SUGER Flashcards
What does Onuf’s nucleus do?
Controls the rhabdosphincter muscle which is voluntary
What is the rhadosphincter?
A striated muscle sphincter - it is part of the external urethral sphincter
What are the types of incontinence?
Stress incontinence
Urge incontinence
Retention with overflow
What is the lower urinary tract comprised of?
Bladder
Bladder neck
Prostate gland (in man)
Urethra and urethral sphincter
What is the function of the lower urinary tract?
To convert the continuous process of excretion into an intermittent and controlled process
What does micturition mean?
The discharge of urine from the bladder
What is stress incontinence?
A condition found mainly in women in which there is involuntary discharge of urine when the pressure of the abdomen increases suddenly e.g. jumping or coughing
What is urge incontinence?
A condition where you have an urgent desire to go to pass urine and there is often leakage - this is due usually to an overactive bladder
What is retention with overflow?
This is where there is an obstruction and this leads to difficulty fully passing urine - pressure build ups lead to frequent leaks
What are the three main functions of the kidneys?
1) Excretion of waste products
2) Maintenance of salt, water and pH balance
3) Endocrine function - secreting hormones
What parts of the nephron are in the cortex of the kidney?
- Bowman’s capsule
- Proximal tubule (convoluted part)
- Distal tubule
What parts of the nephron are in the medulla of the kidney?
- Loop of Henle
- Collecting duct
What is the structure of the loop of Henle?
- Thin descending limb
- Thin ascending limb
- Thick ascending limb
What proportion of the cardiac output is received by the kidneys (both together)?
1/5th - 1L/min
What is the normal urine flow per minute?
1ml/min
What are the divisions of the renal arteries in the kidneys?
Renal artery Interlobar artery Arcuate artery Interlobular artery Afferent arteriole Glomerular capillary Efferent arteriole
What is the glomerulus?
A capillary tuft that is fenestrated and lined on the outside by podocytes with foot process
What is the role of the podocytes and their foot processes?
To aid in the filtration - regulating the passage of proteins from the capillary into bownmans space
What is the role of mesangial cells in the glomerulus?
They alter the filtration rate by contracting and reducing the surface area of the glomerulus
What is the approx. surface area of the glomerulus?
1m squared
What makes up the filtration barrier?
1) Capillary endothelium
2) Basement membrane
3) Foot process and podosytes
What determines the what crosses the filtration barrier?
1) Pressure
2) Size of molecule
3) Charge of the molecule
4) Rate of blood flow
5) Binding to plasma proteins e.g. calcium and hormones such as thyroxine
Negatively charged anions are repelled at the barrier, why?
The basement membrane has a fixed negative charge
What factors favour filtration into bowman’s space?
Increased hydrostatic pressure of capillary
Decreased oncotic pressure of capillary
What factors favour moevement of filtrat back into the capillary?
Decreased hydrostatic pressure of capillary
Increased oncotic pressure of capillary
What is the glomerular filtration rate?
The filtration volume per unit of time
What is the equation for GFR?
GFR = Kf (Pgc-Pbs) - (Onc.gc)
What affect on GFR would the constriction of the afferent arteriole have?
It would decrease
What affect on GFR would constriction of the efferent arterioles have?
It would increase
What affect would dilation of the afferent arteriole have on GFR?
It would increase
What affect would dilation of the efferent arteriole have on GFR?
It would decrease
What is the name of the process in which renal blood flow is maintained?
Autoregulation
What is Tubuloglomerular feedback? Describe it
This is where GFR is regulated by the by the following:
1) Macula densa cells detect NaCl arrival
2) Macular densa release prostaglandins in response to reduced delivery
3) Prostaglandins trigger renin release from granular cells
4) Renin activates renin-angiotensin system
5) GFR increases
What three characteristics must a substance have to be used to measure GFR?
1) Freely filtered
2) Not secreted or absorbed in tubules
3) Not metabolised
How can GFR be calculated using a marker substance?
GFR = Conc in urine x flow rate/Conc in plasma
What is the normal GFR?
approx. 125ml/min
What substance is used clinically to meausre GFR?
Creatinine
What is the filtration fraction equation?
FF = GFR/Renal plasma flow
What is the normal filtration fraction?
20%
What is the concept of renal clearance?
