Bio Final

Substrate feeders

Animals that live in/on food source and move by eating through it (Ex. Caterpiller, Earthworm)

Suspension feeders

Capture food particles from surrounding medium (Ex. Manta Ray, Whale Shark)

Fluid Feeders

Suck nutrient rich fluids from a living host (Ex. Mosquitos, Ticks)

Bulk Feeders

Ingest large pieces of food

**If you add pepsinogen to a test tube containing protein dissolved in distill water, not much protein** 

**will be digested. What inorganic chemical could you add to the tube to accelerate protein**

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**digestion? What effect will it have?**

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HCl or some other acid will convert inactive pepsinogen to active pepsin, which will begin digestion of the protein and also activate more pepsinogen. 

What are the four "food molecules" and what are the components of each?

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Proteins, nucleic acids, lipids, and carbohydrates

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**What is the name for the entire pathway that runs from mouth to anus?**

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Alimentary canal 

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**What kind of specialized rings of muscle regulate the movement of food as it passes through your intestines?**

Ileoceal 

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**What is the epiglottis and what is it doing during breathing and swallowing?**

The epoglottis is usually upright at rest allowing air to pass into the larynx and lungs. When a person swallows the epoglottis folds backward to cover the netreance of the larynx so food and liquid do not enter the windpipe and lungs. 

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The epoglottis is a flap of cartilage located in the throat behind the longue and in front of the larynx. 

What digestive enzyme breaks down proteins in the stomach? How is that enzyme created?

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Pepsinogen and HCl are secreted in the stomach. HCl converts some pepsinogen to pepsin. Pepsin in gastric juice begins to digest protein. 

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**How does your pancreas aid in digestion?**

Enzymes from the pancreas and cells of the intestinal wall digest food molecules. The pancreas is also responsible for neutrlizing the pH of the chime as it leaves the stomach.

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**In what organ are the majority of food nutrients absorbed into your body?**

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The small intestine 

What does it mean when we sav some nutrients are "essential?"

When we say some nutrients are "essential," it means that our body cannot produce them on its own and we must obtain them through our diet. These nutrients are necessary for our body to function properly and maintain good health. Examples of essential nutrients include vitamins, minerals, and certain amino acids. Must be provided by the diet

What is the endocrine system? How does it differ from the nervous system?

The endocrine system is a collection of glands that produce hormones to regulate bodily functions. It differs from the nervous system in that it uses hormones to communicate between cells, while the nervous system uses electrical and chemical signals. The nervous system has faster and less sustained responses while the endocrine has slower and more sustained

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**What are the differences between the central nervous system (CNS) and the peripheral nervous system (PNS)?**

Central nervous system (CNS): 

* The brain
* The spinal cord (vertebrates) 
* Sends Motor Info to the PNS

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Peripheral nervous system (PNS):

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* Located outside the CNS and consists of:
* Nerves (bundles of neurons wrapped in connective tissue)
* Ganglia (clusters of neuron cell bodies) 
* Sends sensory info to CNS

Axon

* Located Between Cell body and myelin sheath
* Propogates action potentials
* Carrys information long distances from one part of the neuron to another
* Some axons carry signals faster especially if the myein sheath is present

Dendrites

* Branches off from the cell body
* Receives signals from other cells

Myelin Sheath

* Wrapped around the axons
* Long skinny thing
* Speeds up signal transmission
* Action potential appears to jump through areas covered in myelin sheath

Synaptic (Axon) Terminals

* Transmits signal to other neurons of effector cells
* Transmits information to the next cell in the chain
* Located at the end of the myelin sheath opposite from the cell body

Action Potential

A nerve signal that is a massive change in the membrane voltage from resting potential to a maximum level and back to the resting potential.

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* A localized electrical event
*  Self-propagated in a one-way chain reaction along an axon 
* An all or nothing event 
* The frequency of action potentials changes with the strength of the stimulus

**What is myelin and how does it influence the speed of an action potential?**

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By acting as an electrical insulator, myelin greatly speeds up action potential conduction. Myelin is an insulating layer that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. It allows electri**c**al impulses to transmit quickly and efficiently along the nerve cells. 

**What is the difference between and excitatory and an inhibitory signal? What part of the neuron "determines" if a new action potential will fire?**

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* __Excitatory__- a neurotransmitter that excites the receiving cell or increasing its ability to develop action potentials
* __Inhibitory__- Inhibit by decreasing its ability to develop action potentials

If you can distinguish two points of pressure that are very close together on your hand, what does that tell you about the size of the receptive fields on vour hand?

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* They are smaller. Smaller = Better localization
* Receptive fields are the area of body providing input to a neuron 

Frontal Lobe

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* Future prediction
* Decision making
* “Thinking”
* Behaviorial inhibition
* The seat of personality
* Fluent speech production (Brocas Area)

Parietal Lobe

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* Sensory processing (taste temp touch) and planning of motor functions

Temporal Lobe

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* Auditory Processing
* Recognition of visual information (like faces)
* Formation of new memories
* Comprehension of language
* Wernickes area

Occipital Lobe

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* Visual processing and vision, damage can cause photosynsetive epilepsy.

