A&P Lab 13 - Class 12: Circulatory System II and Respiratory System

Where is the cardiovascular center located?

In the medulla oblongata

Which types of sensory receptors are received in the cardiovascular centre of the medulla oblongata?

Proprioceptors, baroreceptors, chemoreceptors

What is output from the cardiovascular system via?

The sympathetic and parasympathetic neurons of the autonomic nervous system.

a) Where do sympathetic cardiac acceleratory nerves extend out to?

b) What neurotransmitter do these nerves release?

c) What does this neurotransmitter affect?

a) The sinoatrial node, atrioventricular node, and most of the myocardium.

b) Norepinephrine.

c) The rate and force of heart contractions are increased.

a) Where do parasympathetic cardiac inhibitory nerves terminate?

b) What neurotransmitter do these nerves release?

c) What does this neurotransmitter do?

a) In the SA node, AV node, and atrial myocardium.

b) Acetylcholine

c) Decreases heart rate, and has a lesser effect on decreasing the force of contraction.

The cardiovascular center continuously sends impulses to the smooth muscle in blood vessel walls via:

a) What?

b) What are these?

a) Vasomotor nerves.

b) These are sympathetic neurons that cause vasoconstriction and an increase in blood pressure.

How do hormones help regulate blood pressure?

* Altering heart function
* Altering blood vessel diameter
* Adjusting total blood volume

What does the adrenal medulla release in response to sympathetic stimulation?

The hormones epinephrine and norepinephrine.

What effect do the hormones epinephrine and norepinephrine have on heart rate and force of heart contractions?

An increase

True or False:

Epinephrine and norepinephrine can constrict veins and arterioles

True

Effect of epinephrine on arterioles in skeletal and cardiac muscle

It dilates arterioles in these muscles, and increases blood flow during exercise.

True or False:

The heart is dependent on the nervous system for its rhythmic contractions.

Explain

False.

The heart is not dependent on the nervous system for this.

This is due to autorhythmic fibers which are self-excitable (pacemakers).

Where does cardiac excitation normally begin?

The SA (sinoatrial) node.

Sinoatrial (SA) node

The dominant pacemaker of the heart, which lies in a cellular cluster in the right atrial wall between the inlets of the inferior and superior vena cava.

What does contraction of the muscular walls of the atria immediately follow?

Atrial depolarization

Where is the atrioventricular (AV) node located?

Within the lower interatrial septum.

What does the AV node do?

Relays the impulse from the atria to the ventricles.

P wave

Atrial depolarization

QRS complex

Ventricular depolarization

T wave

Ventricular repolarization

Which branches does the bundle of His divide into?

Left and right.

Where do bundle of His branches extend through (and towards)?

They extend through the interventricular septum toward to apex of the heart.

What are the smallest conductive elements of the heart?

Purkinje fibers

Where are Purkinje fibers distributed?

Throughout the inner walls of the ventricles, throughout the muscular septum separating the two ventricles, and within the muscular papillae (where they make contact with contractile elements of the heart).

Where does the cardiac impulse move after being dispersed throughout the entire inner surface of the ventricles?

Towards the outer surface of the heart, as a generalized wave of depolarization.

In which motion to ventricles contract?

A “wringing”-type action (pushing blood up toward the semilunar valves.

Which node/bundle/fiber matches with the following description:

a) Relays impulse from atria to ventricles.

b) Dominant pacemaker of the heart.

c) Divides up into branches.

d) Distributed throughout the inner walls of the ventricles, muscular septum, and muscular papillae.

a) Atrioventricular (AV) node

b) Sinoatrial (SA) node

c) Bundle of His/AV bundle

d) Purkinje fibers

Electrocardiography

The measurement and analysis of currents associated with heart activity.

Important for the diagnosis of abnormal cardiac function.

How do electrodes of an EKG/ECG work?

Electrodes adhere to the skin and contain an electrolyte (ex. KCl or NaCl) to improve the electrical conductivity of the skin, which has a fairly high resistance.

Myocardial infarcts

Regions of dead myocardial tissue that do not depolarize

Ringer’s solution

A physiological saline solution containing various electrolytes (to keep, for example a heart, moist and in osmotic balance)

Epinephrine causes the heart rate to ___________ (increase/decrease)

Increase

Epinephrine causes the strength of heart contraction to _________ (increase/decrease)

Increase

Application of the chemical, epinephrine, is stimulated by the control of the ____________ (sympathetic/parasympathetic) part of the ANS

Sympathetic

Acetylcholine causes the heart rate to ________ (increase/decrease)

Decrease

Acetylcholine causes the strength of heart contraction to _________ (increase/decrease)

Decrease

Application of acetylcholine simulates control by the _____________ (sympathetic/parasympathetic) part of the ANS

Parasympathetic

Would a 4 degree Celsius Ringer’s solution applied to the surface of a heart increase or decrease heart rate, and why?

Decrease heart rate.

Hypothermia, and calcium channels open slower (causing slower contraction of the heart).

If 37 degree Celsius Ringer’s solution is applied to the surface of the heart, what are the effects (on heart rate), and why?

The heart rate would increase.

Actin binds to myosin more quickly due to calcium channels opening faster (faster contraction of the heart).

What does the term “pulse” refer to?

Alternating surges in pressure (expansion and recoil) in the artery that occur with each contraction and relaxation of the left ventricle.

True or False:

“Blood pressure” refers to arterial blood pressure.

True

Systole

Heart in a contracted state

Diastole

Heart in a relaxed state

Sphygmomanometer

Device used to measure arterial pressure

True or False:

We cannot use a BP cuff or stethoscope to measure venous pressure.

True

Explain why blood pressure and pulse rate changes when posture changes from reclining to immediately standing up.