The colume of plasma from which a substance is completely removed by the kidney per unit of time (usually a minute)
What is the calculation for renal clearance?
Clearance = Urine concentration x urine volume/plasma concentration
What does it mean if the renal clearance of a substance in lower than the GFR?
That it is freely filtered but partially reabsorbed?
What does it mean if the renal clearance of a substance is the same as the GFR?
That it is freely filtered and not absorbed or secreted
What does it mean if the renal clearance of a substance is greater than the GFR?
that it is freely filtered and secreted
What is the volume of filtrate produced each day?
180L
What happens at the proximal tubule?
Bulk reabsorption of: Na+ Cl- Glucose Amino acids HCO3-
Secretion of organic ions
What happens in the Loop of Henle?
1) More Na+ reabsorption
2) Urinary dilution
3) Generation of hypertonic medullary interstitium
What happens at the distal tubule?
1) Fine regulation of: Na+, K+, Ca2+, Pi
2) Seperation of Na+ and H2O
What happens at the collecting duct?
1) Similar to distal tubule
2) Acid secretion
3) Regulated H2O reabsorption
Does the proximal tubule have high or low permeability to water?
High
What is the bulk reabsortion driven by?
1) Basolateral Na/K ATPase
2) Secondary active transport for glucose, amino acids and lactate
What is secondary active transport?
Where the energy used to move a substance across a membrane is not directly from ATP e.g. by an electrochemical gradient
What is glomerulotubular balance?
Where a greater filtered load is matched by more proximal tubular reabsorption
1) Greater filtration load increases oncotic pressure in peritubular capillaries
2) Efferent arteriolar constriction reduces peritubular capillary hydrostatic pressure
Which part of the Loop of Henle is permeable to water?
Descending limb - ascending limb is impermeable
What occurs in the thick ascending limb?
Solute reabsorption
What is the name for the process in which a hypertonic medullary interstitium is generated?
Countercurrent multiplication
Describe the process of countercurrent multiplication
1) Solute reabsorption occurs in the ascending limb i this increases the medullary osmolarity
2) This draws water out from the descending limb which increases luminal osmolality
3) This causes the process to repeat increasing interstitium osmolarity
What are the two types of cell present in the collecting ducts?
1) Principal
2) Intercalated
What cells in the collecting duct are affected by ADH?
Principal cells
What is the role of principal cells?
Involved in sodium/potassium balance via sodium and potassium channels
What is the role of intercalated cells?
Involved in acid-base homeostasis
What are the limits of urine volume?
400ml-20L/day
What actions does angiotensin II have?
1) Vasoconstrictor
2) Stimulates aldosterone release
3) Increases Na reabsorption of proximal tubule
What is the action of ANP?
1) Renal vasodilator
2) Inhibits aldosterone release
3) Closes ENaC channels in collecting tubules
What is the normal pH range for blood?
7.35 to 7.45
Briefly describe how bicarbonate reabsorption occurs
1) Hydrogen ions are pumped into lumen of tubule
2) Bicarbonate and hydrogen ion form carbonic acid
3) Carbonc acid is broken down by carbonic anhydrase to CO2 and H2O
4) CO2 and H2O diffuse into cell
5) Recombine to form carbonic acid with CA enzyme
6) Dissociation occurs - HCO3- is pumped into capillary, H+ pumped back out into lumen
How does phosphate act as a buffer?
1) Alkaline phosphate accepts proton
2) Acid phosphate is impermeable to apical membrane
3) H+ don’t pass into capillaries - excreted
How does the urinary ammonia buffer work?
1) NH3 sythesised from glutamate
2) NH3 diffuses into lumen
3) NH4+ is impermeable to apical membrane
4) Excreted
What type of compensation takes place in respiratory acidosis?
Renal compensation
What is the renal compensation for respiratory acidosis?
1) H+ secretion increases
2) Acid excreted as ammonium
3) HCO3- increases further
What is the renal compensation for respiratory alkalosis?
1) H+ secretion decreases
2) H+ retained
Note: Insufficient H+ secretion for HCO3- reabsorption
What happens to HCO3- and CO2 in Respiratory acidosis?
HCO3- increases
CO2 increases
What happens to HCO3- and CO2 in respiratory alkalosis?
HCO3- decreases
CO2 decreases
What happens to HCO3- and CO2 in metabolic acidosis?
