lactiferous duct to lactiferous sinus to nipple
what causes tenderness of the breast during the second half of periods
- fluctuating hormone levels
- lead to progesterone led oedema in breast segments causing tenderness and discomfort
what are montgomery’s tubercles
raised sebaceous glands in the areola surrounding the nipple core
how does high levels of oestrogen and progesterone affect lactation
they suppress lactation
how do lactating breasts develop in the 1st trimester of pregnancy
cortisol, growth hormone and oestrogen promote the proliferative phase of the epithelial cells
which hormones stimulate the full development of lactating breasts
prolactin, progesterone, human chorionic sommatomammotropin (hCs or human placental lactogen, hPL), adrenal corticosteroids and insulin
in the later stages of pregnancy what accumulates in the stroma of lactating breasts
lymphocytes and plasma cells
how are milk fats discharged from a lactating breast
apocrine process
how are milk proteins discharged from a lactating breast
merocrine process
Where in the skin do blisters most commonly form?
Blisters caused by abrasion normally occur and the dermal/epidermal interface.
Blisters caused by heat may occur at any depth and may involve the deeper layers of
the dermis.
What constitutes a mole?
Moles are formed from a dense aggregation of melanocytes and their attendant
keratinocytes.
Which hormone, when released into the blood stream induces the expression of milk during
breast-feeding?
Tactile stimulation of the nipple during suckling triggers the release of oxytocin by the
anterior pituitary. This causes the myoepithelial cells surrounding the secretory alveoli of the breast to contract and to help to expel the milk
where is the site of vitamin D synthesis
the skin
Where are melanocytes usually found
In the stratum basale (stem cells) layer of the epidermis
Where are melanin transported to keratinocytes in
Melanosomes
What hormones stimulates the production of melanin
MSH and ACTH
How does melanin protect us from non-ionising radiation damage
-it absorbs ultraviolet light
What layer lies between the stratum corneum and the stratum granulosum
Stratum lucida - faint pink layer (most prominent in the palm of the hands and soles of the feet)
What structure do sebaceous glands usually accompany
Hair follicles
How do sebaceous glands discharge their contents
Holocrine secretion (so the entire cell is lost and discharged)
What structures do aprocrine glands usually surround
Hair follicles
Armpit and groin
Anus and genitalia
Ceruminous glands in the ear
How do apocrine glands discharge
Apocrine secretion (cytoplasm that bud off the cell)
What structures are eccrine glands associated with
Found everywhere in the skin
Produce watery secretion
How do eccrine glands secrete their content
Eccrine (merocrine) secretion (exocytosis across the luminal surface of the cells)
They have inner secretory cell and outer myoepithelial cells too
What are Retes pegs
The ridges that the line between the epidermis and dermis found
-basically the wavy demarcation line
What is the dermis that is in between each retes peg called
The papillary dermis
Where can meissner’s corpuscle be found
Dermal papillae between the fingers, palms and soles
Are meissner’s corpuscle encapsulated or myelinated
They are encapsulated but unmyelinated nerve endings
How long are meissner’s corpuscle
30-140um long
What can of sensation are meisner’s corpuscle involved in
Fine touch
What kind of sensation are pacinian corpuscle involved in
Vibration and tickle
How long are pacinian corpuscles
1-4mm long
Where are pacinian corpuscle found
Deep dermis
What is the different of breast tissue in female and males
In males the breast tissue only comprises of the ducts
What is the functional unit of the breast
The terminal duct lobular unit
How are the ducts and lobule of the breast arranged
In two layers
An outer myoepithelial cell
An inner columnar epithelial cell
what is the daily folic acid recommendation for pregnant women
400 micrograms of folic acid from before pregnancy to until 12 weeks pregnant
family history of neural tube defects, diabetes, epilepsy and taking anti-retroviral medicine for HIV means the pregnant women have to take a higher dose 5milligrams
which vitamins are pregnant women advised not to eat too much of
vitamin A because it can cause developmental deformities
what advised are pregnant women given in regards to vitamins D and why
pregnant woman and all adults need 10 micrograms of vitamin D a day
vitamin D regulates the amount of calcium and phosphate in the body
what vitamins might vegan or vegetarian pregnant woman struggle to get
iron and vitamin B12
what foods are pregnant women advised to avoid
- soft blue cheeses
- soft cheeses with white rinds
- raw or partially cooked eggs (salmonella)
- pate (listeria)
- raw or undercooked meats (parasites causing toxoplasmosis an infection)
- unpasteurised milk and untreated water
- liver
- herbal remedy liquorice root
- alcohol
- high levels of caffeine
- swordfish, shark or marlin
preconceptual care and advice for pregnant women
- quit smoking if possibly
- take folic acid supplements
- avoid alcohol
- maintain a healthy weight
- if not, get flu and whooping cough vaccinations
- test for sickle cell and thalassaemia
what does the 8 to 14 weeks dating scan in pregnancy include
- ultrasound to estimate due date of the baby
- check the physical development of the baby
- screening for conditions eg downs syndrome
what does the 20 weeks scan in pregnancy include
- ultrasound to check physical development
- screening for HIV, syphilis and hepatitis B
- also offered the whooping cough vaccine again
what does the 34 scan in pregnancy include
-told about caesarean
-use tape measure to measure uterus
measure blood pressure and test urine for protein
-offered 2nd anti-D treatment if rhesus negative
what is a nulliparous women
Nulliparous is the medical term for a woman who has never given birth either by choice or for any other reason. This term also applies to women who have given birth to a stillborn baby, or a baby who was otherwise not able to survive outside the womb
how does the risk of Down’s syndrome increase with maternal age
1:1,500 at 20 years.
1:800 at 30 years.
1:270 at 35 years.
1:100 at 40 years.
>1:50 at 45 years and over.
