Unit 4 Test (mastering and study questions

Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (the RAAS) work together in maintaining osmoregulatory homeostasis through which of the following ways?

ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the RAAS maintains the osmolarity of the blood by stimulating Na+ and water reabsorption.

The urethra is identified by the letter _____.

D

Name and briefly describe the events of the three main stages of labor.

Dilation- effacement and dilation of cervix. Expulsion- delivery of infant. Placental- delivery of placenta and embryonic membranes

Name and describe the role of the major hormones and local regulators that stimulate labor contractions. What makes this a positive feedback loop?

Estradiol activates the oxytocin receptors in the uterus. Oxytocin- stimulates uterus to contract and stimulates placenta to make prostaglandins which stimulate more uterus contractions. This is a positive feedback loop because it will keep going until the baby is born and the uterus will stop contracting.

Name and briefly describe the four phases of the human sexual response. Which phase(s) are stimulated by parasympathetic / sympathetic innervation?

Excitement- prepares penis and vagina for intercourse. Stimulation of genitalia- maintains plateau phase and prepares vagina for receipt of sperm. Orgasm- rhythmic contractions of reproductive structures. Resolution- organs return to normal state and relax.

Where, in the human reproductive tract, does fertilization typically take place? Where does the early embryo implant?

Fertilization takes place in the oviduct and the embryo implants in the uterus

What is it that metanephridia do that provides for greater control of what is excreted and what is retained in comparison to protonephridia?

Metanephridia are associated with individual segments of earthworms, and are compartments separated by septa. Hydrostatic Pressure drives the fluid into tubule system. There is an external opening for excretion, a pair of open ended tubules in each segment that collects coelomic fluid.

List the three most common mechanisms or categories for contraception, and provide examples of each?

Preventing release of egg and sperm (vasectomy/ birth control pill), keeping sperm and egg apart (abstinence, condom), and preventing implantation of embryo (IUD, morning after pill)

What is the most common, preventable cause of infertility?

STD's are the most preventable cause of infertility.

What ovarian event triggers menstruation in a non-pregnant woman, and what prevents the shedding of the endometrium in early pregnancy?

The deterioration of the corpus luteum → drop in progesterone and estradiol → shedding of the endometrium. CL is not rescued by hCG

How does the concentration and composition of initial filtrate compare to what leaves the proximal tubule?

The filtrate is more concentrated when leaving the proximal tubule because water and salts are reabsorbed.

Explain the difference between the glomerulus and Bowman's capsule. What key event in excretion occurs here?

The glomerulus is inside the bowman's capsule. The glomerulus is the capillary bed inside the bowman's capsule. Filtration happens here by hydrostatic pressure

How does the most common form of oral birth control (i.e., the pill) work?

The pill works by making the uterus uninhabitable

A potassium ion gradient is set up in insect Malpighian tubules through an active transport process. As a result, potassium concentration is higher in the lumen of the tubules than in hemolymph. How would the potassium gradient affect water movement?

There would be a net movement of water into the lumen of the tubules.

Since water loss is the key osmoregulatory challenge facing terrestrial animals, why do they excrete urine?

To excrete nitrogenous waste which is toxic

What is the general trend with regard to kidney anatomy and the differences among mammalian species' abilities to produce hyperosmotic urine?

To produce more hyperosmotic urine, mammalian species have many juxtamedullary nephrons and longer loops of henle.

Glucose is removed from filtrate by _____.

active transport

Which of these is reabsorbed from filtrate? sodium chloride glucose water amino acids all of these

all of these

Freshwater fish excrete nitrogenous wastes as _____.

ammonia

Antidiuretic hormone (ADH) makes the _____ permeable to water.

collecting duct

The outer part of the kidney is the _____.

cortex

The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation in terrestrial vertebrates because _____.

differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient

The high osmolarity of the renal medulla is maintained by all of the following EXCEPT _____.

diffusion of salt from the descending limb of the loop of Henle

To maintain homeostasis freshwater fish must _____.

excrete large quantities of water

The movement of substances out of the glomerulus and into Bowman's capsule is referred to as _____.

filtration

Which process in the nephron is LEAST selective?

filtration

After drinking alcoholic beverages, increased urine excretion is the result of _____.

inhibited secretion of antidiuretic hormone (ADH)

The transfer of fluid from the glomerulus to Bowman's capsule _____.

is mainly a consequence of blood pressure in the capillaries of the glomerulus

Ammonia _____.

is soluble in water

Compared to the seawater around them, most marine invertebrates are _____.

isoosmotic

Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more _____.

juxtamedullary nephrons

Urea is produced in the _____.

liver from NH3 and carbon dioxide

Ammonia is likely to be the primary nitrogenous waste in living conditions that include _____.

lots of fresh water flowing across the gills of a fish

Osmoregulation and excretion are _____.

