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Biol 1201

Exam III

Time: 1-1:50pm, Wednesday,

Nov. 12, 2014

Place: Sc 101

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Birds: More Feathers and Better Flight

The bones of birds are modified for flight; they arehollow and have internal struts for strength. The breastbone forms a large, vertical keel to which

pectoral muscles are attached. These muscles pull

the wings downward during the propulsivemovement in flight. Forelimbs are modified as wings.

Hind legs stabilize and allow for animal to be upright. Feathers function not only in flight, but also inthermoregulatory, display, and other functions.

a unique feature of bird is that in addition to lungs,

they have air sacs at several locations of theirbodies which are interconnected.

4 chambered heart

The nervous system, esp. cerebellum, is morecomplex to accommodate coordination in flight.

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MAMMALS

Key mammalian features include mammary glands, sweatglands, and hair. Mammals also have a four-chamberedheart, more differentiated teeth, more developed brain, andbetter reproductive success.

Reproductively speaking, there are 2 main types of mammalswhich are prototherians and therians. The therians include

marsupials and eutherians.

a. Prototherians - spiny ant-eaters or duck-billed platypus

b. Marsupials - pouch animals like opossums, kangaroos

c. Placental mammals (also referred to as Eutherian mammals)

Following internal fertilization, the embryo develops within auterus. Placenta is very important for the embryo'sdevelopment.

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Primates, a major group of eutherians, split into twomain branches early in its evolutionary history: the

prosimians and the anthropoids. The prosimians include the lemurs, and lorises. Most

prosimian species are arboreal and nocturnal.

Anthropoids are monkey-like primates which are mostlydiurnal, and exhibit social behavior. They include new-world monkeys, old-world monkeys, and apes(gibbons, orangutans, gorillas and chimpanzees).

The Advancements in Human:

1. Bipedal locomotion

2. Smaller jaws

3. Human brains became larger.

3. Humans have complex language and culture, theircommunication abilities are far richer than those of any

other animals.

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I. Charles Darwins Theory of Evolution

Evolution is the change in genetic composition ofpopulations over time. Evolutionary change is observedin lab experiments, natural populations, and the fossilrecord. These genetic changes drive the origin and

extinction of species and the diversification of life.Evolutionary theory is the understanding of themechanisms of evolutionary change.

Darwin and Wallace came up with similar conclusions

through independent studies, and their ideas werepresented to the Linnaean Society of London in 1858.A year later Darwin published On the Origin of Species: First, species are not immutable, but change, or

adapt, over time. Second, the process that produces the changes is

natural selection. Third, divergent species share a common ancestor

and have diverged from one another graduallythrou h time

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II. The HardyWeinberg

Equilibrium A population of sexually reproducing organisms in

which allele and genotype frequencies do not change

from generation to generation is said to be at HardyWeinberg equilibrium.

Five assumptions must be made in order to meetHardyWeinberg equilibrium.

Mating is random.

Population size is very large.

There is no migration between populations.

There is no mutation.

Natural selection does not affect the survival of particulargenotypes.

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III. Evolutionary Agents and Their Effects

Evolutionary agents cause changes in the allele andgenotype frequencies in a population.

These are observed as deviations from the HardyWeinberg equilibrium.

The known evolutionary agents are mutation, gene flow,genetic drift (e.g. bottleneck effect, founders effect),

nonrandom mating, and natural selection.

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Natural selection can act on characters withquantitative variation in three ways:

Stabilizing selection preserves averagephenotype.

Directional selection favors individuals that varyin one direction.

Disruptive selection favors individuals that vary

in opposite directions from the mean.

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Sexual selection acts on characters that determinereproductive success.

If an individual survives but does not reproduce, itmakes no contribution to the next generation. Sexualselection favors traits that increase the chances of

reproduction.

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Introduction to Physiology

Homeostasis is the maintenance of constantconditions in the internal environment of an

organism. Single-celled organisms and simple

multicellular animals meet all of their needs by

direct exchange of substances with the externalenvironment.

Complex, multicellular organisms developedspecialized cells.