when would chorionic villus sampling be offered for Down’s syndrome testing
if less than 13 weeks of gestation
carries a 1-2% risk of miscarriage
when would amniocentesis be offered for Down’s syndrome testing
if beyond 15 weeks of gestation
carries a 0.5-1% risk for miscarriage
give the two types of screening used for Down’s syndrome and when they would be carried out
- serum screening - between 10 and 14 weeks and a day
- ultrasound screening (nuchal translucency) - between 11 and 14 weeks and a day
what is the cut off point of a screening for Down’s Syndrome in England when a pregnant woman will be offered a diagnostic test
1 in 150 chance that a pregnant woman is carrying a baby with Down’s Syndrome so will be offered a diagnostic test
what does the serum screening check for in Down’s Syndrome screening
serum screen measures free beta human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein A (PAPP-A)
-both are produced by placental synctiotrophobasts
an obese pregnant woman is more at risk at
- miscarriage
- gestational diabetes
- high blood pressure or pre-clampsia
- blood clots
- shoulder dystocia
- post partum haemorrhage
- heavier babies
- stillbirth
- needing instrumental delivery like foreceps
- spina bifida
what is ADPKD and what causes it
autosomal dominant polycystic kidney disease causes small fluid-filled sacs called cysts to develop in the kidney eventually leading to kidney failure
caused by a mutation in the gene PKD1 (in 85% of cases) and the gene PKD2 (in 15% of cases)
Wilms’ tumour gene Wt1 is required for the normal formation of
- the genito-urinary system
- situated at chromosome 11p13
- zinc finger DNA binding protein
what is a genotype-phenotype correlation
when the position and nature of the mutation within a gene can determine the manifestation of the condition in an individual
what does the mutation of the Wilms tumour express as0
- mutation at 11p13
- causes a loss of protein
- a nonsense or frameshift mutation
give an example of an x linked renal disease
alport syndrome
- mutation in COL4A5
- affects male
- women are carriers
- COL4A5 is a major component of the basement membrane of the renal glomerulus, the cochlear and lens
- so will cause bilateral high frequency sensori-neural hearing loss in 80 to 90% in affected males
- so will cause anterior lenticonus in 15 to 20% of affected males
give an example of an autosomal recessive renal condition and how it presents
Bartter Syndrome
- impaired salt re-absorption in the thick ascending loop of Henle
- presents as pronounced salt wasting, hypokalaemia, metabolic alkalosis and hyercalciuria
- disruption to all types of Na/K/Cl transporters
- can be a result of consanguinity
what is an error
any preventable event that may cause or lead to patient harm
what is an adverse event
incident resulting in harm to a patient which is not a direct result of their illness or other chance event
what is a near miss
an event which arises during care and has the potential to cause harm but fails to develop further thereby avoiding harm
what is an error of omission
when required action is delayed or not taken
what is an error of commission
where wrong action is taken
explain what a skill based error is
performing a routine skill and if distracted making a mistake e.g writing 5 milligrams instead of 0.5 milligrams (a slip) or a dose of medication delivered late (lapse)
explain what a rule/knowledge based error is
an incorrect plan or action performed in a complex situation due to inexperience or poor communication of information e.g wrong formula applied to adjust dosage on medication of patient with renal problems (rule based error or failing to apply NICE guildelines due to lack of awareness (knowledge-based error)
what is involuntary automaticity
when errors are not identified because people are going through the motiond but are not thoroughly engaged in the checking process
what is positive transfer
previous experience applies to new situation
what is negative transfer
previous experience conflicts with new situation
give 4 information processing limitations
- automaticity
- cognitive interference
- selective attention
- cognitive biases
What does the external genitalia of the vagina consist of
- the mons pubis
- the labia major
- the labia minor
- the clitoris
Which part of the vagina is thinly keratinised
-the vulval end
What epithelium lines the vagina
-stratified squamous epithelium
In a vagina, what would show the woman is of childbearing age
- a thickened epithelium
- it is usually thin before puberty and after the menopause
How is the vaginal epithelium kept moist
- beneath the epithelium is the lamina propria containing many small blood vessels
- fluid diffuse from these vessels to help keep the vaginal epithelium moist
What surrounds the vaginal epithelium
-fibro-muscular tube containing a mixture of collagen, elastic and smooth muscle fibres
Where do the glands of Bartholin secrete mucus
-the lower end of the vagina at its junction with the vulva
During the menstrual cycle, how does the vagina deter the entry of pathogenic organisms
- the surface cells of the vagina and cervix accumulate glycogen and many flake off (desquamation) following ovulation
- the desquamated cells rupture and bacteria feed on the glycogen generating lactic acid
- the lactic acid creates a low pH within the vagina to deter the entry of pathogenic organisms
What epithelium covers the cervical canal between the internal and external os
-columnar epithelium thrown into folds
What epithelium covers the cervix
-non-keratinising stratified squamous epithelium
What is the cervical transformation zone
The junction between the stratified squamous epithelium of the ectocervix and the simple columnar epithelium of the endocervix
- also called the squamo-columnar junction
- it does not always lie on the external os
How does the consistency of the mucus produced by the cervical lining change during the menstrual cycle and pregnancy
- the mucus is thin and watery during the first half of the menstrual cycle
- but becomes viscous after ovulation and during pregnancy
- it serves as a plug to prevent the entry of micro-organism into the uterine cavity
What is a common site for the development of cancerous lesions, infections and erosion
-the transformation (transition) zone
Describe the myometrium of the uterus
- the body and fundus of the uterus have 3 poorly defined layers of smooth muscle and these are the myometrium
- these are lined by epithelial endometrium
How do the cells of the myometrium change during pregnancy
- the cells of the myometrium are hormonally sensitive
- they increase in number (hyperplasia) and become enlarged (hypertrophy)
Which arteries and veins supply the endometrium of the uterus
-large arteries and veins that run between the inner and middle layers of the myometrium supply the epithelial lining (endometrium) and give rise to spiral arteries of the endometrium that play a significant part of the process of menstruation
During pregnancy, what is the major mechanism by which the uterus grows
-hypertrophy of the uterus muscle cells (rather than hyperplasia)
What epithelium lines the uterus
Simple columnar epithelium with tubular glands
What occurs in the endometrium in the proliferative phase of the uterus
- first half of the menstrual cycle
- the thickness of the stroma and the length of the tubular glands increases
What occurs in the endometrium in the secretory phase of the uterus
- second half of the menstrual cycle
- the tubular glands secrete and the stroma differentiates to create an environment conducive to the implantation of a fertilised ovum
What happens to the endometrium during menstruation,if fertilisation does not occur
-most of the endometrium (the decidua layer) is shed at menstruation leaving only the bases of the glands and the surrounding stroma from which a new endometrium is established at the next menstrual cycle
How does oestrogen contribute to the proliferative phase of menstruation
-oestrogen stimulates the growth of the endometrium and the upregulation of progesterone receptor expression
How long does the proliferative phase of the menstrual cycle take
10 days
What occurs after the proliferative phase of the menstrual cycle
- ovulation
- the endometrium enters the secretory phase
What is an endometrial pipelle biopsy
-a biopsy that is a thin sliver of tissue is shaved from the lining of the uterus parallel to its surface
How long does the secretory phase of the menstrual cycle last
12 days
What causes menses (period) to occur in relation to the secretory phase of the menstrual cycle
