Final Exam Flashcards
What is the major function of the renal system?
To filter blood plasma and remove animal body waste and unnecessary molecules.
What are the unnecessary molecules being filtered out by the renal system under normal conditions?
Urea/uric acid, creatinine, and other environmental toxins
What molecules filtered through the renal system reflect animal physiology? provide examples.
Endocrine and metabolic activities. ex) hormones and hormone metabolites, blood glucose, and creatinine
Besides filtering waste, what are the other major functions of the renal system?
Maintain physiological levels of solutes and pH, and maintain physiological levels of water, blood volumes, and blood pressure.
What are the non-major functions of the renal system?
Secretion of erythropoietin to increase red blood cell numbers, convert vitamin D into the active form for calcium absorption in gut, and excretion of pheromones.
What are kidneys?
Organs important for blood plasma filtration, secretion and reabsorption, and urine formation.
What are ureters?
Tubes (1per kidney) that transport urine to the bladder.
What animals are ureters found in?
Fish, amphibians, and mammals.
Where do ureters transport urine in most birds, reptiles, and amphibians?
To the hindgut where it is excreted out the cloaca.
What is the bladder?
The organ in mammals that hold urine.
What is the urethra?
The tube that transports urine from the bladder for excretion.
What is the renal cortex?
The outer most region of the kidney. The location of plasma filtration
What is the renal medulla?
The inner region of the kidney. Has osmotic potential.
What is the renal pelvis?
The area of the kidney in which urine is collected before entering the ureter.
What is the nephron?
The small, microscopic tubule system responsible for blood plasma filtration, secretion, reabsorption, and urine formation. Millions in each kidney.
Where does the nephron tubule system begin and end?
Begins in the cortex and a portion extends into the medulla.
What qualities of kidneys depends on species?
Shape, prevalence of renal lobes, renal pyramids, and true renal pelvis.
In the cortex, what does each kidney include?
A Bowman’s capsule
What is the function of the Bowman’s capsule?
Filtering plasma into the nephron tubule system through the glomerulus.
What is the glomerulus?
A collection of special capillaries found in the Bowman’s capsule that filter plasma into the tubular component.
Nearly all plasma contents except large proteins are filtered into ________.
Tubules
What do some capillaries outside the Bowman’s capsule do?
Secrete molecules into the tubule system.
What happens to important molecules needed by the animal?
They are reabsorbed back out of the tubule and into the capillaries.
The tubule is long, convoluted, and lined with ________ ____ that help reabsorb molecules through _______ and _______.
epithelial cells, channels, carriers
Where does waste/toxic substances continue to after the kidney nephron?
They continue to the renal pelvis, ureters, and bladder for excretion.
Where does osmoconcentration and urine formation occur in the nephron?
Across the membrane of the nephron in the medulla.
What are the nephron tubule structures?
The Bowman’s capsule, the proximal tubule, the loop of henle, the distal tube, and the collecting duct.
Multiple nephrons drain into a _________ ____.
collecting duct
What are the lobes of the cow kidney called?
Lobules
All collecting ducts drain into the _____ _____.
renal pelvis
What does the Bowman’s capsule collect?
The glomerular filtrate.
What occurs in the proximal tubule?
Uncontrolled reabsorption and secretion of selected substances
What is the function of the loop of henle?
It establishes an osmotic gradient in the renal medulla that is important to the kidney’s ability to produce urine of varying concentration.
What occurs in the distal tubule and collecting duct?
Variable, controlled reabsorption of Na+ and H2O and secretion of K+ and H+. Fluid leaving the duct is urine, which enters the renal pelvis.
What are the nephron blood vessels?
The afferent arteriole, the efferent arteriole, the glomerulus, and the peritubular capillaries.
________ occurs in the glomerulus.
Filtration
________ occurs from the peritubular capillaries into tubule. Capillaries continue into ______ and then _____ _____.
Secretion, venules, renal veins
What is the function of the afferent arteriole?
Carry blood to the glomerulus
What is the function of the efferent arteriole?
Carry blood away from the glomerulus.
What are the functions of peritubular capillaries?
Supply the renal tissue with oxygen and make exchanges with fluid in the tubular lumen.
Initial filtration at the glomerulus is not _______.
selective
What is meant by initial filtration at the glomerulus not being selective?
Everything in blood except cells/ cellular material and large proteins are filtered.
Reabsorption along tubule is highly ______ and achieved through ________ ________ _________.
Selective, assisted membrane transport
What major substances are reabsorbed through the nephron tubule?