Cells, tissues, organs, organ systems

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Physiology is the study of how organisms

workthe study of the functions of all theparts and processes of living systems.60% of human body is water (2/3 within

the cell, 1/3 outside the cell). Extracellular fluid (ECF) consists of

plasma and interstitial fluid that bathes

every cell of the body. Individual cells gettheir nutrients from this interstitial fluid anddump their waste products into it.

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Physiological systems include regulatory systems andcontrolled systems. The controlled systems include effectors

which effect changes in the internal environment, and arecontrolled by commands from regulatory systems.

Regulatory systems:

Obtain, integrate, and process information Issue commands to controlled systems

Contain sensors to provide feedback information that iscompared to the set point

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The regulatory systems may work via negative feedback, positivefeedback, or feedforward information: Negative feedback causeseffectors to counteract the influence that creates an error signal.

E.g. slow down when you are tired of running. Positive feedbackamplifies a response, increases deviation from a set point. E.g.urination, defecation, contraction of uterus. Feedforwardinformation anticipates internal changes and changes the set

point. e.g. increase of heart rate before you begin the race.

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Epithelial tissues are sheets of densely

packed and tightly connected cells that coverinner and outer body surfaces. Epithelial cellsmay have protective, absorptive, or transport

functions. Connective tissue consists of cells embedded

in an extracellular matrix that they secrete.

The nature of the matrix differs among types ofconnective tissues, but an important componentis protein fiber secreted by the tissue cells. Themost common protein fiber is collagen.

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Muscle tissues are made of elongated cells

capable of contracting due to the sliding ofprotein filaments past each other.

Three types of muscles (smooth, cardiac, andskeletal) exist and their contractions areregulated by the nervous system in 2 ways

(voluntary and involuntary)

Nervous tissue serves as lines ofcommunication and controlling centers forbasically two main types of activities: muscular

AND secretory.

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Nervous System - brain and spinal cord and theperipheral nervous system. This is the master control

system. Cardiovascular System - the heart and the blood

vessels. Digestive System - from the mouth to the anus. Respiratory System - the respiratory passageway and

the lungs. Excretory System - kidneys, bladder, ureter and

urinary tract Endocrine System - the "other" master controlling

system that regulates homeostasis of all other organs,second to the nervous system

Reproductive System - organs and tissues forproducing the gametes.

Generally, the regulatory systems controlling the

activities of organs and organ systems consist of thenervous system and the endocrine system.

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NERVOUS SYSTEM

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Neurons are specializedcells of the nervous system

that receive, encode, andtransmit information.

Neurons with their support

cells (glial cells) make upnervous systems.

Most neurons have fourregions: a cell body,dendrites, an axon, and

axon terminals.

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Sodium-potassium pumps in all animal cells create gradients of Na+ and K+ acrossthe cell membrane. The inside of the cell is usually negative relative to the outside,because leak channels allow some ions (K+) to diffuse out. Ion channels in themembrane are selective and allow some ions to pass more easily. The directionand size of ion movement depends on the concentration gradient and the voltagedifference of the membrane. These two forces acting on an ion are itselectrochemical gradient.

Membrane potential is the electrical potential, the charge difference, across themembrane.Resting potential is the membrane potential of a resting neuron.An action potential, or nerve impulse, is a rapid, large change in membrane

potential. Action potentials are generated by openings and closings of ionchannels.

Some ion channels are gated: Open and close under certain conditions: Voltage-gated channels respond to change in voltage across membrane, Chemically-gated

channels depend on molecules that bind or alter channel protein, Mechanically-gated channels respond to force applied to membrane. Gated ion channels changethe resting potential when they open and close.The membrane is depolarized when Na+ enters the cell and the inside of theneuron becomes less negative. If gated K+ channels open and K+ leaves, the cellbecomes more negative inside and the membrane is hyperpolarized.

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Any stimuli (light, sound, touch) received by the dendrites arerelayed from the neuron as an electrical message. At the endof the axon, this message reaches a junction called thesynapse.