- the spiral arteries briefly shut, then open again and leak blood into the stroma
- the temporary anoxia and hydrolic pressure of the blood disrupts the stroma causing the decidua to detach and the period to begin
Which hormones are required for the successful transformation of the proliferative phase to the secretory phase of the menstrual cycle
- progesterone
- oestrogen
How would you differentiate when the endometrium is in the secretory phase and whether it is early, mid or late
- large vacuole-like accumulations of glycogen stores below their nuclei to synthesis mucin to line the surface of the uterus and nourish the concepsus in case fertilisation occurs
- the endometrial glands start to have an irregular sacculated appearance and secretions appear in the lumen
- the stroma become oedematous in places and the arteries within it lengthen and take on a spiral form
How long are the uterine/fallopian tubes
10cm
Name the 4 parts of the fallopian tubes
- isthmus
- ampulla
- infundibulum
- an intramural part embedded in the wall of the uterus
How does the fimbriae interact with the ovary during ovulation
-the fimbriae becomes erect at ovulation and claspes the ovary during ovulation to ensure the ovum is safely transported to the fallopian tube
What changes occur to the cilia of the fallopian tube at ovulation
-they become longer and beat stronger soon after ovulation
What are the smooth muscle layers of the fallopian tube
- an inner circular layer
- outer longitudinal layer
What epithelium lines the fallopian tube
-simple columnar ciliated epithelium with mucous secreting cells too
What connects the ovary and the upper posterior surface of the broad ligament
- the mesovarium (mesentry)
- the mesovarium is continuous with the surface layer of the ovary called the germinal epithelium
What does the germinal epithelium consist of
-a layer of cuboidal cells sitting on a thickened basement membrane
What are the 3 parts of the ovary
- hilum
- medulla
- cortex
What does the medulla of the ovary contain
-stromal cells including some testosterone-secreting cells similar to the leydig cells of the testis
What does the cortex of the ovary contain
- primordial germ cells
- may also contain follicles in one or more stages of development (from primary to atritic follicles)
At what week of pregnancy do the germ cells migrate into the ovary
10th week of uterine development
What occurs around the time of birth with regards to oogenesis
-the germ cell start oogenesis at week 10 and reach prophase 1 of meiosis (primary oocytes)
When does the primary oocyte continue developing
-after puberty a small group of primary oocytes (frozen at the prophase 1 of meiosis) continue developing at each menstrual cycle
What are atritic follicles
Follicles in the ovary that start to differentiate and fail
Give a brief summary of how follicular development occurs
- the cortex contains dormant primordial follicles which are germ cells enclosed in theca (from stromal cells)
- the theca consists of a single layer of squamous cells (primordial cells) which differentiate into a theca interna (inner granulosa cells) and theca externa (outer flattened cells)
- the granulosa cells secrete oestrogen
- the follicle becomes a secondary follicle and the germ cell develops a prominent zona pellucida that seperates it from the theca
- the follicle develops a fluid filled antrum and the oocyte is attached to the periphery by a stalk of granulosa cells (cumulus oophorus)
- follicle is now a mature Graafia follicle
- when oocyte is released fro the Graafian follicle, the theca then becomes the corpus luteum and continues to secrete oestrogen and progesterone even after the end of a menstrual cycle incase fertilisation and implantation occur
what hormone causes the corpus luteum to keep releasing oestrogen and progesterone, for how long and why
- lutinising hormone
- 10 days after ovulation
- to support and maintain the endometrium layer during the second half of the menstrual cycle
If fertilisation and implantation occurs, how long does the corpus luteum continue to support the endometrium and what happens afterwards
- 4 weeks
- the placenta takes over
What do the thecal lutein cells do
-produce oestrogen
After their use is exhausted, what do the corpus luteum become
- the corpus albicans
- a pale staining fibrous mass
After an ovum has been released, what happens to the Graafian follicle
-the antrum of the follicle collapses often leaving a central blood clot
What are the attachments of the ovary
- to the broad ligament by the mesovary
- to the uterus by the utero-ovarian ligament
- to the pelvic wall by the suspensory ligament
Where would the primordial follicles be found
At the periphery of the cortex of the ovary
What is the primordial follicle surrounded by
-a single layer of epithelial cells (granulosa cells)
How does the primordial follicle become the primary follicle
- FSH secreted from the anterior pituitary gland stimulates follicle development
- oocyte enlarges
- zona pelucida forms directly around the oocyte
How does the primary follicle develop into secondary follicles
- continued FSH production causes formation of antrum
- theca interna and theca externa develop
- cumulus oophorus develops
How does the secondary follicle develop into graafian follicle
- continued FSH
- ovum is surrounded by thick zona pelucida
- then surrounded by a layer of granulosa cells (corona radiata)
- then more granulosa cells
- then theca interna
- then theca externa
What does leutinisation mean
- accumulating lipids into the cell
- this usually occurs in the theca interna and granulosa cells
When does regression of the corpus luteum occurs after ovulation if pregnancy does not occur
8 to 9 days
What are the two types of cells of the fallopian tube and where are they found
Ciliated (infundibular end of the fallopian tube)
Secretory (uterine end)
What are what were formerly known as the peg cells and basal cells of the fallopian tube now recognised as
Peg cells are secretory cells
Basal cells are lymphocytes
What are the two layers of endometrium
- the stratum basalis (layer that remains)
- the stratum functionalis (also divided into the stratum compactum towards the top and the stratum spongiosum) the functional layer or decidua
What causes the menstural phase of the endometrium
-withdrawal of progesterone
What is a distinctive feature of the endocervix apart from its epithelium
-contains crypts
What 10 structures does the vulva encompass
- mon pubis
- labia majora
- labia minora
- hymen
- bartholin’s glands
- skein’s glands
- introitus
- clitoris
- vulvular vestibula
- urethral meatus
What is the female version of the male prostate and what epithelium is it lined by
- skein’s glands (also called periurethral glands)
- lined by pseudostratified columnar epithelium
what diseases are obesity a risk factor for
- type 2 diabetes
- cancer
- coronary artery disease and stroke
- osteoarthritis
- respiratory effects
- infertility and impotency
define obesity
abnormal or excessive fat accumulation resulting from chronic imbalance between energy intake and energy expenditure that presents a risk to health
what BMI is classed as obese
> 30kg/m2
obese class 1 = 30-34.9kg/m2 obese class 2 = 35-39.9kg/m2 obese class 3 = >40kg/m2
what BMI is classed as overweight
<18.5kg/m2
what BMI is classed as normal range
18.5 - 24.9kg/m2
what BMI is classed as overweight
25-29.9kg/m2
give some characteristics of Prader Willi Syndrome
- short status
- almond shaped eyes
- small/mis-shaped hands and feet
- intellectual impairment
- reduced life span, hyperphagia (over eating) and obesity
what is the genetic cause of Prader Willi Syndrome
- deletion of one of the paternal chromosome (15)
- deletion of two maternal chromosomes (15)
what does a proopiomelanocortin (POMO) deficiency result in
hyperphagia an early-onset obesity due to loss of melanocortin signalling at the melanocortin 4 receptor (MC4R)
what is chronic kidney disease
any form of chronic damage kidney damage and also the circumstance where a patient estimated glomerular filtration rate (eGFR) is less than 60 ml/min/1.73m2
so from stage 3 to stage 5
what is haematuria
the presence of blood in urine
what is proteinuria
the presence of abnormal quantities of protein in the urine, which may indicate damage to the kidneys.
what is acute kidney injury (acute renal failure)
Acute kidney injury (AKI) is a sudden episode of kidney failure or kidney damage that happens within a few hours or a few days. AKI causes a build-up of waste products in your blood and makes it hard for your kidneys to keep the right balance of fluid in your body.
