module 2+3: evil chris questions>;0 Flashcards
an animal having an alimentary tract with two openings instead of one has the advantage of:
- continuous feeding
- one way flow of food and waste
- evolution of special digestive processes localized along the tract
the order of digestion of food in the alimentary canal, starting from the oral cavity is:
carbohydrates > proteins > nucleic acids > fats
explain why food has to be digested before absorption can occur:
- food can only be absorbed after it has been broken down into small molecules
- food has to be broken down into simple molecules so that the animal taking in the food can either metabolize or use the molecules to build up its own body components specific of the species
what happens if too much gastrin is produced?
too much HCL break down mucus and cause ulcers
following the consumption of a highly salty meal, which of the following would be a likely consequence in a human?
decreased secretion of aldosterone
osmoconformers have body fluids that are ______ to the environment. osmoregulators have body fluids that are_____ to the environment
isotonic, hypotonic or hypertonic
sharks living in a marine environment compensate for their hypotonic system relative to the sea by
excreting massive amounts of water
aquatic organisms that are hypotonic relative to the surrounding water tend to
gain salts from the environment
when placed in a hypotonic (less solute) solution what occurs to a cell
an animal cell would burst but a plant cell would not
the sodium-potassium pump transfers
3 sodium ions out and 2 potassium ions in
the most important structure involved in concentrating urine within the nephron is
loop of henle
in the kidney the correct sequence of formation of urine involves the following processes
glomerular filtration, reabsorption, tubular secretion
reabsorption of chloride ions from the glomerular filtrate in the kidney tubule is carried by
diffusion
explanation for a marine star dying after being placed in fresh water
sea star is hypertonic to freshwater and could not osmoregulate
why do sodium ions enter the cell when voltage-gated sodium channels are opened in neurons
- the sodium concentration is much higher outside the cell than inside
- sodium ions are attracted to the negatively charged interior
an action potential is generated by
massive influx of sodium ions
within a neuron, information moves from
dendrite to cell body to axon
the chemical that diffuses across the synaptic gap, establishing communication between two neurons is called
neurotransmitter
how do myelin sheaths increase the speed with which action potentials are propagated along an axon?
they cause action potentials to “jump” down the axon rather than travel in a continuous path along every site on the axon.
the resting potential of a neuron is due mostly to
open potassium channels
short interval of time during which restimulation after action potential is not possible is called
hyperpolarization
whether a synapse is excitatory or inhibitory depends on the
type of neurotransmitter
after the action potential begins, sodium voltage gated channels are most likely
open
in saltatory conduction
an action potential jumps along a myelinated axon from one node of ranvier to the next
action potential event sequence
- neuron is stimulated at the dendrites
- sodium gates open then close
- potassium gates open
- the cell is fully repolarized
- the cell is fully depolarized
- the neuron is in a polarized resting state
the specificity of a hormone is due to
specialization of target-organ receptors
paracrine communication refers to interactions between cells resulting from
direct contact of neighbouring cells at tight junctions
many nonsteroid hormones act upon their target cells by causing
the activation of adenylate cyclase
the endocrine system
- releases chemicals into the bloodstream for distribution throughout the body
- releases hormones that alter the metabolic activities of many different tissues and organs
- produces effects that can last for hours, days or even longer
- can alter gene activity in cells
smooth muscle differs from both cardiac and skeletal muscles in that
membranes of smooth muscle cells are depolarized by stretching
A novel species of butterfly has evolved the ability to attack birds that prey on it, injecting cardioglycosides it extracts from the milkweed on which it feeds. True or false, In this situation, the cardioglycoside would be considered both a venom and a poison.
true
milkweeds and cardioglycosides are toxic and that some animals accumulate toxins as poisons to protect themselves from predators
T or F: Birds that fly between north and south might use a magnetic compass but animals that move up and down cannot use magnetic fields to navigate.
false
T or F: Statocysts only work in animals that are neutrally buoyant because the statoliths in the statocysts are the same density as water.
false
In a hair cell receptor, the key point is that the hairs on the apical end of the cell are different lengths. This permits the cells to detect a direction of fluid flow, such as anterior to posterior. True or false: If the hair cells were the same length, they could detect fluid movements in both direction.
false
the ability to detect the movement would require there to be a change in distance between the tips, and the only way that happens is if the hairs differ in length.
Cayenne peppers taste hot because they bind to thermoreceptors and cause local heating.
false
no local heating involved at all
Oligodendrocytes produce the myelin that covers motor neurons in flight muscles of insects.
false
The CNS is subdivided between the Afferent neurons and efferent neurons. The efferent neurons include the motor system and autonomic system, which includes the sympathetic, parasympathetic and enteric divisions.
false
afferent and efferent neurons are in the peripheral nervous system. That carry information to/from the CNS.
