Bio-1030
Describe a negative feedback loop
Stimulus that opposes the outer stimulus to return to the set point (ex, sweating as a response to heat)
Describe the structure of the phospholipid bilayer
A polar, hydrophylic, head and non-polar, hydrophobic, tails
What type phospholipid chain is the most fluid?
Short and unsaturated
How does the cell maintain homeostasis
Acting as a selective barrier
Describe active transport
Movement from an area of low concentration to an area of high concentration (against the concentration gradient) with the use of ATP
Isotonic
When the concentration of solute inside the cell is equal to the concentration outside the cell
what are the two systems used to maintain homeostasis?
endrocrine system and nervous system
briefly describe the Endrocrine system
Releases hormones throughout the body, influencing distant cells in a slow and widespread response
How does the endocrine system release hormones?
with endocrine glands into the capillaries
What must a target cell have in order for a hormone to act on it?
A receptor molecule that recognizes the hormone
stimuli is recieved by the_____
Dendrites and cell body
synaptic stimuli is summed at the ____
Axon Hillock
what does the Na+-K+ pump do when the neuron is at rest?
pumps Na+ ions out of the cell and K+ ions into the cell
Why is there a negative resting potential inside the neuron?
The K+ ions leaking out the cell
At rest, a cell is ____ charged inside
negativley
What is resting value of the cell?
-70mV
Difference between primary and secondary active transport
Primary active transport uses ATP while secondary uses an electrochemical gradient
When a neuron gets excited it becomes ___
less negative/depolarized
what causes the positive spike in membrane potential
rapid fire of Na+ ions into the cell
what leads to depolarization?
Na+ channels closing at a membrane potential of +40mV, with K+ channels remaining open, allowing ions to leave the cell
What causes hyperpolarization?
An overshoot in K+ ions that leave the cell
Why cant a neuron fire another action potential during the refractory period?
Na+ channels are closed and K+ ions are open
What does "refractory period" refer to?
When the inside of the membrane voltage is below resting point (below -70mV)
What prevents the "leaking" of positive ions out the axon?
Myelin sheath
When a signal is excitatory this means...
the cell is depolarized
when a signal is inhibitory this means...
The cell is hyperpolarized
hearing relies on...
mechanoreceptors
An Endotherm refers to...
An animal that generates heat to maintain its body temperature (human)
An ecotherm refers to...
An animal whos body temperature is determined by its enviornment (fish)
A homeotherm refers to...
An animal that has a generally stable body temperature by balancing heat loss and gain
A pokilotherm refers to...
An animal with a variable body temperature
With an increase in temperature, an ectotherms metabolic rate will...
increase
an endotherms metabolic rate is lowest when...
they are doing absolutely nothing
How does body size impact metabolic rate?
Metabolic rate increases with body mass raised to the 3/4
true or false? A gram of mouse has a higher metabolic rate compared to a grame of elephant while a whole elephant has a higher metabolic rate compared to a whole mouse?
true
Musles are composed of...
multinucleated fibers
what are the two proteins muscles use to generate force?
Myosin and actin
describe the organization of skeletal muscles
Muscle belly- Muscle bundle- Muscle fiber- Myofibril
Describe the structure of the myofibrils
thin and thick filaments wrapping around them. Two thin actin filaments and thick myosin filaments
what is a muscle fiber?
a single muscle cell
what is a sacomere?
The contractile unit of muscle (where the muscle contracts). The region between two Z-discs
What type of filaments are actin?
thin filaments
what type of filaments are myosin?
thick filaments
What is titin?
coils that function that a spring to prevent muscles from stretching too far
What is sliding filament theory?
During a contraction your muscles do not shrink. The actin and the myosin overlap.
How does the cross bridge cycle begin?
Myosin binds to ATP, causing it to detach from actin
What is step two of the cross bridge cycle?
The myosin head catacyzles the hydrolysis of ATP, forming ADP and P, causing the myosin head to cock back
What is step 3 of the cross bridge cycle?