How is chronic kidney disease monitored
- using an estimated glomerular rate filtration (eGFR) graph
- calculated from serum creatinine which is usually high when the glomerular filtration rate is low (vice versa)
What factors can affect serum creatinine levels
- meat intake can cause short term increase
- people with large body and muscle mass e.g body builders produce more creatinine
- those taking dietary protein and creatinine supplements
- Afro-Caribbean heritage
- trimethoprim which inhibits the secretion of creatinine by kidney tubules so raises serum creatinine
- fibrates can alter muscle creatinine metabolism and increase serum levels
monitoring ckd
Get the results of tests for serum urea and electrolytes, eGFR, corrected calcium,
phosphate, HbA1c if diabetic, lipids, full blood count, and urine ACR (preferably an
early morning sample)
how is acidosis diagnosed
by serum bicarbonate <22 mmol/L
what are some symptoms of kidney failure
- lethargy
- sleep disturbance
- itching
- nausea
- vomiting
what are the two types of dialysis
heamodialysis - uses an external machine and filter (dialysis membrane) to remove waste and excess water from the body
-done 3 times a week and takes about 2 to 4 hours
peritoneal dialysis - uses fluid placed into the patient’s abdominal cavity through a peritoneal dialysis catheter to remove excess waste and water (the patient’s peritoneal membrane is used as the filter)
-done 4 to 5 times a day but can be done at home so might be more tasking
Aspects of care for transplant patients that staff should be aware of
- As a result of long-term immunosuppression, transplant patients have an increased risk of cancer.
- The commonest site is the skin and you should encourage pale skinned patients to wear a hat and use sunscreen, even when it is not sunny.
- The risk of lymphoma is also increased. This can present with weight loss, sweats, sickness abdominal pain and altered bowel habit.
-Joint pain is common in transplant patients.
- Avoid prescribing non-steroidal antiinflammatory drugs because of their potential nephrotoxicity.
-When treating gout, do not start allopurinol in patients taking the immunosuppressant drug azathioprine.
-Allopurinol blocks the breakdown of the active metabolite of azathioprine (mercaptopurine), which can lead to potentially fatal bone marrow suppression and
low white blood cell count.
what are the two types of peritoneal dialysis
CAPD - which stands for Continuous Ambulatory Peritoneal Dialysis - happens throughout the day, at home or at work, while the person goes about his or her daily life. Between 1.5 and 3 litres of fluid is run in four times a day, exchanging for the fluid from the previous exchange. This takes about 30-40 minutes.
APD - Automated Peritoneal Dialysis - in which the dialysate solution is changed by a machine, at night, while you are asleep. The machine will exchange 8-12 litres over 8-10 hours and then leave 1-2 litres to dwell during the day.
problems with peritoneal dialysis
There can be problems with fluid leaks in the groin or around the catheter when dialysis starts. These problems can be managed easily.
Infections are the major risk - either in the exit site or most importantly in the tummy itself, peritonitis. This shows as tummy pain, a fever and a cloudy fluid bag. It is important to ring the kidney unit immediately if a cloudy bag develops. Peritonitis is treated with antibiotics added to the bags and may need admission to hospital for a few days. Rarely, the infection may be so bad that the catheter has to be removed.
In the long term, there can be a thickening of the peritoneal membrane so that it does not work efficiently. The dialysis fluid may need to be changed or switched to haemodialysis
what is main restriction of patients on dialysis
-restriction of water intake through drinks and food
how much is renal blood flow
about 1L/min
how much is urine flow
1ml/min
what is the filtration coefficient
Filtration coefficient is the product of the permeability of the filtration barrier and on the surface area available for filtration
what does the kidney do
- maintain balance of salt, water and pH
- endocrine function (secreting hormones)
- excrete waste products
what is glomerular filtration
-passage of fluid from the blood into Bowman’’s space to form the filtrate
give 3 proteins in podocytes
Nephrin
Podocin
CD2AP
what are pedicels
the foot processes of podocytes
what molecules can pass through the filtration barrier of the glomerulus
-small molecules and ions up to 10kDa e.g glucose, creatinine, uric acid, potassium
why can albumin not easily pass into the tubule
has a molecular weight of 66kDa and is negatively charged so is repelled by the filtration membrane
what is tamm horsfall protein
Tamm-Horsfall protein (THP) is a glycoprotein produced exclusively by renal tubular epithelial cells within the distal loop of Henle, and it is one of the most abundant urine proteins in mammals.
what is nephrotic syndrome
Nephrotic syndrome is a kidney disorder that causes your body to pass too much protein in your urine. Nephrotic syndrome is usually caused by damage to the clusters of small blood vessels in your kidneys that filter waste and excess water from your blood.
