Transportation

Transportation

the circulatory system

Circulatory system

The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homeostasis.

HEART

The human heart is one of the most important organs responsible for sustaining life. It is a muscular organ with four chambers. The size of the heart is the size of about a clenched fist.

The human heart functions throughout a person’s lifespan and is one of the most robust and hardest working muscles in the human body.

HEART

Besides humans, most of the other animals also possess a heart that pumps blood throughout their body. Even invertebrates such as grasshoppers possess a heart like pumping organ, though they do not function the same way a human heart does.

Position of Heart in Human Body

The human heart is located between the lungs in the thoracic cavity, slightly towards the left of the sternum (breastbone). It is derived from the embryonic mesodermal germ layer.

The Function of Heart

The function of the heart in any organism is to maintain a constant flow of blood throughout the body. This replenishes oxygen and circulates nutrients among the cells and tissues.

Following are the main functions of the heart:

• One of the primary functions of the human heart is to pump blood throughout the body.

• Blood delivers oxygen, hormones, glucose and other components to various parts of the body, including the human heart.

• The heart also ensures that adequate blood pressure is maintained in the body

EXTERNAL STRUCTURE OF HEART

• Triangular in outline

• hollow muscular structure

• 2/3 is tilted towards left side

• reddish brown in colour

• externally 5 vessels are visible

• it is divided into 2 grooves

• right groove is bigger than the left

Pericardium

The human heart is situated to the left of the chest and is enclosed within a fluid-filled cavity described as the pericardial cavity. The walls and lining of the pericardial cavity are made up of a membrane known as the pericardium.

The pericardium is a fibre membrane found as an external covering around the heart. It protects the heart by producing a serous fluid, which serves to lubricate the heart and prevent friction between the surrounding organs. Apart from the lubrication, the pericardium also helps by holding the heart in its position and by maintaining a hollow space for the heart to expand itself when it is full

Internal Structure of Heart

The internal structure of the heart is rather intricate with several chambers and valves that control the flow of blood.

Chambers of the Heart

Vertebrate hearts can be classified based on the number of chambers present. For instance, most fish have two chambers, reptiles and amphibians have three chambers. Avian and mammalian hearts consists of four chambers. Humans are mammals; hence, we have four chambers, namely:

1.Left atrium

2.Right atrium

3.Left ventricle

4.Right ventricle

Chambers of the Heart

• Atria are thin, less muscular walls and smaller than ventricles. These are the blood-receiving chambers that are fed by the large veins.

• Ventricles are larger and more muscular chambers responsible for pumping and pushing blood out to the circulation. These are connected to larger arteries that deliver blood for circulation.

  
  

• The right ventricle and right atrium are comparatively smaller than the left chambers. The size difference is based on their functions. The blood from the right side flows to lungs, while blood arising from the left flows to body.

  
  

Open Ended

Why does the blood from right side of the heart is pumped to lungs

Why does the blood from right side of the heart is pumped to lungs

The blood is being pumped into the lungs for the oxygenation of our blood to supply oxygen to all the body parts.

Blood Vessels

In organisms with closed circulatory systems, the blood flows within vessels of varying sizes. All vertebrates, including humans, possess this type of circulation. The external structure of the heart has many blood vessels that form a network, with other major vessels emerging from within the structure. The blood vessels typically comprise the following:

Blood Vessels

Veins supply deoxygenated blood to the heart via inferior and superior vena cava, and it eventually drains into the right atrium. Capillaries are tiny, tube-like vessels which form a network between the arteries to veins.

Arteries are muscular-walled tubes mainly involved in supplying oxygenated blood away from the heart to all other parts of the body. Aorta is the largest of the arteries and it branches off into various smaller arteries throughout the body.

Valves

Valves are flaps of fibrous tissues located in the cardiac chambers between the veins. They ensure that the blood flows in a single direction (unidirectional). Flaps also prevent the blood from flowing backwards. Based on their function, valves are of two types:

valves

• Atrioventricular valves are between ventricles and atria. The valve between the right ventricle and right atrium is the tricuspid valve, and the one which is found between the left ventricle and left atrium is known as the mitral valve.

• Semilunar valves are located between the left ventricle and aorta. It is also found between the pulmonary artery and right ventricle.