After the myosin head is cocked back, the head binds to actin, forming a cross bridge
How does the cross bridge cycle end?
ADP and P are released, causing a power stroke that generates force and causes the thin filament to slide relative to the thick filament and the sarcomere to shorten
How would the cross bridge cycle be affected by a lack of ATP
Actin and myosin will remain bound
What are the two steps to bulk flow?
Ventilation and circulation
when can the cross bridge cycle take place?
When myosin binding sites on the actin are exposed
What are the two proteins that allow the myosin binding sites to be exposed?
Calcium ions bind to *troponin* which causes the movement of *tropomyosin*, exposing the binding sites
What causes muscles to contract
signals from motor neurons, causing *depolarization* of the skeletal muscle cell
binding of neurotransmitter to receptors on a vertebrate muscle cell causes
An influx of sodium, causing depolarization
where does maximal force come from?
A lengthening muscle contraction
What does muscle force depend on?
stimulation frequency
What is forced summation?
The result of repeated muscle stimulation
What is tetanus?
The contraction of muscles after forced summation
Why is a motor units size significant?
Controls how finely a muscles force can be controlled
ex. fingers have thin motor neurons for precision while lets have thick motor neurons
A sprinter would have what type of fiber and why?
Fast twitch fibers as they are large and are able to generate great amounts of force quickly
A marathon runner would have what type of fiber and why?
Slow twitch fibers as they develop force more slowly, are well supplied with oxygen and resist fatigue
What is active ventilation?
Expending metabolic energy to contract the muscles of the respirtory system creating ventilatory currents (humans breathing)
What is passive ventilation?
When the enviornmental air or water currents induce flow to and from the gas exchange membrane with no use of metabolic energy (ex.aquatic animals)
Fish have ____ respiration and ____ blood flow
unidirectional and countercurrent
What is responsible for the efficiency of gas exchange in fish gills?
A large surface area for gas exchange, minimized path length for diffusion and counter-current flow of blood and water
____ pressure draws air into the lungs and ____ pressure expels air from the lungs. This is called ____
negative, positive and tidal ventilation
Gas exchange takes place where?
The alveoili
What signals the chemoreceptors to stimulate the respiratory muscles?
High CO2 levels
Are red blood cells needed for a functioning circulatory system?
suprisingly no
What are the components of mammal blood?
Plasma, white blood cells, platlets and red blood cells
Why is having a high hematocrit good?
It allows more oxygen to flow to the tissues
Does CO2 or O2 have a higher solubility in plasma?
CO2
How is O2 transported?
O2 diffuses into blood, then RBC and then binds to a heme group
Whats an open circulatory system?
When blood is not enclosed in the blood vessels
Where would you find O2 in a mammals bloodstream?
Dissolved in blood plasma and attached to heme groups of hemoglobin in red blood cells
Which vessel takes blood away from the heart?
artery
Which vessel delivers deoxygenated blood to the heart
veins
What direction does blood flow through the heart
right atrium- right ventricle- left atrium- left ventricle
Where does blood enter the heart?
superior vs inferior vena cavas
How do cardiac muscle cells differ from skeletal muscle cells?
cardiac cells generate action potentials on their own, independently of the nervous system
What protein transmits electrical signals in cardiac cells
gap junctions
What causes contraction in the heart?
depolarization of the pacemaker
What are the essential components of homeostasis?
Sensors, effectors and responses
What would be an organism that does not maintain homeostasis?
Conformer
What is acclimatization?
A reversible and slow response to an enviornmental change
What composes the cell membrane?
lipids, proteins and carbohydrates
Why are unsaturated fatty acids more fluid than saturated ones?
Double bonds reduce tightness
What is facilitated diffusion?
A form of passive transport that allows larger molecules to cross a cell membrane with the help of channel proteins.
is ATP required for facilitated diffusion?
No
What is osmosis?
movement of molecules from an area of high concentration to low concentration
What is the metabolic rate?
The overall rate of energy use by an organism (can be measured in oxyen)
who made the mimic?
Edwin