Glucose (GLUT and SGLT), amino acids and ions (various channels and carriers), and water (aquaporins)
How much of filtered sodium , water, glucose, and amino acids are reabsorbed?
99-100%
Substances are reabsorbed out of the tubule lumen into the ________ _____ and then ________ _______ to continue through circulation.
interstitial space, peritubular capillaries
What distinct barriers must a substance cross in order to be reabsorbed?
The luminal membrane, the cytosol, the basolateral cell membrane, the interstitial fluid, and the capillary wall.
What path does Na+ follow for reabsorption?
Lumen —> tubular cell —-> the basolateral Na+/K+ pump —> interstitial fluid —> capillary
What path does Cl- follow for reabsorption?
lumen —> CFTR or ClC channel —> tubular cell lateral space —> interstitial fluid —> capillary
What path does H2O follow for reabsorption?
lumen —> AQP-1 water channel —> proximal tubular cell (following sodium) —> AQP-1 water channel (next to the basolateral Na+/K+ pump) —> interstitial fluid —> capillary
When are channels and carriers for important substances present in the proximal tubule?
Always present
What is reabsorption for important substances in the distal tubule and collecting duct regulated by?
Hormones
How do hormones regulate reabsorption of important substances in the distal tubule and collecting duct?
They stimulate the presence of channels and carriers. Allows body to balance substances
What major hormones regulate reabsorption in the distal tubule and collecting duct?
Vasopressin and aldosterone
What processes are driven by the Na+/K+ ATPase pump in the tubule cell basolateral membrane?
Transport of sodium by channels and carriers from tubule lumen through apical cell membrane into cell, water and chloride reabsorption, and the activity of glucose and amino acid carriers
What hormones act on the distal tubule and collecting duct and what do they do?
Aldosterone increases the number of tubule cell sodium pumps and channels for sodium reabsorption. Vasopressin increases water absorption by increasing the number of aquaporin channels (AQP-2)
How is water reabsorbed in the proximal tubule?
Passively by osmosis through aquaporin (AQP-1) channels.
___% of glucose is typically reabsorbed along proximal tubule.
100
What happens in the proximal tubule if blood glucose concentrations are too high?
Glucose will be reabsorbed from the tubule until reaching a threshold, after which, glucose begins to be excreted in the urine.
It is important for the animal to regulate the rate of _____ filtration in the kidney.
Plasma
What does too much plasma filtration result in?
The loss of important substances and water.
What do mechanisms that regulate plasma filtration involve?
Modifications to the glomerulus
What is glomerular filtration rate (GFR)?
The volume of plasma filtered from the renal glomerular capillaries per unit of time.
What is the GFR of an adult human?
115-125 ml/min or 180 L/day
What does GFR mostly depend on?
Net filtration pressure in glomeruli
GFR reflects ______ function.
kidney
The structure of the glomerulus promotes _______.
Filtration
Which is smaller, efferent arteriole radius or afferent arterial radius?
Efferent arteriole radius
What does the smaller radius of efferent arterioles cause?
An increase in capillary blood pressure in the glomerulus
What does the increase in capillary blood pressure in the glomerulus do?
It helps to overcome opposing pressures, resulting in a net filtration pressure in tubule.
What can influence net filtration pressure?
Changes in afferent arterial pressure
Reducing the radius of afferent arterioles _____ blood flow into the glomerulus and ______ friction. Achieved by special ______ ______ cells.
reduces, reduces, smooth muscle
What are the smooth muscle cells around afferent arterioles called?
Juxtaglomerular cell or JG cells
Why is the fluctuation of afferent arteriole pressure important?
Important to correct for fluctuations in animal mean arterial pressure that would affect filtration and animal water or solute balance.
An increase in MAP would greatly ______ GFR and animal solute and water loss.
increase
Vasoconstriction _______ blood flow into the glomerulus and _______ GFR.
decreases, decreases
Vasodilation ______ blood flow into the glomerulus and _______ GFR.
increases, increases
___________ prevents unintentional shifts in GFR and solute and water loss due to changes in MAP.
Autoregulation
What mechanisms achieve autoregulation?
Myogenic activity and tubuloglomerular feedback
What is the myogenic activity of the afferent arterioles?
The more the JG cells stretch due to increases in blood pressure, the more they constrict, reducing blood flow into glomerulus
What is tubuloglomerular feedback?
The distal tubule senses changes in sodium concentrations and filtrate volume in tubule due to changes in GFR. Special distal tubule cells (the macula densa) sense sodium and filtrate volume and release paracrine factors that effect JG cell constriction.