mechanisms that maintain volume and composition of body fluids

The osmoregulatory/excretory system of an earthworm is based on the operation of _____.

metanephridia

As filtrate moves down the loop of Henle, the surrounding interstitial fluid becomes _____ concentrated than the filtrate, so _____ leaves the filtrate.

more ... water

Under the influence of antidiuretic hormone (ADH), _____ is produced.

more concentrated urine

Which of these is the functional unit of a kidney?

nephron

In animals, nitrogenous wastes are produced mostly from the catabolism of _____.

proteins and nucleic acids

The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of _____.

protonephridia

Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____.

reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce

The _____ are the major blood vessels transporting blood to the kidneys.

renal arteries

Urine formed by a kidney collects in the _____ before being drained from the kidney by the _____ and transported to the _____.

renal pelvis ... ureter ...urinary bladder

The movement of substances from the blood into the proximal tubule is known as _____.

secretion

The osmoregulatory process called secretion refers to the _____.

selective elimination of excess ions and toxins from body fluids

Materials are returned to the blood from the filtrate by which of the following processes?

selective reabsorption

Osmoregulatory adjustment via the renin-angiotensin-aldosterone system can be triggered by _____.

severe sweating on a hot day

Which arrow indicates the direction of a gradient of increasing solute concentration in the interstitial fluid surrounding a nephron?

solute concentration increases in interstitial fluid as you go down the nephron

Increased antidiuretic hormone (ADH) secretion is likely after _____.

sweating-induced dehydration increases plasma osmolarity

The force driving simple diffusion is _____, while the energy source for active transport is _____.

the concentration gradient; ATP

An appropriate group of animals to examine to observe a Malpighian tubule would be _____.

the insects

Urea is _____.

the primary nitrogenous waste product of humans

What is the function of the trophoblast in the human embryo

the trophoblast is the outer layer of the blastocyst and it forms the placenta

Within a normally functioning kidney, blood can be found in _____.

the vasa recta

As a result of the non-selectivity of the kidney's filtration of small molecules, _____.

useful substances must be selectively reabsorbed

Describe the various stimuli that result in the secretion of ADH, RAAS, and ANP. What are the sources of the various hormones/enzymes? What are the specific actions of each?

ADH: stimulus- osmoreceptor cells in the hypothalamus monitor blood osmolarity. Increased salt concentration stimulates ADH release from the posterior pituitary. RAAS: the juxtaglomerular apparatus releases the enzyme, renin in response to blood pressure. Renin and ACE catalyze. Angiotensinogen (renin) → angiotensin (ACE at lungs) → angiotensin II. Angiotensin II stimulates thirst, vasoconstriction, secretion of ADH. ANP: corrects if BP is too high. Is produced when cells of atria are stretched Inhibits secretion of renin, aldosterone, and ADH (makes collecting ducts less permeable, more dilute urine). inhibits NaCl reabsorption in collecting ducts. Increases glomerular filtration rate.

What drives the movement of water into the Malpighian tubules of insects? Where are useful solutes and water reabsorbed, and what is the primary form of nitrogenous waste in insects?

Actively pumping salt and nitrogenous waste into the tubules and water will follow. Useful solutes are reabsorbed in the rectum, causing water to follow. The primary form of nitrogenous waste in insects is uric acid.

What are the main habitat requirements for successful external fertilization? How does the energetic investment compare between external and internal fertilization?

Aquatic and moist environment is necessary for external fertilization. The external fertilization uses less energetic investment compared to internal fertilization.

What do experimental observations of Daphnia reproduction tell us about the hypothesized advantages/disadvantages of sexual versus asexual reproduction? Under what conditions is each form of reproduction favored?

Asexual reproduction is favored during unstressful times in the environment (lacking predators). Sexual reproduction is favored in times of stress. This shows that sexual reproduction gives recombination that helps the success of offspring in stressful times.

Why is it that natural selection has favored photoperiod over temperature as the main factor for the timing of reproductive cycles in temperate environments?

Because if temperature is the main factor and you have to reach a temperature threshold and one year may be different and the threshold may not be reached.

Filtrate is formed as fluid is forced through the walls of the glomerulus and, initially, collects in the structure

Bowman's capsule

Name and describe the various forms of asexual reproduction.

Budding- small outgrowth breaking off intentionally. Fission- growth of equal size breaking off intentionally. Fragmentation- event breaks off fragment (not intentional). Parthenogenesis- producing eggs that develop without fertilization.

Briefly define the terms filtration, reabsorption, secretion and excretion as they apply to movement between blood and excretory tubules.

Filtration is filtering body fluids across an epithelium to produce a filtrate in excretory tube. Reabsorption is reclaiming valuable solutes from the filtrate from the excretory tube. Secretion is adding nonessential solutes and wastes to the filtrate from the capillaries to the excretory tube. The final filtrate is excreted from the excretory tubule.

