THE CIRCULATORY & LYMPHATIC SYSTEM 31 JULY 2013 · 2018-05-01 · THE CIRCULATORY & LYMPHATIC SYSTEM 31 JULY 2013 Lesson Description In this lesson we: Explain the mechanisms for

THE CIRCULATORY & LYMPHATIC SYSTEM 31 JULY 2013

Lesson Description

In this lesson we:

Explain the mechanisms for controlling the cardiac cycle and heart rate (pulse).

Describe how pulse and blood pressure are measured.

Discuss the relationship between the blood system and lymphatic system.

Explain the functions of lymphatic system.

Mention diseases of the heart and circulatory system.

Key Concepts

Cardiac Cycle

Regulation of Heartbeat

Heart and lungs functioning is regulated by the medulla oblongata in the brain.

Nerve impulses are sent from medulla oblongata to the sino-atrial node (pacemaker) of the

heart.

The sino-atrial node controls the systole and diastole of all the cardiac cells – ensures that

the whole heart works as one unit.

An increase in the CO2 level in the blood stimulates chemoreceptors in the aortic arch and

the carotid arteries.

Chemoreceptors convert the stimuli into impulses - relayed to the medulla oblongata.

The medulla oblongata sends impulses to stimulate the sino-atrial node = heart will beat

faster

Cardiac Cycle

To understand the cardiac cycle, note the following:

The duration of one heartbeat is approximately 0,8 seconds.

Normal heartbeat rate is approximately 72 – 75 beats per minute.

The contraction of the heart muscle is called systole (think ‘S’ for stressed).

The relaxing of the heart muscle is called diastole

Heartbeat

When you listen to the heartbeat, there are two distinct sounds - the first sound is loud

(LUBB) and the second sound is softer (dubb).

The lubb sound is when the atrio-ventricular valves close when the ventricles contract.

The dubb sound is when the semi-lunar valves close in the aorta and pulmonary artery. This

prevents the flow of blood back into the ventricles as the ventricles relax.

ventricles fill

ventricles pump

Both sets of

chambers fill

A doctor listens to the heart with an instrument called a stethoscope.

A person’s pulse can be felt when pressing any of the fingers (not the thumb), against the

wrist at the brachial artery or at the neck against the carotid artery.

The pulse is a result of pressure caused by the blood, as it is forced out through the aorta.

Pulse

The alternate expansion and contraction of arteries

Blood Pressure

Blood pressure is the result of the pumping action of the heart and the size of the blood

vessels.

Results in pressure build-up in the arteries.

Pressure is important, because this keeps the blood flowing to all the parts of the body.

Blood pressure - A sphygmomanometer is an instrument used to measure blood pressure,

and it recorded as two numbers, written as a ratio like this:

Blood pressure is typically recorded as two numbers, written as a ratio like this:

Read as "117 over 76

millimeters of mercury"

Systolic

The top number, which is also the higher of the two numbers, measures

the pressure in the arteries when the heart beats (when the heart muscle

contracts).

Diastolic

The bottom number, which is also the lower of the two numbers,

measures the pressure in the arteries between heartbeats (when the heart

muscle is resting between beats and refilling with blood).

Hypotension: lower blood pressure than normal

Hypertension: higher blood pressure than normal

High blood pressure can be aggravated by diet like too much salt can cause hypertension.

High blood pressure can sometimes go undetected and may eventually lead to death – called

the ‘silent killer’.

Blood pressure can be increased by:

o smoking and excess alcohol intake

o stress

o adrenalin surges

o water retention

o poor diet and high cholesterol

o obesity

o lack of exercise

Lymphatic System

A secondary transport system consisting of one way system of vessels that collects and returns

excess tissue fluid to blood system.

