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