ANSC 3311 Exam 1

Homeostasis

The state of equilibrium in the living body with respect to various functions and to chemical composition of the fluids and tissues

Examples of homeostasis

Body temp, pH, blood pressure, heart rate, oxygen and hydration

Regulation

Maintained within very narrow limits

Control

Can vary widely from their normal steady state with no harm caused

Controls are required

to achieve regulation

Ie: change in heart rate can alter how blood pressure is controlled

The control system

A group of interconnected and interacting components relating a given input to a given output

(blood pressure: heart, vasoconstriction/dilation)

Output =

Input in many closed systems

Components of a Control System

Measure of a system by output ( the regulated component)

Controlled system produced by the output

Sends signal to integrator usually in CNS

Integrator takes note of whether or not the output is correct based on the input

Error sent to the controller usually in the CNS controls the signal to that system

If no error system continues normally

In error state they send a signal to indicate what needs to change within the controlled system

Closed Loop

Continuous loop ( most physiological properties are closed loop) Output=Input

Open Loop

Output doesn't regulate input (something requiring lots of power in a short time, like kicking a ball)

Setpoint

Set area that the input wants you to be at (preferred point of variable) can change temporarily

Servomechanism

The control system, what responds to change in output

Gain

Ratio of output to input when =1 it's a steady state and nothing is changing

Steady-States

Ratio = 1

Transient response

Between steady states, period of adaption (time that it takes is called the lag time)

HR (msec)

Some adjust quickly some slowly (lag time changes)

Blood Glucose example

Regulated based on availability

Insulin: controlled

Anaerobic

Can occur in an oxygenated state but also without oxygen

Requires glucose and energy investment step

NADH and ATP may go to ETC

In absence of oxygen only makes ATP and Lactate

Occurs in cytosol

ATP is _____ in Myokinase

AMP

PCr

In muscle with fairly limited store can come with ADP to create ATP (can only sustain power outage for about 10 seconds)

Energy stores

Horse has a massive amount of glycogen in muscle: gives greater anaerobic capacity

Production of NADH and FADH

Occurs in the mitochondria

Fatty Acid Oxidation

through beta oxidation allows for use into ATP (small energy investment step)

129-130 ATP production

"Fat burns in a flame of carbohydrate" Why?

Oxaloacetic acid is a byproduct of glycolysis and is required for complete oxidation of FFAs

"Fat burns in a flame of carbohydrate" What does this mean?

MUST have some level of glucose/glycolysis to utilize FFAs, can never completely rely on fat as an energy source CHOS always required

Energy Sources

CHOs

-Glycogen

-Blood Glucose

Fat

- Intra- and extra-

stores

Protein

Major sites of glycogen storage

liver and muscle

Glycogen can be depleted by

a lot of exercise

Blood glucose is an

immediate source of CHOs but if no other source of CHOs you will fatigue

Fatty acids

Muscle does not contain some fat, immediate energy store

Protein

Can be used but it is not desirable, it is pulled from broken-down muscle, generally a last resort

(I.e.: starvation, long or high intensity can also cause this)

Aerobic Respiration

Respiration that requires oxygen

CHO, fat and protein substrates

36-138 net ATP

CO2 end product

Slow rxn time

lasts hours

Fick Principle

Can measure extraction/utilization of a substance using venous and arterial concentrations and flow rates

Fick Principal Equation

VO2 = Q x (a-v) x O2

Q= Cardiac Output

A= Arterial

V= Venous

O2= Hormone/ metabolite

High arterial concentration indicates

Usage

High venuous concentration indicates

production

Respiratory Exchange Ratio

RER = VCO2/VO2

RER meaning

> 1.0 = anaerobic

1.0= CHO

0.7-0.8 = CHO, Fat

<0.7 = Fat

Energy Expenditure

VO2: Oxygen uptake (measure of aerobic metabolism of an individual)

VO2 max: max aerobic capacity of an individual

Relative value is the ratio of the two

Body cares about relative cost of VO2 max

VO2 max is effected by

Health

Age

Fitness status

Altitude

Effect of Speed and Slope on VO2

VO2 max will plateau at a certain point, and is adaptable based on a variety of factors

