Adv Phys Exam III

ion and water balance

• osmotic homeostasis

• ionic homeostasis

• removal of nitrogen

• regulators vs conformers

  • iono, osmo

  • more mechanisms = slower rate of change for conformers (bc more layers between inside and outside)

• must balance osmotically!!

  • best option is regulation of ions and osmolarity

ion and water balance 2

• environments

  • air outside, water inside humans, body slowing rate of water loss

• ingested materials

• smaller slope = regulator (internal vs external change is not as drastic)

• steeper slope = conformer (more drastic change as they change with envmnt)

solutes

• perturbing

  • solute results in large change in protein folding/function

• compatible

  • solute does not effect protein folding/function

• counteracting

  • solutes interact with each other and balance each other out or act more like a compatible solute

extracellular solutes

• regulators have differences in their iono and osmo concentrations

regulation of cell volume

• water follows osmotic gradient

  • when ions are pumped into a cell, water follows and causes the cell to swell

  • pumping ions out causes water to follow and shrink the cell

• maintain concentrations to regulate water movement

• when ions come in from the environment/food and the cell swells with water, the cell responds by pumping ions out and preventing the swelling

systems to regulate osmotic and ionic balance

organs affecting salt balance

• exchange with environment

  • gills (gas and salt exchange, can also respond)

  • intestines/GI

  • integument (skin)

• responding to changes from exchange

  • kidneys (change urine on a regular basis)

  • salt gland (concentrate salts and get them out)

  • rectal gland (remove salts from body)

epithelial tissue

• different transporters/channels on luminal and basolateral surfaces

  • ion channels, aquaporins, active (primary/secondary)

• tight junctions

• have large numbers of mitochondria

• diverse cell types

integument/skin

• regulate aquaporins

  • less aquaporins = less water movement (good for dry environment animals)

• hydrophobic substances

  • mucous, lipid secretions

• cuticle

  • acts as a seal

• stratum corneum

• calluses

fish gills

• pavement cells (PNA^-)

  • import Na⁺

• chloride cells (PNA⁺)

  • import Cl^-

[direction of channels depends on external environmet]

fish gills (10-12)

when salmon is in freshwater, it pumps less sodium out because less is coming in (more NKCC). in seawater, more salt is coming in so more needs to be pumped out (more Na/K ATPase)

salt glands - reptiles/birds

• environment

  • salty environments, around the sea or other places where excess salt needs to be removed from the body

• secretory tubules dump salt

  • really salty fluid leaves first, blood will continually pump salt into the lumen, and lumen pumps salt the other way so the smaller gradient can be maintained without having to use as much energy to pump things farther (like if you had a large gradient)

• countercurrent flow

  • maintains small gradients throughout the vessels so there is constant exchange

rectal gland - elasmobranchs

• salt excretion

• basolateral side invaginated (SA)

• Na⁺, Cl^- move to lumen of gland

kidney - vertebrates

kidney

• ions

• osmolarity

• blood pressure

• pH

• excretion (removal of anything from the body)

• hormone production

mammalian kidney

• nephron (work force of the kidney)

• filtration

  • from blood to nephron using bulk flow

• reabsorption

  • nephron to blood by selective transport

• secretion

  • from blood to nephron by selective transport

• excretion

  • leaving body (E = +F - R + S)

[anything in blood is staying inside the organism, anything in the nephron will eventually go into the urine and leave the body]

mammalian kidney 2

Filtration

• glomerulus (1)

  • capillary bed

• bowman’s capsule (2)

  • around capillary

Reabsorption

• proximal tubule (3)

  • majority of reabsorption

• loop of Henle (4)

  • sets up gradients to concentrate

• distal tubule (5)

  • majority secretion (secretion so far down the tube stops “waste” from being reabsorbed further down the nephron)

• collecting duct (6)

  • top has majority secretion

[“waste” is a broad category, meaning toxins like urea, foreign substances, or things we have in excess (excess sodium, etc)]

filtration

• bulk flow process

• blood to nephron

  • 20% of volume filtered out

• blood pressure

• interstitial pressure (BCapsule)

