A&P Exam 2 Flashcards
Sections on Chapter 10 and 12
Pathways of ATP Synthesis
Anaerobic (makes some ATP)
glycolysis breaks down glucose to pyruvic acid in cytoplasm – occurs w/o oxygen, produces lactic acid (lowers pH and stimulates pain neurons)
Aerobic (makes a lot of ATP)
Continues oxygen supply needed, makes h2o and co2
Anaerobic glycolysis
E source for peak muscular activity
produces 2 ATP molecules per molecule of glucose
Breaks down glucose from glycogen stored in skeletal muscles
Produces lactic acid
Muscle Energy
Resting (fatty acid catabolized in mitochondria; ATP produced is used to build energy reserves) Moderate activity (glucose and fatty acids catabolized in mitochondria and ATP is used for contraction) Peak Activity (Most ATP produced thru glycolysis with lactic acid as by-product; mitochondria only supplies 1/3 ATP consumed) -- Oxygen consumption rates increase initially 3-4 then levels off --> to allow mitochondria to make enough ATP
What limits muscle energy during exercise?
Depletion of glycogen, blood glucose, loss of fluid and electrolytes
Fatigue
progressive weakness and loss of contractility from prolonged use
Causes:
ATP synthesis declines as glycogen is consumed
ATP shortage causes failure of membrane potential and excitability
Lactic acid lowers pH of sarcoplasm inhibiting enzyme function
Motor nerve fibers use up their acetylcholine
Endurance
ability to maintain high intensity exercise as based on maximum oxygen uptake and nutrient availability
VO2 max –> proportional to body size, peaks at age 20, larger in trained athletes and males
What is endurance dependent on?
Supply of organic nutrients
Fatty acids, amino acids, and glucose
Carbohydrate loading is used by some athletes to pack glycogen into muscle cells
Oxygen Debt
vigorous energy causes dramatic change in muscle chemistry
After exercise, rate of oxygen uptake doesn’t immediately return to previous levels
Oxygen Debt = extra amount of O2 needed to return body to resting state (typically extra 11 liters are consumed, depends on health of person tho)
What are the purposes for extra oxygen during oxygen debt?
Replaces oxygen reserves (myoglobin, blood hemoglobin, in the air of the lungs and in the plasma)
Reconverting lactic acid to glucose in kidneys and liver (Cori Cycle)
Serving elevated metabolic rate that occurs as long as body temperature remains elevated by exercise
What is the best diet for exercising?
High carb! you have extra glycogen storage for your body and you recover faster
Fats and Proteins have glucose, but it needs the liver to convert it to glycogen and it takes way longer and you won’t exercise as well
(of course, mixed diet is the best, just don’t cut out your carbs and sugar is worse than fat)
What are the functional characteristics of muscle fiber types?
Slow-twitch: type 1 fibers, 100 msec/twitch (fibers contract slowly and fatigue resistant (more mitochondria, extensive capillary supply)
Fast-twitch: type 2 fibers, 7.5 msec/twitch
What are the two ATP forming pathways?
oxidative fibers (slow-twitch) glycolysis fibers (fast-twitch)
White muscle
mostly fast-twitching, glycolytic
Red muscle
slow oxidative, red because of capillaries, myoglobin, and mitochondria
Strength and conditioning
Factors that increase strength of contraction
muscle size and fascicle arrangement, size of motor units, and frequency of stimulations, length of muscle at start of contraction and fatigue
Resistance training (weight lifting) stimulates hypertrophy due to synthesis of myofilaments
Endurance training (aerobic exercise) produces increase in mitochondria, glycogen, and density of capillaries
Neurons
generate and transmit nerve impulses
Neuroglia (glial cells)
supporting cells (all the other cells in nervous tissue that’s not neurons) – brace, separate, and protect neurons (includes phagocytes)
Central Nervous System
brain and spinal cord enclosed in bony coverings
Peripheral Nervous System
all nervous tissue outside CNS
Nerve
bundle of nerve fibers (bundle of axons) with connective tissues and blood vessels
Functional Division of PNS (sensory)
Sensory (afferent) divisions (receptors to CNS)
Receptos are sensory structures that detect change (ie: neurons or specialized cells like eye, ear, tactile corpuscles, Pacinian and Meissner’s)
Functional Division of PNS (motor)
Motor (efferent) division (CNS to effectors)
Effectors are target organs that respond by doing something
Divided into SNS and ANS
Somatic Nervous System (SNS)
Controls skeletal muscle contractions
Voluntary and involuntary
Autonomic Nervous System (ANS)
Visceral motor system
Autonomic regulation of smooth muscle, cardiac muscle, and glandular secretions at SUBCONCIOUS LEVEL (we don’t have control over this)
The Two Sections of the Autonomic Nervous System (ANS)
Sympathetic nervous system
General action to mobilize body’s resources under stress, to induce the fight-or-flight response
Continuously active at basal level to maintain homeostasis
Parasympathetic Nervous System
Slows heart rate, increase intestinal and gland activity, and relaxes sphincter muscles
Cocaine
inhibits removal of dopamine from synapses in some areas of the brain
Can cause long-term changes in reward system (even immediate use can cause intense changes in the VTA/Nucleus Accumbens)
Serotonin
CNS neurotransmitter: regulation of mood, appetite, sleep, muscle contraction, and some cognitive functions including memory and learning
SSRI’s – Selective Serotonin Reuptake Inhibitor (inhibits reabsorption of serotonin by synaptic knobs)
Gamma-aminobutyric acid (GABA)
Inhibitory effects
Function not well known, abundant in CNS and regulates neuronal excitability
GABA release appears to reduce anxiety (ie: Xannies)
Inhibitory GABA-ergic Synapses
Signal from axon hillock releases GABA, crosses synaptic gap and causes the release of Cl-
Neuropeptides
Larger than neurotransmitters (2-40 amino acids)
Stored in axon terminals as larger secretory granules - due to size, don’t need larger concentration and lasts longer due to longer time needed to break them down
Some can be triggered from non-neural tissue (ie: hunger pains/food craving from the stomach) and can also act as hormones
Neuromodulators
alter rate of neurotransmitter release (presynaptic neuron or change in postsynaptic cell's response to NT) Includes opiates (endogenous, natural, and semi-synthetic) affecting nociceptors (pain perceptor)
Mechanisms of neurotransmitter function
Direct (opening and closing gate of ion channel)
Indirect (using a secondary messenger to open the gate
Cessation and Modification of a Neural Signal
diffusion of neurotransmitter away from synapse
reuptake
breaking down neurotransmitter (acetylcholinesterase)
Spacial Summation
simultaneous stimuli applied at different locations that have cumulative effect
more than 1 synapse active at a time
