circulatory system:

The Circulatory System

Carries blood and dissolved substances to and from different places in the body

The heart: 

Is a four chambered muscular pump lying just left of the midline of the chest beneath the sternum bone 

The circulatory system supplies: 

Fuel (sugars) - digestive system

Oxygen - respiratory system 

Waste out: 

C02

Water 

Our circulatory system is a double circulatory system. 

The right side deals with deoxygenated blood

The Left side deals with oxygenated blood

How does the heart work? 

Step one: 

The heart beat begins when the heart muscles relax and blood flows into the atria 

Step Two: 

The atria contract and the valves open allowing blood into the ventricles

Step Three: 

The valves close to stop the backflow of blood

The ventricles contract forcing the blood to leave the heart

The atria are relaxing and filling with blood

Red Blood Cells : 

They are a biconcave disc that is round and flat - NO nucleus

They contain haemoglobin- a molecule designed to hold and carry oxygen

They can change shape without breaking as it squeezes single file through capillaries 

They are made continuously in bone marrow and live around 120 days 

They are destroyed in the liver and spleen and the molecules they are made from are recycled to make new RBCs

Anemia: results if the rate at which they are destroyed exceeds the rate at which they are produced 

Transport of Oxygen: 

Haemoglobin: carries oxygen

Carries about 25x more oxygen than it would be able to without haemoglobin

Carbon Monoxide Poisoning: 

Colourless, odourless gas. 

Combines with haemoglobin like oxygen but does not let go which limits available binding space for oxygen to be carried to the tissue and the animal/human suffocates

White blood cells: 

Many different types and they all contain a big nucleus

Two main types: 

• Lymphocytes:  some lymphocytes fight disease by making antibodies to destroy invades by dissolving them 

Other lymphocytes make antitoxins to break down poisons

• Macrophages: ‘eat’ and digest micro-organisms

Platelets: 

Platelets are bits of cell broken off larger cells 

Platelets produce tiny fibrinogen fibres to form a net. 

This net traps other blood cells to form a blood clot

Blood clotting: the mechanism that causes blood to clot is easily seen when you/your animals are injured 

Minor injuries occur all the time in areas that experience wear and tear like the intestine, the lungs and the skin.

Without clotting mechanism: animals would quickly bleed to death from minor injury and internal haemorrhage. 

This is what happens in animals and humans with clotting disorders (e.g: haemophilia) 

As well as animals that are poisoned with rat poisons (like warfarin)

Calcium and vitamin K are essential for the blood clotting process

A deficiency can cause clotting problems

PLASMA: 

A straw coloured liquid that carries the cells and platelets which help blood clots

It can contain useful things like: 

• C02 

• Glucose 

• Amino acids

• Proteins 

• Minerals

• Vitamins

• Hormones

• Waste material 

HAEMOLYISIS: 

The breakdown of the plasma membrane of RBCs to release haemoglobin

When collecting blood from an animal it is important to make sure there is now water in the syringe or tube as weather will move into the cells due to osmosis and eventually burst them

Too much movement due to shaking the tube or sucking up the blood too vigorously can also break down the plasma membrane and cause haemolysis 

BLOOD GROUPS: 

• Group O

• Group A

• Group B 

• Group AB  (rarest group) 

Blood groups are the result of different molecules called antigens on the outside of RBCs 

Blood groups exist in many animals 

There are 3 blood groups in cats

Blood Volume (slide 40) 

• Blood accounts for 6-1% of an animal's body weight (depending on species and stage of life)

• Animals cannot tolerate a loss greater than 3% of the total volume 

Blood pressure: 

• Measured systolic (when the left ventricle contracts) over the diastolic pressure (when the pressure in the left ventricle relaxes)

• Avg: BPI 20/80mmHg

SUMMARY: 

Arteries take blood away from the heart. Arteries have thick, muscular walls and elastic fibres. Veins carry blood towards the heart and also have valves.  Capillaries link arteries and veins and have one-cell-thick walls. Blood is made up of four main things: plasma, the liquid part of the blood; red blood cells to carry oxygen; white blood cells to protect the body from disease; and platelets to help blood clot.