Vitamin 1 Thiamine

From Pork, legumes, peanuts, whole grain

Interesting fact Helps turn carbs into energy for the body

Vitamin C

Citrus fruits, broccoli, tomatoes, green peppers

Interesting fact It can cause scurvy if you dont get enough

Mineral 1 Calcium

Found in milk and dairy products and dark vegatables

Supports bone strength

Mineral 2 chlorine

Found in table salt

Interesting fact Used for a lot of cleaning applications

Free response 2

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**Modern-day humans in developed countries must be vigilant to prevent obesity. Why does our evolutionary past, and how it influenced our bodies, make this battle even more difficult for humans today?**

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people carrying so-called thrifty genes that enabled the efficient storage of energy as fat between famines would be at a selective advantage. In the modern world, however, people who have inherited these genes deposit fat in preparation for a famine that never comes, and the result is widespread obesity. 

**The Sodium-Potassium pump helps to maintain the resting potential of a neuron. Describe the steps detailing how the pump works. Your answer should include the ions involved, where they are moving, how many are moving (at one time), and how it maintains specificity (think**

**"shapes").**

Ap stage 2 Depolarization

A stimulus \n opens some Na+ channels; \n if threshold is reached, an \n action potential is \n triggered

AP stage 3

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More Na+ channels \n open, K+ channels remain \n closed; interior of cell \n becomes more positive. \n Membrane polarity \n becomes the reverse \n of resting state. \n 3 \n 1 \n 2 \n 3

AP stage 1 resting state

Voltage- \n gated Na+ and K+ \n channels are closed; \n resting potential is \n maintained by ungated \n channels (not shown)

AP stage 4 repolarization

Na+ \n channels close and \n inactivate; K+ channels \n open, and K+ rushes out; \n interior of cell becomes \n more negative than outside

AP stage 5

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The K+ channels close \n relatively slowly, causing \n a brief undershoot.

Cell body

Processes information from dendrites

Nerve

* a bundle of axons traveling together

Electrochemical gradient

Combination of electrical gradient (more positively charged ions outside the cell more negative inside) and chemical gradient (more potassium inside more sodium outside)

Membrane potential

Difference in charge inside and outside the cell

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What is the resting potential of a neuronal membrane

\-70 millivolts (inside of the cell is approximately 70 millivolts less positive than the outside of the cell)

Established by electric gradient and chemical gradient

The point where the cell achieves electrochemical equilibrium

Electrochemical equilibrium

The concentration gradient and the electrical gradient for each ion are equal and oppisite

How do ions move across the membrane with their concentration gradient

Protein (IOn) channels

* The ions move through the channel through passive diffusion along their concentration gradient
* Some ion channels are always open but some require a signal to open or close (ex. three sodiums and a phosphate for sodium potassium pump)
* Voltage gated channels open when the membrane potential reaches a certain value
* Ligand gated channels open when bound with a specific molecule

Ligand gated channels open when

bound with specific molecule

Voltage gated channels open when

* opened when membrane potential reaches a certain value
* typically only allow one ion through at a time
* have channels for sodium and potassium
* Three states open closed inactive

Mechanically gated channels open

physical stimulus like changes in length or pressure

Are most ion channels selectively permeable

Yes this means they only let certain ions through (sodium potassium pump)

Graded potential

* a small change in membrane potential
* can vary in size and be positive or negative
* these are transient and often don’t result from the opening of voltage gated channels
* When this happens the neuron moves quickly to get back to resting potential
* This is accomplished by the sodium potassium pump

Sodium Potassium pump

* Uses energy from ATP hydrolysis to actively transport ions against their concentration gradient
* Three sodium out two potassium in
* For a neuron to be ready to fire it must be maintained around resting potential

Thresehold

* energy requirement to fire a neuron


* Around -55 millivolts
* Triggers an action potential at the axon hillock which then travels down the axon

Overshoot

when the membrane potential rises so much that it becomes positive and the sodium gate inactivation channel shuts

Repolarization

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* The change in membrane potential opens the potassium voltage gates as well although the open more slowly (after sodium gate)
* Due to potassium electrochemical gradient potassium flows out of the cell
* This makes the cell less positive and eventually negative

Hyperpolarization

* Cause by potassium voltage gate lowering membrane potential
* Potassium gate is slow to close which causes membrane potential to become more negative than resting potential for a brief period
* This is when potassium gates close
* Sodium channels close and inactivation gate opens

Absolute refractory period

* The period of time a neuron cannot fire another action potential no matter how strong the stimulus
* Prevents action potentials from happening again to quickly
* Prevents action potential from traveling backwards along the axom

Relative refractory period

* During hyperpolarization the sodium voltage gate closes and the inactivation gate opens
* This means if stimulated the sodium gates could open
* However it would take a larger than normal stimulus to activate these gates because the cell is hyperpolarized

Does the power or max voltage of an action potential change?

* No only the frequency of the action potential will change
* Larger stimulus allow the neuron to fire more freuquently due to the relative refractory period
* A neuron will fire many more times per second for a large stimulus (sharp pain) than a smaller stimulus (a slight breeze)