Include the role of baroreceptors.

When reclining, blood accesses the heart more easily because it is not combatting gravity. This means that pulse and blood pressure will decrease.

Baroreceptors detect this change in pressure.

Explain the changes in blood pressure and pulse rate immediately after exercise, and once exercise has ceased for 5 minutes.

After exercise, blood tends to pool in the extremities, and less blood is able to reach the heart. This causes a decline in cardiac output, causing BP to drop.

(During exercise, contracting muscles help deliver blood to the heart).

How would you expect a trained athlete to differ from an “unfit” person with respect to the effects of exercise on pulse rate and blood pressure.

Athletes’ heartrates tend to fluctuate less between rest and activity.

What would be the effect of drinking a cup of a highly caffeinated beverage on pulse rate?

Caffeine is a stimulant, which will cause a higher HR (quicker contractions of the heart, and likely a higher BP).

Hypertension

High blood pressure (consistently above normal)

Why is prolonged hypertension dangerous?

High BP forces the heart to work harder to pump blood to the rest of the body. This can increase the risk of heart attack.

Explain the effect of “hardening of the arteries” on the diastolic and systolic components of blood pressure

(Arteriosclerosis).

This could result in high blood pressure.

Valsalva maneuver

Increases intrathoracic pressure, can be used to demonstrate the effect of thoracic pressure changes on venous blood pressure.

What happens with blood pressure during Valsalva maneuver?

Blood pressure increases

Three bony projections of the nasal cavity:

Superior, middle, and inferior nasal conchae.

Where does the palate lie?

Between the nasal cavity and the mouth.

Compare the anterior vs. posterior portion of the palate.

* Anterior: Rigid (due to bone reinforcement), called the hard palate.
* Posterior: Lacks bone, called the soft palate.

From the nasal cavity, where does air pass?

Successively through the three regions of the pharynx:

* Nasopharynx
* Oropharynx
* Laryngopharynx

Which regions of the pharynx are also common to the digestive tract?

* Oropharynx
* Laryngopharynx

How many pieces of the cartilages makes up larynx?

Nine

What is the largest of the nine pieces of cartilages which makes up the larynx?

The thyroid cartilage

What makes up the thyroid cartilage?

Hyaline cartilage

Epiglottis

An elongated flap which extends diagonally over the entrance to the larynx.

What is the only laryngeal cartilage composed of elastic cartilage?

The epiglottis

What is the “adam’s apple”?

Thyroid cartilage

From the larynx, where does air enter?

The trachea

The trachea divides into two smaller branches:

Left and right primary bronchi

What do primary bronchi divide into?

Smaller secondary bronchi (one for each lobe of the lung)

What do secondary bronchi divide into?

Tertiary bronchi

What do tertiary bronchi divide into?

Bronchioles

What do bronchioles divide into?

Terminal bronchioles

What do terminal bronchioles divide into?

Respiratory bronchioles

What do respiratory bronchioles divide into?

Alveolar ducts

What do alveolar ducts terminate in?

Alveolar sacs

What is free movement of the lungs in the thoracic cavity facilitated by?

Pleural membranes.

What lines the thoracic wall?

Parietal pleura

What covers the outer surface of each lung?

Visceral pleura

Between parietal and visceral pleura is:

A potential space, the pleural cavity (contains just enough pleural fluid for lubrication).

When the lungs fill with air, what do the moist visceral pleura adhere to?

The moist parietal pleura.

How is ciliated pseudostratified epithelium (of the trachea) specialized for its protective function in the respiratory tract?

The cilia brushes dust and debris out of airways

Why is there cartilage around the trachea?

To prevent its collapse when the esophagus is distended by food.

What type of epithelium is found in the alveoli?

What is the function of this epithelium?

Simple squamous epithelium.

The thinness of this epithelium allows for a gas exchange, the main role of alveoli.

Two different respiratory movements involved in breathing (into the lungs):

Inspiration/inhalation

Two different respiratory movements involved in breathing (out of the lungs):

Expiration/exhalation

Atmospheric pressure

Pressure of the air outside the body

Intrapulmonary pressure

Force exerted by gases within the alveoli of the lungs during respiration

During inspiration, muscular contraction causes the thorax to ______(a)______ (increase/decrease) in size.

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This, in turn, causes a(n) ______(b)______ (increase/decrease) in the intrapulmonary pressure.

\
Since the pressure within the lungs is now ____(c)____ (greater/less) than atmospheric pressure, air moves into the lungs.

a) Increase

b) Decrease

c) Less

Intrapleural pressure

Pressure within the pleural cavity

Explain what would happen, with respect to the lungs, if intrapleural pressure and atmospheric pressure become equal.

The lungs would collapse. In order for the lungs to maintain their shape, intrapleural pressure must be negative (related to atmospheric pressure).

Spirometer

Apparatus used to measure long volumes and capacities

Tidal volume (TV)

The volume of air inspired/expired with each normal, quiet respiration.

What muscles are involved during normal, quiet inspiration?

Diaphragm and external intercostals

Expiratory reserve volume (ERV)

The volume of air that can be forcibly expired after a normal expiration.

Average value for tidal volume

Around 500ml

Average value for expiratory reserve volume

Around 1200ml

Vital capacity

Maximum amount of air that can be moved into and out of the lungs from a maximal inspiration to a maximal expiration.

Average value for vital capacity

Around 4800ml

What muscles are involved during forced inspiration?

Diaphragm and external intercostals

Normal expiration is primarily a matter of passive recoil of the lungs, but forced expiration involves the contraction of the:

Abdominal muscles

Inspiratory reserve volume (IRV)

The volume of air that can be forcibly inhaled after a normal inspiration