Disease states


Disease states

  1. Explain the Frank-Starling and Laplace laws in relation to stroke volume to cardiac output.

Frank-Sterling is a law explaining the interrelationship between the three heart factors; stroke volume (SV), end diastolic pressure (LVEDP) and the ability of the muscle to contract. The cardiac muscle has the ability to adjust and increase or decrease its force of contraction in response to the venous return and therefore as a result influencing the systolic volume. Systolic volume is the amount of blood pumped by the left and right ventricles in a single contraction. In this law, increase in ventricle end diastolic pressure leads to intrinsic response of cardiac muscle by increasing its contractility hence raising the stroke volume. Cardiac output is the amount of blood pumped by the heart in 60 seconds. Therefore, cardiac output is the product of stroke volume and heart rate (pulse rate). Evidently, the cardiac output is directly proportional to stroke volume where the heart rate is constant (Costanzo, 2010).

Laplace law on the other hand, is a law explaining the interrelationship between tension, pressure and radius of the blood vessels. It states that; for a particular blood pressure that increases the radius of the blood vessels, it also leads to a linear proportional increase in tension. Therefore, blood pressure is directly proportional to tension in the blood vessels. The blood vessels that are normally under high blood pressure such as the arteries have to be thick enough to withstand the tension. Increased blood pressure increases the tension of blood vessels leading to increased stroke volume. With increase in stroke volume the cardiac output also increases since it is the product between stroke volume and heart rate (Guyton, 2012).

Cardiac output (CO) = stroke volume (SV) x heart rate (HR)

  1. How Frank-Sterling and Laplace laws relate to underlying pathology of the heart failure.

Heart failure is a heart condition whereby the heart is unable to effectively pump blood and efficiently supply all body parts with blood for perfusion. It is also referred to as congestive heart failure and may be as a result of various causes. In congestive heart failure, the ventricle muscles are unable to effectively contract and eject enough blood despite the amount of blood in them. In relation with the Frank-Starling law, with increased end diastolic ventricle pressure due to increased preload and after load volumes, the contractility of the cardiac muscle decrease due to the pathology. This results in reduced stroke volume due to the poor contraction and consequently contradicting the law. This law therefore is only true and applicable in a normal functioning heart (Berne, 2008).

In relation with the Laplace law, the reduced cardiac muscle contractility t leads to reduced stroke volume. Blood pressure is the product between the stroke volume and the blood vessel resistance. Therefore with reduced stroke volume, the blood pressure too reduces subsequently reducing the vessel wall tension. As the end observation of chronic congestive heart failure, the blood vessel walls especially the arteries are expected to undergo adaptive atrophy due to prolonged hypotension and reduced pressure stress on them and become thinner (Selkurt, 2014).

  1. Mode of transmission and presenting signs and symptoms for:

Measles –it is contagious viral disease whose viruses is harbored in the nasal and throat mucus of infected individual and is transmitted through respiratory droplets. (Air borne) (Livols i, 2011).

Signs and symptoms. Complications of measles.

1. High fever above 38 0C 1.severe pneumonia

2. Running nose (coryza) 2.Encephalitis

3. Koplik spots in the buccal cavity 3.Ear infections and diarrhea

4. Red watery eyes 4.Premature birth and low birth weight in expectant mothers

Mumps: this is a viral disease involving the parotid glands and it is transmitted through saliva and mucus droplets that are released through sneezing and coughing. (Air borne) (Schneider, 2009).

Signs and symptoms.

2. Fatigue

3. Swelling and tenderness of the parotid glands

4. Headache muscle aches

5. Loss of appetite


1. Hearing loss due to the inflammation and destruction of the ear and parotid glands below the ear. The infection can further progress and spread to the brain and cause encephalitis and meningitis. In some cases it may cause pancreatitis, inflammation of the testes and miscarriage in pregnant women .the causative agent has some cell receptors similar to the ones found in the immunologically privileged sites such as the placenta and the testes. Upon reaching there, an inflammatory process is initiated by the body hence causing the destruction of testes sand miscarriage. A similar occurrence happens in the pancreas (Brown, 2012).

Pertussis (whooping cough): this is a respiratory system disease caused by Bordetella pertussis that has a characteristic paroxysmal cough. It is an air borne disease that is transmitted by inhalation of saliva and mucus droplets through coughing and sneezing (Jarolim, 2013).

Signs and symptoms of pertussis Complications of pertussis

1. Nasal congestion 1.Pneumonia

2. Rhinorrhea 2.Hypoxic encephalopathy

3. Sneezing 3.Otitis media

4. Low grade fever 4.Epistaxis

5. Projectile vomiting 5.Seizures

6. Conjunctiva suffusion 6.Cerebral hemorrhage, coma and death.

Chicken pox: this is an air borne disease that is caused by varicella zoster virus and it is transmitted by saliva and mucus droplets released through coughing and sneezing. It can be transmitted too through contact with contaminated object (Livols i, 2011).

Signs and symptoms: these include; fatigue, fever, loss of appetite, red rashes on the skin.


Can cause skin bacterial infection due to the reduced skin integrity and ease of entry of microorganisms to cause an infection. It can also lead to pneumonia as these infections can reach the respiratory system mainly the lungs through blood and can eventually lead to toxic shock too. The exposed open skin at the busting sites of rashes can result too to loss of water from the body and result in dehydration (Brown, 2012).


Berne, R. (2008). Human physiology. St.Louis: Mosby.

Brown, A. (2012). Medical surgical nursing. Philadephia: Saunders.

Costanzo, L. (2010). Physiology. Philadephia: Elsevier.

Guyton, A. (2012). Textbook of medical physiology. Philadelphia: Saunders.

Jarolim, D. (2013). Internal medicine. New York: Springer-Verlag.

Livols i, V. (2011). Pathology. Philadephia: Harwai Pub.

Schneider, A. (2009). Human pathology. Philadelphia: Lippincolt Williams.

Selkurt. (2014). Physiology. Boston: Little brown.