HCO3- decreases
CO2 decreases
What happens to HCO3- and CO2 in metabolic alkalosis?
HCO3- increases
CO2 increases
What two hormones do the kidneys release?
1) Erythropoietin
2) Renin
What is the function of erythropoietin (EPO)?
Stimulates bone marow - promotes RBC maturation
Where is EPO made?
Peritubular cells in interstitial space of renal cortex
What does the urinary system originate from embryologically?
Intermediate mesoderm
What are the three overalpping kidney systems that develop from the intermediate mesoderm?
1) Pronephros
2) Mesonephros
3) Metanephros
Which of the three overlapping embryological systems does the permenant kidney form from?
Metanephros
What does the pronephros comprise of?
7-10 solid cell groups called Nephrotomes (they disappear at the end of the fourth week)
What does the mesonephros comprise of?
A ridge and a duct - the duct is lateral to the ridge (appears at 4th week)
Where does the urogenital ridge form?
On the medial side of the mesonephric ridge
What are the two sources of the metanephros system?
1) Metanephric blastema
2) Ureteric bud
What does the metanepheric blastema give rise to?
Excretory units
What does the ureteric bud give rise to?
Collecting system
Describe what happens as the ureteric bud forms the collecting system?
1) Dilates - forms renal pelvis
2) Splits - future major calyces
3) Major calyces bud to form minor cayces and collecting tubules
What is the position of the kidneys in development?
Develop in pelvis then move cranially
How does the blood supply change to the kidneys during development?
In pelvis they receive pelvic branches of aorta but when they ascend they receive blood directly from aorta - lower vessels usually degerate
At what point does the metanephros start functioning?
12th week
Where does the urogenital sinus come from?
Cloaca - divided by urorectal septum
What are the parts of the urogenital sinus? What do they form?
Upper - Urinary bladder
Pelvic (middle) - Prostatic and membranous urthra
Phalic - Penile urethra
How does the prostate develop (briefly)?
Prostatic urethra proliferates forming outgrowths (endodermal origin)
Prostate connective tissue and smooth muscle is mesoderm in origin
Which parts of the hindgut remain intraperitoneal?
Transverse colon - maintains dorsal mesentery
Sigmoid colon - also retains mesentery
Which part of the hingut is retroperitoneal?
Descending colon - loses mesentery
What type of organs are the rectum and anal canal?
Infraperitoneal - develop in intraperitoneal space
What does the cloaca divide into?
1) Primitive urogenital sinus
2) Anorectal canal
What is the epithelial lining of the anal canal?
Upper 2/3 = Simple columnar
Lower 1/3 = stratified squamous
What is the name of the line which divides the upper 2/3 and lower 1/3 of the anal canal?
Pectinate line
The lower 1/3 of the anal canal differs superiorly and inferiorly, how?
Superiorly - stratified non-keratinized squamous epithelium
Inferiorly - stratified keratinized squamous epithelium
The line between - Hilton’s white line
What is the blood supply to the anal canal?
Upper 2/3 = superior rectal artery
Lower 1/3 = inferior rectal artery
What is the embryological origin of the upper 2/3 of the anal canal?
Endoderm
What is the embryological origin of the lower 1/3 of the anal canal?
Ectoderm
What does the epidermis originate from embryologically?
Ectoderm
What are the main type of cells that make up skin?
Keratinocytes
What are the non-keratinocytes that are present in skin?
Melanocytes
Langerhans cells
Merkel cells
What are keratinocytes?
Epithelial cells that contain keratin
Keratinocytes have immune properties how?
They produce:
Interleukins
Interferons
Growth Factor
What are the 5 epidermal layers?
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
What is the Stratum Basale?
A single layer of mitotically dividing cells attached to the basement membrane - these cells produce the keratinocytes
What are melanocytes developed from?
Melanoblasts which originate in neural crest
What do melanocytes do?
Produce melanin - transfer to keratinocytes
What are Langerhans cells in skin developed from?
haemopoetic bone marrow cells
What is the role of Langerhan’s cells in the skin?
They are antigen-presenting cells so have immune function
What is the role of merkel cells?
Neuroendocrine cells - act as mechanoreceptors and mediate tactile tension
What does the dermis originate from embryologically?
Mesoderm
Where do the primordial germ cells originate from?
Epiblast
Where do the germ cells migrate to?