1. The presynaptic region is in the axon terminal. The cell thatsends the message is called the presynaptic cell.

2. The synaptic cleft is actually a space between the presynapticregion and the target.

3. On the post-synaptic or target side, there might be anotherneuron, or muscle or gland. The cell membrane at the post-

synaptic region has receptors specific for different types ofneurotransmitters. Once the neurotransmitter and receptorsare coupled, this will lead to further actions in the target cell.Acetylcholine is the most well known neurotransmitter, and isgenerally excitatory. The cell that receives the message is

called the postsynaptic cell.Synapses can be excitatory or inhibitory. Spatial summation adds

up messages at different synaptic sites.Temporal summation adds up potentials generated at the same

site in a rapid sequence.

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Nervous systems can be divided into CentralNervous System (CNS) and Peripheral NervousSystem (PNS). The brain and spinal cord together

constitute the central nervous system (CNS). The afferent portion of the peripheral nervous

system carries information to the CNS. The efferent

portion of the peripheral nervous system carriesinformation from the CNS to the muscles and glandsof the body.

Efferent pathways can be divided into a voluntarydivision (conscious movements) and aninvoluntary, or autonomic, division (physiological

functions).

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Neuronal circuits

It is important to remember that nervous systemsdepend on neurons working together. When perception or sensing "something" leads to

motor action with only the sensory and motor neuron

involved in the most simple circuit, a monosynapticreflex arc is formed. Most neuronal networks are more complex and

involve interneurons. Sensory input that activates the

motor neuron of one muscle also inhibits the opposingmuscle. This coordination is achieved by aninterneuron, which makes an inhibitory synapse withthe motor neuron of the antagonistic muscle.

Thus the reciprocal inhibition of antagonistic musclesinvolves an interneuron between the sensory neuronand the motor neuron and, therefore, at least twosynapses.

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Functional Subsystems of the Nervous System

The nervous system is engaged in many tasks at the sametime, a property known as parallel processing of information.

Specific tasks are carried out by subsystems, which include thespinal cord, reticular system, limbic system, and cerebrum.

The spinal cord conducts information between the brain andorgans of the body, integrates information coming from theperipheral nervous system, and issues motor commands.

In the spinal cord - grey matter is H-shaped, rich in neuronalcell bodies, also has glia and blood vessels; white matterinclude axon fibers which are myelinated and appear white;also has glia and fewer blood vessels.

Spinal nerves leave the spinal cord at regular intervals; eachone has two roots, one connecting to the dorsal horn of thegray matter and the other connecting to the ventral horn. Theplacement of the sensory (afferent) and motor (efferent)neurons are orderly: Sensory axons get into the spinal cord viathe dorsal horn, and the ventral horn contain motor neurons.

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The reticular activating system is distributed throughthe core of the brainstem (medulla, pons, and

midbrain). Information routed through the reticularsystem influences the level of arousal of the nervoussystem. For example, it controls sleep andwakefulness. Damage to the brain or spinal cord

below the reticular activating system can result inparalysis but leave sleepwake cycle behavior normal. Damage above the level of the reticular activating

system can result in coma.

The limbic system is important for the emotion, motivation,

emotional association with memory, feelings of pleasure andpunishment. The amygdala is involved in fear and fearmemory. The hippocampus is necessary, in humans, for theformation of long-term memory.

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The cerebral hemispheres are the dominant structuresin the mammalian brain.

A sheet of gray matter called the cerebral cortexcovers each cerebral hemisphere.

Under the cerebral cortex is white matter.

In general, the left hemisphere of the brain controlsthe right side of the body; the right hemispherecontrols the left side, except in the head. However,

the two hemispheres are not symmetrical with respectto all functions, e.g., language abilities reside in theleft hemisphere. Different regions of the cerebralcortex also have specific functions.

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Cerebral cortex can be further divided into regions or lobeseach with specific functions and all regions are connected via

the axons to connect various functional regions together. a. The frontal lobes - best described as having to do withreasoning, planning, coordinating, controlling, and executingbehavior. Deficits in this area of the brain create problems forthe individual such that they become impulsive and cannot planfor future events.

b. The parietal lobe integrates sensory information from variousparts of the body.

c. The occipital lobe is located behind the parietal lobe in theback of the head and its main function is to receive and processvisual information.

d. The temporal lobe sits beneath the frontal and parietal lobesand serves to receive and process auditory information. The

association areas of the temporal lobe are important for facerecognition and understanding spoken language.

