BIOL 5600 Lab Final Review

Blood/hydrostatic pressure

The outward force of blood against artery walls as it is pushed through the body

Total peripheral resistance

Blood viscosity; radius of blood vessels

Cardiac output

Amount of blood pumped by each ventricle per minute

Stroke volume

Amount of blood pumped by each ventricle in 1 heartbeat

Cardiac output formula

CO = HR x SV

Hormonal control

Long term control via

Kidney (renin)

Adrenal cortex (aldosterone)

Right atrium (atrial natriuretic peptide)

Neural control

Short term control via sympathetic and parasympathetic pathways

Sympathetic pathway

Vasomotor center in medulla oblongata stimulated

ACh binds to N2, epinephrine binds to B2 and a1

HR and SV increase

Parasympathetic pathway

Cardiac inhibitory center in medulla oblongata stimulated

ACh binds to N2 then M2

Heart rate decreases

No direct effect on TPR

Activation of VMC

Inhibits activity of the VC

Inhibition of VMC

Causes vasodilation of blood vessels

Activation of VC

Inhibits the activity of the VMC

Chemoreceptors

Found in carotid and arch of aorta

Direct effect on respiratory centers close proximity to VMC

When BP is low

A build up of waste products (CO2 and H ions) occurs

Baroreceptors

Located in the arch of the aorta and carotids

Respond to stretching of blood vessels (stimulated increase BP)

Afferent signals from the aorta via CN X

Signals from carotids via CN IX

Controls minute-to-minute fluctuations not extreme highs/low

When BP rises

Blood vessels stretch sending signals to the medulla

Inhibit the VMC

Activation of the VC

Yields a decrease in blood pressure

When BP falls

Fewer impulses are sent to the medulla

VMC is activated

Causes the inhibition of the VC

Yields an increase in blood pressure

Systole

Contracting of ventricles

Diastole

Relaxing of ventricles

Dicrotic notch

As the semilunar (aortic) valve closes this notch marks the place where the blood comes back up and hits the semilunar valve

Pulse pressure

Systolic pressure - diastolic pressure

Directly related to SV and inversely related to HR and TPR

Mean arterial pressure (MAP)

= (PP/3) + diastolic pressure

The average arterial pressure throughout one cardiac, systole, diastole cycles

Influenced by CO and TPR

Calculating HR from an ECG

HR = 60/R-R interval

ACh

Stimulate all nicotinic and muscarinic receptors in the body

Atropine

Blocks muscarinic receptors on the heart

ACh added after atropine

Stimulating the N2 receptors on parasympathetic and sympathetic

Causing the release of ACh and epinephrine/norepinephrine respectively

Only target tissue receptors available are B1 and A1

Frog heart is

3 chambered

2 atria 1 ventricle

Sinus venosus

Located in right atrium

Pacemaker of the heart- made up of excitable, myogenic tissue, and beats at its own intrinsic rate

Causes contraction of the atria and sends a conductive signal to the AV node

The SV evolved to become the SA node in mammals

Round cells

Pacemaker cells that generate the action potentials

Contains special ion channels called Slow Na channels

Slow Na+ channels are open most of the time and allow the slow leak of Na across the membrane-causing a slow depolarization

Ca2+ channels open, causing a rapid influx of Ca, depolarization

Repolarization opening of K+ outward movement of K+ ions

Elongated cells

Conductive cells that send the signal to the atria to contract and then to the AV node

Like the Bundle of His in mammals, but not as organized

Parasympathetic innervation of SV

Vagus Nerve

Long pre-ganglionic

Short post-ganglionic

Muscarinic receptors of the SV are associated with K+ channels

K+ leaves the cell, hyperpolarizes the membrane and decreases HR

Sympathetic innervation of ventricles

Short pre-ganglionic fiber

Long post-ganglionic fiber

Epinephrine from postganglionic fibers stimulate beta 1 receptors on the ventricle associated with Ca2+ cahnnels

Ca2+ comes into the cell, increasing rate of AP propagation and increasing activity

Starling's Law

The more the heart muscle is stretched, the more forceful the subsequent contraction

Occurs when venous return is increased

Venous return

Amount of blood entering the heart from the inferior and super vena cava

This stretches the ventricle and causes an increased force of contraction

How is an increase in venous return stimulated?