What paracrine factors does the macula densa release?
ADP, adenosine, and nitric oxide
What is the juxtaglomerular apparatus (JGA)?
Location where the ascending distal tubule, after the loop of henle, contacts glomerulus.
What does the juxtaglomerular apparatus involve?
Paracrine communication between the macula densa and juxtaglomerular cells.
What extrinsic factor controls GFR?
The sympathetic nervous system
How does the sympathetic nervous system effect GFR?
It constricts JG cells, causing afferent arterial vasoconstriction, decreasing GFR and solute and water loss. Helps to avoid filtration and maintain blood volume and pressure.
What does sympathetic control of GFR contribute to?
Long-term adjustment of blood volume and pressure by avoiding plasma filtration and solute and water loss.
Low blood pressure within the heart triggers activation of sympathetic neurons that extend directly to the kidneys. This ______ afferent arteriole, _______ GFR, and ________ blood volume.
constricts, reduces, increases
The sympathetic nervous system also triggers _____ secretion from JG cells that activate the ___________________ system, increasing blood volume and pressure.
renin, Renin-Angiotensin-Aldosterone
What is the Renin-Angiotensin-Aldosterone system triggered by?
Low blood pressure sensed by baroreceptors (extrinsic), low blood pressure in kidney sensed by JG cells (intrinsic), low sodium and filtrate volume sensed by the macula densa (intrinsic)
What are the steps of the Renin-Angiotensin-Aldosterone system?
- Renin secreted by JG cells into blood
- Renin converts angiotensinogen to angiotensin I
- Angiotensin I converted to angiotensin II (ACE enzyme)
- Angiotensin II travels to adrenal cortex causing it to secrete aldosterone
- Aldosterone travels to kidney, increasing sodium reabsorption from tubule system.
- Water follows sodium by osmosis in tubule system
- Water enters bloop, increasing MAP.
Where is angiotensinogen converted to angiotensin I?
In the blood
Where is angiotensin I converted to angiotensin II?
In the lungs
Where is aldosterone secreted into?
The blood
____________ and activation of __________ stimulate vasopressin release from animal posterior pituitary.
Angiotensin II, osmoreceptors
What stimulates animal thirst and salt hunger?
Angiotensin II
What does aldosterone increase in relation to sodium and potassium channels?
Increases gene transcription of sodium and potassium channels that are distributes along the kidney distal tubule and collecting duct apical membrane.
Along the apical membrane, Na+ is transported into the ____ and K+ is transported into the _____ _____.
cell, tubule lumen
What does aldosterone increase in relation to sodium-potassium ATPase pumps?
Increases transcription of sodium-potassium ATPase pumps that are distributed along the basolateral cell membrane.
Along the basolateral membrane, sodium is pumped into the ________ ____. Water follows by osmosis through ________.
interstitial space, aquaporins
What does increased K+ stimulate and what does this help with?
Aldosterone secretion from the adrenal cortex, helps remove excessive K+ from the animal body.
What are atrial natriuretic peptides (ANPs) released by?
Heart atria myocardiocytes in response to increase blood volume/pressure.
What are the functions of ANPs?
Reduce sympathetic output to heart and arteriole smooth muscle, which reduces CO, TPR, and MAP. Inhibits the Renin-Angiotensin-Aldosterone system, increasing kidney sodium and water secretion in urine, reducing blood volume.
When an animals is in ideal fluid balance, an ______ _____ is produced at a moderate rate.
Isotonic urine
How does solute or osmotic pressure of isotonic urine compare to normal tissues?
The same (usually 300 mOsm in animals)
What happens when an animal is in dehydration?
The kidneys produce a small amount of concentrated urine (low water volume, high solute concentration)
What is anti-diuresis?
Decreased production of urine
What happens when an animal is hydrated?
The kidneys produce a large amount of dilute urine (large water volume, low solute concentration)
What is diuresis?
Increased production of urine
What is reabsorption of water in the loop of henle accomplished by?
Action of vasopressin on the distal tubule and collecting duct
What is mOsm when entering the medulla before the loop of henle?
300 (equal to location in medulla)
What is mOsm after the loop of henle/first water absorption?
600 (equal to location in medulla)
What is mOsm after the second water absorption?
900 (equal to location in medulla)
What is mOsm after the third water absorption?
1200 (equal to location in medulla
What is mOsm before first NaCl absorption?
1000
What is mOsm after first NaCl absorption?
700 (medulla at 900)
What is mOsm after second NaCl absorption?