Oxygen deficit

Lag in consumption at the start of exercise

EPOC

Oxygen debt (excess post exercise oxygen consumption)

Always larger than the deficit because slow phase takes more time to achieve homeostasis

Fast phase

Primarily the drop off

Slow Phase

Replenishing enzymes, protein repair and tissue repair

Metabolism

Sum of all chemical rxns occurring in a living organism

Energy conservation

Chemical energy -> electrical or mechanical energy -> heat

Catabolism

Breakdown of complex substances

Anabolism

Build up of complex substances

When there is a catabolic and anabolic balance

No net charge

Greater catabolism there is

a loss of process

Ie. Bone loss

Greater anabolism

there is growth

Appropriate in young animals

Inappropriate can result in tissue damage or injury

Energy Metabolism

Energy usage by an organism

The rate at which organized energy is converted into heat

Direct calorimetry

Measure of heat production (kJ or Cal) Primarily through O2 consumption, good for aerobic metabolism

Indirect calorimetry

Measure chemical changes

exercise harder to perform due to equipment needed

C6H12O6+ 6O2 -> 6CO2 + 6 H2O + Energy (673 Cal , 2820 kJ)

CO2 production

is not as effective a measure of energy metabolism as O2 consumption

Can change easily through non-metabolic processes

I.e. hyperventilation

Energy yield per mL of Co2

varies greatly

What effects metabolic rate

Physical activity: individuals with greater lean mass have greater metabolic rate

Environmental Temperature: cold raises basal metabolic rate

Digestive processing

Body Size

Age: slows as you age

Sex: males have higher metabolic rate

Endocrine Activity

Circadian Rhythms: decreases as you sleep

Basal Metabolic rate

BMR

Temperature in thermal neutral zone

Fasting

Resting

Amount of energy an organism needs just to stay alive

Surface Area

Body mass

Horse: large body mass not a lot of surface area

Dog: less body mass to surface area

Gravity effects

Circulation

Movement and Locomotion

Surface area/ Volume ration effects

Respiration

Digestion

Water Balance

Thermoregulation

Bipedal vs Quadrupeds

Metabolism and body size

Smaller animals have higher metabolic rate than larger animals

Kleiber's Rule

For eutherian mammals

Oxygen consumption (VO2)=(Mass)^0.75

Small animals have relatively more per gram VO2 as an elephant

Roles of skeletal system

Locomotion

Protection of vital organs

Provides structure

Bones and joints create levers

Attachment for muscles

Functions below physiological limit

7-10x normal force to cause failure

Tendon and Ligament structure

Mostly extracellular matrix

Very few actual cells, with exception of fibroblasts

Water is a very important component that acts as a lubricant

Allows college to freely stretch

ECM

Proteoglycans

Glycosaminoglycans

Collagens

Crimp Pattern

Organized become more linear as they stretch, if damaged pattern is disturbed fibroblasts produce extracellular proteins

Bone Structure

Weight bearing bones, mostly long bones

Site of red and white blood cell development

Compressive forces are supported by inorganic mineral content to provide resistance to outside forces

Bone cells minor component

Tissue Turnover

Normal

Repair/regrowth of damaged tissue

Rate dependent on tissue

Tissue Turnover: tendons and ligaments

Very slow process

Very few fibroblasts and are relatively inactive therefore takes longer

Metabolic capacity is limited

Tissue Turnover: Bone

Repairs much faster but still limited

More metabolically active can repair quicker

An entire skeletal system can turnover in three years

Bones respond relatively rapidly when new pressure is exerted

Modeling

Change in the size or the shape of the tissue

In bone an independent action of osteoclasts and osteoblasts which results in change in shape or size of bone

Tissue needs change such as muscle mass growth due to power lifting

Remodling

Coordination reaction of absorption and growth

Osteoclast resorb and osteoblast replace tissue

Size and shape do not change

Tissues needed to adapt to activity or changes in activity such as damage occurring

