I need help with good solid answer that I can review with each one of these to l
ID: 73138 • Letter: I
Question
I need help with good solid answer that I can review with each one of these to learn any help would be wonderful
Nervous system
1) Describe the structural and functional subdivisions of the nervous system. Describe the three parts of a reflex, distinguishing the types of neurons involved in the reaction.
2) Describe the structural features of neurons and explain how these structures contribute to function.
3) Explain how resting potential is generated.
4) Explain how an action potential is produced and the resting membrane potential restored.
5) Explain how an action potential propagates itself along the neuron; why action potentials move in only one direction; and how action potentials relay different intensities of information.
6) Compare the structures, functions, and locations of electrical and chemical synapses.
7) Compare excitatory and inhibitory postsynaptic potentials.
8) Compare the functions of the somatic nervous system and autonomic nervous system.
9) Compare the structures, functions, and interrelationships of the parasympathetic & sympathetic divisions of the autonomic nervous system.
Digestion
10) Describe why metabolic rate varies depending on activity level, body size, and body temperature. Explain how ectotherms and endotherms thermoregulate.
12) Define and distinguish between suspension and suction feeders and feeding by active swimming.
13) Describe the role of the main hormones and enzymes involved in digestion & absorption
14) Name the functional components of saliva.
15) Describe the different types of chemical digestion that occur in the small intestine and explain how the structure of the small intestine promotes nutrient absorption.
16) Explain the role of accessory organs in nutrient absorption.
17) Relate function to the structure of the colon and the rectum.
18) Compare the digestive tracts of herbivores and carnivores.
19) Explain what happens to the nutrients that plants take up from the air and soil.
20) Explain how water is transported through xylem.
21) Explain how stoma allow leaves to regulate water loss and carbon gain.
22) Explain how phloem transports carbohydrates.
23) Explain how and why most plants depend upon bacteria to supply nitrogen. Describe the special relationship between legumes and nitrogen-fixing bacteria.
Explanation / Answer
NERVOUS SYSTEM: STRUCTURE AND FUNCTION
Nervous systems receive sensory input, interpret it, and send out appropriate commands
A.) The nervous system
– Obtains sensory information
– Processes sensory information
– Sends commands to effector cells (muscles) that carry out appropriate responses
B.) The central nervous system (CNS) consists of
– Brain
– Spinal cord (vertebrates)
C.)Peripheral nervous system (PNS)
– Located outside the CNS
– Consists of
– Nerves (bundles of fibers of sensory and motor neurons) and
– Ganglia (clusters of cell bodies of the neurons)
D.) Sensory neurons
– Conduct signals from sensory receptors
– To the CNS
E.)Interneurons in the CNS
– Integrate information
– Send it to motor neurons
F.) Motor neurons convey signals to effector cells
Neurons are the functional units of nervous systems
A.) Neurons are
– Cells specialized for carrying signals
– The functional units of the nervous system
B.) A neuron consists of
– A cell body
– Two types of extensions (fibers) that conduct signals
– Dendrites
– Axons
C.) Myelin sheaths
– Enclose axons
– Form a cellular insulation
– Speed up signal transmission
A neuron maintains a membrane potential across its membrane
A.) At rest, a neuron’s plasma membrane
– Has potential energy—the membrane potential
– Just inside the cell is slightly negative
– Just outside the cell is slightly positive
– Resting potential—voltage across the plasma membrane
A.) The resting potential exists because of differences in ion concentration inside and outside a cell
– Inside a cell
– K+ high
– Na+ low
– Outside a cell
– K+ low
– Na+ high
A nerve signal begins as a change in the membrane potential
A.) A stimulus
– Alters the permeability of a section of membrane
– Allows ions to pass through
– Changes the membrane’s voltage
B.) A nerve signal—an action potential
– A change in the membrane voltage
– From the resting potential
– To a maximum level
– And back to the resting potential
The action potential propagates itself along the neuron
A.) Action potentials
– Are self-propagated in a one-way chain reaction along a neuron
– Are all-or-none events
B.) The strength of the stimulus changes
– The frequency of action potentials
– But not the strength of action potentials
Neurons communicate at synapses
A.) Synapses are junctions where signals are transmitted between
– Two neurons
– Or between neurons and effector cells
B.) Electrical synapses
– Electrical signals pass between cells
A.) Chemical synapses
– Sending (presynaptic) cell secretes a chemical signal, a neurotransmitter
– The neurotransmitter crosses the synaptic cleft
– The neurotransmitter binds to a receptor on the surface of the receiving (postsynaptic) cell
Chemical synapses make complex information processing possible
A.) Some neurotransmitters
– Excite the receiving cell
– Inhibit the receiving cell’s activity by decreasing its ability to develop action potentials
B.) A neuron may receive information
– From hundreds of other neurons
– Via thousands of synaptic terminals
A.) The summation of excitation and inhibition
– Determines if a neuron will transmit a nerve signal
A variety of small molecules function as neurotransmitters
A.) Many small, nitrogen-containing molecule serve as neurotransmitters
– Acetylcholine is a neurotransmitter
– In the brain
– Between neurons and muscle cells
– Biogenic amines
– Important in the CNS
– Serotonin and dopamine affect sleep, mood, attention
– Amino acids important in the CNS
– Some are excitatory
– Some are inhibitory
– Neuropeptides
– Substance P mediates perceptions of pain
– Endorphins decrease perception of pain
– Nitric oxide
– A dissolved gas
– Triggers erections
CONNECTION: Many drugs act at chemical synapses
A.) Many psychoactive drugs
– Act at synapses
– Affect neurotransmitter action
B.) Caffeine counts inhibitory neurotransmitters
C.) Nicotine acts as a stimulant
D.) Alcohol is a depressant
ANIMAL NERVOUS SYSTEMS
EVOLUTION CONNECTION: The evolution of animal nervous systems reflects changes in body symmetry
A.) Radially symmetrical animals
– Nervous system arranged in a weblike system of neurons
– Nerve net
B.)Most bilaterally symmetrical animals exhibit
– Centralization—presence of a central nervous system
– Cephalization—concentration of the nervous system in the head region
C.)Vertebrate nervous systems are
– Highly centralized
– Cephalized
Vertebrate nervous systems are highly centralized and cephalized
A.) Central nervous system (CNS)
– The brain and spinal cord
– Contains fluid-filled spaces
– In ventricles of the brain
– In the central canal of the spinal cord
– Surrounding the brain
B.) Peripheral nervous system (PNS)
– Nerves—cranial nerves and spinal nerves
– Ganglia
C.) Two functional components of the PNS
– Somatic nervous system—mostly voluntary
– Autonomic nervous system (ANS)—mostly involuntary
D.) Somatic nervous system
– Carries signals to and from skeletal muscles
– Mainly in response to external stimuli
E.) Autonomic nervous system
– Regulates the internal environment
– Controls
– Smooth muscle
– Cardiac muscle
– Organs of various body systems
Opposing actions of sympathetic and parasympathetic neurons regulate the internal environment
A.) Parasympathetic division of ANS
– Primes the body for activities that gain and conserve energy for the body
B.) Sympathetic division of ANS
– Prepares the body for intense, energy-consuming activities
The vertebrate brain develops from three anterior bulges of the neural tube
A.) The vertebrate brain evolved by the enlargement and subdivision of the
– Forebrain
– Midbrain
– Hindbrain
B.) In birds and mammals
– Size and complexity of the cerebrum
– Correlates with their sophisticated behavior
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