400 (medulla at 6000
What is mOsm after third NaCl absoprtion/when leaving the medulla)?
100 (cortex at 300)
What is mOsm when entering the medulla in the distal tubule?
100 continuously as the tubule descends
Is water reabsorbed in the distal portion of the nephron?
No
Filtrate in the proximal tubule is ______ with the surrounding cortex region.
isotonic
The descending limb of the loop of henle is _______ to water.
permeable
Describe water permeability in the hairpin and thin ascending limb of the loop of henle.
Low water permeability but permeable to sodium due to leak channels. Sodium leaves lumen into medulla tissues
Describe solute transport and water permeability in the thick ascending limb of the loop of henle.
Sodium and chlorine actively transported out of the lumen, impermeable to water. Sodium pumped out, water stays in.
The medulla interstitial fluid becomes __________ and the exiting loop filtrate is ______ as it enters the distal tubule and collecting duct.
osmoconcentrated, dilute
Why is osmoconcentration achieved in the loop of henle?
The close proximity and crosscurrent flow of tubular filtrate between the descending and ascending limbs
How is NaCl reabsorbed from the thick ascending limb?
Transported out of the lumen by active transport
What is the effect of NaCl reabsorption in the thick ascending limb?
Increased osmolarity of the interstitial fluid of the medulla
The solute concentration of the descending limb _______ as water is attracted to the more concentrated interstitial fluid in the medulla.
increases
How is a vertical osmotic gradient established in the countercurrent system?
Established as countercurrent flow of tubular filtrate continues to deliver more NaCl into the medulla interstitial fluid.
Tubular filtrate exiting the loop and entering the distal tubule is _______.
hypotonic (100 mOsm)
Where does tubular filtrate exiting the loop and entering the distal tubule empty?
The collecting duct
The collecting duct continues through the medulla tissue with ____ solute concentration.
High
What does the solute concentration of the collecting duct cause?
An increase in potential water reabsorption from the duct
What does permeability of the collecting water depend on?
Vasopressin (AVP or antidiuretic hormone, ADH)
What does vasopressin trigger in the collecting duct?
Insertion of aquaporins (AQP-2) into the apical membrane, allowing for water reabsorption. Urine becomes hypertonic
What does binding of vasopressin on receptor sites of a principle cell activate?
The cyclic AMP (cAMP) second-messenger system within the cell
What is the function of cAMP?
Increase the opposite luminal membrane’s permeability to water by promoting the insertion of AQP-2 channels into the membrane.
The luminal membrane is _________ to water in the absence of vasopressin.
impermeable
How does water exit principle cells in the distal tubule?
Through different aquaporins (AQP-3 or AQP-4) permanently positioned at the basolateral border
Water enters the blood when exiting principle cells in the distal tubule. What does this cause?
An increase in blood volume and pressure
What occurs during animal dehydration in the collecting duct?
AVP secretion is increased, and water is reabsorbed from the collecting duct by osmosis through AQP-2 channels.
During animal dehydration, reabsorbed urine from the distal tubule is picked up by ________ ________ and conserved for the body.
Peritubular capillaries
What can concentration of urine exiting the distal tubule reach during dehydration?
1,200 mOsm
When hydrated, animal AVP secretion is ____ and water is not _________.
low, reabsorbed
What can the concentration of urine leaving the distal tubule be as low as?
100 mOsm
During hydration, excess water is ________.
eliminated
Describe water conservation adaptations in water dwelling animals. Provide an example.
Weak osmoconcentrators, primarily cortical nephrons. Lesser ability to establish a strong osmoconcentration in medulla and lesser ability to reabsorb water by osmosis. Ex) beaver
Describe water conservation adaptations in desert-dwelling mammals.
Strong osmoconcentrators with primarily juxtamedullary nephrons. Greater ability to establish strong osmoconcentration and increased potential for water reabsorption. Ex) Kangaroo Rat
What are cortical nephrons?
Nephrons with short loops of henle.
What are juxtamedullary nephrons?
Nephrons with long loops of henle
What are some causes of renal disease?
Cellular damage to the nephron from excessive solutes (diabetes and glucose), toxins such as ethylene glycol (anti-freeze), obstruction of urine flow through nephron that reduces GFR and damages tissues (kidney stones, large prostate)
How does ethylene glycol cause renal damage?
Affects blood pH and destroys the kidney by depositing calcium oxalate crystals in tubules.
What is the bladder lumen wall lined with?