LYMPHATIC SYSTEM

all tissues are bathed in the tissue fluid consisting of waste materials from the cell

It is called as tissue fluid as it is the waste material excreted by the cells/tissued after cellular respiration

it contains toxic materials and if mixed with blood would be harmful to the human body

lymphatic system consists of the following

• lymph nodes : which purify the lymph and then mixes with the blood

• Lymph vessels : vesseld which carry lymph

• Lymph : It is the tissue fluid which is excreted by the tissues

Lymphatic syste,m runs parallel to the venous system and then when the lymph is purified it is deposited into the venous system

Coagulation of blood

Initially when an organism is hurt it gets signals and all the platelets are thereby accumulated near the wound/hurt so as to stop the external blood flow.

Then, prothrombin is converted to by thrombikinase and thrombin converts fibrinogen to fibrin.

Flow chart for the coagulation of blood

• As discussed alreaady fibrin is formed and this fibrin is nothing but a solid mass of the blood and platelets.

• These are accumilated near the wound edges and they don't let the blood flow out of our body

Types of circulation

Circulations can be divided into 2 categories depending upon the

1. No. of time blood flowing to heart

2. Passage of the blood

Depending on number of times blood is flowing to heart we have:

• Single circulation : In this case blood would be flowing to heart only once to the heart

• The blood which comes from the tissues collecting CO₂ from the tissues after cellular respiration would be pumped to gills (respiratory organ) for oxygenation and blood is pumped directly to the organs from gills

Double circulation

• Here blood comes to heart twice

• Once, it carries CO₂ from the tissues after cellular respiration from the tssues

• Then it is pumped to lungs for oxygenation

• After oxygenation in lungs blood again comes to heart and then it is ttransported to body parts for nutrients, oxygent etc...

Depending upon passage of blood

• We have these divisions as follows

• Open circulation : It has no vessels and the nutrients are directly supplied to the body parts by diffusion principle. It has no blood vessels and best example is cockroach.

• Closed Circulation : Here blood flows through blood vessels like arteries and veins and blood only transports all the essential nutrients to the body. Best example is the human body.

Cardiac cycle

One contraction and one relaxation of heart is called as Cardiac cycle

This is neede to pump the blood to body parts

Steps inculde

• Joint diastole : imaginary phase where all 4 chambers of heart would be in resting phase

• Auricular systole : after the auricles receive deO₂ blood from the body parts, They contract and blood is pushed to the ventricles

Steps inculde

• Ventricular systole : When all the blood is pumped to the ventricles the auricles now relax and blood tries to flow from the ventricles to auricles. Therefore tricuspid and bicuspid valves forcefully close making a sound "LUB"

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Steps inculde

• Ventricular Diastole : Now the whole blood is pumped into the aorta and P.artery by the ventricles. When ventricles start relaxing Aortic and Pulmonary valve close making the sound "DUB"

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FACTS OF CARDIAC CYCLE.

• The complete cycle of cardiac cycle just completes in 0.8 seconds

• "LUB" is a sharp sound

• "DUB" is a feeble sound

BLOOD PRESSURE

• A constant pressure would be maintained in our body by the blood flow

• This pressure varies from one part to another

• We usually measure B.P in the left upper arm and it would be 120/80

• SPHYGMOMANOMETER is used to measure Blood Pressure

Transportation in plants

Plants have xylem and phloem to transport water and minerals and food respectively

Transportation in plants

• Xylem and Phloem

• Root pressure

• Transpiration

Xylem and Phloem

• Xylem is the complex tissue of plants, responsible for transporting water and other nutrients to the plants.

• Phloem is living tissue, responsible for transporting food and other organic materials.

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Root pressure

• Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day.

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Transpiration

• This process of elimination of excess water from the plant body is known as transpiration. It is generally the evaporation of water from the surface of the leaves.

• During the process of transpiration, water molecules in the plant tissues are removed from the aerial parts of the plants. Only a small amount of water absorbed by the plants is utilised in growth and development. The rest is eliminated in the form of transpiration.

Multiple Choice

1. Thread like structures which hold the vlves in position are called as

• Chordae tendinae

• Corpus luteum

• Spindle fibres

• All of the above