• fish detect fish
• platypus bil can detect prey
• homin pigeons use magnetite to accurately navigate
• pit vipers sense infared radiation from prey

• simple visual organ
• eyecup containing endings of photoreceptor cells detect the presence or absence of light
• layer of pigment casts shadows, so can detect direction of light
• does not form visual images

compound eyes (arthropods)

• many light detectors 
• each light detection unti makes up one facet
• lens and crystalline cone focuse light onto rhabdom

keep light from one ommatidium leaking into adjacent ammatidium

found in vertebrates some mollusks and in some snaila and annelids

light transmitted through pupil to retina at the back of the eye

photoreceptors trigger electrical changes in neurons

sensitive to low intensity light

do not disciminate colors

used mostly at night

require more light for stimulation

detect color

fewr cones than rods in human retina

a modified neuron

outer segment contains pigment

inner segment contain nucleus and othe organelles

synaptic terminal-neurotranmitter filled vesicles fuse with membrane, interact with postsynaptic neurons

Olfactory sensitivity is highy variable

T/F ?

True

depends on the density of olfactory receptor cells 

Olfactory receptors have long cilia with specific receptors to bind with specific receptors to bind odor molecules?

T/F ?

True

only one type of odor receptor expressed per olfactory receptor cell

taste buds are clusters of chemosensory cells that detect particular molecules in food molecules dissolved in salivia

located in folds of tingue papillae

tips of sensory receptor cells in tastebuds have microvilli that extend to the taste pore

1. hydrostatic
2. exoskeleton
3. endoskeleton

water-filled cavity surrounded by muscle

water is nearly incompressible, so hydrostatic pressure can be used to extend parts of the body

external skeleton surrounding and protecting body

vary in complexity and durability and thickness

interior muscles connected to skeleton components for movement

internal structures

do not protect the body surface but interal organs

Axial

Appendicular

muscle is a grouping of contractile cells bound together by cinnective tissue

white blood cells

defend against infection and disease

conduct blood away from the heart

smaller in diameter, branches of arteries

smallest and narrowest vessels in the body

site of gas and nutrient and waste exchange

capillaries come together to drain into these

thin walls

thinner and less elastic than arteries

return blood to the heart

21% oxygen

78% nitrogen

less than 1% carbon dioxide and other gases 

the hollow tube about 5 inches long that starts behind the nose and ends at the top of the trachea 

and esophagus

• water moves between adjacent body compartments by osmosis down an osmotic gradient
• changes salt concentration in one compartment will lead to changes in fluid distribution between compartments
• shrinking or swelling cells can rupture plasma membranes leading to cell death. 

loss of water by evaporation 

fish can lose water or gain water as water passes over the gills. 

gain water when ventilating gills

kidneys produce copious dilute urine

specialized gill epithelial cells transport Na+ and Cl- from water into fish capillaries

lose water acorss gills

produce very little urine

drink seawater to replace water lost

expend energy to tranport exess salt out of body through gill epithelial cells

total concentration of dissolved solute molecules/Liter

150 mM NaCl-solution = 300 mosm/L

one Na+ and one Cl made when salt dissociates

a major portion of an animals body mass

solventfor chemical reaction

transport vehicle

salts dissociate in solution into charged ions

electrolyte balance important

imbalance can alter membrane potential or disrupt other cellular activities.