3/28/13

I.
     B. Predation
          2.
               d. Keystone Predator
                    ii. Maintain Species Diversity- preys on the most commonly occurring species leaving more resources for the less commonly occurring species.
     C. Symbiosis- "living together". At least one species in the relationship has a lifelong dependance on the other. Three types:
          1. Parasitism (+/-)- When one species (parasites) lives off of and on or in another (host).
          2. Mutualism (+/+)- both species benefit.
               a. Flowering Plants and Pollinators- 70% of plants flower.

               b. Lichen- an alga and a fungus. Fungus excretes digestive enzymes break down substrate to get nutrients (N, P, S, Na+, K+, etc) and alga photosynthesizes to make sugars and fats. First step in soil formation.

               c. Commensalism- (+/0)- one species benefits and the other is unaffected. Epiphytes- plants that live on other plants- Orchids

Communities
I. interactions
A. Competition- resources. 2 types
1. Intraspecific- within the same species (population)
2. Interspecific- between 2 or more species. Leads to the Principle of Competitive Exclusion-when 2 or more species are competing fo the same resources, 1 will "win".  The other/s will either become extripated or they will shift their niche.  Niche- an organism's profession.  Leads to Resource Partitioning- resources are divided up by competing species.  Ex. elk, moose, deer/ broadleaf, conifers.  Exotic Species (non-native)- on the mainland the natives usually win.

Ecology part 3

III. Other Factors
    B.
       2. Survivor ship Curves

      3. Cohort Sizes
-Cohort: particular age class

IV. Population Survival Strategies: 
2 types:

 A. r-selected: (weeds, insects, rodents, fish, grasses)
Age at first Reproduce- Early
Lifespan- short
Maturity- Early
Number of Offspring-Many
Early Mortality?- YES
Parental Care?- NO
Size- Small
Succession Type- Pioneer

B. k-selected: (humans, larger trees, large herbivores)
Age at first Reproduction- Late
Lifespan- Long
Maturity-Late
Number of Offspring- Few
Early Mortality?- NO
Parental Care?- YES
Size- Large
Succession Type- Climax

Other Factors that Affect Growth

III. Other Factors that Affect Growth
      A. Sex Distribution
           1. In a polygamous population to max. growth: Females > Males
           2. In a monogamous population to max. growth: Females = Males
      B. Age Distribution
          1. The younger a population is, the faster it grows.

Ecology

Ecology- the study of the interactions between organisms and their enviorment. 4 levels:
1. Population- a group of individuals of the same species living within the same area. (Territory)
     2. Community- all of the populations that interact within a given area.
     3. Ecosystem- community plus all the abiotic- nonliving, factors that affect it.
     4. Ecosphere- gloabl ecology

Population Ecology
I. Population Dynamics- How populations change.
    A. Growth- what factors affect it?
         1. Emmigration (-) Movement out
         2. Immigration (+) Movement into
         3. Natality (+) Birth Rate
         4. Mortality (-) Death Rate
    B. Growth Rates- 3 types
         1. Arithmetic- same amount of increase within each growth period. Bad way to calculate growth. 
           

          2. Exponential- population grows by the same percent (%) each year. Use this when a population is small with lots of room to grow. (J-shaped curve)

            equation: delta N/delta t = rN
             delta N= change in # (unknown)
             delta t= change in time
             r= % rate (convert % to decimal)
             N= current #

Example:
cattle herd; 2011= 50, 2012=60, 2013= ?

delta N/1= rN

delta N= (.2)(60) = 12     60+12= 72

       3. Biological- population will eventually slow down and stop due to resource limitations.Eventually it will reach its carrying campacity- the maximum number a given enviorment can support on a long-term basis.
(S-shaped cuve)


Equation
 delta N/ delta t= rN(K-n/K)
K= carring capacity

Example:
cattle herd; 2011= 50, 2012=60, 2013=?