TEST: 

1. The liquid part of the blood is known as: 

2. There are 2 main types of cells in the blood: they are: 

3. The most numerous cells in blood are:

4. The main function of the red blood cells is: 

5. How would you tell a white cell from a red cell when looking at them through a microscope? (Give 2 differences) 

6.  How does the blood help fight invasion by bacteria and viruses? 

7. What would happen to blood if there were no platelets? 

Complex organisms: 

Circulatory system 

• Made up of 3 parts

Organ: 

• heart

Tissue & cells

• Blood vessels

• Arteries

• Veins

• Capillaries

Blood

• Red blood cells

• Plasma 

• White blood cells

All animals have: 

Muscular pump = heart

Tubes = blood vessels 

Circulatory =’blood’ 

Vertebrate heart: 

 4-chambered heart

-atria (atrium 

Thin wall 

Collection chamber

Receive blood 

-ventricles 

Thick wall pump 

Pump blood out

Fish: 2 chambers

Amphibian: 3 chambers

Reptiles: 3 chambers 

Birds & mammals: 4 chambers

LUB DUB  LUB DUB

4 valves in the heart 

-flaps of connective tissue

- prevent backflow 

Heart sounds 

• Closing of valves - “lub”

• Force blood against closed AV valves

“Dub”

Force of blood against semilunar valves 

Heart murmur: 

Leaking valve causes a hissing sound 

Blood squirts backwards through valve

Arteries - arterioles -capillaries - venules -veins

Arteries – 

• blood flows away from the heart – 

• thicker walls • 

• provide strength for high pressure pumping of blood – 

• elastic & stretchable • 

• maintains blood pressure even when heart relaxes

Veins – 

• blood returns to the heart 

• thinner-walled 

• blood travels back to heart at low speed & pressure 

why low pressure? 

•  far from heart 

• blood flows because muscles contract when we move 

•  squeeze blood through veins 

 valves in large veins 

• In larger veins, one-way valves allow blood to flow only toward the heart

• 
  

Capillaries 

•  very thin walls 

•  allows diffusion of materials across capillary 

•  O2 , CO2 , H2O, food, waste

CIRCULATION OF BLOOD 

2-part system 

1.  Circulation to lungs 

2. blood gets O2 from lungs 

3.  drops off CO2 to lungs 

4.  brings O2 -rich blood from lungs to heart

5.  Circulation to body 

6. pumps O2 -rich blood to body 

7.  picks up nutrients from the digestive system 

8.  collects CO2 & cell wastes

Lungs 

•  pick up O2 / clean out CO2 

 Small Intestines 

• pick up nutrients from digested food 

 Large Intestines 

• pick up water from digested food  

Liver 

• clean out worn-out blood cells

HOMEOSTASIS 

 Homeostasis 

= keeping the internal environment of the body balanced 

• need to balance food & O2 in 

•  need to balance energy (ATP) production 

•  need to balance CO2 & waste out 

Exercise 

• heartbeat faster 

•  need more ATP 

•  bring in more O2 & food; remove more CO2 & waste out 

Disease 

• poor lung or heart function = heart beat faster 

• need to work harder to bring in O2 & food & remove wastes

Blood is a tissue of fluid & cells 

 plasma 

•  liquid part of blood 

• dissolved salts, sugars, proteins, and more 

• cells 

 red blood cells (RBC) 

• transport O2 in haemoglobin 

 white blood cells (WBC) 

•  defense & immunity 

Platelets

•  blood clotting

CARDIOVASCULAR DISEASE: 

Atherosclerosis & Arteriosclerosis 

•  deposits inside arteries (plaques) 

• develop in the inner wall of the arteries, narrowing their channel 

• increase blood pressure 

• increase risk of heart attack, stroke, kidney damage