  • fluid already in Bowman’s Capsule pushes back against the flow (a little bit)

• oncotic pressure of blood

• Filtration Pressure = P_GC - P_BC - π_GC

[if all fluid is lost, cells shrink and form a clot]

[changing blood pressure, arteriole pressure, capillary pressure, etc. will change filtration pressure]

filtration 10.22

• podocytes wrap around capillary and change how much surface area is exposed for filtration (less SA → less filtration)

• kidneys need higher filtration, so glomerular filter is fenestrated (most can get out, but not big things like blood cells and proteins)

reabsorption

• selective process - nephron to blood

  • mediated transport, diffusion → lipid soluble + water

• 99% can be reabsorbed (but more filtration = more excretion)

  • toxins may be secreted before the distal tubule because they cannot be reabsorbed, only excess can be reabsorbed, which is why it needs to be secreted later

  • distal can also reabsorb any extra things needed (like fine-tuning after typical needs from the proximal tubule have been absorbed)

renal threshold

• when mediated transporters become saturated (no more binding spots), reabsorption threshold is reached

• filtrate above reabsorption threshold goes into urine

secretion and excretion

• selective process → using transporters, can saturate (reach a max)

• blood to nephron → leaving the body via urine

• removal of excess or wastes →

• filtration - reabsorption + secretion

secretion, excretion, pH

• pH regulated by gas exchange and osmotic balance systems

• CO₂ + H₂O ^←→ H₂CO₃ ^←→ H⁺ + HCO₃^-

  • CO₂ produced during metabolism, increase by tissues, decreased in lungs because of exhalation/removal of CO₂ to envnmnt

  • bicarbonate more soluble in blood

  • renal system works with the back half of the system

regulation of ventilation

• respiratory general pattern generator

  • chemosensory input (CO₂, pH, O₂)

  • mechanoreceptors

    • Hering-Breuer reflex (limits lung expansion)

  • voluntary control

  • emotions

carbon dioxide in the blood

• dissolved (small amount ~7%)

• carbaminohemoglobin (when CO₂ is bound to hemoglobin) (~25%)

• Bicarbonate (~70%) (buffering system in EXC fluid)

• H₂O + CO₂ ←→ H⁺ + HCO₃^-

  • deoxygenated blood released O₂, bound CO₂

  • oxygenated blood released CO₂, bound O₂

carbon dioxide in the blood

• Bohr Effect (↓ affinity for O₂)

  • increase in H⁺ binding to Hb releases more O₂

• Haldane effect (↓ affinity for CO₂ and H⁺)

  • oxygenated blood releases CO₂ and H⁺

• Chloride Shift

  • when tissue cell is pumping bicarbonate out, it exchanges it for chloride

  • bicarbonate put back into lungs, chloride is removed

[more CO₂ in tissues]

oxygen in blood/lymph

• oxygen equilibrium/dissociation curve

• saturation

  • bound/available x 100%

oxygen in blood

• shifts in dissociation curve

  • type of binding protein (exercise = more CO₂)

  • pH (low pH = low affinity for O₂)

  • CO₂ (more = low affinity for O₂)

  • temp (higher = low affinity for O₂)

  • DPG ( higher = low affinity for O₂)

    • released by RBCs during hypoxia

oxygen in blood 11.34

oxygen in blood 11.37

regulation of ventilation

modification of urine

• must filter fluid before modifying

• glomerular filtration rate

  • affected by pressures

  • affected by surface area available

  • adjust urine using reabsorption (nephron to blood) and secretion (blood to nephron)

modification of urine 2

GFR (↑filtration rate → faster flow, less time for reabsorption)

• myogenic regulation (smooth muscle contracts when stretched → limits pressure in capillaries)

  • muscle (myo) creation (genic)

• tubuloglomerular feedback (compares blood to nephron on the way to urine, ↑ or ↓ GFR)

  • distal tubule → glomerulus

• mesangial control

  • changes surface area, potocytes

• pressure natriuresis

  • more solutes in blood = more water in blood, increases blood volume and pressure (increases filtration rates, decreases sodium reabsorption)