Which trimester is characterized by the development of all the major organs, and which trimester is characterized by the most dramatic increase in size?

First trimester is characterized by the development of all the major organs. Second and third trimester are characterized by dramatic increase in size.

What terms are used to describe an aquatic animal's tolerance or intolerance to varying ranges of solute concentrations in the surrounding water?

Stenohaline- intolerance, euryhaline- tolerance

How do chondrichthyan fish osmoregulate. How do their solute and ion concentrations compare to seawater? What ions or solutes are involved in maintaining solute gradients? How are excess ions of varying types removed from the body?

Hyperosmotic and hypoionic to seawater. NaCl, Mg2+, and SO4 2- are involved in maintaining solute gradients. Salt is gained through the gills by diffusion and through food and water intake. Salt is lost through rectal gland excretions and feces. Mg and SO4 are lost through urine

What word would you use to describe the total solute concentration of the body fluids of most vertebrates in comparison to seawater? To freshwater?

Hypoosmotic to seawater, hyperosmotic to freshwater

Why is the function of protonephridia so much more important in freshwater flatworms in comparison to marine flatworms?

In freshwater flatworms, dilute fluid is excreted functioning in osmoregulation. In marine flatworms, they are isoosmotic so there is no net gain or loss of H2O and the ammonia diffuses out.

How is an estrous cycle different from the ovarian & uterine cycle of humans and other primates

In the estrous cycle, the endometrium is reabsorbed rather than shed. Sexual receptivity is limited to a period called estrus and the frequency and length varies between animals.

How does the collecting duct contribute to the cortex-to-medulla osmotic gradient?

In the inner medulla, the collecting duct becomes permeable to urea. Some urea diffuses out of the duct and into the interstitial fluid, which contributes to the high osmolarity in the inner medulla.

Name and briefly describe the functions of the major reproductive organs and structures of human males and females. Identify these structures/organs as primary sex organs, reproductive tract, or accessory organs.

Males primary: testis- produce androgens and sperm Males secondary: epididymis- sperm mature and are stored here, vas deferens- duct sperm travel through, urethra- duct it travels through during ejaculation Male accessory: seminal vesicle (behind bladder)- contribute to 60% of volume of semen, prostate gland- where vas deferens and seminal vesicle meet, bulbourethral gland- produce lubrication for intercourse Female primary: ovaries- oocytes (egg cells) mature in follicles Female secondary: oviduct (fallopian tube) - transports the egg to the uterus... fertilization happens here, uterus- where fertilized egg implants, cervix- tissue around opening between uterus and vagina, vagina- where sperm enters Female accessory: endometrium- inner lining of uterus, uterine wall-, follicles- functional unit of the ovary.

What is the functional significance or role of the ammonia (NH3) produced by epithelial cells in the proximal tubule?

NH3 is released to bind to H+ and create NH4 as a pH buffer.

Describe the processes of active salt excretion at the cellular level. What transporters and/or channels are involved? What type of gradients are established to facilitate movement across the cell membrane? What ions are moving into or out of the cell?

Na/K pump creates a gradient that lets sodium in. Na/K/2Cl cotransporter moves Cl into the cell- building up the concentration of K and Cl ions. Cl diffuses out of the cell on the opposite side and Na follows because of electrochemical gradient. Electric gradient favors the diffusion of Na.

What is the major difference between males and females in terms of HPG axis regulation - particularly with regard to feedback mechanisms?

Negative feedback mechanism in males, positive feedback in females

Briefly describe some of the mechanisms employed by non-mammalian terrestrial vertebrates that enable them to conserve water while excreting nitrogenous wastes.

Non-mammalian terrestrial vertebrates reabsorb salt in their distal tubules and excrete large volumes of dilute urine and lose ammonia via diffusion. Amphibians act similarly in the water but on land the epithelial lining of the urinary bladder can reabsorb water.

How does the permeability of the loop of Henle vary along its length? How does the osmolarity of the filtrate leaving the loop of Henle compare to initial filtrate?

On the descending limb of the loop of henle, it is permeable to water for the reabsorption of water by aquaporins. On the ascending limb it is permeable to salt for salt reabsorption. This causes the filtrate to be less concentrated by normal body fluids.

Besides germ cells, what are the other important cell types in testes and ovaries, and what are their major functions in the context of reproduction?

Oocytes- egg cells in ovary, follicular cells- produce and secrete estradiol/ incorporate vitellogenin into oocyte/ form corpus luteum. Leydig cells ( interstitial cells)- produce androgens (testosterone). Sertoli cells ( nurse cells)- nourish developing sperm/ sequester testosterone/ secrete inhibin .

How does osmolarity differ from molarity? How will the osmolarity of two solutions separated by a water-permeable membrane affect the movement of water across the membrane?