Genital ridge
The arrival of germ cells causes the epithelium of the genital ridge to proliferate and form what?
Primitive sex chords
What signals the development of MALE genitals?
Y chromosome has gene called the Sex Determining Region which codes for a protein called Testis Determining Factor
What happens in the absence of the Testis-Determining Factor?
Female development occurs
In males what do the Primitive sex cords form?
Testis cords (medullary cords)
When the Testis cords break up what do they form?
Rete testis
What is the name of the fibrous connective tissue that forms under the epithelium of the genital ridge?
Tunica Albuginea
What do the remaining excretory tubules of the mesonephric system give rise to?
Efferent ducts that link the rete testis and Mesonephric duct
What structures does the Mesonephric duct form?
Epididymis
Vas deferens
Seminal vesicles
Ejactulatory duct
The seminferous tubules are formed at birth. True or false?
False - the testis cords remain solid until puberty
Where do the testis form?
Posterior abdominal wall - they descend into the scrotum before birth
What happens to the Mullerian Duct in males?
It degenerates
What causes the Mullerian Duct to degenerate in males?
Anti-Mullerian hormone
What cells produce the Anti-Mullerian Hormone?
Stertoli cells
What do the urethral folds form in males?
Scrotum
What substance mediates the majority of male genital development?
Testosterone
What happens to the primitive sex cords in females?
They dissociate into cell clusters
Second generation cords form called cortical cords what happens to them?
They split into isolated cell clusters and surround the germ cells - form follicular cells
What happens to the mesonephric duct and excretory tubules in females?
They degenerate
What does the Mullerian ducts form?
1) Uterine tubes
2) Uterus
3) Cervix
4) Upper Vagina
What is the differentiation of the Mullerian duct stimulated by?
Oestrogen
Where does the oestrogen come from in embryonic development?
1) Ovaries
2) Mother
3) Placenta
What does the urogenital sinus form in females?
1) Lower vagina
2) Labia Majora
3) Labia Minora
4) Clitoris
What do the urethral folds form in females?
Labia Majora
What is the name for the production of spermatozoa?
Spermatogenesis
What is the name for the extention of peritoneum that covers the testes anteriorly?
Tunica vaginalis
What is the role of stertoli cells?
1) Nurture sperm development
2) Form blood-testis barrier
Why is there a blood testis barrier?
It is to protect the developing sperm from the immune system as the sperm do not have the same genetic information as somatic cells in the body
What do the seminiferous tubules drain into?
Rete testis
What is another name for the foreskin?
Prepuce
Why are the testes outside of the body?
To keep the testes at a lower temperature than the body - this is needed for their development
What is the mechanism for keeping the testes cooler than the body?
Heat exchange in the Pampiniform plexus - this is where the returning blood in the veins cools the warmer blood coming in the testicular artery
What happens in meiosis I to the genetic material?
The homologous chromosome pairs are seperated
What happens in meiosis II to the genetic material?
The duplicate sister chromatids
Spermatogonia produce two types of daughter cells, what happens to them?
Type A remain outside blood-testis barrier and produce more daughter cells
Type B differentiate into primary spermatocytes
What is formed after meiosis I?
2 Secondary spermatocytes
What is formed after meiosis II?
4 spermatids
What is spermiogenesis?
The transformation of spermatids into spermatozoa
What happens in spermiogenesis?
The spermatids sprout a tail and they discard their cytoplasm
How many sperm are made per gram of testis per second?
300-600
What is the blood-testis barrier formed by?
Tight junctions between the basement membrane under the sertoli cells
How long does it take for spermatogenesis to be completed?
64 days
What are the efferent tubules?
Ciliated ducts that collect spermatazoa from the rete testes and transport them to the epididymis
What is semen made up of?
- Seminal vesicle fluid
- Prostatic secretions
- Sperm
- Bulbourethral fluid
Semen also contains fructose, why?
To provide energy for the sperm so they can be mobile
Semen contains prostaglandins, why?
To stimulate female peristaltic contractions
Why is meiosis important in gamete formation?
1) Prevents polyploidy - where there is two (or more) copies of the genetic information
2) Increases genetic variability
When does meiosis I begin in female gamete formation?
In utero before 12 weeks
When does meiosis I end?
Puberty - it arrested at metaphase 1 until puberty occurs
When does meiosis II occur?