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Peripheral Nervous System

PNS includes 31 pairs of peripheral (spinal) nerves fromneck down and 12 pairs of cranial nerves from headregion.

Cranial nerves may be purely sensory, purely motor, ormixed sensory and motor in function.Peripheral (spinal) nerve - 31 pairs, are mixed sensory

and motor in function.

Autonomic nervous system (ANS) is a subsystem of thePNS. ANS maintains steady state within the internalenvironment.

The autonomic nervous system is categorized into twoparts: the sympathetic and parasympatheticdivisions.

These two divisions work in opposition to each other,

one causing an increase in activity, the other adecrease.

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The passage way of images takes sort of a backward route When

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The passage way of images takes sort of a backward route. Whenlight passes through the cornea, it has to go through the aqueous

humor and vitreous humor in front and behind the lens to reachthe retina. When passing through the retina, it excites thephotoreceptors which are in the deepest layer of the retina. Thephotoreceptors release neurotransmitters which in turn affect

several layers of neurons. It is the ganglion cells that finallytransmit the visual information towards the vision centers of thebrain. Axonal processes from this neuronal layer form the opticnerve which exits from the eyeball to lead to the brain.

There are two types of vertebrate photoreceptors: cones

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There are two types of vertebrate photoreceptors: conesand rods. Rod cells are more sensitive to light. Cone

cells respond to different wavelengths of light for colorvision. Cones also provide the sharpest vision. Thefovea has only cone cells.

There are no photoreceptors where blood vessels andbundles of axons going to the brain pass through theback of the eye. This creates a blind spot on the retina.

The lens bends light and focuses the light passingthrough cornea and pupil to project to the back of theeye onto the retina. The thicker the lens, the moresharply the light is bent. The lens is almost spherical forfocusing near objects and much more flat or ovoid forfocusing distant objects.

To create three dimensional vision the eyes see overlapping

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To create three-dimensional vision, the eyes see overlapping,yet slightly different, visual fields. The brain integrates

information from two eyes in a crossed pattern.

The optic nerves from the two eyes appear to join together at

the optic chiasm. Axons from half of each retina cross in theoptic chiasm and go to the other side of the brain. Informationfrom the retina is transmitted through the optic nerve to a relaystation in the thalamus, and then to the brains visual

processing area, the occipital (or visual) cortex, whichintegrates visual information.

Cells in the visual cortex are organized in columns; the columns

alternate left eye, right eye, and so on.Cells in the border of a column are binocular cells which receiveinput from both eyes measure disparity of the stimulus and

where it falls on each retina.

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Understanding Higher Brain Functions

1. Input from spoken language

2. Input from written language

Brocas area, in the frontal lobe in front of the primary

motor cortex, is essential for speech. People with damage to Brocas area have speech

deficits, though they still can read and understandlanguage.

Wernickes area in the temporal lobe is more involvedwith the sensory aspects of language.

Damage to Wernicke s area leads to an inability to

speak sensibly or understand spoken or writtenlanguage.

Angular gyrus in the parietal lobe is essential forintegrating written language

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Learning: Modification of behavior by experience.

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Learning: Modification of behavior by experience.

Memory: What the nervous system retains.

Associative learning occurs when two unrelated stimuli become linked toa response.

A conditioned reflex is a type of associative learning.Types of memory:

Immediateevents happening nowShort-termlasts 10 to 15 minutes

Long-termlasts from days to a lifetimeMemories are transferred from short- to long-term.

Hippocampal or limbic system damage may prevent this transfer.

Declarative memory is of people, places, and things that can be recalledand described.

Procedural memory is how to perform a motor task and cannot bedescribed, e.g., how to ride a bicycle.

Memories can have emotional content.The amygdala is necessary for the emotion of fear and formation of fear

memories.Memories can also have positive emotional contentrecalling them

activates parts of the brain associated with pleasure.