Increasing ventricular stretch via manipulation of the myograph position

Effect of decreased temperature

Myosin ATPase: cleaves ATP slower

Ca2+ ATPase: cleaves ATP slower

Acetylcholinesterase: efficiency slows

Myosin ATPase cleaving ATP slower

lower force of contraction, longer contractile period

Ca2+ ATPase cleaves ATP slower

longer relaxation period

Acetylcholinesterase slowing down

Longer contractile period

Initial incrase in force

Slower heart rate increases fill time

More blood in the heart will cause it to stretch

Epinephrine

Neurotransmitter of sympathetic system

When added to ventricle, it stimulates beta 1 receptors

Ca2+ comes into the cell, increasing the rate of depolarization

Increased HR and SV

Pilocarpine

Parasympathomimetic

When added to the heart, it stimulates muscarinic receptors

K+ leaves the cell, decreasing the rate of depolarization

HR decreases

Effect of ACh

ACh is the neurotransmitter of the parasympathetic system

When added to the heart, it stimulates muscarinic receptors

K+ leaves the cell, decreasing the rate of derpolarization

HR decreases

Effect of atropine followed by ACh

Atropine is a muscarinic receptor antagonist- and a competitive inhibitor of ACh

Blocks parasympathetic response

Heart rate increases, then no change

Sensors

Chemoreceptors

Processors

Respiratory control centers of the medulla and pons

Effectors

Respiratory muscles

Eupnea

Normal breathing

Cyclic on/off

Produces a rate of 12-15 breaths/min

Factors that influence depth/rate of ventilation

In order of importance: H+ in central arterial blood, CO2 in peripheral arterial blood, O2 levels

CNS hierarchy

Hypothalamus (highest autonomic control center)

Nuclei in pons and medulla

Medullary control (VRG and DRG)

Pontine respiratory centers

Ventral respiratory group

In pons/medulla junction

Rhythm generation

Autonomous depolarization via spontaneously firing neurons: potential pacemaker

2 sub-nuclei populations: excitatory (inspiratory) and inhibitory (expiratory)

Dorsal respiratory group

Located in medulla, near CN IX and X

Gets input from chemo and baroreceptors

Communicates this info to the VRG, adjusts the rhythm of the inspiratory/expiratory cycle

Pontine respiratory centers

Modify the activity of the medullary neurons

Smooth out the transition from inspiratory to expiratory set by the basic rhythm of the VRG

Transmit impulses to the VRG DRG- fine tunes the breathing depth and rhythms during sleep, vocalization, and exercise

Central chemoreceptors

Located in the medulla oblongata

Central chemoreceptors are very sensitive to H+ ions- triggers 70% of response

Respond to increases in H+ derived from CO2

CO2 effects

H+ formed in the periphery cannot cross the tight junctions of the BBB capillary system, so CO2 must cross

The CO2-derived H+ will then stimulate the central chemoreceptors, which then stimulate the respiratory centers

Peripheral chemoreceptors

Located in the aortic bodies (at aortic arch) and the carotid sinus (near burification of carotids)

Respond to an increase in arterial CO2

If blood levels of CO2 rise, these receptors send afferent messages to the DRG, signaling an increase in respiration to blow off the excess CO2

Hyperventilation

Breathing rate is higher than necessary, causing a decrease in CO2

This drives the bicarbonate buffer reaction to the left; H+ ions are lost, resulting in respiratory alkalosis

CO2 will not be detected by central and peripheral chemoreceptors in the medulla and aortic arch

The VRG will modify breathing (less rapid/decreased depth)

Oxygen deficit

Volume of O2 that was unable to meet the ATP requirement demands at the beginning of exercise

Buildup of lactate is converted to glucose

HR, RR, and temperature take time to return to normal levels

ATP and creatine stores need to be replenished

During exercise

Before steady state is reached, ATP demands increase immediately and faster than aerobic metabolism processes can respond. So, anaerobic metabolism provides additional ATP until a steady state is reached