Puberty
When does meiosis II end?
Fertilization - it is arrested until fertilization
At what point do male and female gonads differentiate?
Week 6
What is the hormonal state before puberty?
1) Low pulsatility amplitude of GnRH and secretion
2) Low levels of FSH, LH and gonadal sex steroids
What happens to the relevant hormones at puberty?
1) Increased amplitude of GnRH and GHRH
2) Increased levels of FSH, LH and sex steroids
3) Increased levels of growth hormone
What are primordial follicles?
They are single oocytes surrounded by a layer of epithelial cells (granulosa cells)
What stimulates follicular development?
Cyclic FSH secretion
What happens in the formation of the primary follicle?
1) Granulosa cells proliferate
2) Oocyte enlarges
3) Stroma organised into connective tissue
4) Zona pellucida forms directly around oocyte
What happens in the formation of the secondary follicle?
1) Formation of antrum - filled with follicular fluid
2) Connective tissue differentiates into theca interna and theca externa
3) Oocyte supported in antrum by stalk of granulosa cells
What is the name of the stalk of granulosa cells that supports the oocyte?
Cumulus oophorus
What is the name of a mature follicle?
Graafian follicle
What happen in the formation of the Graafian follicle?
1) Ovum surrounded by thick zona pellucida
2) Layer of granulosa cells surround oocyte known as corona radiata
3) There is a basal lamina
4) There is a developed theca interna and externa
What happens to the follicle after ovulation?
It converts into a corpus luteum
What does the corpus luteum do?
Secretes progesterone and oestrogen
What is the fate of the corpus luteum?
It persists if pregnancy occurs, if not it regresses
What happens to the corpus luteum after it regresses?
Forms a corpus albicans - eventually resorbed or replaced by ovarian stroma
What are the four segments of the uterine tube?
1) Intramural
2) Isthmus
3) Ampulla
4) Infundibulum
What is the intramural part of the fallopian tube?
The part that is inside the uterine wall
What is the isthmus part of the fallopian tube?
A thick-walled part - narrow
What is the ampulla part of the fallopian tube?
An expanded part of the Fallopian tube
What is the infundibulum of the fallopian tube?
A trumpet-shaped opening to the peritoneum which has fimbrae
What are the layers of the fallopian tube lining?
1) Mucosa
2) Muscularis
3) Serosa
Describe the structure of the mucosa of the fallopian tube
Thrown into branching folds - plicae
has three types of cells: Secretory, ciliated and intercalated
Describe the structure of the muscularis of the fallopian tube?
Inner circular layer with outer longitudinal layer
What is the serosa of the fallopian tube?
Connective tissue covered by mesothelium
What are the three layers of the uterus?
1) Endometrium
2) Myometrium
3) Serosa
The endometrium is composed of two layers, what are they?
1) Stratum basalis
2) Stratum compactum and stratum spongiosum (functional layer)
The endometrium undergoes a proliferation phase, what is it?
Where glands proliferate, become tortuous and show mitotic activity
There is no luminal secretions
Stomal cells are spindled and compact
What is the proliferation phase stimulated by?
Oestrogen
The endometrium undergoes a secretory phase, what happens in the early phase?
sub-nuclear vacuoles form
What happens in the mid part of the secretary phase?
Intraluminal secretions occur, glands become more rounded and there stroma oedema
What happens in the late part of the secretory phase?
The glands become elongated and there are more luminal secretions
Stroma has spiral arterioles
What stimulates the secretory phase?
Progesterone
What happens in the menstrual phase?
Stomal haemorrhage occurs and theres stromal and glandular fragmentation
What initiates the menstrual phase?
Progesterone withdrawl
Describe the myometrium
Three layers (poorly defined)
Inner longitudinal
Middle circular
Outer longitudinal
What is the endocervix?
The part of the cervix past its enterance
What is the ectocervix?
The entrance to the cervix
What is the endocervix lined by?
Simple ciliated columnar epithelium
What is the ectocervix lined by?
Stratified non-keratinized squamous epithelium
What is the vagina lined by?
Stratified non-keratinizing squamous epithelium
What are the three layers of the vagina?
1) Mucosa
2) Muscularis
3) Adventitia
What is the labia minora lined by?
Mostly stratified non-keratinizing squamous epithelium
What is the labia majora lined by?