[higher filtration rates lead to more loss, because time for reabsorption is decreased]

modification of urine 3

• clearance = basically measures the rate at which a substance is '“cleared” from the blood

• GFR = C

  • filtration (freely filtered)

  • no reabsorption

  • no secretion

• C = (U_xV)/P_x

  • v = vol of urine, u = urine conc, p = plasma conc

  • U_xV = amount of substance in urine

  • amount in urine / conc in plasma

[inulin meets the qualifications for C = GFR, filtered only and never reabsorbed]

[if clearance of X (C_x) is greater than clearance of inulin (C_i), the only way to remove more X from the blood is by secretion] [if C_x < C_i, reabsorption is needed to put more X back in the blood]

modification of urine 4

• concentrating urine

  • reabsorption = N → B

  • secretion = B → N

• loop of Henle (length)

• countercurrent multiplier system

  • helps maintain a small but constant gradient

  • pick up little things when we really need them

modification of urine 5

• vasopressin/ADH (anti diuretic hormone)

  • ↑ reabsorption of water

  • inserts aquaporins in the collecting duct (very few on it before this)

• adlosterone

  • renin → angiotensin (constrict vessels, ↑bp) → aldosterone

    • renin released by kidneys due to ↓ blood pressure, helps ↑bp

  • ↑ reabsorption of sodium (water follow sodium), ↑ secretion of potassium

  • inserts sodium-potassium ATPase pump to use for this

• atrial natriuretic peptide

  • ↓ reabsorption of sodium/natrium (water follows), ↓ secretion of potassium

  • ↓ ADH and aldosterone release

  • ↑ GFR

modification of urine 6

variety of genes = Na/K channels, Na/K ATPase

dehydration

• ↓ blood volume, ↓ blood pressure, ↑ osmolarity

  • sweating in heat, losing more water than salt

  • vomiting, losing water

  • want an increased ADH to reabsorb water

  • low blood vol says increase aldosterone, high salt says do not increase aldosterone (mixed signals, need a tiebreaker so body prioritizes osmolarity)(if osmolarity gets off, all systems are affected because cells shrink or lyse)

    • aldosterone will be slightly inhibited

vertebrate kidneys

• loops of Henle helps to create concentrated urine, animals that live in water do not need one

• reptiles don’t have one because they have salt glands and tough/dry skin that minimizes water loss (better barriers)

invertebrate kidneys

• direct excretion

• protonephridia

• metanephridia

insect kidneys

malphagian tubules

• stellate cell

• principal cell

hormones

• cation transport

• myokinins

• fluid

nitrogen wastes

• ammonia

  • ammoniotelic

  • least energy, need lots of water to wash it out

  • in fish

• urea

  • ureotelic

  • more energy to assemble bonds, less toxic, middle ground

  • in mammals

• uric acid

  • uricotelic

  • more energy to assemble bonds, less toxic, gets rid of the most nitrogen

  • in birds

nitrogen waste pathway

• coming from breakdown of proteins/amino acids

  • carnivores have more nitrogenous waste to get rid of (high protein diet)

nitrogen wastes

factors

• diet

• water available

• metabolic costs

digestion

• purpose

• features

• ingesting

  • motility (movement and mechanical digestion) (physical mushed around, broken down into smaller chunks) (regulated by body)

  • secretions (communication and chemical digestion of foods, breaking chemical bonds) (regulated by body)

  • digestion (due to motility and secretions)

  • absorption (done mostly by mediated transport, GI tract has epithelial cells. gradient created to diffuse water [osmosis], nonpolar/small particles use simple diffusion, some transcytosis)

• egestion (excretion, waste removal)

digestion 2

• nutrient groups

• energy groups

• energy needs

  • SDA: how much energy does it actually take to do the metabolism (some bonds easier to break than other, proteins are difficult = more energy to break down, higher SDA)