which pressure remains constant and which pressure changes along the length of the capillary in the glomeruli
HYDROSTATIC PRESSURE constant along length of capillary
OSMOTIC PRESSURE rises along length of capillary
what is the glomerular filtration rate
Glomerular filtration rate is the filtration volume per unit time (minutes)
explain autoregulation in the kidney
- pressure within afferent arteriole rises
- stretches vessel wall –triggers contraction of smooth muscle
- arteriolar constriction
- prevents an increase in systemic arterial pressure from reaching the capillaries
- reverse happens when systemic arterial pressure falls
how do the macula densa cells of the distal convoluted tubules communicate with the granular cells of the afferent arteriole
- macular densa cells release prostaglandins in response to reduced NaCl delivery
- this acts on granular cells, triggering renin release, activating the renin-angiotensin system
give the formular for measuring the glomerular filtration rate
GFR = Um (concentration of M in urine) x urine flow rate / Pm (concentration of m in plasma)
what is the normal glomerular filtration rate
125ml/min
what formular is used to calculate the filtration fraction
filtration fraction = GFR / renal plasma flow
if GFR is 120ml/min and the renal blood flow is 1L/min
then renal plasma flow would be 600ml/min as plasma is 60% of blood and cells are 40%
so filtration fraction would be 120/600 = 0.2 or 20%
what is renal clearance
The volume of plasma from which a substance is completely removed by the kidney per unit time (usually a minute)
what would the clearance rate of a substance be equal to
the glomerular filtration rate so 125ml/min
Clearance = urine concentration x urine volume
plasma concentration
what is the clearance rate of urea and what does this mean
65ml/min
-less than the glomerular filtration rate so it was filtered and partly reabsorbed
what is the clearance rate of glucose and what does this mean
0ml/min
-filtered and completely reabsorbed
what is the clearance rate of para-aminohipporate (PAH) and what does this mean
625ml/min
-filtered and completely secreted
what are the 3 factors that determine glomerular filtration rate
- hydrostatic and oncotic pressure
- surface area
- permeability
what is standard bicarbonate
Standard bicarbonate is the bicarbonate concentration standardised to pCO2 5.3kPa and temp 37
What is renal tubular acidiosis
increased blood acidity because the renals tubule cannot remove the protons in the blood
How are protons excreted from the proximal tubule
- bicarbonate and protons join and convert into carbonic acid
- carbonic anhydrase type 4 in the brush border of the apical side of the proximal tubule converts the carbonic acid into water and carbon dioxide
- water and carbon dioxide diffuse across the into the cells of the proximal tubule from the filtrate in the lumen of the tubule
- carbonic anhydrase type 2 converts the water and carbon dioxide into protons and bicarbonate
- a sodium bicarbonate transporter in the basolateral side of the cell transports sodium and bicarbonate into the peritubular capillary
- a sodium hydrogen exchanger on the apical side transports sodium from the urine filtrate into the cell and protons out into the filtrate in the lumen of the tubule
How are protons excreted from the alpha intercalated cells of the distal tubule
- bicarbonate and protons join and convert into carbonic acid
- carbonic anhydrase type 4 in the brush border of the apical side of the proximal tubule converts the carbonic acid into water and carbon dioxide
- water and carbon dioxide diffuse across the into the cells of the proximal tubule from the filtrate
- carbonic anhydrase type 2 converts the water and carbon dioxide into protons and bicarbonate
1-the hydrogen ATPase on the apical side of the cell pushes protons back into the filtrate in the lumen of the tubules
2-the hydrogen potassium ATPase on the apical side of the cell which pushes hydrogen into the urine filtrate in the lumen and potassium back into the cell
How do alpha intercalated cells of the distal tubule move bicarbonate into the peritubular capillaries?
- the bicarbonate chloride antiporter on the basolateral side of the cells moves exchanges bicarbonate for chloride ions
- then a potassium chloride symporter on the basolateral side of the cell moves both the potassium and chloride back into the blood
- a simple chloride channel on the basolateral side of the cell allows the chloride to passively move from the cell into the blood
- sodium potassium pumps on the basolateral side of the cell move 2 potassium ions into the cell and 3 sodium out of the cell and into the blood
What do the protons in the lumen of the distal convoluted tubules bind to to form
- phosphates to form dihydrogen phosphate H2PO4-
- ammonia to form ammonium NH4+
- they are peed out
How does aldosterone affect the principal cells of the distal tubule?
- potassium channels on the apical side move potassium from the cells into the filtrate in the lumen
- epithelial sodium channels (ENAC cells) on the apical side moves sodium from the lumen into the cells
- sodium potassium pump on the basolateral side of the cell pumps 2 potassium in from the blood and 3 sodium out into the blood
- the basically is how sodium is moved from the urine into the blood and potassium is moved from the blood into the urine
What is the main issue in renal tubular acidosis type 1 (distal tubular acidosis)
- the alpha intercalated cells are unable to secrete hydrogen
- the build up of protons in the cells will lead to build up of protons in the blood (acidemia)
- could be caused by genetic mutation in the hydrogen ATPase pump or the hydrogen potassium ATPase pump on the apical side of the cell
- could be caused by medication (lithium or amphotericin B) which makes the apical side of cells permeable so the hydrogen can simply diffuse back across from the lumen into the blood
- could be caused by genetic mutation in the bicarbonate chloride pump which stops it transporting bicarbonate into the blood causing acidemia as well
What is the main issue in renal tubular acidosis type 1 (proximal tubular acidosis)
- brush border is unable to absorb bicarbonate
- genetic mutation of the sodium bicarbonate cotransporter on the basolateral side of the cell mean less bicarbonate transported into the blood causing acidemia
- buildup of bicarbonate in the cells means less bicarbonate can get into the cell from the lumen
What is fanconi syndrome
- loss of protein (proteinuria)
- loss of glucose (glycosuria)
- lose of urea (urikosuria)
- loss of amino acids (aminoaciduria)
- loss of phosphate (phosphaturia)
- can be inherited or caused by medication (tetracycline group of antibiotics)
What is renal tubular acidosis type 3
- defect in both the proximal and distal tubule
What is renal tubular acidosis type 4 (hyperkalemic acidosis)
- aldosterone deficiency (eg Addisons disease)
- aldosterone resistance in the collecting ducts (eg mutation in the ENaC cells)
- affects both principal (hyperkalemia)and alpha intercalated (acidemia) cells
What forms the bladder
The allantois (an anterior outgrowth of the cloaca)
When does the cloaca divide
Between week 4 and week 7
What does the cloaca divide into
Urorectal septum
Anorectal canal
When do the glomerular capillaries start to form
By week 10
When does the metanephros start functioning and how
Week 12
-urine is passed into the amniotic cavity and mixes with amniotic fluid which is swallowed by the fetus and recycled through the kidneys
How does the position of the kidney change in embryonic development
- the kidney develops in the pelvis
- but shifts to a more cranial position in the abdomen
Caused by
-diminution of body curvature and growth of the lumbar and sacral region
What does the metanephric blastema form
The glomeruli and tubules of the kidney
What does the ureteric tube form
Collecting tube and ureter
Another name for Wolffian duct is
mesonephric duct
Another name for Mullerian duct is
Paramesonephric duct
What does SRY gene mean
Sex determining region on the Y chromosome
What protein does SRY produce
Testis determining factor
In a male, which cells are derived from the surface epithelium of the genital ridge
Sertoli cells
In males, which cells are derived from the connective tissue of the genital ridge
Leydig cells
Hormone from hypothalamus that stimulates release of growth hormone
Growth hormone releasing hormone (GHRH)
Hormone that inhibits the release of growth hormone from the hypothalamus
Somatostatin (SMS) or somatotrophin release inhibitory factor
What does the genital tubercle form in a man or woman
Male - penis
Female - clitoris
What does the urethral folds form in a man or woman
Male - penile urethra
Female - labia minora
What does the urethral groove form
Female - vestibule
What is dihydrotestosterone
Dihydrotestosterone (DHT) is made from testosterone by an enzyme. DHT is five times more potent than testosterone. DHT is primarily used by the body in the prostate, skin, and hair follicles.