Excess post-oxygen consumption (EPOC)

volume of oxygen consumed after exercise that is above resting level. During this time, CO2 is blown off and ATP levels are restored

Respiratory exchange ratio

Ratio of volume of CO2 produced to volume of O2 consumed per unit of time

RER close to 1

carbohydrate

RER close to 0.8

Protein OR mixed substrate profile

RER close to 0.7

Fat

The sensors that receive signals within the ventilation system are known as

chemoreceptors

The processors that oversee control of ventilation are the respiratory centers of the

medulla and pons

The effectors that are controlled by the processors are the

respiratory muscles

Normal breathing is known as ____, a cyclic on/off process that produces a rate of _____ breaths per minute

eupnea; 12-15

In order of importance, factors that influence depth and rate of ventilation are

H+ in central arterial blood; CO2 in peripheral arterial blood; O2 levels

The ______ is the highest autonomic control center over respiration.

hypothalamus

The hypothalamus delegates to nuclei in the ___ and ____

pons; medulla

Within the medulla, control over ventilation is exerted via the ____ and ____ respiratory groups

ventral; dural

Within the pons, control over ventilation is overseen by the ____ respiratory centers

pontine

The ventral respiratory group (VRG) is located in the

pons/medulla junction

The ventral respiratory group is responsible for rhythm _____ of the inspiratory/expiratory cycle

generation

The VRG autonomously depolarizes via spontaneously firing neurons, acting as a

potential pacemaker

There are two sub-nuclei within the VRG: excitatory, which oversees _____, and inhibitory, which oversees _____

inspiration; expiration

The dorsal respiratory group (DRG) is located in the

medulla, near CN IX and X

The DRG receives input from _____ and relays that input to the ____

chemoreceptors and baroreceptors; VRG

The DRG is responsible for rhythm _____ of the inspiratory/expiratory cycle

adjustment

The pontine centers ____ the activity of the medullary neurons, and _____ the inspiratory/expiratory transition set by the VRG

modify; smooth out

The pontine centers also transmit impulses to the DRG/VRG, fine-tuning breathing ___ and ___ during sleep, vocalization, and exercise

depths; rhythms

Central chemoreceptors are located in the ______, and are very sensitive to ____, which triggers approx. ____% of response

medulla oblongata; H+; 70

H+ can't cross tight junctions of the blood-brain barrier, so ____ must cross instead

CO2

CO2-derived H+ stimulates the ______, which then stimulate the ____

central chemoreceptors; respiratory centers

Within the BBB, CO2-derived effects result in an _____ in respiration rate and depth

increase

Peripheral chemoreceptors are located in the _____ and the ____

aortic bodies; carotid sinus

Peripheral chemoreceptors respond to an increase in

CO2 in peripheral arterial blood

If blood CO2 rises, peripheral chemoreceptors send afferent messages to the ____, signaling an _____ in respiration to blow off excess CO2

DRG; increase

During hyperventilation, breathing rate is higher than necessary, causing a ____ in CO2

decrease

Hyperventilation drives the bicarbonate buffer reaction to the ____; H+ ions are ____, resulting in respiratory ____

left; lost; alkalosis

CO2 ___ detected by central and peripheral chemoreceptors in the medulla and aortic arch

is not

Hyperventilation causes the VRG to modify breathing to become ___ rapid, with ___ depth

less; decreased

The oxygen deficit is the ____ of O2 that was ____ to meet the ATP requirement demands at the ____ of exercise

volume; unable; beginning

During exercise: before steady state is reached, ATP demands increase ____ than aerobic processes can respond. So, _____ metabolism provides additional ATP in the meantime

immediately/faster; anaerobic

Excess post-oxygen consumption (EPOC) is the ____ of oxygen consumed after exercie that is ______ the resting level

volume; above

During EPOC, _____ is blown off, and ATP levels are ____.

CO2; restored

The respiratory exchange ratio (RER) is the ratio of volume of ____ to ____ consumed per unit of time

CO2; O2

The value of RER indicated what _____ is being burned as energy

macromolecule

An RER close to 1 indicates _____ is used for fuel

carbohydrates