end of metabolism begin of nervous system

How man ATP are produced from a molecule of glucose entering the KREBS cycle aerobically?

32 ATP

How many ATP are produces from glycogen entering the Krebs cycle aerobically

33 ATP

How does consistent aerobic exercise improve lactate metabolism (the 'lactate shuttle')?

It improves transport of lactate away from working muscle via MCT1 and MCT4 transporters into the bloodstream. During exercise, that lactate travels to the liver or other tissues to be repackaged and used as a substrate to support ATP demands.

Once lactate reaches the liver, what happens to it (Cori Cycle)?

The liver converts lactate back into glucose via gluconeogenesis (the Cori Cycle), improving lactate clearance. Faster clearance raises your lactate threshold capacity. Lactate can also enter mitochondria, convert to pyruvate, and enter the TCA cycle via oxidative phosphorylation to help produce ATP.

Name the 5 things (know for exam!) that improve substrate use during exercise as an aerobic adaptation.

1) Increased mitochondrial enzymes, 2) increased capillary number & density, 3) improved blood oxygen transport, 4) higher cardiac output, 5) faster lactate recycling.

Besides substrate use, what other aerobic enzyme/substrate adaptations occur with training?

Aerobic enzymes increase (often from more/larger mitochondria); increased intramuscular glycogen stores (for aerobic & anaerobic use); increased intramuscular triglyceride stores (for endurance training).

Why does lactate threshold occur at a higher %VO2max with training?

Due to an increased ability to metabolize lipid, increased enzymes of the Krebs cycle and electron transport chain (ETC), and increased capillary density/number. This lets you maintain higher intensity before switching to anaerobic metabolism, and at a given submaximal intensity you rely more on lipid — sparing glycogen and limiting fatigue.

What 3 things make up 'aerobic metabolism at its best'?

1) Increased mitochondrial density & volume. 2) Increased blood supply (increased cardiac output + increased capillaries around muscle fibers for oxygen transfer). 3) Increased myoglobin within muscle fibers.

Since steady-state, lower-intensity cardio leans on fat for energy, is it the best method for improving body composition?

Short answer: no, not necessarily. All exercise has the potential to support positive body composition changes, but steady-state cardio isn't necessarily the BEST option for body recomposition in many cases.

Define the 3 separate concepts: body composition, fat metabolism, and the 'three very separate discussions.'

Body composition = fat mass vs. fat-free mass. Fat metabolism = the body's ability to break down and mobilize fat for energy. The three separate discussions are: weight loss vs. body recomposition vs. fat oxidation — plus energy expenditure tied to specific exercise types.

What 3 factors specifically affect fat oxidation (ability to mobilize fat for energy)? And what other broader factors affect weight loss/recomposition/fat oxidation overall?

Fat oxidation depends on: 1) substrate availability, 2) muscle mass levels, 3) training status & muscle activation. Broader factors: exercise variables, training status, starting health status, habitual diet, sleep, genetics (among others).

How much atp does a 16 carbon fatty acid chain net produce?

106 ATP

What are the fat energy sources available to the body?

Circulation chylomicrons/ triglycerides (minor source),

Adipose cell triglycerides

Muscle cell triglycerides

What stimulates the release of free fatty acids (FFA) from muscle triglycerides during exercise?

Epinephrine

Is fat contribution drug exercise diet dependent or fixed?

Diet dependent

At mildly intense (~25% VO2Max), what% of energy may come from fat, and from where?

About 80%, mostly from adipose issue-derived serum free fatty acids

At moderately intense exercise (up to 65% vo2max), where does fat-based energy shift to?

Fat-based energy now comes from muscle triglycerides rather than adipose tissue

What is the “crossover concept”

The balance between carbs and fa metabolism during sustained exercise - at low-to-moderate intensity

(<60% VO2max) lipoids are main fuel; at high intensity

(>75% VO2max) glycogen lysis and type II fiber recruitment shift the body to carb as dominant fuel source

What is the crossover point

Exercise intensity at which fat and carb utilization curves intersect

What three factors affect the crossover point?

1.) exercise intensity 2.) endurance training statues 3.) body comp

At high-intensity exercise (> 85% VO2Max), what happens to FFA oxidation and carb Oxidation

FFA oxidation decreases, carb oxidation increases.