  • keto diets are heavy in protein, takes more energy to break things down, loss in body weight

ingestion

• accidental/random

  • directing water flow and cells grab things from the environment

ingestion 2

• sense food/prey

  • chemoreceptors

  • electromagnetic receptors

• attract/capture

ingestion 3

• feeding structures

  • structure/function relationships

ingestion - teeth

• canines for carnivores

• molars for herbivores

  • food source and teeth shapes tend to match up (sharp for shredding/tearing, flat for grinding/mashing)

GI tract

• two-way gut

  • simple gut: less surface area, best simple particles and gas/nutrient exchange

  • complex gut: more surface area for exchange, better absorption

GI tract 2

increased surface area

• more places for transporters, channels, enzymes to digest

• mucosal folds in the stomach/intestines

• spiral valves

• villi covered with epithelial cells sealed off by tight junctions

  • enterocytes, forces things to go through the cells instead of around them, covered in microvilli)

GI tract

• one-way gut

  • no mixing, allows for compartmentation

• specialized compartments

  • can hold rocks, bacteria, pH ranges (like stomach being more acidic than the rest of the body)

• length of tract is related to digestibility of food

  • longer intestinal tracts in mammals

  • chickens/birds have a crop that stores little rocks to help crush seeds, because they don’t have teeth

motility

digestion depends on motility and secretion (both regulated by bodies)

• peristalsis

  • wave-like contraction that helps move food in one direction (mouth → anus. in cows: mouth → first stomach → mouth → GI tract)

  • for moving

• segmentation

  • circular muscle contraction (circumference around the muscle), pushes stuff back and forth

  • for mixing (digestive enzymes and food) (helps push stuff along the walls into the center, and things in the center to the walls to increase absorption)

• migrating motor complex

  • clears out GI tract, strong wave-like contractions. clears out non-digestible items

  • cleaning motility

salivary glands

• secrete enzymes → made of proteins, active in specific pH ranges

  • saliva enzymes only active in the neutral pH, not in the stomach. the more you chew your food, the more time enzymes will have to break things down

• soften food → due to water

regulation of gastric secretions

enzymes

• help to chemically digest food

hormones → communication, send signals between GI tract and brain

• gastrin (histamine) - ↑ acid production in stomach

  • produced by stomach

• VIP (vasoactive intestinal peptide)

  • produced by intestine

• somatostatin - ↓ acid production

  • produced by stomach

• GIP (gastric inhibitory peptide) - ↓ acid and motility in stomach, ↑ insulin production

  • produced by intestine

• secretin - ↓ acid production

  • produced by intestine

other → range of functions

• acid (immune and digestion), bicarbonate (neutralize acid released from another area)

stomachs

• crop (birds, collect small stones to grind seed)

• mono-gastric stomach → one compartment

  • rumen (first stomach) used to ferment/break down things, food sent back up to the mouth, then to reticulum (second stomach)

• digastric stomach

• sphincters → bands of smooth muscle separating one area from another along a “tube”

stomach

mucosa layer

• acid

  • denatures proteins and immune protection

  • affects food

• enzymes

  • pepsin(ogen) [proteins], gastric lipase [lipids]

  • affects food

• mucous/bicarbonate

  • protect the stomach wall, bicarbonate neutralizes H ions along the walls so acid is not constantly touching the stomach walls

  • glycoproteins inside sticky mucous to absorb water, bicarbonate mixed in, stays along the stomach walls lining

regulation of intestinal secretions

• CCK (cholecystokinen)

  • release enzyme for fat and protein digestion, bile emulsifies fat (lack of gallbladder makes it harder to digest fat, has to rely on bile from liver)

  • stimulated by fats and proteins

• motilin

  • stimulated by fasting

  • ↑ motility → MMC

• VIP (vasoactive inhibitory peptide) - ↓ acid production and motility

  • produced by intestine, also in stomach

• GIP (gastric inhibitory peptide OR glucose dependent insulinotropic peptide) - ↓ acid and motility in stomach, ↑ insulin production

  • produced by intestine, also in stomach

• secretin - ↓ acid production

  • produced by intestine, also in stomach

stim to be released by acid entering intestine

intestines - small

small intestine is where the majority of motility, secretion, digestion, and absorption happen