Stratified keratinizing squamous epithelium
What are the two main glands in the female genitalia?
1) Bartholin’s gland - mucus secreting
2) Minor vestibular glands - mucus secreting
What occurs to the female genitalia in menopause?
There is ovary, endometrium, cervix and vagina atrophy
How long is the menstrual cycle normally?
28 days
Between what days does menstruation take place in the cycle?
Day 1-7 (lasts between 3 and 7 days)
What happens in days 8-11 of the menstrual cycle?
The endometrium thickens in preparation for an egg
What day does ovulation take place in the cycle?
Day 14
What happens between days 18-25?
Corpus lueum fades away if pregnancy has not occurred
What happens at days 26-28 in the menstrual cycle?
The endometrium detaches from the uterus wall and leads to menstruation
What two mechanisms are responsible for sperm transport in the female reproductive tract?
1) Sperm motility
2) Contractions of the female reproductive tract
How long can sperm be “stored” in the human female reproductive tract?
5 days
What process do sperm have to go through before they can fertilize the ovum?
Capacitation
What happens in capacitation?
1) Sperm head membrane is changed so it can fuse more easily
2) The sperms motility increases
What is the Zona Pellucida?
A glycoprotein layer that surrounds the oocyte and is vital in binding spermatozoa for fertilization
What is a pronuclei?
The nucleus of a sperm of oocyte in the process of fertilization before fusion has taken place - they are still haploid
What is the process syngamy?
1) Male and female pronuclei migrate to centre
2) Haploid chromosomes pair and replicate
3) Pronuclear membranes breakdown
4) Mitotic spindles form
5) 46 chromosomes line at the equator
How long after fertilization does the first cleavage occur - division?
Approx. 24 hours
What is responsible for developmental control prior to the 4-8 cell stage?
Maternally derived stores of RNA laid down in oogenesis
What is responsible for development control at the 4-8 cell stage and onwards?
The embryonic genome - at this stage it is activated
At day 4 compaction occurs, what does this involve?
1) Cells flatten - maximising intracellular contacts
2) Tight junctions form
3) Polarisation of the outer cells occurs
At what stage does differentiation start to occur?
Day 5
At day 6 the oocyte undergoes “hatching” what does this refer to?
The embryo hatching from the zona pellucida
What two groups of layers have you got a differentiation?
1) Trophoectoderm
2) Inner mass cells
What do the inner mass cells comprise of?
1) Extra embryonic membrane
2) Extra embryonic mesoderm
3) Extra embryonic endoderm
4) Embryonic ectoderm
5) embryonic mesoderm
6) Embronic endoderm
What forms the chorian and placenta?
1) Chrorioic ectoderm (from trophoectoderm)
2) Extra embryonic mesoderm
What forms the amnion?
Extra embryonic membrane and mesoderm
What forms the yolk sac?
Extra embryonic mesoderm and endoderm
What forms the fetus?
Embryonic ectoderm, mesoderm and endoderm
What is the metabolic and biosynthetic activity and nutritional requirements at early cleavage?
Low - nutritional requirements are simple (low glucose and non-essential amino acids
What is the metabolic and biosynthetic activity and nutritional requirements at the blastocyst stage?
High - nutritional requirements are complex (high glucose and essential and non-essential amino acids and vitamins
What provides the exogenous nutrients to the blastocyst?
1) Cumulus cells
2) Fallopian tube secretions
3) Uterine secretions
What is the implanation window of the blastocyst?
19-22 days
What causes attachment of the blastocyst to occur?
1) Apical surface of endometrium has integrins
2) Trophoblastic cells also express intergrins
Integrins are adhesion molecules
What does the trophoblast differentiate into?
1) Cytotrophoblast
2) Syncytiotrophoblast
What does the synctiotrophoblast do?
Penetrates the basal lamina and erodes endometrial stroma - this erodes the vessels forming blood filled lacunae
What happens in the decidual reaction phase?
Progesterone primed endometrial stromal cells adjacent to blastocyst differentiate into metabolically active secretory cells - decidual cells
What prevents the embryo being attacked by the mother immune system?
Leucocytes in the endometrial stroma release interleukin-2 which prevents maternal recognition
What is the role of hCG?
Sustains early pregnancy, supports the corpus luteum and therefore progesterone production
In addition to supporting the development of sperm what else do sertoli cells do?