Osmolarity is the total concentration of all solutes in a solution. Molarity is moles of solute per liter of solution. A solution with the higher osmolarity will flow to across to an area of low concentration.

What are the respective roles of oxytocin and prolactin in breastfeeding?

Prolactin- stimulates milk production and may inhibit ovulation. Oxytocin stimulates milk release and suckling encourages oxytocin release

Why would it be particularly advantageous or necessary for birds to produce uric acid as their principle nitrogenous waste in the same environment in which mammals produce urea?

Reproductive strategy: if youre encased in impermeable egg, you are stuck with uric acid as only option bc it is the least toxic

Tissues of sharks are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. What can you infer about the movement of sodium and chloride in these animals?

Sodium and chloride will diffuse into shark gills from seawater down their concentration gradient.

Within what structures of testes and ovaries, do sperm and oocytes mature, respectively?

Sperm mature in the epididymis. Oocytes mature in the follicle.

Outline the major stages of spermatogenesis and oogenesis, with an emphasis on what form or stage of cell division is occurring at each stage.

Spermatogenesis: 1 spermatocyte → 2 secondary spermatocytes → 4 spermatids → 4 sperm cells (meiosis) Oogenesis: 1 primary oocyte (mitosis) → 1 polar body and 1 secondary oocyte → meiosis up to metaphase I → fertilization → finish meiosis → polar body and fertilized egg.

In what type of environment would you expect to find animals that exhibit anhydrobiosis?

Temporary water (puddle from rain water)

What is the major event that marks the transition from the follicular phase to the luteal phase of the ovarian cycle? What is the major change in hormone secretion that follows this event, and what is the source?

The LH surge marks the transition from the follicular phase to the luteal phase of the ovarian cycle which causes ovulation. This causes the follicular tissue to transform into corpus luteum and the CL secretes progesterone and estradiol.

Briefly explain the function of chorionic villi in the placenta?

The chorionic villi in placenta prevent direct mixing of blood between the embryo and the mother. Diffusion happens across the chorionic villi

Explain the relationship between the ability to produce urine that is hyperosmotic to most body fluids and the orientation of the collecting ducts in the kidneys.

The collecting duct runs from the cortex to the medulla, The osmolarity gradient of the collecting duct causes the filtrate to become increasingly concentrated as it loses more and more water to the hyperosmotic interstitial fluid of the inner medulla.

How does the composition of initial filtrate vary from the composition of blood?

The composition of initial filtrate is similar to blood except there is no blood cells or large proteins.

Which of the following statements is true? The kidneys regulate water and blood glucose in terrestrial vertebrates. The kidneys are paired organs that remove nitrogenous wastes from the urine. The kidneys are paired organs that regulate water and electrolyte balance in terrestrial vertebrates. Most humans have one kidney, which regulates water and electrolyte balance, removes nitrogenous wastes from the blood, and eliminates the wastes in the urine.

The kidneys are paired organs that regulate water and electrolyte balance in terrestrial vertebrates.

The excretion of salt across gill epithelia and salt glands might be described as "indirect active transport". Why?

The sodium potassium pump uses ATP to create an electrochemical gradient that allows everything else to occur via facilitated diffusion

Describe an example of a threat that climate change might impose of the successful timing of reproductive cycles?

The temperature change cues some plants to develop toxic characteristics to avoid being eaten. As the temperature raises, the plants may be cued to do this earlier before they can feed animals that are migrating such as caribou.

Which male and female structures are considered homologous, and which structures that are similar in function have separate embryonic origins?

The testes and ovaries are homologous because they come from the same structure. The tissues in structures are also homologous such as the clitoris and labia to the penis and scrotum. The mullerian and wolffian structures are not homologous but have similar functions.

What the basic energetic trade offs involved parental investment in reproduction?

There are fewer gametes required, which is less of an energetic cost but the parental investment is an energetic cost.

What are the tradeoffs associated with the production of ammonia, urea, and uric acid as nitrogenous waste products?

Water balance- most water loss with ammonia, least with uric acid. Toxicity- ammonia is most toxic, uric acid is least toxic. Energy cost- takes ATP to transfer ammonia to urea and uric acid, ammonia has least energetic cost but is most toxic. Reproductive strategy- where can waste go in embryo- uric acid buildup in encased eggs, ammonia can diffuse out of some eggs.

What is the endocrine mechanism that leads to the LH surge?

When estrogen reaches certain threshold, LH surges in positive feedback mechanism

Among sequential hermaphrodites, what is the presumed advantage of protandry?

When you are small, you make the small gametes first (sperm). When you are large, you make the large gametes later in life (eggs). You use less energy when you are small so you can grow and invest more when you are larger.

A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that _____.

they operate an extensive set of active-transport ion pumps

The most abundant solute in urine is _____.

urea (and other nitrogenous wastes)

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that _____.

urea is less toxic than ammonia