What is base excess
- quantity of acid required to return the pH to normal under standard conditions
- can be used to calculate bicarbonate dose to correct acidosis, the formular is 0.3xWtxBE
- called base deficit in acidosis
What does the arterial blood gas measure
- pH
- pO2
- pCO2
- Standard HCO3-
- standard base excess
- may include others (lactate, sodium, potassium)
How we interpret acid-base status
- hendersons
- stewarts theory
Give the henderson-hasselbalch equation
pH = pKa + log([A-]/[HA])
OR
pH = 6.1 + log ([HCO3-]/0.03 X pCO2)
In the stewart’s strong ion difference what does the pH and HCO3- depend on
- pCO2
- concentration of weak acids (total plasma proteins e.g albumin)
- strong ion difference (Na+, Mg2+, Ca2+, Cl-, lactate, ketoacids)
Causes of metabolic acidosis
- failure to excrete H+ e.g renal failure, hypoaldosteronism, type 1 renal tubular acidosis
- excess H+ load e.g lactic acidosis, ketoacidosis, ingestion of acids (salicylate, ethylene glycol)
- HCO3- loss e.g diarrhoea, type 2 renal tubular acidosis
Give the clinical features and compensatory mechanisms of metabolic acidosis
Clinical features are sighing respirations (Kussmaul’s resps), tachypoea
Compensatory mechanism is hyperventilation to increase CO2 excretion
How would you investigate metabolic acidosis
-using the anion gap
What is a normal anion gap range
10-16
What does a wide anion gap (a high value) indicate
- lactic acidosis
- ketoacidosis
- ingestion of acid
- renal failure
What does narrow anion gap (a low value) indicate
(I.e high chloride)
- GI HCO3- loss
- renal tubular acidosis
Give the formular of the anion gap
Anion gap = [Na+] + [K+] - [Cl-] - [HCO3-]
What are the causes of metabolic alkalosis
- alkali ingestion
- GI acid loss e.g vomiting
- renal acid loss e.g hyperaldosteronism, hypokalaemia
What is a compensatory mechanism for metabolic alkosis
- hypoventilation (limited by hypoxic drive)
- renal bicarbonate excretion
What is respiratory acidosis
CO2 retention leading to increased carbonic acid dissociation
What causes respiratory acidosis
-any cause of respiratory failure e.g COPD
What are the compensatory mechanism for respiratory acidosis
- increased renal H+ excretion
- bicarbonate retention (if chronic)
What is respiratory alkalosis
CO2 depletion due to hyperventilation
What are the causes of respiratory alkalosis
- Type 1 respiratory failure
- anxiety/ panic
What are the compensation mechanisms of respiratory alkalosis
-increased renal bicarbonate loss (if chronic)
What is hyperemesis gravidarum
-extreme morning sickness but the cause is unknown
What is the normal urine flow rate
1ml/min
What is the glomerular filtration rate
120ml/min
Explain the actions of aldosterone on principal cells
- aldosterone is a steroid hormone that acts on transcription
- it increases the expression of ENaC, Na/K ATPase
- mineralocorticoid receptor is also activated by cortisol
What enzyme prevents the entry of cortisol into renal tubular cells
11-beta hydroxysteroid dehydrogenase
What is the importance of meiosis
- prevent polyploidy
- germ cell differentiation
- increases chromosomal combinations and genetic variability
- contributes to genetic or bio-diversity
What kind of division occurs in meiosis 1 in females
- a reduction division
- 46XX = 23X +23X
At what phase in meiosis 1 stop in females and till when
Stops at metaphase 1 until puberty
-resumption triggered by LH surge
What kind of division occurs in meiosis 2
- equational
- 23X = 23X + 23X
At what phase in meiosis 2 stop in females and till when
Stops at metaphase 2 until fertilisation
What does the paramesonephric duct develop into
- fallopian tubes
- uterus
- upper 2/3 of the vagina
What is thelarche
-onset of female breast development
What is pubarche
-appearance of sexual hair
What is adrenarche
-onset of androgen-dependent body changes such as growth of axillary and pubic hair, body odor and acne
What is the normal range of ph in the body
pH7.35 -7.45
[H+] = 45 - 35 nmol/l
What should the minimum urine pH be
pH = 4.5
How do carbohydrates and fats help to contribute to the dietary acid load
- they produce carbonic acid
- which is converted to CO2
How do proteins contribute to the dietary acid load
- they produce non-carbonic acids e.g sulphur
- amino acids are excreted by the kidneys
Give examples of buffers within the body
- plasma protein (albumin)
- haemoglobin
- extracellular bicarbonate
- intracellular carbonate
- phosphate
Where is 90% of HCO3- reabsorbed and what does this cause
- the proximal tubule
- pH falls from 7.4 to 6.7
Which side of the proximal cells is HCO3- impermeable to
-the apical membrane
Name the carrier proteins involved with HCO3- transport in the proximal tubule
- Na+/H+ antiporter in the apical membrane = secretes H+
- Na+/3HCO3- symporter in the basolateral membrane = moves Na+ and 3HCO3-
Which is the commonest urinary buffer
-alkaline phosphate (HPO4 2-)
Which type of phosphate is impermeable to the apical membrane
-acid phosphate (H2PO4-)
What is ammonia synthesised from
-glutamine
Which form of ammonia/ammonium diffuses into the lumen and which is impermeable to the apical membrane
NH3 ammonia diffuses into the lumen
NH4+ is impermeable to the apical membrane
What is net acid excretion
Net acid excretion = titratable acidity + ammonium - HCO3-
Free H+ ion excretion is trivial and ignored
Give 6 consequences of acidosis on the body
Cardiovascular - arryhythmia, myocardial depression, vasodilation, circulatory collapse
Hyperkalaemia
Neurological - lethargy to coma
Bone - growth disorders and fractures (if chronic)
Give 4 consequences of alkalosis on the body
Hypokalemia
Tetany - increased Ca2+ binding to albumin as H+ leaves (pH sensitive ion channel effects)
Myocardial depression
Describe the relationship between H+ and K+ in the cells of the collecting ducts
H+ in causes more K+ out of cells (electrical gradient)
Causes of respiratory acidosis
- hypoventilation
- COPD
Causes of respiratory alkalosis
- hyperventilation
- hypoxia
Causes of metabolic acidosis
- renal failure
- GI HCO3- loss
- excess acid production
Causes of metabolic alkalosis
- vomiting (pyloric stenosis)
- volume depletion
What is hypercapnia
- also known as CO2 retention or hypercarbia
- abnormally elevated carbon dioxide level in the blood
What is the renal compensation for respiratory acidosis
- H+ secretion increases (acid is secreted as ammonium)
- HCO3- increases further and pH returns to normal
(More likely to be observed in chronic hypoventilation rather an acute morphine overdose)
What is renal compensation for respiratory alkalosis
- H+ secretion decreases
- H+ retained
- pH returns to normal
- HCO3- excreted as insufficient H+ secretion for HCO3- reabsorption
- plasma HCO3 falls further
What is the respiratory compensation for metabolic acidosis
- low pH will stimulate chemoreceptors which enhance respiration
- causing a decrease in pCO2
Give the respiratory compensation for metabolic alkalosis