Phagocytose faulty sperm
Describe Leydig cells’ function, appearance and location?
1) Cluster of cells in the interstitium between tubules
2) Produce testosterone
3) Large amount of SER
4) Reinke’s crystals
What are the tubuli recti?
They connect the seminiferous tubules to the rete testis
Describe the rete testis
1) Irregular anastomosing channels
2) Cuboidal epithelium
3) Microvilli and cillia
What are the three parts of the epididymis?
Head, body and tail
What is the function of the epididymis?
Storage and maturation of sperm
What is the epithelium of the epididymis?
Pseudostratified columnar epithelium with stereocilia
What is the structure of the Vas deferens?
Pseudostratified columnar epithelium with 3 layers of muscle
What happens to the prostate in aging?
Stroma and glands both undergo hyperplasia
What is another name for Bulbourethral glands?
Cowper’s
What do the bulbourethral glands do?
Secrete lubricating mucus
What are the parts of the uterus?
Body
Fundus
Neck
Os - opening
What is the uterus supported by?
1) Broad ligament
2) Round ligament
3) Cardinal ligaments
4) Rectouterine ligament
5) Vesicouterine ligament
What is a transvaginal ultrasound used for??
To assess thickness of the uterus lining and the ovaries - involves insertion of probe
What is a sonohysterography?
A more in-depth investigation into the uterus using ultrasound and injected fluid
What are the benefits of ultrasound?
1) Real-time imaging
2) Minimally invasive
3) Not believed to be harmful
What happens in a hysterosalpinography?
1) Catheter inserted into uterine cavity
2) Contrast injected
3) Contrast flows into fallopian tubes
4) X-ray image obtained
When are scans usually taken in pregnancy?
1) 12 weeks
2) 20 weeks
What is the purpose of the 12 week scan?
To assess date of pregnancy: looks at heart beat, crown-rump length, number of fetuses and nuchal translucency
What is the purpose of the 20 week scan?
To assess for any abnormailites
What happens if possible abnormalities are found?
1) Second scan
2) Councelling
3) Further investigations
When are MRI’s NOT done in pregnancy ?
First trimester
When do the exocrine functions of the pancreas begin?
After birth
When do the endocrine functions of the pancreas begin?
10-15 weeks
Is the pancreas retroperitoneal or intraperitoneal?
Retroperitoneal
What cells carry out exocrine functions?
Acinar cells
What cells carry out endcrine activity?
Islets of Langerhans
Which type of cells is significantly dominant in the pancreas?
Exocrine
What doe the alpha cells in the islets of Langerhans produce?
Glucagon
What do the beta cells in the islets of Langerhans produce?
Insulin
What do the delta cells in the islets of Langerhans produce?
Somatostatin
Describe briefly the process of insulin secretion from the beta cells?
1) Glucose enters through GLUT2 transporter
2) Glucose metabolism occurs - ATP formed
3) Potassium channels close - depolarises membrane
4) Calcium channels open
5) Insulin secretory granules fuse with membrane and release insulin
What feature shows that insulin has been produced endogenously?
Presence of C peptide
What is proinsulin?
Contains A and B chains of insulin joined by C peptide (disulphide bridges hold the two chains together)
The release of insulin is biphasic, what does this mean?
1) First phase is rapid release of stored hormone
2) Second phase is slow as it is the release of newly synthesised hormone
Describe the mechanism in which insulin acts of muscle and fat cells
1) Insulin binds to insulin receptor on cell
2) Intracellular signalling takes place
3) GLUT4 vesicle mobilized to plasma membrane
4) GLUT4 allows glucose to move into cell
What is the short-term response to high glucose?
Glycogenesis
What is the long-term response to high glucose?
Lipogenesis
What is the short-term response to low glucose?
Glycogenolysis - breaking down glycogen
What is the long-term response to low glucose?
Gluconeogenesis - make glucose
Where are the primary glucose sensors?
Pancreatic islets
Where are glucose sensors found other than pancreatic islets?
Medulla
Hypothalamus
Carotid bodies
What is the gut hormone that stimulates insulin release?
Incretins
Where does glucose go in the body?
40% liver
60% periphery (mainly muscle)
What supplies the anterior pituitary with blood?
Through portal venous circulation from the hypothalamus
What are the hormones released by the hypothalamus?
