BIO 199 #Exam 3 - Chapter 49, 45, 42, 43

Differentiate between osmotic adaptations in freshwater fish versus those in marine fish.

• freshwater fishes must retain electrolytes and keep water out

• marine bony fishes must excrete electrolytes and keep water in

Describe the actions of filtration, reabsorption, and secretion.

Filtration: fluid in the blood is filtered into the tubule system, leaving cells and large proteins in the blood, and a filtrate composed of water and all of the blood solutes. This filtrate is modified by the rest of the tubule system to produce urine for excretion.

Reabsorption: reabsorption is the selective movement of important solutes from the filtrate in the tubule system to the extracellular fluid, returning to the bloodstream via peritubular capillaries ions

Secretion: secretion is the movement of substances from the blood into the extracellular fluid, then into filtrate in the tubule system

Name the primary components of the kidney.

• renal pelvis

• renal cortex

• renal medulla

Describe the structure of the nephron.

• juxtamedullary nephrons: have long loops that dip deeply into the medulla

• cortical nephrons: have shorter loops

Compare hydrostatic skeletons, exoskeletons, and endoskeletons.

hydrostatic skeletons: The skeleton of most soft-bodied invertebrates that have neither an internal nor an external skeleton. They use the relative incompressibility of the water within their bodies as a kind of skeleton.

exoskeletons: An external skeleton, as in arthropods.

endoskeletons: found in vertebrates and echinoderms, are rigid skeletons that form the body’s framework and offer surfaces fro muscle attachment

Explain how animals with hydrostatic skeletons move.

• muscles act on the fluid in the body’s central space

• as locomotion begins → anterior circular muscles contract, pressing on the inner fluid and forcing the front of the body to become thin as the body wall in this region extends forward

Describe the action of flexion and extension and the relationship between opposing muscle groups

flexion: the movement that reduces the angle of the joint (contraction of hamstrings)

extensors: will widen the angle at the joint (contraction of quads)

Explain the sliding filament mechanism of muscle contraction.

a muscle contracts and shortens because its myofibrils contract and shorten. when this occurs, the myofilaments do not shorten; instead, the thick and thin myofilaments slide relative to each other. The thin filaments slide deeper into the A bands, making the H bands narrower until, at maximal shortening, they disappear entirely, This also making the I bands narrower, as the Z lines are brought closer together.

Differentiate between slow-twitch and fast-twitch muscle fibers.

slow twitch fibers: rich capillary supply numerous mitochondria and aerobic respiratory enzymes, and a high concentration of myoglobin pigment. These fibers can sustain action for a long period of time without fatigue

fast-twitch fibers: have fewer capillaries and mitochondria than slow-twitch fibers and not as much myoglobin. Fast-twitch fibers are adapted for the rapid generation of power and can grow thicker and stronger in response to weight training. However, they lack endurance characteristics of slow-twitch fibers.

Contrast the relative concentrations of important ions inside and outside cells.

The sodium and chloride ion concentrations are lower inside the cell than outside, and the potassium concentration is greater inside the cell. These concentration differences for sodium and potassium are due to the action of a membrane active transport system which pumps sodium out of the cell and potassium into it.

Explain how the resting potential is established.

the resting potential is due to the action of the sodium-potassium pump and the greater permeability of the membrane to potassium

Distinguish between electrical and chemical synapses.

Electrical synapses: direct cytoplasmic connection formed by gap junction between the pre and postsynaptic neurons

chemical synapses: when synapses are viewed under a light microscope, the presynaptic and postsynaptic cells appear to touch, but when viewed with an electron microscope, most have a synaptic cleft, a narrow space that separates these two cells.

Explain how neurotransmitters work and how medications such as SSRIs work.

Serotonin is one of the chemical messengers (neurotransmitters) that carry signals between brain nerve cells (neurons). SSRIs block the reabsorption (reuptake) of serotonin into neurons. This makes more serotonin available to improve transmission of messages between neurons.

Describe how gated ion channels work.

sensory stimulus causes these ion channels to open or close, depending on the sensory system involved

Explain how sound waves in the environment lead to production of action potentials in the inner ear.

the structure of the ear allows pressure waves to be transduced into nerve impulses based on mechanosensory cells like those in the lateral line system

List the five taste categories.

• sweet

• sour

• salty

• bitter

• umami/savory

Describe how taste buds and olfactory neurons function.

• taste buds and olfactory neurons work together to create perceptions of flavor. Taste buds are clusters of taste receptor cells, or gustatory cells, that are located around

  papillae on the tongue, soft palate, upper esophagus, cheek, and

  epiglottis. These papillae detect the five elements of taste perception: saltiness, sourness, bitterness, sweetness, and savoriness.

• Olfactory neurons detect volatile odorants. When you smell something, particles get trapped in mucus produced by the olfactory epithelium at the back of your nose. These particles bind to sensory receptors in the nose, causing an action potential.

• Taste and smell work together at the back of the throat. When you taste something before you smell it, the smell lingers internally up to the nose causing you to smell it.

Explain how a vertebrate eye focuses an image.

Light enters the eye through a transparent cornea, which begins to focus the light. Focusing occurs because light is refracted (bent) when it travels into a medium of different density.

Describe how photoreceptors function.

Light waves are captured by photoreceptors. All photoreceptors employ some version of the pigment opsin to detect changes in levels and frequencies of light.

Explain how the compound eye of a fly, the human eye, and the eyespot of a ribbon worm could have a common evolutionary origin

• Historically morphological evidence suggested that eyes in the various animal phyla were examples of convergent evolution.

• Pax6 in eye development

  • genes discovered that code for transcription factor important in lens development

    • Pax6 in mice, eyeless in flies