IB Biology Review

Circulatory System

Why do we need blood circulation?

Move blood around the body toBring oxygen to cellsTake away carbon dioxideTake away other metabolic wasteBring metabolic reactants (sugar)Bring waterBring hormonesBring antibodiesBring nutrientsDistribute heat

Basically, to keep our bodies doing what they do!

What are the components of the circulatory system?

HeartArteriesVeinsCapillaries

Remember Arteries Away from heartArteries have oxygenated bloodVeins have deoxygenated blood

A Closer Look at the Heart

Identify the structures of the heart.

1

2

3

4

5

6

7 8 9

10

11

12

13

14

15

Be able to draw something like this.

Atrioventricular valves

Semilunar valves

Pulmonary veins

The Path of Blood through the Heart

Deoxygenated blood comes from body through superior and posterior vena cavaEnters right atriumGoes through atrioventricular valveEnters right ventricle, pumped into pulmonary arteryPasses through semilunar valveGets oxygen from lungsEnters left atrium via pulmonary veinsGoes through atrioventricular valveEnters left ventricle, pumped into aortaPasses through semilunar valveBlood goes to rest of the body

How Blood Gets Oxygen

(2) Goes from right ventricle to pulmonary artery(3) Goes to lungs(4) Comes through pulmonary vein to left atrium(5) Goes to left ventricle(6) Goes through aorta(7) (8) To body!

Which arteries help out the heart?

Coronary arteries supply heart muscle withOxygenNutrients

How does the heart know when to pump?

The heart beats by itself (myogenic)

The SA node sends an electrical signal to the walls of the atriaThis causes them to contract (think about when you get electrocuted, your hand snaps back because your muscles contract)

SA signal reaches the AV node, which delays the signalAV node sends signal to ventricles, which contractAtrioventricular valves snap shutAfter blood leaves ventricles, semilunar valve closes to prevent back flow

Composition of Blood

Blood is made ofPlasmaErythrocytes (red blood cells)Leucocytes (white blood cells)

PhagocytesLymphocytes

Platelets

1. Which vessel carries deoxygenated blood? (1 mark)

A. The pulmonary arteryB. The coronary arteryC. The aortaD. The pulmonary vein

Correct answer: A

IB Exam Question

2. What is the function of the right ventricle? (1 mark)

A. Pumping blood into the pulmonary arteryB. Pumping blood into the pulmonary

veinC. Pumping blood into the aortaD. Pumping blood into the coronary artery

Correct answer: A

IB Exam Question

3. Draw a labelled diagram to show the internal structure of the heart. (6 marks)

Award [1] for each of the following structures clearly drawn and labelled correctly in a diagram of the heart.left and right ventricle;left and right atria;atrioventricular valves;semilunar valves;aorta and vena cava;pulmonary artery and pulmonary vein;ventricle wall thicker than atria;left ventricle wall thicker than right ventricle wall;Do not award marks for a diagram with only the ventricles or atria. However, it is not necessary to show the cordae tendinae.

IB Exam Question

4. Explain the relationship between the structure and function of arteries, veins and capillaries. (8 marks)

([3 max] for information on arteries)thick wall / elastic fibres to help withstand the high(er) pressure;outer fibrous coat prevents artery from rupturing under the high pressures;valves in aorta and pulmonary artery to prevent back flow into ventricles in diastole;layers of (smooth) muscle to allow arteries to contract / elastic recoil;allows the pressure to be altered (vasoconstriction and vasodilation);

([3 max] for information on veins)thinner wall (than arteries) since pressure low(er);very little muscle since not needed for constriction;valves to prevent back flow between pulses;

([3 max] for information on capillaries)no muscle / elastic tissue since pressure very low;endothelial layer one cell thick to allow permeability / diffusion of chemicals / tissue fluid;no valves since pressure very low;

IB Exam Question

5. Outline the control of the heartbeat in terms of myogenic muscle contractions, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline). The heart beats by itself (myogenic)SA node (pacemaker) in the heart muscle produces an electrical signal across nerves throughout walls of atria to begin cycle This nerve impulse causes the atria to contract SA signal reaches atrioventricular (AV) node which delays the electrical signalElectrical signal spreads across nerves, causing ventricles to contractAtrioventricular valves snap shutAfter ventricles are emptied, semilunar valves closeUnder certain circumstances, adrenaline carries messages from the brain to pacemaker telling the pacemaker to speed up the beating of the heart

IB Exam Question

6. State four substances that are transported by blood. (4 marks)

NutrientsOxygenCarbon dioxideHormonesAntibodiesUreaHeat

IB Exam Question