Physiology Flashcards
physiology
analysis of the function of living organisms; applies physical and chemical methods to biology
comparative
study of the diversity and modulation of highly conserved properties of organisms
comparative physiology contributes to:
ecology - describes adaptations to diverse environment
evolution - correlates function with structure which can help determine relatedness
adaptation
a trait that improves an organisms performance (fitness) in its environment
homeostasis
any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival
3 functional components to homeostasis
- receptor - takes in sensory information
- control center - determines the set point and regulates the body’s response
- effector - carries out the response
doping drugs
- PEDS
- Anabolic steroids
- HGH
- EPO - erythropoietin
- Testosterone
Peds
build muscle mass and strength
increase oxygen delivery to exercising tissue
mask pain and injury
decrease weight
anabolic steroids
stumulate muscle and bone cells to make new protein by changing gene expression
increases protein synthesis capacity of the cell
Testosterone
causes male reproductive and secondary sex traits
side effects:
males- balding, infertility
females- facial hair, thicken vocal cords
general- increased heart disease, liver cancer, kidney damage
HGH
naturally occurring protein produced by pituitary gland stimulates bone and muscle growth and reduces body fat side effects: type 1 diabetes acromegaly- overgrowth of hands, feet and face heart problems kidney failure with long term use
influence of physics on physiology:
- gravity - circulation, movement and locomotion
2. surface area: volume - respiration, digestion, water balance, thermoregulation
isometric scaling
everything grows in proportion
allometry
the study of differential growth; biological scaling
if body temp is too high…
proteins denature
inadequate O2 supply (affinity for Hb decreases with increasing temperature)
membrane structure alterations
if body temp is too low …
metabolism isn’t fast enough to maintain homeostasis
freezing of cells
inadequate O2 supply
4 methods of human heat exchange:
- Radiation - infared wavelength without contact 60% heat loss
- Conduction - direct transfer 3%
- Convection - air/fluid across body surface 15%
- Evaporation - water from body surface 22%
poikilotherms
ectotherms - temp fluctuates with environment (conformers)
homeotherms
endotherms - constant body temp (regulators), heat derived from metabolism
poikilotherm (ectotherm) benefits:
5x slower metabolic rate than homeotherms
can devote larger proportion of energy budget to reproduction
good colonisers of poor/arid environments
poikilotherm (ectotherm) costs:
no nocturnal environmental niches
cannot sustain high activity bursts - go to anaerobic = high lactic acid = rapid fatigue
homeotherm benefits:
can sustain high activity bursts
nocturnal activity in all habitats
able to exploit colder habitats
forage widely and migrate over long distances
homeotherm costs
require large body sizes with relatively low SA;Volume
fast metabolic rate
bad colonisers of poor/arid environments
thermoneutral zone
range of temps in which the animal doesn’t have to expend energy to maintain body temp
hyperthermia
when evaporative cooling cannot counteract heat gain; body temp is above normal and cannot be reduced
vasoconstriction (warms)
diameter of blood vessel decreases
blood flow to skin decreases
less heat lost to environment
raises internal temp
shivering
skeletal muscles consume ATP and generate heat
countercurrent heat exchange
hot artery flows by colder veins and exchanges heat so cold blood doesn’t flow to heart
brown fat
has lots of mitochondria and a richer blood supply - new borns and hibernators
hormones that increase cellular metabolism:
Adrenaline - released from adrenal medulla, stimulate flight or fight which increases heart rate
Thyroxine - hypothalamus signals thyroid to release thyroxine = elevates metabolic rate
vasodilation (cools)
blood vessels dilate
blood moved to skin and blood heat is lost to environment
2 main concerns of water balance:
- balance uptake of water from and loss to external environment
- reduce build up of toxic by products of metabolism
passive movement
along a concentration gradient
active movement
add energy to move against concentration gradient
influences of rate of passive movement
membranes size of ion temp of solution electrical charge of ion concentration gradient
osmolarity equation
(particles/molecule of solute) x (moles/litres)
tonicity
the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion, refers to the behaviour of a cell in a solution
hypertonic environment
cells will shrink
hypotonic environment
water enters cell = cell may possibly burst
hypo-osmotic
tissue osmolarity is less than the cell = high H20 gradient, water moves out of cell
hyper-osmotic
tissue osmolarity higher than cell, water moves into cell§
iso-osmotic
osmolarity of tissues and cell is equal
marine teleost
hypo-osmotic to ambient water
high salt environment
lose water to environment via osmosis
salt gain by diffusion in gills
getting rid of salt: chloride cells in gills
- Na/K ATPase builds huge gradient using ATP
- Na/K ATPase pump Na out of Cl cell
- Na/Cl symporter moves 1 Na and 2 Cl into cell