Transitional epithelium (umbrella cells) that cover smooth muscle. Allows for large fluctuations in volume and stretch.
What is the bladder-urethra opening guarded by?
An internal urethral sphincter (smooth muscle) and an external urethral sphincter (skeletal muscle)
What are mechanoreceptors in the bladder wall stimulated by? What does their stimulation cause?
Stretch caused by large urine volume. Activates parasympathetic neurons and bladder wall contracts, pulling the internal urethral sphincter open. Neural signals to the brain stimulate the urge to urinate.
What is micturition?
Urination
How is the external urethral sphincter opened?
Voluntary contraction
What is the major function of reproduction?
Pass on animal genetics and continue species survival
What is the benefit of asexual reproduction?
Fast way to produce offspring and pass on genetics
What is the benefit of sexual reproduction?
Greater genetic variation to overcome environmental change
What is budding or fission?
An animal produces a copy of itself without embryonic development
What is the parthenogenesis?
Egg is essentially self fertilized and develops into an embryo. Ex) komodo dragon
Eggs and sperm are ______ cells.
Haploid
What are germ cells?
Egg and sperm
What is sexual dimorphism?
Differences in appearances, shape, size, behavior, etc. between males and females of a species.
Oviparous
Eggs are laid, fertilized, and eggs develop completely outside the female’s body. Young feed on egg. Most insects, fish, amphibians, some reptiles
Oviviparous
Eggs are fertilized in female but then laid before young hatch. Young feed on egg yolk. Some sharks and reptiles, all birds and monotremes.
Viviparous
Fertilization and development of young within the female’s body to completion or near completion. Young feed on some yolk but then mother’s nutrients through placenta or rudimentary placenta. Most mammals- placental and marsupials
Precocial
Hatchling or newborn needs modest parental care for survival
Altricial
Hatchling or newborn requires considerable parental care for survival
Gonads
The primary reproductive organs, produce germ cells. Males gonads are testes and female are ovaries
How do female birds differ in gonads?
They have one functional ovary (left ovary)
Oocytes
Eggs or ova
Ovaries produce female germs cells through _________.
Oogenesis
What sex steroids do ovaries produce?
Estradiol (E2) and progesterone (P4)
Testers produce sperm through ___________.
Spermatogenesis
What sex steroids are produces by testes?
Testosterone (T), dihydrotestosterone (DHT), and some E2
Reproductive tract
System of ducts and reproductive functions
What is the function of the male reproductive tract?
Sperm maturation and transport
What are the functions of the reproductive tract in females?
Egg transport, fertilization, and embryo and fetal development.
What is the function of accessory sex glands?
Secrete products into ducts that aid in reproductive processes, particularly in males.
Genitalia
The internal and external parts of the reproductive system
Male internal mammalian genitalia.
Testes, epididymis, vas deferens, accessory sex glands
Female internal mammalian genitalia.
Ovaries, fallopian tubes or oviduct, uterus, cervix, vagina
Male external mammalian genitalia.
Penis and scrotum
Female external mammalian genitalia.
Vulva (includes the labia majora/minora, clitoris, and vestibule)
Oogenesis
Development of an oocyte in ovary
Ovulation
Release of mature oocyte for possible fertilization
Pregnancy (gestation)
Development of young inside female
Parturition
Giving birth or laying eggs in some species
Lactation
Nourishing offspring with colostrum and milk
Female reproductive tract in order from ovaries to vagina.
Ovary, oviduct or fallopian tube, uterus, cervix, vagina
Oviduct function
Transport oocyte and sperm, site of fertilization
Uterus function
Protects and nourishes developing young, produces eggshell in birds and reptiles
Cervix
Protective barrier and passageway for sperm and young during birth
Vagina
Organ for copulation and delivery of young
What does uterus type depend on?
Uterine or cervical structure
Bicornuate uterus
Poorly to highly developed uterine horns (mares, cows, bitch, queen, cow)
Simplex uterus
No uterine horns (primates)
Duplex uterus
Two cervixes (marsupials, rabbits)
Clitoris
Arousal tissues in some species (mechanoreceptors)
Left and right labia majora and minora
Protective barriers of the female reproductive tract
Ovaries
Paired organs that contain eggs. Site of oogenesis and female sex steroid production
Ovarian follicles
Structures, sometimes fluid filled, that contain an oocyte and supportive cell. Cells produce estradiol (E2)
Corpus luteum (CL)
Structure that develops after a follicle has ovulated or released an egg. Supportive cells differentiate and produce progesterone (P4).
When does oogenesis and germ cell meiosis in females occur?