Astrocytes are a type of glial cells in the central nervous system that have a number of support functions, including maintenance of the blood-brain barrier.
true
The AMPA receptor is an ion channel but a NMDA receptor is not an ion channel.
false
Mammals use the hormone gonadotropin-releasing hormone (GnRH) from the hypothalamus to trigger the release of FSH and LH from the pituitary, which alters hormone production by the gonads. True or false. All of these hormones are tropic hormones.
true
In mammals, after the follicle releases the ovum, the next steps for the follicle depends on whether the ovum is fertilized and implants in the uterine wall. True or false: The remnants of the follicle receive their instructions via paracrine stimulation.
false
The placenta is composed of many cells. Any two cells would share at least half their genes, but not all cells would share the same genome.
true
Insects use the antagonistic hormones juvenile hormone and ecdysone to regulate development. Both hormones are derived from the pathway used to produce cholesterol, and both are hydrophobic. True or false: If you were looking to characterize their receptors, you would be well advised to begin the analysis looking at the proteins in the cell membrane of target tissues.
false
Trehalose is produced from the breakdown of glycogen, which is usually present as large branched polymers of glucose. True or false, the osmolarity of a solution with 1,000,000 glucose molecules would be the same regardless of whether they existed as a 500,000 trehalose molecules or 1 glycogen particle.
false
An important part of the control of blood glucose levels is the secretion of insulin and glucagon by the pancreas. True or False: If glucose is high, insulin will reduce the secretion of glucagon, an example of a negative feedback pathway.
false
The epithelial lining of the gut is composed of smooth muscle cells that are arranged either longitudinal or circular layers.
false
The lumen of the small intestine is made acidic by the actions of a proton pump in parietal cells.
false
Leptin is a hormone that increases appetite. When animals have low leptin synthesis, low levels of leptin receptors, or insensitive leptin receptors, this signaling pathway is impaired and animals lose their appetite.
false
A new snake is discovered with a venom that targets the CaATPase in the SR of skeletal muscles. True or false. In the presence of the venom, the skeletal muscle could contract but would be unable to relax.
true
Lactation, as we define it, is possible from the repurposing of existing genes, evolving new or different functions in mammals. These mammalian genes include alpha-lactalbumin, lactotransferrin, lactose, and casein.
false
The p50 of hemoglobin for oxygen is higher under conditions that cause a decrease in oxygen affinity of hemoglobin.
true
The pathway for blood goes from left ventricle to pulmonary artery, pulmonary vein and back to the right atrium.
false
The contraction phase of the heart is systole and the relaxation phase is diastole. Thus, diastolic blood pressure is the pressure in the circulation when the heart has filled but not yet ejected the blood.
true
A cow is forced to run on a treadmill. Researcher find that when it runs, its respiration rate doubles, its hemoglobin oxygenation does not change, its cardiac output doubles, and its heart rate also doubles. Based on these observations, you would predict that the stroke volume doesn’t change.
true
In mammals, myoglobin is the most important carrier of oxygen and carbon dioxide in the blood.
false
Frogs can breathe oxygen across the skin, as well as via the lungs. If a frog is in hypoxic (low oxygen) water, it would lose oxygen from the body across the skin unless there was a means to direct blood away from the skin capillaries.
true
Countercurrent systems increase the efficiency of exchange between two systems flowing in the same direction.
false
Hemoglobin shows cooperative oxygen binding, meaning that as oxygen concentration increases, it is easier for the hemoglobin molecule to bind a second oxygen once the first one is bound.
true
You have two solutions: 1 M glucose and 0.25 M NaCl. The glucose solution has a higher osmolarity.
true
Salmon hatch in freshwater, and after a period of time as small parr, they remodel their physiology in preparation for the transition to seawater (smoltification). The smolts then migrate to seawater. Thyroid hormone promotes the synthesis of Na K ATPase- the sodium pump- which has an important role in excretion of excess Na from the body. True or false: You would expect thyroid hormone to be higher in parr than smolts.
false
Osmolarity of body fluids is important to regulate because the membranes of cells are impermeable to solutes and water
false
Osmoregulators control the osmotic gradients between the environment and the extracellular fluid, but their cells have the same osmolarity as the extracellular fluid.
true
The adaptive immune system includes both responses mediated by cytotoxic cells and responses of extracellular proteins that are present in body fluids.
true
Consider a single B cell. It may make an antibody or a receptor that binds the same antigen. True or False: The antibody and receptor have the exact same sequence, and the only difference is whether the B cell secretes the protein.
false
Immunization works by stimulating memory cells to produce abundant antibody.
false
Cytotoxic T cells use their receptors to bind onto infected cells that display the antigen of the pathogen that infects it.
true
In contrast to passive transport, all forms of active transport require ATP as a source of energy.
false
Depolarization of a neuron occurs when Na channels open and Na rushes out of the cell.
false
Striated muscles have thick and thin filaments whereas smooth muscle does not.
false
Ectotherms regulate a combination of heat production and heat loss to ensure that their body temperature remains within a narrow range.
false
You are comparing two cells at rest, both with the same internal ion concentrations and in a solution with the same external ion concentrations, and under these conditions the equilibrium potential for K is the same, -90 mV. They also have the same collection of ion channels, but in cell A, the K channels are open and in cell B the K channels are closed. The resting membrane potential for cell A is -60 mV. It is likely that the resting membrane potential for cell B is greater than that in cell A.
true
The following elements of a muscle are arranged in increasing order of size: thin filament, thick filament, sarcomere, myofibril, myofiber, muscle.
true
In comparing two animals, species A and species B. Species A has a troponin with a higher affinity for Ca. This would likely result in a muscle that contracts faster following excitation, if all other components are similar between species.
true
Many processes are dependent on body size, due in part to the fact that as animals get larger, their surface area increases more than does their volume.
false
During an action potential, the membrane potential first moves toward the equilibrium potential for Na+, then at peak depolarization, moves away from the equilibrium potential for Na+, toward the equilibrium potential for K+.
true
