BIO Exam 3

Action Potential

Depolarization and depolarization of an excitable cell

Mechanoreceptors

- pressure ---> depolarization of the cell
- Frequency of the action potential reflects the amount of pressure being applied
- more pressure --> more frequent action potential
- respond to movement and forces (touch, feel, hearing)

Chemoreceptors

- Molecule binds to protein receptor which leads to depolarization of cell
- Means of detecting food
- Smell (olfaction)
- respond to chemical substances

Thermoreceptors

Respond to heat

Photoreceptors

- respond to light
- relaxation/contraction of the lens determines level of focus

Lateral Inhibition

if a given neuron is activated then neighboring neurons can be inhibited which sharpen the edges (sharpens perception)

Light

changes shape of retinal molecule
g-protein coupled receptor is activated
cell is hyper-polarized

Opsins

most animals only have 3 (green, red, blue)

Graded Potential

refers to membrane potential which can vary by amplitude

Structure of Muscles

- Muscles grouped together in a bundle which group together
- Sarcomere --> Myofibril --> Muscle Fiber

Muscle Fiber

- Elongated cells and have many nuclei

Motor Unit

- Smallest functional unit of the nervous system
- Each fiber is controlled by one motor neuron
- Single motor neuron can control multiple muscle fibers

Actin and Myosin Interaction

- Myosin head binds to ATP which leads to detachment from actin
- Myosin head catalyzes hydrolysis of ATP forming ADP and P
- Myosin head binds to actin forming cross bridge

Muscle Contraction

- Action potential from the motor neuron leads to release of ACH and depolarization of muscle cell
- Depolarization leads to release of Ca2+ and causes change in Ca2+

Slow Twitch Muscle Fibers

Move more slowly and help the body moving longer

Fast Twitch Muscles

Help you move faster but for shorter periods of time

Hydrophilic Hormones

- Do not cross lipid bilayer
- Activate signal transduction pathways
- Responses occur more quickly
- Effects last hours and not long lasting
- Receptors located on the outer cell membrane surface

Hydrophobic

- Cross lipid bilayer
- Alter gene expression and produce protein
- Response is slower
- Effect can last days/months
- Binds to intracellular hormone receptors in cytosol or cell nucleus

Releasing Hormones

Are peptide hormones, produced in the hypothalamus

Direct Hormones

Act directly on the non-endocrine tissues

Positive Feedback

- occurs to increase the change or output
- results of a reaction is amplified to make it react more quickly (contractions in childbirth)

Negative Feedback

- Occurs to reduce or change output
- Results of reaction is reduced to bring back system to stable state

High Blood Sugar

- Pancreas signaled ---> Insulin released
- Muscle and liver take up glucose and store is as glycogen
- Decrease in blood glucose

Low Blood Sugar

- Pancreas signaled ---> glucagon released
- Muscle and liver break it down and release glycogen
- Glucose released ---> increase in blood glucose

Determination of where blood flows

smooth muscle relaxation and contraction determines where blood flows

Bulk Flow

* movement of substances through a vessel or tissue due to pressure differences

Arteries

- More oxygenated
- Carry blood away from the heart
- lower volume (10-15%)
- Higher pressure

Veins

- Less oxygenated
- carry blood towards the heart
- higher volume (65-70%)
- lower pressure

Pressure in capillary beds

- Pressure higher on the arterial side where unloading occurs
- Pressure lower on the venous side where loading occurs

Pathway of blood

- Deoxy. blood enters from right atrium form the inferior and superior vena cava
- Deoxy. blood passes through the right aortic valve and enters the right ventricle
- Deoxy. blood is pumped in the pulmonary arteries and through the pulmonary valve
- Oxy. blood returns from the lungs to the left atrium
- Oxy. blood enters the left ventricle through the left aortic valve
- Oxy. blood is pumped by the left ventricle through the aortic valve into the systemic circulation

SA (sinoatrial) Node

pacemaker, generates an electrical signal that causes the heart atria to contract

Sympathetic Nervous System

- releases epinephrine and norepinephrine to speed up the heart rate
- System controls the fight or flight response and prepares body for strenuous activity

Parasympathetic Nervous System

- releases acetylcholine to slow down the hear rate
- System regulates functions, regulates during times of rest

Pathways of Contraction in Atria and Ventricles

- SA Node generates action potential that spread through the atria and contract in unison
- Signals from the SA node reach the AV node which activates and fires
- Action potentials are transmitted through a set of modified muscle fibers
- The polarization spreads from the modified muscle fibers through the entire ventricle and contracts

Rhythmic Action Potentials and Ion Channels

- Acetylcholine binds to G-protein coupled receptor that triggers opening of K+ channels, hyper-polarizes and closes the Ca2+ channels ---> slowing of heart rate
- NE binds to G-protein coupled receptor that triggers the opening of Ca2+ channels, depolarizes ---> increase in heart rate

Nitrogenous Waste

Must be eliminated by renal organs

Glomerulus

- Filters blood
- As blood enters each nephron it enters clusters of tiny blood cells (glomerulus)
- Thin walls of glomerulus allow smaller molecules, wastes and fluids to pass into tubules

Concentration Gradient in Kidney

- Nephron generates and provides opportunity to control what is excreted

Nephron

- Unit is repeated over and over to make the final structure of the kidney

Loop of Henle

- primary function is the recovery of water and sodium chloride
- Allows the production of urine that is more concentrated than blood which limits the amount of water needed for intake
- Consists of the descending and ascending limbs

Descending Limb

- Permeable to water, liquid reaching the bend of the loop is reacher in salt and urea and does a passive transport of water

Thick Ascending Limb

Liquid returns through the limb and sodium chloride diffuses out of the tubule into the surrounding tissue where the concentration is lower

Thick Ascending Limb

the tubule wall can effect further removal of salt, even against the concentration gradient in an active transport process

ADH

Peptide hormone, allows for reabsorption of water coming out kidney

Hemoglobin

- has 4 subunits (quaternary structure)

CRH

- can act as a neurotransmitter when released from neurons in the brain
- can produce a sense of anxiety/fear in certain regions

Surface Area of Digestion

increasing surface area allows for better access to breaking down food, for digestion and absorption

Peristalsis

series of muscle contractions in the digestive tract

Amalyase

found in saliva, breaks down starches, carbohydrates

Lipase

breaks down lipids

Pepsin

breaks proteins into amino acids

Large Intestine

- reabsorption of water, minerals, ions (Na & Cl)
- Formation of storage and explusion of feces
- Houses bacteria

Hepatic Portal System

venous system that return blood from the digestive tract and the spleen to the liver

Leptin

peptide hormone released by fat cells in proportion to adiposity, it is released in proportion to how much adipose tissue you have in your body

Evaporation

great amount of heat is lost in transition of liquid to gas, lots of energy occurs

Conduction

direct transfer of thermal motion between molecules of objects in direct contact, heat goes from higher to lower temp. object

Radiation

electromagnetic waves of all objects, can transfer heat between two objects not in direct contact

Convection

transfer of heat by movement of air or water

Inhibitory Postsynaptic Potential

temporary hyper polarization of postsynaptic membrane caused by the flow of negatively charge ions into the postsynaptic cell , pushing away from the threshold

Excitatory Postsynaptic Potential

synaptic inputs that depolarizes the postsynaptic cell, bringing the potential closer to threshold and closer to firing an action potential

Cardiac Muscle

branched and striated, each fiber has a nucleus and at the end of intercalated discs

Smooth Muscle tissue

not striated, smooth, one nucleus in each fiber, found in digestive system, arteries and veins, bladders