Benefits of aerobic metabolism over anaerobic

No acidic byproduct, more total energy per substrate (though slower); can use fat and protein (not just carbs); waste products are water and CO2 (easily cleared).

*What are 5 mechanisms behind improved substrate use with aerobic training?*

1.) inc. mitochondrial enzymes 2.) inc. capillary n umber/ density 3.) improved blood oxygen transport 4.) higher-cardiac output 5.) faster lactate recycling

How does endurance training affect lactate threshold

Is occurs at higher % of VO2Max, allowing higher intensity before switching to anaerobic metabolism.

What is homeostasis and who coined the term?

The ability of an organism/ cell to maintain internal equilibrium by adjusting physiological processes;

Coined by Walter B. Cannon (Harvard, 1932)

5 exercise-induced challenges to homeostasis

1.) inc. body temp, 2.) changes in acid0base balance, 3.) hypohydration 4.) changes in blood pressure 5.) altered blood glucose

What is a positive feedback loop?

Loop that promotes/ intensifies a process - e.g. increased acidity during exercise further stimulating inc. blood flow

What is negative feedback loop?

Loop that diminishes a process to return o baseline - e.g., inc. body heat riggers sweating, which cools the body

What is a neuron?

A nerve cell that initiates, receives, and transmits info/ messages throughout the body

What are the 3 main components of a neuron and their functions?

Dendrites (receive impulses, send to CELL body); Cell body/ soma (contains nucleus, mitochondria, ribosomes); Axon (send impulse from cell body to another neuron or target tissue)

What % of CNS cell types are neurons?

~10%

What is an action potential?

En electrical charge/ impulse initiated and sent by a neuron once a threshold stimulus is reached

Why do axon lengths vary so much(mm to over a meter?)

Due to the distance from he spinal cord to the target cell (e.g., a tall persons axon from spinal cord to foot muscles

Describe 3 primary neuron structural types

1.) multipolar (many dendrites, single axon, multiple processes from cell body);

2.) Pseudo unipolar (sensory neurons, single fused axon + dendrite process);

3.) Bipolar (1 axon + 1 dendrite, primarily sensory

Describes the structure of motor (efferent) neurons

Cell body located in the spinal cord, Lon axon that innervates muscle fibers, short dendrites that receive impulses from other neurons

What are the 3 functional neuron types?

Sensory (AFFERENT) neurons - carry messages from sensory receptors to CNS;

Motor (EFFERENT) neurons - carry messages from CNS to muscles

Inter neurons - connect sensory and motor neurons

What is neuroglia, and what % of CNS cell do they make up?

Supporting cells that make up ~90% of CNS cells; cannot initiate/ conduct electrical signals by provide support/ nourishment to neurons and form myelin sheaths

What is the function of myelin sheaths

Inc. the velocity at which a nerve impulse travels along the axon

What is a synapse?

The point of connection and communication between two excitable cells

Describe the basic synapse communication process.

The presynaptic neuron releases a neurotransmitter, which diffuses across the synaptic cleft; if enough binds to receptors on the target cell, a response is triggered

Q: What is a neurotransmitter?

A chemical substance that binds to and activates a receptor on a target cell

What are receptors, and what do they bind to?

Proteins designed to bind specific substances (ligands) such as neurotransmitters or hormones; each neurotransmitter has its own unique receptor for communication accuracy

What happens when a neurotransmitter binds to its receptor?

The receptor opens ion channels — each receptor type allows only one type of ion to pass through

Outline the overall nervous system organization from top down.

Nervous System → CNS (brain, spinal cord, interneurons) & PNS (motor/efferent and sensory/afferent neurons) → Somatic (voluntary) & Autonomic (involuntary) Nervous Systems → Autonomic splits into Sympathetic ("fight or flight," noradrenaline) & Parasympathetic ("rest," acetylcholine)

What neurotransmitter drives the sympathetic ("fight or flight") system?

Noradrenaline (norepinephrine) — adrenergic system

What neurotransmitter drives the parasympathetic (relaxing) system?

Acetylcholine — cholinergic system