• enzymes are made/secreted in inactive/proenzyme form so they don’t being breaking down the cell they’re in

• activated by acid (in stomach) OR enzymes in the intestine (enterokinase and enteropeptidase)

  • these enzymes activate the digestive enzymes

• “pro—” or “—ogen” tells you it’s in inactive form

intestines - absorption

• first real absorption

  • because most of chemical digestion, ↑SA and time

• secretions from liver, pancreas, and gallbladder

  • as well as intestinal wall to a lesser extent

enzymes for digestion

• lipases

  • lipids/fats

• proteases

  • proteins

• peptidases

  • peptides

• amylases

  • carbs

• disaccharidases

  • sugars/carbs

• nucleases

  • DNA/RNA

  • less about energy, more for defense

symbiotic digestion

• enterosymbionts

  • symbiotic organism in GI tract

  • bacteria helping to digest fiber/cellulose

• exosymbionts

  • live outside an organism’s body

• endosymbionts

  • live inside organism’s body

absoprtion

• diffusion

  • small, lipophilic things and water (osmosis)

• mediated transport

  • most ions and nutrients (selective)

  • specificity, affinity, saturation, competiton

• transcytosis

  • larger peptides and some fats

tight junctions between epithelial cells (sealed off)

absorption of lipids

• bile to emulsify fats, easier to digest after that

• multiple trips to the liver to metabolize diff products to diff densities

• lymph dumps fats into larger veins

• high density fats are better to help to scrub/clear out vessels (prevents plaques)

• low/intermediate density fats can get into cells easier

control of digestive processes

• nervous system

  • nervous network in gut and CNS

  • myenteric plexus regulates motility

  • submucosal plexus regulates secretion (gets input from mucosa)

• endocrine system

  • hormones

• enteric nervous system

regulation of feeding

• leptin

  • produced by adipose tissue (fat)

  • more tissue when you have eaten more

  • inhibits feeding center

• ghrelin

  • produced by the stomach

  • stimulates feeding center when empty

• peptide YY

  • produced by the colon

  • inhibits feeding center when full

• insulin

  • produced by the pancreas

  • in response to high glucose

[keep big picture focus, how can information from around body regulate food input]

changes between meals

• sources of energy

  • carbs → shorter term, fast access

  • lipids → longer term, slower access, more energy needed

• energy expenditure

  • how rapidly do you need the energy

• use of energy

  • what is energy being used for

changes between meals - snakes

• snakes do not eat very often

• before feeding, they break down intestinal and muscle walls to use as energy

• after feeding, they use energy to rebuild the walls for digestion

thermal physiology

• T_A = ambient temp

• T_B = body temp

  • both are for heat exchange between organism and environment

• factors

  • behavioral → how body is arranged, where the organism is (open vs shelter)

  • biochemical → what is being consumed, chemical rxns of breakdown (proteins vs fats)

  • physiological → blood flow, insulation, etc.

• ΔH = ΔH_metabolism + ΔH_conduction + ΔH_convection + ΔH_radiation + ΔH_evaporation

thermal energy types

• conduction

  • touching, direct contact

• convection

  • movement of air, water

• radiation

  • movements of energy source itself (light rays)

• evaporation

  • loss of heat by putting energy into water, liquid to gaseous form

• SA: Vol

  • higher SA:Vol ratio, more room to exchange heat with environment

insulation

regulating heat loss

• thickness

  • thicker fur → more insulation

  • thicker layer of subcutaneous fat → more insulation

• density

• polarity

  • fats/lipids are not polar (bad heat conductors, helps keep heat inside)

thermal strategy terms

• ectotherms

  • rely on outside temps

• endotherms

  • regulate their own temps

• homeothermic

  • maintain a similar temp on a regular basis

• poikilothermic

  • wider range of internal temps

[endotherms are typically homeothermic, but some endotherms (ice fish, tropical fish) are ectothermic and homeothermic because their environments do not change much]