During fetal life
Describe oocyte development.
Oocytes arrest development in the first meiotic division as primary oocytes. After puberty, one primary oocyte reaches maturity and is ovulated about once a month until menopause.
Polar body
The cells produced from the primary oocyte that never reach maturity. 3 for each mature oocyte. Degenerate when created.
Atresia
Oocytes dying off after birth
How often does ovulation occur in cows, pigs, humans, and mice?
Every 21 days in cows and pigs, every 28 days in humans, every 4 days in mice.
What are ovarian follicle growth and ovulation controlled by?
GnRh produced in the hypothalamus, LH and FSH produced by the anterior pituitary.
What is puberty in males and females largely influenced by?
Nutrition, growth, and age
What are other factors can control puberty? What do these factors activate?
Photoperiod or season, presence of opposite sex/pheromones, social interactions, genetics, and stress. Activate neurons that control GnRH neurons in the hypothalamus, increasing GnRH secretion into HH blood portal system.
What cells increase FSH and LH secretion in response to GnRH?
Gonadotrope cells
What do FSH and LH promote in females?
FSH promotes follicle growth and LH promotes follicle growth and ovulation in females
Where are oocytes arrested in meiosis stored?
In a primordial follicle
An oocyte is selected to continue development and the follicle and oocyte grow in response to ____.
FSH
Fluid accumulates in the selected follicle and it forms an _______. __ and ___ stimulate the growing follicle to produce _______.
Antrum (Antral follicle), LH and FSH, estradiol
What happens during ovulation?
The follicle ruptures and the oocyte is released into the oviduct. The follicle tissue then forms a corpus luteum. LH stimulates the CL to produce progesterone.
At puberty, follicle growth is ________. After puberty, ovulation of a large antral follicle and formation of the CL once occurs ____ a cycle. The next ovulation usually occurs from ________.
continuous, once, the other ovary
What is different about ovulation in multiparous species?
They will ovulate multiple large follicles from both ovaries.
What is ovulation triggered by?
A large concentration of follicle estradiol that stimulates large concentrations, or surges, of GnRH and LH.
In some animals, the act of _________ triggers surges of LH and ovulation. What animals?
copulation/ mating. camels, mice, cats, and rabbits
What are the two types of reproductive cycles in mammals?
Estrous and menstrual cycles
Follicular phase
A large antral follicle grows, produces E3, stimulates a surge of GnRH and LH, and ovulates.
Luteal phase
Always follows the follicular phase. The ovulated follicle tissue becomes a CL and produces P4 in response to low concentrations of LH. Longest phase
What does P4 do if fertilization occurs?
Supports development of young internally and mammary gland growth
Estrous cycle
Reproductive cycle in non-primate mammals
What is day 0 of estrous designated by?
Signs of female sexual receptivity (estrus or heat). Ovulation occurs during estrus.
Polyestrus
Animals that have repeated cycles throughout the year. Includes most mammals.
Seasonal polyestrus
Repeated cycles during fall or spring. Includes sheep and horses
Monoestrus
One or two cycles a year. Includes dogs
Anestrus
Animal that has stopped cycling. Can be caused by pregnancy, lactation, disease, age, or nutritional deficiency.
Menstrual cycle
Essentially the same process as estrous with these exceptions: Uterine tissue is sluffed off during cycle resulting in menstruation, some do not display sexual receptivity at time of ovulation, day ) designated by menstruation and not ovulation.
Arcuate nucleus (ARC) and preoptic area (POA)
Hypothalamic nuclei in males and females that contain gonadotropin releasing hormone (GnRH) neurons.
What are the functions of ARC and POA?
In males, they secrete GnRH into HH blood portal system in tonic (continuous, low amplitude) pulses. In females, ARC neurons secrete GnRH into blood portal system in tonic, low amplitude pulses but the POA can release surge pulses of GnRH and is called the surge center.
What happens during the follicular phase?
Tonic release of GnRH stimulates FSH and LH secretion from the anterior pituitary and FSH stimulates a group of follicles to grow (recruitment). The FSH and LH stimulate the large follicle to produce large concentrations of E2, creating positive feedback on the POA.
What does positive feedback on the POA cause?
Surges of GnRH, causing surges of LH, ultimately leading to ovulation.
What happens during the follicular phase in species that ovulate 1-2 oocytes?
The smaller antral follicles die but one continues to grow and ovulate (dominant follicle)
LH stimulates follicle _____ cells to produce _________.
theca, testosterone
FSH stimulates follicle _______ cells to convert __ to __.
granulosa, T2, E2
What are the physical affects of E2?