Structure

Made up of:

o Lymph nodes

o Lymph vessels

o Lymph

Lymph Vessels & Blood Vessels

Functions

Collect tissue fluid and return it to the blood system

Fight Infection by:

o Filtering out microorganisms in the lymph nodes

o Destroying microorganisms by antibody production

o Mature and store lymphocytes

Transport digested fat away from intestine

Cardiovascular Disease

Atherosclerosis & Arteriosclerosis

Deposits inside arteries (plaques)

o Develop in inner wall of the arteries, narrowing their channel

o Occurs when the coronary arteries that supply the heart muscle become blocked.

o Partially blocked it causes angina.

o Fully blocked it causes a myocardial infarction or a heart attack.

Increase blood pressure.

Increase risk of heart attack, stroke, kidney damage.

Normal Artery Hardening of Arteries

Risk Factors

genetics

diet (high in animal fat)

exercise & lifestyle

o smoking

o lack of exercise

Symptoms

Uncomfortable pressure, fullness, squeezing pain, pain spreading to the shoulders, neck and

arms.

Chest discomfort and light headedness

Anxiety/nervousness

Paleness or pallor

Increased irregular heart rate

Cerebrovascular Accident or Stroke

Blood vessel in the brain becomes blocked by atherosclerosis- the tissue supplied by the artery dies.

Embolus – which is a traveling blood clot.

Symptoms

Sudden numbness or weakness of the face, arm or leg, especially on one side of the body.

Sudden confusion, trouble speaking, or understanding.

Sudden trouble seeing in one or both eyes.

Sudden trouble walking, dizziness, loss of balance or coordination.

Sudden numbness or weakness of the face, arm or leg, especially on one side of the body.

Sudden confusion, trouble speaking, or understanding.

Sudden trouble seeing in one or both eyes.

Sudden trouble walking, dizziness, loss of balance or coordination.

Correction

Stents Bypass Surgery

Name Gender Age Heart Rate

(at rest) Heart Rate

(after exercise)

Questions

Question 1

Choose the correct answer and write the correct letter corresponding to the correct answer in the

table below (failure to do so will result in you losing marks):

Question

Number: 1.1 1.2 1.3 1.4

Total

4 x 2 = [8]

Answer

1.1 The valve between the right atrium and right ventricle:

A semi-lunar

B bicuspid

C tricuspid

D mitral

1.2 The SA node is situated in the:

A right atrium

B right ventricle

C left atrium

D left ventricle

1.3 The tough membrane surrounding the heart is called the:

A epimysium

B perimysium

C pericardium

D myocardium

1.4 The blood vessel that takes de-oxygenated blood from the organs of the abdomen to the liver

…

A hepatic vein

B hepatic portal vein

C mesenteric vein

D inferior vena cava

Question 2

Write down the correct biological term for the following descriptions in the spaces provided.

Number Description Biological Term

a.) The blood vessels that supply the heart muscle with

oxygenated blood

b.) The series of events that takes place every time the

heart beats

c.) The term used to describe the period when both the

atria and ventricles relax

d.) The thick, muscular wall between the left and right

side of the heart

4 × 1 = [4]

Question 3

Describe pulmonary circulation (the blood flow between the heart and the lungs) and explain how the

heart is suited to perform its function.

Content: (17)

Synthesis: (3)

Total: (20)

Question 4

Study the following diagram and answer the questions

Provide (from the graph):

a.) Resting heart rate of the camel, human, mouse and bat

b.) How much time more does the bat’s heart beat compared to: i. human ii. camel

c.) Suggest how the bat’s heart rate would change i. when it is flying fast ii. when it hibernates

d.) Describe the trend regarding the heartbeat of animals that can be observed from the data presented.

Links

Understanding Blood Pressure Readings: http://www.heart.org

Blood & circulation: www.worldofteaching.com

Heart disease: www.extension.missouri.edu/hesfn/heartdisease

www.nhscience.lonestar.edu/biol

Reference List

1. Via Afrika Life Sciences; Grade 10 Learner’s Book; M. Bowie, A. Johannes, R. Mhlongo, E.

Pretorius.

2. Spot On, Life Sciences Learners’ Book, C Dawson, P Holm, G Jackson; H Skinner