thermal strategy chart

thermal strategy - heterotherms

↓ T_B to save energy

• temporal heterotherms - time: overnight

• regional heterotherms (area of body)

metabolic rates and temps

• thermoneutral zones

  • eurythermic - wider range

  • stenothermic - narrow range

• low 70s for humans

• organisms cannot cool themselves down because every metabolic process loses energy as heat, body if fighting against itself when trying to decrease heat

membranes and temps

colder = more stable, warmer = more fluid

• homeoviscous adaptation

  • length of FA chains

  • saturation of FA

  • phospholipids

  • cholesterol levels (create space between hydrocarbon tails, increase fluidity)

enzymes and temp

• folding patterns

  • functional proteins

• stability

• ionization

• heat shock proteins

• temp range

[temp, salt/ion conc, pH all affect protein folding]

freezing temperatures

• ice formation

  • osmolarity

  • pierce membranes, expands inside cells

  • water freezes first, sugars and other things freeze after

• nucleators

  • start formation of ice crystals

• anti-freeze

  • prevents formation of ice crystals

thermogenesis

• T_B homeostasis or pyrogens/fever

  • increase in the set point, heat needs to be generated to reach it

  • temp change can be whole body or local

• shivering

  • futile muscle contractions

• futile cycles (no real purpose, but heat is generated)

  • enzymatic rxn - final product not made

  • antagonistic muscles

  • altering functions

  • leaky membranes - constantly using energy to pump things up a gradient because they fall back through the membrane

  • non-shivering thermogenesis

adaptations of muscle heater and electric organs

• trans-differentiation

• billfish heater organ

  • uncoupled Ca²⁺ release and contraction

  • Ca diffuses down the gradient and is pumped back up → heat is released

• electric organ

  • lose sarcomeres, increase in size

  • arranged in stacks

thermogenesis - adipose tissue

mitochondria has a dual membrane, uses oxidative phosphorylation to produce ATP

• if membranes are leaky, H+ can fall back into the cells and will continue to cycle in and out because of active transport

• brown adipose tissue: leaky membranes in mitochondria so lots of “pumping” but no ATP formed

regulation of temp - feedback loop

• too cool down, release more heat to environment

  • ideally, decrease heat production

• to warm up, keep heat in and generate more

heat loss

• piloerection

  • raise up fur, more distance, more insulation

  • lowered hair, less distance, allows for more heat loss

• vasomotor response

heat loss - countercurrent exchange

• countercurrent exchange

  • blood flows out through arteries (warm blood), vein is coming back from feet (cold blood), countercurrent allows for heat exchange to blood in the vein can warm up before it gets to the core of the body. blood in artery will cool by the time it gets to the feet, minimizing heat lost to the environment

  • continual exchange

heat loss - evaporation

evaporation

• sweating

• panting

breathing

• cold air comes in, longer pathway allows air to be warmed before it gets to lungs

• nasal breathing conserves heat and moisture (water) (low temp)

• mouth breathing loses water and heat (high temp)

hypometabolic states

• regional or temporal heterothermy

  • for short periods of time

• relaxed endothermy

  • hibernation → long term

  • torpor → routine, daily cycle

↓ T_B means less energy requirement, so metabolic rate can decrease

• also decreased O₂ use and CO₂ production

reproduction

• genetic

  • passing on DNA

• behavioral

• physiological

  • changes in body function

• hormonal regulation

  • producing gametes, sexual maturation

• bottom line - need to pass on genetic info

asexual reproduction

• cloning

  • budding

• parthenogenesis (self-fertilizing)

  • automictic → smaller cells with ½ DNA = polar bodies (only used to remove the half DNA they have during meiotic division)

  • homozygous offspring only (no differentiation, second polar body has identical DNA)

• Thelytoky

  • starts and ends homozygous

• Arrhenotoky

  • starts heterozygous, can end homo (asexual) or heterozygous (sexual)

  • benefits (asexual) → no need to find a mate, you can reproduce at any time; quick reproduction; saves a bit of energy