Effects female brain, stimulating sexual receptivity in some animals. Causes production of vaginal/cervical mucus for copulation and sperm transport. Stimulates smooth muscle contraction of reproductive tract for oocyte/sperm transport.
Reproductive tract physiological effects of E2.
Increased blood flor, increased edema of tissues, increased secretion of mucous, increased leukocytes, increased smooth muscle motility, increased growth of uterine glands.
Lordosis
Curvature of spine into the mating posture
Signs of estrus
Increased animal activity and standing to be mounted, increased reproductive tract blood flow and swelling. Soliciting, jumping, head-to-flank, standing heat
What happens during the luteal phase?
After ovulation, follicle theca and granulosa cells differentiate into luteal cells. Theca cells become small luteal cells and granulosa cells become large luteal cells. Blood vessels grow within the tissue and the corpus luteum forms. Tonic release of LH stimulates luteal cells in the CL to produce progesterone.
What does progesterone prepare the female reproductive tract and physiology for?
Pregnancy
What type of feedback does P4 have on the surge center?
Negative feedback. Ovulation does not occur during the luteal phase.
Physiological affects of P4
Prepare female for gestation and internal development of young. Stimulates uterine glands to secret substances that support the embryo. Cervix constricts and secretes thick mucus to act as a barrier. Stimulates mammary gland growth. Inhibits uterine smooth muscle contractions. Inhibits negative immune responses towards embryo.
How is progesterone used in animal agriculture?
Used to hold the female in non-ovulatory state until ovulation and insemination is desired. Controlled internal drug release. Also used in birth control to inhibit ovulation and reduce sperm transport through cervix in humans.
What happens if pregnancy does not occur?
The uterus or ovary, depending on the species, will produce a luteolytic factor that causes the CL to degrade and disappear from the ovary (luteolysis). Progesterone then decreases which allows the female to begin a new follicular phase and ovulate for another attempt at conception.
What is the luteolytic factor?
Prostaglandin F2 alpha (PGF2a)
What happens without signals from the embryo?
The CL degrades (luteolysis) and a new cycle begins.
What is menstruation in primates caused by?
A reduction in P4 following luteolysis.
What promotes endometrial cell proliferation in primates?
Follicle E2
What does CL P4 promote in the luteal phase?
Endometrial cell maintenance and secretion
What does a decrease in P4 lead to?
Vasoconstriction of endometrial arteries. Reduced blood flow results in tissue necrosis, sluffing, and menstruation.
Where does fertilization occur?
The oviduct
What happens on the zona pellucida (outer layer) of oocyte?
When a sperm cell meets the oocyte, proteins on the sperm cell membrane bind to receptors. The sperm enters the oocyte cytoplasm and outer layer becomes impermeable to additional sperm. Within an hour, sperm and egg nuclei (pro-nuclei) fuse to form a nucleus and zygote.
Conceptus
Refers to embryo and early placental tissue
What are the stages of blastula formation?
Zygote, 2-cell stage, 4-cell stage, morula, blastula
The inner cell mass of the blastula becomes the _______ and the trophectoderm becomes the _________.
fetus, placenta
Where does the early conceptus migrate?
Into the uterus to hatch from the zona pellucida
___________ ___________ between the conceptus and endometrium is important to maintain pregnancy.
Paracrine communication
What does the cow conceptus secrete?
Interferon tau (IFNT) to signal its presence and disrupt luteolysis
Maternal recognition of pregnancy
The conceptus of many species releases a conceptus factor that disrupts luteolysis
What is the early conceptus in cattle, sheep, and pigs?
An elongated structure
What type of placenta do cattle have?
Cotyledonary placenta
What structures make up the placentome and what are their appearance?
Caruncles (light pink) and cotyledons (dark red)
What is the male reproductive tract from sperm production to ejaculation?
Testis seminiferous tubules, efferent ducts, epididymis, vas deferens (ductus deferens), ejaculatory duct, urethra through penis
Where is sperm produced?
In the testis seminiferous tubules
What happens in the efferent ducts?
Sperm is transported from the seminiferous tubules to epididymis
What is the function of the epididymis?
Store and mature sperm
What is the function of the vas deferens (ductus deferens)?
Sperm is transported to the ejaculatory duct
What are the male accessory sex glands?
Seminal vesicles, prostate, and bulbourethral glands
What do male accessory sex glands produce?
Seminal fluid
Semen is __% sperm and __% seminal fluid
10, 90
What are the three major functions of male accessory sex glands?