=(.2)(60)(100-60/100)
=(12)(.4)
=4.8 round to 5
=2013=65

II Regulation of Muscle Contraction
A. The Motor Cortex of the brain (Kenzie) releases motor impulse (Erin) down pathway leading to target muscle
B. It reaches the Synaptic Knob (Bryan) where a Neurotransmitter (Ach-Brennan) is released into the Neuromuscular Junction - the synapse between nerve and muscle
C. Ach bonds to receptor sites on the Sarcoplasmic Reticulum (SR-Holden) Membrane which surrounds and permeates muscle and also holds a resting charge. The SR will now "fire" and release Ca2+ (Carson) ions into the muscle fibers.
D. Ca2+ will now bond to Troponin (Maddie). Troponin is a smaller protein found along the length of a larger, cable-like, protein called Tropomyosin.
E. This causes the Tropomyosin cable to shift position exposing the Actin Binding Sites (Rachel) to the Myosin Heads (Bryar). RESULT: CONTRACTION.
NOTE: The regulation of Muscle Contraction (strength and duration) is directly controlled by the amount of Ca2+ that are bonded to Troponin molecules at any one time.

Muscle Contraction (Skeletal)

• Skeletal Muscles are arranged in Antagonistic Groups.
•  Every Muscle is connected on two sides by tendons.
• Muscles are composed of multicellular structures called muscle fibers (visible)
• Muscle Fibers are composed of long multinucleated cells that stretch across the entire muscle.
• Muscle cells are composed of subcellular tubules called Myofirils. Each myofibril is composed of two major protiens called myosin and actin.
• Each myofibril  is divided in structures call sarcrameres which are the structural and functional uint of a muscle.

I The Sacromere- muscles are made up entirely of these structures.
A. When a muscle is relaxed, there is a protien that covers the Actin Binding Sites and this will Not allow teh myosin bonds to bond, so the two fibers, Actin and Myosin will slide freely across one another.
B. However, when an electrical impulse is sent to the muscle, the actin binding sites are exposed, the myosin heads will bond to jthe creating crossbridges.
C. This changes the structure of the myosing head and it will ratchet the actin strand toward the A-Zone. closing the distance between the myosing head and the acting binding site.
D. Once this happends the Myosing head reverts back to it's original structure and position.
E. The head will now find a new actin binding site and the process will continue until:
1The muscle is fully contracted
2 The electrical impulse stops.
3ATP Runs out- cramp, Rigor rigor Mortis:I(Stiffness of Death)

Split Brain- Happens when the Corpus collosum is severed. Usually because of a surgical proceure, used to stop seizures in epileptics.  *(images seen from the right side are transmitted to the left and vice versa)
-The Visual cortex is in the occipital lobe, in the back of the head, this is where we "see" images.
-The Auditory cortex is in front of the Visual; this is where we "hear" -it is not counter (right ear to right brain, left ear to left brain)
-Motor cortex is between the Frontal and the Periatal lobe. (controls motor neurons) -Is Counter.
-Behind it, in the periatal lobe, is the Sensory cortex, where sensory neurons "report to"

Lecture 3/8/2013

III.Forebrain
     C. Hypothalamus-Thermostat, Chemostat (pH, blood sugar), site of Base Emotions (Anger, Euphoria, Hunger, Thirst, Sex)
     D. Cerebrum - 80%, Convoluted to increase surface area because majority of electrical activity is on the surface. Divided into 2 hemispheres (Left and Right) connected by the Corpus Callosum.

The Right Hemisphere controls and receives to and from the Left side of the Body and vice versa.
Vision - The Right Visual Field goes to the left Hemisphere and vise versa.

B) Broca's Area - Produces motor speech. 90% of us it is in the left hemisphere.
W) Wernicke's Area - Produces motor speech meaning.

The Brain

I. Hindbrain
    A. Medulla Oblongata- connects directly to spinal cord. Reflexes (coughing, sneezing, reflex arcs, etc.) Last structure to "die" when oxygen runs out. Responsible for basic body function: heart rate and breathing.
     B. Cerebellum- coordinates complex motor skills. Athletics, dance, etc.