-increased pH inhibits the chemoreceptors which reduce respiration
What would the pH, HCO3- and pCO2 for respiratory acidosis and metabolic alkalosis look like
Respiratory acidosis
- decreased pH
- increase HCO3-
- increase pCO2
Metabolic alkalosis
- increased pH
- increased HCO3-
- increased pCO2
What would the pH, HCO3- and pCO2 for respiratory alkalosis and metabolic acidosis look like
Respiratory alkalosis
- increased pH
- decreased HCO3-
- decreased pCO2
Metabolic acidosis
- decreased pH
- decreased HCO3-
- decreased pCO2
Give 3 endocrine functions of the kidney
- secrete renin leading to angiotensin 2
- produces erythropoietin
- activates vitamin D
Which cells generate erythropoietin (EPO)
-the peritibular cells in the interstitial space of the renal cortex
What does erythropoietin do
- stimulates the maturation of red blood cells
- attaches to receptors on the early red blood cell progenitor
- inhibits apoptosis (survival factor) allowing differentiation into red blood cells
What conditions can lead to increased erythropoietin production
- anaemia
- altitude
- cardiopulmonary disorders
What conditions can lead to decreased erythropoietin production
- polycythaemia
- renal failure
What is the principal adaption to acidosis
Increased ammonia production
Where is ammonia synthesised in the nephron
-the proximal tubule
What regulates erythropoietin
Hypoxia inducible factor (HIF-2)
How does hypoxia inducible factor (HIF)-2 regulate erythropoietin (EPO)
TBC
How is ammonia/ammonium reabsorbed into the nephron
-in the loop of Henle by the medullary countercurrent system
Give a brief summary of vitamin D activation and its effects
- the liver produces 25-OH cholecalciferol
- the kidney converts this into 1, 25-diOH cholecalciferol(calcitriol)
This causes
- the intestine to increase absorption of Ca2+ and PO4
- the bone to increase resorption releasing more Ca2+ into the blood
- the kidney to increase reabsorption Ca2+ and PO4
- the parathyroid to decrease parathyroid hormone (because parathyroid inhibits bone resorption)
When is a pregnancy ultrasound taken
12 week
- a dating scan
- look at nuchal thickness (thickness of the skin on the back of the neck of the baby)
- check for abnormalities (eg Down Syndrome)
- check for heartbeat
- check crown to rump length
Describe the actions of the lower urinary tract during micturition cycle
Voiding
-detrusor contraction sufficient to effect bladder emptying
From voiding to storage
- urethra contracts
- detrusor contraction is switched off
Storage (98% of normal state)
-detrusor relaxed, sphincter contracted
Switch from storage to voiding
- urethral relaxation then
- bladder neck funnels
- detrusor contraction begins
What is the parasympathetic innervation to the lower urinary tract muscle
S3 to S5
- drive detrusor contraction
- cholinergic
What is the sympathetic innervation to the lower urinary tract
T10 to L2
- urethral contraction
- inhibit detrusor contraction
- noradrenergic
Which areas of the brain control micturition
- frontal cortex
- septal region
- hypothalamus
- pontine micturition centre
Give a brief summary of the neural organisation of the micturition process
- higher centres e.g frontal cortex
- midbrain (periaquaductal grey)
- pontine centres (pontine micturition centre and pontine storage center)
- sacral centres (detrusor nucleus and Onuf’s nucleus)
- detrusor
- urethral sphincter
Are there any gap junctions in the bladder
-no gap junctions
List the 4 classes hormones fall into
Amino acid derivatives e.g adrenaline (ephinerphrine)
Small peptides e.g vasopressin
Proteins e.g insulin
Steroids e.g testosterone
What is the embryological origin of the posterior pituitary gland
- neurohypophysis
- neuronal origin
- the posterior pituitary is a down growth of the brain and is joined by the stalk to the median eminence of the mid-brain in the 3rd ventricle
- cell bodies of its nerve endings lie in the supra-optic nucleus and the para-ventricular nuclei of the hypothalamus
What is the embryological origin of the anterior pituitary gland
- adenohypophysis
- from the roof of the primitive gut tube
- adheres to the front of the posterior pituitary and surrounds the pituitary stalk (pars tuberalis)
What is a portal system
-one that starts and ends as capillaries
How were the cells of the anterior pituitary gland previously classified
Alpha cells or acidophils stained with acid dyes
Beta cells or basophils stained with basic dyes
Chromophobes stained weakly with both dyes
Give the 5 categories the new classification system for the cells of the anterior pituitary gland, their percentage within the anterior pituitary and an example of what they secrete
System is the immunohistochemical staining procedures using antibodies
Somatotrophs 50% (GH) Lactotrophs 25% (PRL) Corticotrophs 15-20% (ACTH, alpha MSH, beta-lipotrophin, beta-endotrophin) Gonadotrophs 10% (FSH, LH) Thyrotrophs 1% (TSH)
Cells that secrete both prolactin and growth hormone are called
-somatomammotrophs
Give examples of the hormones thought to have been produced by acidophils, basophils and chromophobes in the anterior pituitary
Acidophils - growth hormone or prolactin
Basophils - thyrotrophs (TSH), corticotrophs (ACTH) and gonadotrophs (LH, FSH)
Chromophobes - not yet differentiated so dont produce hormones
What do all cells of the anterior pituitary gland have in common
-all produce peptide based hormones that they store in granules within their cytoplasm
How do granules distribution differ amongst acidophils, basophils and chromophobes
Acidophils and basophils both have small dark hormone containing granules in their cytoplasm
Chromophobes have few or no granules
What are herring bodies and where can be they be found
- swollen nerve terminals containing dark staining neuro-secretory granules
- in the posterior pituitary gland
What protein is oxytocin and vasopressin usually bound to in the posterior pituitary gland
-neurophysin (a carrier protein)
From which nuclei in the brain do the neurons that give rise to the Herring bodies originate
- supraoptic or paraventricular nuclei located in the walls of the 3rd ventricles of the brain
- these nuclei receive input from the hypothalamus
What effect does oxytocin have on the breast and the uterus individually
Breast
- during lactation, oxytocin causes contraction of the myoepithelial cells of the secretory alveoli of the breast aiding expression of the milk
- also causes contraction of the smooth muscle in the nipple causing it to be erect
Uterus
-during childbirth oxytocin causes contraction of the muscles of the uterus and dilation of the birth canal
What is the upgrowth of the anterior pituitary gland surrounding the pituitary stalk called and what type of cells does it contain
- pars tuberalis
- contains mostly gonadotrophic cells
Where is the pineal gland a projection from
The 3rd ventricle below the corpus callosum
What makes the pineal gland radio opaque and visible on x-rays