Increase pH in male urethra and female reproductive tract for sperm health, support sperm with important nutrients, produce a mating plug in some species.
Penis
Copulatory organ and passageway for urine and semen
Scrotum
External sax that contains testes in some mammals. Important for regulating testes temperature.
What happens to testes during fetal development?
The testes descend through the inguinal canal, an opening in the abdominal wall, into the scrotum
Spermatogenesis in mammals typically requires a temperature that is _________ body temperature.
less than
What structures help to regulate temperature in testes in animals with a scrotum?
The pampiniform plexus, cremaster muscle, and tunica dartos
Cryptorchidism?
A condition in which the testes do not descend through the inguinal canal, resulting in abnormal spermatogenesis.
What temperature in celsius is blood in the body and blood that goes to the testis?
39 in body and 33 to testis
Human ejaculation is usually _ mL and contains ___ to ___ million sperm cells. Pig ejaculation is about ___ mL and contains __ to __ billion sperm cells.
2, 150 to 600, 250, 20 to 60
How long does it take to produce a sperm cell?
70 days
How is sperm developed along the seminiferous tubule?
In waves. Different developmental stages at different points along the tubule for continuous supply of mature sperm.
Describe spermatogenesis in males.
At puberty in males, spermatogenesis and germ cell meiosis is continuous. Sperm are produced in millions or billions throughout life. Spermatogonium, a type of stem cell, continuously divides to make primary spermatocytes. During meiosis, a single primary spermatocyte makes four spermatids that become spermatozoa.
Spermatogonia are _________. Primary spermatocytes are _________.
diploid x2
Acrosome
The head of sperm
Midpiece
Location of mitochondria
Tail
Location of microtubules
What can male fertility be assessed on?
Sperm morphology and motility
Sperm head morphology varies with _______.
species
What doe LH and FSH stimulate in males?
Male sex steroid production and spermatogenesis
How often to pulses of GnRH, LH, and FSH occur in males after puberty?
4 to 8 times a day
LH stimulates _______ cells to make __________ in males.
leydig, testosterone (T)
FSH stimulates _________ cells to make __________________ and _______ from the leydig cell testosterone.
sertoli, dihydrotestosterone (DHT), estradiol
_ and ___ are essential for spermatogenesis (mitosis of spermatogonia, meiosis or primary spermatocytes)
T, DHT
What happens before birth driving formation of the male internal and external genitalia and decent of testes into the scrotum?
Some T and DHT is made
What happens during after and after puberty in males?
Growth, maturation, and maintenance of the male reproductive system.
What are the affects of male androgens?
Promotes libido. Male pattern of hair, antler, or feather growth. Deepening of the voice (growth of larynx and vocal cords). Muscle growth (myosin/actin protein synthesis). Bone growth at puberty. Aggressive behavior and seeking of females in some species.
What happens when too much T, DHT, and E2 is produced?
Negative feedback reduces GnRH and LH/FSH secretion
What helps to maintain testicular tissue growth an size?
LH, FSH, and E2
What does doping with T cause?
Negative feedback on LH and FSH, resulting in reduced testicular size
Male seasonal breeders
Photoperiod affects melatonin secretion from the epiphysis which affects GnRH secretion. Sperm production will increase along with testicular weight, T synthesis, and reproductive behavior.
Corpus Cavernosum
Penile tissue that fills with blood from deep artery during erection. Veins constricted due to swelling. Pressure builds and tissue swells
Corpus spongiosum
Penile tissue around urethra that fills with blood but does not apply pressure. Cushions urethra so that it remains open when cavernosum swells. Allows transport of semen through urethra during erection.
What is the pathway of erection.
Stimulation of mechanoreceptors in glans penis, parasympathetic and sympathetic supply to penile arterioles, penile arterioles dilate, erection, compressed veins, sustained erection. Sympathetic supply to bulbourethral glands and urethral glands (prostate) simultaneously, mucus production, lubrication
What happens during arrousal?
The penis arterioles dilate, the tissue fills with blood and the veins are compressed, reducing blood flow. Sympathetic activity causes sequential contraction of smooth muscles in the prostate, reproductive ducts, and seminal vesicle to deliver semen to the urethra. Filling of urethra with semen triggers neurons to activate skeletal muscles at the base of penis. Contraction increases pressure within penis, expelling semen.
What does orgasm involve?
Increased pelvic muscle contraction, heart rate, and respiration. Release of oxytocin in CNS provides feeling of please in some mammals