fresh water teleost
hyper osmotic to ambient water low salt environment salt lost by diffusion water uptake by osmosis active uptake of Na and Cl
Ammonia - bony fishes, aquatic amphibians, aquatic invertebrates
toxic
free to make
highly soluble in water
urea - mammals, most amphibians, cartilaginous fish
less toxic than ammonia
requires energy: 1.5 ATP
uric acid - birds, insects, reptiles
insoluble in H2O
excreted as semi solid - allowing organism to conserve water
not toxic
requires energy: 5 ATP
generalised excretory organs:
kidneys
Malpighian tubules
contractile vacuoles
nephridia
specialised excretory organs:
salt glands, gills, liver - porphyrin, rectal glands
metabolic waste disposal, 3 steps:
- FILTRATION - blood fluids collected, some solutes returned in the body, others stay in the filtrate
- REABSORPTION - selective transport of needed filtered substances back to tissue fluid/blood to be circulated in the body
- SECRETION - filtrate joined by unneeded substances from the blood and tissue fluid
contracting vacuoles
pump water out of the cell
maintaining a suitable concentration of ions and molecules inside the cell
2 main divisions of kidney
cortex and medulla
cortex contains
convoluted tubules
glomeruli
bowman’s capsule
medulla
collecting ducts
long loops of henle
Malpighian tubules
collect water and uric acid from blood
epithelium pumps solutes from haemolymph to tubule lumen
empties into midgut
water and useful materials reabsorbed by hindgut
salt reabsorbed from rectum
water moves in via osmosis
nitrogenous waste eliminated with faeces
regional homeothermy
- core body temp: narrow margins
- peripheral body temp: limbs etc, varies considerably
thermoregulation methods:
- behavioural control; repositioning body in the environment to control temp
- physiological control; neural responses (immediate) - e.g. shivering, sweating; acclimatisation responses (long-term) - e.g. changes in insulation
in hot environments endotherms maintain normal temp by:
limiting heat gain and increasing heat dissipation
limiting heat gain - large animals
low SA;Volume ratio - take longer to heat up
have thicker pelage - insulate body from external heating
increasing heat dissipation
conduction, convection, radiation thin cuticle highly vascularised lightly insulated large surface areas allen's rule - warmer climate = larger size of appendages
sweating
extrusion of water through sweat glands onto the skin
- passive
- high salt loss
- no convection
- no effect on blood pH
panting
evaporative cooling through the respiratory system surfaces
- active (requires muscle contraction)
- no salt loss
- convection - increases cooling
- increased ventilation = increased pH
can cool brain during periods of high levels of activity
endotherms coping with cold environments
increasing heat production (thermogenesis)
limiting heat loss
effects of freezing:
- drastic reduction in gas diffusion
- drastic reduction in enzyme function
- osmotic dehydration due to freezing of extracellular wall
bergman’s rule
increased size with increased cold temp
2 strategies of dealing with freezing temps
- freeze avoiding/supercooling
2. freeze tolerance
freeze avoidance/supercooling
an increase in solutes reduces freezing point
e.g. insects:
produce high amounts of glycerol
lowers freezing point
willow gallfly larvae can supercool to -60!
Freeze tolerance
ability to tolerate freezing of extracellular fluids
cryoprotectants reduce ice crystal formation
endocrine and exocrine functions
controls activities that require long duration: metabolism osmoregulation and digestion growth and development reproduction
endocrine
glands, blood or lymph, circulate round whole body
exocrine glands
ducts, epithelial surface
holometabolous
complete metamorphosis
hemimetabolous
incomplete metamorphosis
corpora allata
endocrine gland which generates juvenile hormone - plays crucial role in metamorphosis
key components of the insect endocrine system:
neurosecretory cells
corpora cardiaca
corpora allata
prothoracic glands
neurosecretory cells
translate neural signal into chemical stimuli; produce secretions called neurohormones; large cell nucleus
corpora cardiaca
a neurohemal organ that stores brain neurohormones
prothoracic glands
secrete a hormone called ecdysone under stimulation of the brain hormone
major insect hormone types
neurohormones
ecdysteriods
juvenile hormone
prothoracicotrophic hormone
neurohormones
most diverse class regulate various developmental and metabolic processes
ecdysteriods
moulting and sex hormones
prothoracicotrophic hormones
act on prothoracic glands which release ecdysone
ecdysis
moulting - controlled by ecdysone
juvenile hormone
secreted by corpora allata
regulates developmental transition
regulates egg production and mating behaviour
pupation occurs when
juvenile hormone levels decline and ecdysone levels are high - at minimum juvenile hormone levels adult forms
vitellogenesis
production of yolk proteins transferred into the egg
oviposition
egg laying
semiochemicals
small organic compounds that transmit chemical messages
used by insects for intra- and inter- species communication
receptors usually located on sensilla hairs on legs or antennae
aerobic respiration equation
glucose + oxygen –> CO2 + ATP