II. Midbrain- (+ Hindbrain=Brainstem)
     A. Superior and Inferior Colliculi- involved in coordination of visual and auditory stimuli
     B. Reticular Fornation- "Internal clock." Regulates states of consciousness

III. Forebrain
     A. Basal Ganglia, Amygdala, and Hippocampus- Long-term memory
     B. Thalamus- Relay center for the brain.
     C. Hypothalamus- Thermostat

March 6, 2013

IV. Synapse
     A. Excitatory
          1. When the nerve impulse reaches the synaptic knob, sodium comes rushing in, making the interior positive. (35+)
          2. This knocks Ca2+ off of its binding sites on the inner membrane, and it bonds to the synaptic vessicles.
          3. This releases excitatory neurotransmitters into the synaptic cleft where it bonds to the receptor sites on the post-synaptic membrane of the next neuron.
          4. This opens the sodium gates, making the resting charge closer to the threshold (-50). It it reaches -50mv, it will "fire".
     B. Inhibition - post-synaptic neuron is less likely to fire.
          1. Same
          2. Same
          3. An inhibitory neurotransmitter is released into the cleft and it bonds to receptor sites on the post-synaptic neuron.
          4. This opens chlorine channelse and chlorine diffuses in, making the interior more negative (-90) and less likely to fire.

Note 1: All neurotransmitters must be immediately broken down by enzymes or else their effect will continue long after the impulse stops.

Note 2: These neurotransmitters are constatly battling with one another in the synapses of our body. The Parasympathetic Nervous System is the reason why our neurons are less likely to fire at night.

Note 3: Summation - When the sum total of Excitatory (+) and Inhibitory (-) neurotransmitters "add up" to the Post-synaptic neuron reaching the threshold. 2 types:
     1. Temporal - one or a few neurons are firing enough times within a given unit of time to achieve summation. (quickly putting your finger on a piece of ice)
     2. Spacial - many neurons fire at once and release enough neurotransmitters to achieve summation (putting your whole hand quickly on the table)

Beginning from All or Nothing- How, then, does one perceive the intensity of a stimulus?

1. The number of times a neuron fires per unit time (per second). Two different lag times: charges and reset time.
2. The number of neurons firing. Greater number of neurons firing means greater intensity.

IV. The Synapse - Junctions between neurons. 2 types of synapses:

1. Mechanical synapses - axon abuts the dendrite. Automatic transfer of electricity. 
2. Chemical synapse- axon doesn't abut the dendrite. Message goes from electrical to chemical and then back to electrical. All of our synapses are chemical. 

There are 2 "events"  that can happen at the synapse:
A. Excitation-when the pre-synaptic neuron releases an excitatory neurotransmitter to cause the post-synaptic neuron to be more likely to "fire."

March 1 The Action Potential

B. The Action Potential- When the Neuron "fires".
    1. A stimulus (motor or sensory) will cause the gated Na+ Channels to open more (unknown mechanism) at the 1st Node of Renvier at the Axon Hillock.
     2.This causes the resting charge to raise (become less negative)
     3.If, enough Na+ enters to get the charge to -50 Mv ( the Threshold) the Na+ channels open wide and Na+ comes rushing in causing the internal charge to move to +35 Mv (firing charge)
     4. Cl- will be left behind by the Na+ and for 1/2 of 1 ms the external environment is negative. This is the electricity.
    5. Most of the Na+ will travel laterally. The Na+ that travels into the cell body, has no effect, but the Na+ that travels to the next node will cause that to reach the threshold, and it will fire there.
    6. The Na+, again, will travel laterally. As it moves to the previous node, no effect will occur because the potential for firing has not been reset by the Na+/K+ pumps (it takes 3 ms to reset) this is why the impulse is 1-directional. But, when it travels to the node that is set to fire the same thing will happen there and this continues down the line to the end of the neuron.
All or Nothing Rule- When a neuron fires it will always fire at 100% intensity.