1) GHRH
2) GnRH
3) TRH
4) Dopamine
What hormones are released from the anterior pituitary galnd?
1) GH
2) LH
3) FSH
4) ACTH
5) TSH
6) Prolactin
What are three main issues that can occur from a pituitary tumour?
1) Pressure on nerves - particularly optic nerves
2) Pressure on normal pituitary - hypopituitarism
3) Functioning tumour - secretes hormones
What would happen if the pituitary tumour pressed on the optic chiasm?
Bitemporal hemianopia
What does the posterior pituitary gland originate from?
Neural tissue - large numbers of glial-type cells
What two hormones are released by the posterior pituitary gland?
1) Vasopressin
2) Oxytocin
What is the function of vasopressin?
Controls water reabsorption
What is the function of oxytocin?
1) Expression of milk from the glands to the nipples
2) Contractions of the uterus - initation of labour
Where in the posterior pituitary gland is vasopressin released from?
Supraoptic nuclei
Where in the posterior pituitary gland is oxytocin released from?
Paraventricular nuclei
The hormones released by the posterior pituitary are formed in the hypothalamus - how do they get to the posterior pituitary gland?
In the axoplasm of the neurons
What triggers vasopressin release?
Osmoreceptors in hypothalamus - day to day
Baroreceptors in brainstem and great vessels - in emergency
What is the condition in which you lack vasopressin?
Crainial diabetes insipidus
What is the condition in which you are resistant to vasopressin?
Nephrogenic diabetes insipidus
What is oxytocin stimulated by in women?
Suckling
What leads to the release of thyroid hormones from the thyroid gland, starting at hypothalamus?
1) Hypothalamus releases Thyrotropin-releasing hormone
2) This stimulates the release of Thyroid-stimulating hormone from the anterior pituitary gland
3) this stimulates the release of the thyroid hormones
What are the hormones produced by the thyroid gland?
1) Thyroxine (T4)
2) Triiodothyronine (T3)
3) Calcitonin
What is stored in the follicles of the thyroid gland?
Thyroglobulin
What is the actions of thyroid hormones?
1) Increasing metabolism
2) Growth and development
3) Increased catecholamine effect
What is the action of calcitonin?
Works to reduce calcium levels by:
1) Inhibiting osteoclasts
2) Stimulating osteoblast activity
3) Inhibits calcium reabsorption in renal tubules
What effect does calcitonin have that is the same as PTH?
It inhibits phosphate reabsorption in the renal tubules
What cells produce calcitonin?
C cells or parafollicular cells
What is produced in the Zona glomerulosa of the adrenal glands?
Mineralocorticoids - Aldosterone
What is produced in the Zona fasciculata of the adrenal gland?
Glucorticoids - cortisol
What is produced in the Zona reticularis?
Androgens
What is produced in the medulla of the adrenal gland?
Catecholamines - e.g. adrenaline
What is the name for the part of the adrenal gland that contains the Zona glomerulosa, fasciculata and reticularis?
Adrenal cortex
What is the function of ACTH?
It stimulates corticosteroid synthesis
What are the actions of glucocorticoids?
1) Increased glucose mobilisation
2) Maintenance of circulation - vascular tone, salt and water balance
3) Immunomodulation - dampens immune response
How are glucocorticoids transported?
1) Corticosteroid-binding globulin (CBG) (90%)
2) Albumin-bound (5%)
3) Free (5%)
What affect do glucocorticoids have on hypothalamus and pituitary gland?
Inhibit CRH and ACTH release - negative feedback
What happens in the plasma and urine when there is endocrine salt loss?
Plasma: Sodium = low, potassium = high
Urine: Sodium = high, potassium = low
What stimulates androgen production in the adrenal glands?
ACTH (not gonadotrophins like in gonads)
What is different about the adrenal medulla?
It is part of the autonomic nervous system
Which is produced in greater amounts in the adrenal medulla, adrenaline or noradrenaline?
Adrenaline - 80%
Noradrenaline - 20%
What does endocrine mean?
“Within” - this is where the glands secrete into the blood stream
What does exocrine mean?
“Outside” This is where the glands secrete substances into ducts which transport to site of action
What is the other name for the anterior pituitary gland?
Adenohypophysis
What is the other name for the posterior pituitary gland?
Neurohypophysis
What inhibits prolactin secretion?
Dopamine