-calcium accumulations in the capsule of the pineal gland (brain sand)
Which type of innervation does the pineal gland recieve
-autonomic nervous system
What does the pineal gland secrete and why is this important
- melatonin
- regulates the diurnal rhythms
Is the pineal gland covered by the meninges
Yes
What is stomatodeum
- a depression between the brain and the pericardium in an embryo
- it is the precursor of the mouth and the anterior lobe of the pituitary gland
- the thyroid gland arises from it
Embyologically, where does the thyroid gland arise from
-the floor of the mouth (stomatodeum)
What is the foramen cecum of the tongue
- the terminal sulcus
- divided the anterior 2/3rd of the tongue and posterior 1/3 of the tongue
What can sometimes link the thyroid gland to the foramen cecum of the tongue
-a midline ligament called the thyroglossal ligament (duct)
Name two hormones the thyroid gland synthesises
- thyroxine
- calcitonin
What type of epithelium lines the follicles of the thyroxine epithelial cells
-simple cuboidal epithelium
What is thyroglobulin and where can is it stored
- thyroglobulin is the stored inert form used to make tyroxine
- found in the colloid of the follicles of thyroxine producing cells of the thyroid gland
How would you determine whether cells of the thyroid gland were metabolically active or not
-a metabollically active cell would have cuboidal epithelium rather a flatter cells, a lumina with little colloid rather than full
Describe the two stages of thyroid follicle activity
Synthetic phase
-the cells synthesise thyroglobulin and secrete it into their colloid storing it
Resorbtive phase (secretory phase)
- the cells reabsorb the thyroglobulin and break it down into tetra-iodothyronine (T4) which they release into the blood stream
- cells enlarge and appear cuboidal
Which cells within the thyroid produce calcitonin
C cells (parafollicular cells)
What does calcitonin do
- an antagonist of parathormone produced by the parathyroid glands
- calcitonin lowers serum calcium level by increasing uptake of calcium into the bones (and muscles)
- inhibits absorption of calcium from the gut and reabsorption of calcium at the kidney
Where can C cells be found
- in clumps between the follicles of the thyroid
- sometimes trapped between the basement membrane and the epithelial cells of the follicles
What stimulates the secretion of calcitonin by C cells
- if the level of calcium in the blood rises
- calcitonin lowers serum calcium level by increasing uptake of calcium into the bones (and muscles)
- inhibits absorption of calcium from the gut and reabsorption of calcium at the kidney
What type of cells does the parathyroid gland contains
Adipocytes
Secretory cells arranged in clusters or cords (e.g small chief cells that have pale cytoplasm and lots of small granules, Oxyphil cells whose role is uncertain)
Which hormone does the chief cells of the parathyroid cells produce and what does it do
- parathormone
- increases serum levels of calcium by resorption of bone
- also promotes absorption of calcium from the gut and reabsorption of calcium by the kidney
What does parathormone do
- increases serum levels of calcium by resorption of bone
- also promotes absorption of calcium from the gut and reabsorption of calcium by the kidney
- antagonist to the calcitonin hormone
Where are pancreatic islets most numerous
-in the tail of the pancreas
How much mass of the pancreas does the pancreatic islets make up
5%
Give the 4 secretory cell types and their percentages found in the pancreatic islets
Beta cells (70%) - secrete insulin Alpha cells (20%) - secrete glucagon Delta cells (8%) - secrete somatostatin Polypeptide secreting cells (2%)
How can the cells types of the pancreatic islets be distinguished
immunohistochemically
What effect does the secretion from alpha cells from the pancreas have on the liver
Alpha cells secrete glucagon which causes the breakdown of glycogen stores in hepatocytes in the liver and the release of glucose into the blood stream
Insulin has an antagonist effect
What do the cortex and medulla of the adrenal gland and why?
Cortex -steroid hormones
Medulla - adrenaline and noradrenaline (epinephrine and norepinephrine)
-they have different embryological origin
Which blood vessels would hormones be secreted into
Veins/venules
Describe the 3 zones of the adrenal gland cortex, what they produce and how the cells are arranged
Zona glomerulosa (rounded clumps of cells) - secrete aldosterone and other mineralocorticoids
Zona fascicularis (parallel cords of cells) - secrete cortisol and other glucocorticoids
Zona reticularis (anatamosing cords of cells) - secrete dehydroepiandrosterone (DHEA) and other androgenic hormones
What are the two types of secretory cells in the medulla of the adrenal glands
Adrenaline secreting cells
Noradrenaline secreting cells
What are secretory cells of the medulla of the adrenal glands influenced by
- steroid hormones from the blood drained from the cortex of the adrenal glands
- autonomic (sympathetic innervation mainly) system
- excitement and stress
Which hormone secreting glands are derived fro the primitive gut tube
- anterior pituitary gland
- thyroid gland
- parathyroid gland
- endocrine pancreas
The cells of the suprarenal medulla are derived from two distinct embryonic primordia. What are they
- derived from the neural crest
- like most cells from the neural crest, they synthesise melanin and a small granule can usually be seen in their cytoplasm
-cells of the suprerenal medulla are modified post-ganglionic axons of the sympathetic nervous system
Besides the adrenal glands, where else in the body may catecholamines occur
Catecholamines are produced mainly by chromaffin cells of the adrenal gland medualla
Also found in he postganglionic fibres of the sympathetic nervous system
Which is the only endocrine gland that has a different epithelium and why
- the posterior pituitary gland
- contains neural cells as it is a downgrowth of the hypothalamus
What cells are the supporting cells of the anterior pituitary gland
Sustentacular cells
What protein is stained for immunohistochemically in sustentacular cells
S100 proteins
How is thyroid distinguished from the parathyroid gland immunohistochemically
The presence of calcium oxalate crystals in thyroid and not the parathyroid
Which cells increase in number as we age in the parathyroid
The oxyphils
What protein is stained for the in the adrenal gland medulla with immunohistochemical tests
S100 proteins
Which structures are tested for S100 protein in immunohistocehmical stains
- the sustentacular cells of the anterior pituitary gland
- the adrenal gland medulla
What do the somatostatin and pancreatic polypeptide hormone secreted from the pancreatic islets do individually
Somatostatin - inhibits gastric cells and slows gastric acid secretion
Pancreatic polypeptide -reduces gut motility and delays gastric emptying