Inactivity

Joint immobilization, bed rest, horse on stall rest

Changes in composition

Less collagen fibril density, fewer small fibers and greater amount of larger fibers impacts flexibility of that tendon or ligament, decreased water and proteoglycan content (decrease lubrication properties) can disrupt parallel nature of collagen fibers

Cannot stretch as well

Activity

Maintain tendons and ligaments to 80-90% of their maximal capacity, only 10-20% increase during

Increase in proteoglycan content, increased collagen. Actual change is fairly limited

Functional Adaptation

Long term exercise will increase bone mineral density which increases the strength of the bone, increases in cross sectional area of the bone, allows the pressure on the bone to be distributed over larger surface area so there is a decrease in stress

Structural Changes

Changes in bone size and thickness: increase amount of bone

Material Changes

Important to consider, new bone first starts as collagen and first has different mechanical properties, can have areas that are stronger than other areas. Progression and will have different properties until calcification

Negative Effects of adaptation

Extremely intense or frequent exercise can cause micro damage in the bone and without rest can become micro fractures which lead to fractures. Rest is crucial for positive effects to bone

Bone Mass

influenced by age

Peak in late teens and early 20s

Rate of loss more rapid when exercise is stopped

Cardiovascular: swimming, biking not much load bearing on bones

Running: increase bone mass

Mechanotransduction

How a cell interprets mechanical cell/movement

Mechanocoupling usually through a sensor: such as stretch

Different cell types have different mechanosensors

Biomechanical coupling

on a cell membrane or in a cell: the receptor changing the signal it is receiving, stimulation of cell signaling pathways, release of paracrine or autocrine factors

Changes in gene and protein expression which changes function

Cell to Cell signaling

Not usually one cells that receiving the signaling, many cells working together to carry out the response

Hierarchal Tissue

Muscle fibers grouped together: surrounded by connective tissue

Vasculature

Blood supply

Myofibrils

Arranged in a way that they can contract

Multi nucleated

Support metabolism of that cell, many mitochondria

Muscles are arranged in

sarcomeres, stacked end on end, smallest unit of contraction, the shorter to allow contraction. Fibers slide along each other

Terminal of cisternae

T Tubule responsible for ca 2+ storage and release critical for contraction

sarcoplasmic reticulum

Criss-crosses inbetween myofibrils

Myosin

Thick filament

Actin

Thin filament

In resting state actin and myosin

overlap

In contracting state actin and myosin

they slide along each other, the length of actin and myosin filaments is constant

Head walks along myosin

Z line

Where sarcomeres attach end to end: it wouldn't shorten muscle if there were mitochondria in the sarcomere

Neuromuscular Junction Outline

Nerve impulse reaches end of motor nerve

Acetylcholine released, binds with receptors on motor end plate

Depolarization of sarcolemma

Initial Muscle Contraction steps

Neural signal is stimulated to contract by motor neurons, into motor end plate

As action potential reaches end of motor neuron acetylcholine is released and disperses across the synaptic cleft between neuron and muscle membrane and binds with receptors at the end plate

Depolarizes the sarcolemma which makes it permeable to sodium which reverses the polarization called the end plate potential

Depolarization also travels along the membrane and throughout the cell is the start of contraction

Excitation Contraction Coupling

Depolarization is the action potential

Travels across the muscle membrane and comes in the t tubules around the muscle fibrils : Ca2+ release from the sarcoplasmic reticulum calcium binds to troponin and sits on tropomyosin and is bound to the actin molecules

When calcium binds to troponin it causes it to changes shape which pulls troponin and actin and uncovers a myosin binding sit on actin

Myosin binds to actin and causes ATP to be hydrolyzed to ADP and it causes the binding arm to twist and shortens the whole thing

This process will continue as long as calcium is bound to troponin and ATP is present calcium is sequestered into the SR and causes tropomyosin to go back to the original shape and actin has no where to bind (active requires ATP)

Cross Bridge Cycle

ATP requirement to activate myosin and myosin detach, calcium pumps is an active process, runs out of ATP it stays contracted (rigor mortis)

Contractions are

repeated movements