  • disadvantages → no genetic diversity

gametogenesis - sexual

• oogenesis - has pauses

  • pause in meiosis I

  • 1 oocyte/oogonium

  • 2-3 polar bodies

  • larger gametes (due to unequal division of polar bodies) (provides raw materials for growth)

• spermatogenesis - continuous

  • no paise

  • 4 sperm/spermatogonium

  • smaller gametes (more traveling, only supply DNA)

• advantage: creates diversity, natural selection processes

• disadvantage: you have to find a mate (timing, resources, etc have to line up)

[meiosis has two divisions, mitosis has only one]

mitosis/meiosis

mitosis

• two identical cells

meiosis

• four cells (two identical, other two identical)

spermatogenesis

• occurs in testes

  • Sertoli cells - make sperm

  • Leydig cells - produce testosterone

• packages as semen with other secretions

  • water for motility/transport

  • bicarbonate buffer (acid in the female reproductive tract would kill sperm if buffer was absent)

  • glucose, amino acids for nutrition

  • mucous → sticky, holds sperm in a group to protect them from acid while they adjust to it

  • prostaglandins → more motility in female repro-tract (smooth muscle contractions do most of the work for moving sperm while in mucous)

oogenesis

• oviparous - chicken

  • offspring “hatch” from egg

  • ovi = egg

• viviparous - mammals

  • live birth, no egg to hatch from

  • nutrition from parent during gestation

  • vivi = live

• ovoviviparous - sharks

  • grows in egg → egg hatches in female reproductive tract → “live” birth

  • egg live birth

oogenesis conditions

• environment

  • land fertilization: harder shell, less permeable

  • water or internal fertilization: can use a layer of “gel” but no real shell

• source of nutrition

  • only egg → needs lots or nutrition or parent releases lots of offspring to increase chances of survival

  • from mom → smaller oocyte because nutrition is provided during development

fertilization

release of sperm from body

• spray over eggs

  • no direct transfer

• copulation

  • direct transfer - lining up openings, no insertion

  • hemipene - insert organ into female

  • blood pressure - increased blood leads to increase in size and stiffness (allows for insertion)

  • Os penis - actual bone (walruses, raccoons)

[dogs have an os penis and they use blood pressure (combination)]

fertilization variations

• multiple matings → OR some females can store sperm and then eject it if a better mate comes along, or can store it until conditions are optimal for fertilization

  • polyandry - multiple sperm from several males fertilize offspring

• delayed implantation (embryonic pause) → fertilization occurs, then the process pauses

  • rodents, kangaroos, river otter

sex determination

mammals

• XY (M), XX (F)

  • XXY, XXX, or XØ are possible (will not be able to reproduce), but not YØ (cannot survive)

birds, butterflies

• ZZ (M), ZW (F)

bees

• diploid (F), haploid (M)

tortoises, crocodiles

• temperature-dependent sex determination (warmer temps = ↑ number of females, cooler temp = ↓ number of males)

hermaphrodites

• protogynous

  • female first → male later in life

• protandrous

  • male first → female later in life

vertebrate reproductive hormones

• FSH

  • follicle stimulating hormone (helps increase gamete numbers, more production)

  • follicle holds egg

• LH

  • luteinizing hormone

  • forms corpus luteum from remains of follicle, increase production of gonad

• CG → mammals only (signals implantation so placenta will be created)

  • chorionic gonadotropin, made by placenta, letter before indicates species

  • hCG = human

  • bCG = bovine

• GnRH controls release

  • Gonadotropin Releasing Hormone (comes from hypothalamus)

  • releasing hormones come from hypothalamus, tropin = growth/increase (so more gonads produced)

reproductive hormones

steroid hormones (verts)

• progesterone

• androgens

• estrogens

ecdysteroids (inverts)

steroid hormone synthetic pathways

• the enzymes ultimately determine what the final product is

male control loops

GnRH – stimulates FSH and LH

• LH

  • Stimulates Leydig (interstitial) cells to produce testosterone (inhibits GnRH and LH)

• FSH

  • Stimulates Sertoli (nurse, sustentacular) cells to produce sperm and Inhibin