BLOOD

DEFINITION:

It is a red colored, viscous, alkaline (pH about 7.4) fluid flowing through the body of higher animals. It is a connective tissues. The adult human body consists of 5-6 liters of blood.
It has two components:

• Fluid plasma.

• Solid formed elements. (The elements including corpuscles and postulate)

BLOOD PLASMA/ FLUID PLASMA:

It is the colorless liquid part of the blood. It forms about 55% of the blood (about 3 liters). It is non- living part and its 90% part is composed of water, in which a large number of organic and inorganic substances are dissolved.

Functions of blood plasma:

• Maintains osmotic pressure and viscosity of the blood.

• It helps in transport of various substances like food, water and other substances from all parts of the body for many purposes such as assimilation, oxidation and storage.

• It acts as a protein reservoir.

• It also helps in clotting of blood.

• By the circulation of blood heat is distributed throughout the body to maintain the body temperature constant and uniform. 

Its composition is as follows: 

• Water (92%)

• Soluble components: Proteins, glucose, amino acid, triglycerides, urea, hormones etc. 

BLOOD CORPUSCLES/ SOLID FORMED ELEMENTS:

• The blood corpuscles make up the 40-45% of the blood. These blood corpuscles are found freely suspended in the liquid plasma.

• There are three types of solid elements:

1- Red blood corpuscles or cells (RBC’s)

2- White blood corpuscles or cells (WBC’s)

3- Platelets.

Red blood corpuscles (RBC’s) /Erythrocytes:

• They are small biconcave circular cells also called erythrocytes.

• They are thicket at their edges than in the center.

• The erythrocytes are flexible so that they can pass through the narrow capillaries easily.

• They number 5.8 million per cubic mm in adult males and 4.2 cubic mm in adult females.

• Their number is higher in early infancy.

• The adult red blood cells do not have nucleus, mitochondria or endoplasmic reticulum.

• Hemoglobin is composed of an iron containing pigment called haeme and a protein called globin. The hemoglobin pigments combine with oxygen to form oxyhaemoglobin in the lungs.

• The life span of these cells is only about 120 days.

Functions of RBC’s: 

• It helps in exchange of gases, and is called respiratory pigments.

• They maintains the viscosity of blood, acid-base and ionic balance.

• The disintegration of haemoglobin leads to formation of many other pigments like bilirubin, biliverdin, etc. in liver.

 White blood corpuscles(WBC’s):

• They are also called Leucocytes.

• Hey lack haemoglobin and are therefore colorless.

• They are nucleated and amoeboid.

• The amoeboid nature of the leucocytes helps them to squeeze through the walls of the blood vessels in order to engulf bacteria.

• WBC s are commonly known as POLICE OF THE BODY; because they protects the body by killing germs.

• They number 5000 to 9000 per cubic mm .

• The ratio of WBC to RBC is 1:7.

Functions of WBC's/ Leucocytes:

• Defense against diseases : They have the ability to differentiate between their own body cells and foreign cells .WBC's destroy bacteria and protect the body. 

• Production of Anti bodies: The WBC's are involved in the production of antitoxins and antibodies that neutralize, kill or poison the germs.

• WBC's can be induced to produce anti bodies with the help of vaccinations thus prepairing the body for an attack.

Blood Platelets/Thrombocytes:

• Blood contains fragments of larger bone marrow cells known as platelets.

• They are small, round, biconvex cells that do not have a distinct nucleus.

• They are also called Thrombocytes.

• They number 250,000 to 400,000 per cubic mm of blood.

• Their life span is 8 to 14 days .

• They are destroyed in the spleen.

Functions of platelets:

• Helps in blood clotting.

• Help in the repair of damaged Endothelium.

• The clot forms is made denser smaller by the action of platelets, called clot Retraction. 

 

BLOOD CIRCULATORY SYSTEM:

DEFINITION:

The circulatory has to ensure that the materials reach all the cells of the body and in time. 
‘’The system involved in the transport of various substances within the body of an animal is called circulatory system’’.  

TYPES OF BLOOD CIRCULATORY SYSTEM:x

There are two types of blood circulatory system:

•  Open circulatory system.

•  Closed circulatory system.

OPEN CIRCULATORY SYSTEM:

• The blood enters and circulates in the interestial spaces (space between the tissues).

• The exchange of materials between the cells and the blood is done directly.

• The blood vessels are open- ended as they open into the common cavities called the HOEMOCOEL. For example: Insects.

• The blood does not flow inside the blood vessels, instead it remains filled in the open spaces called SINUSES, so the tissues of the body are virtually floating in the direct contact with the blood.

• After exchange of materials with the tissues, it enters the HEART which pumps the blood into the blood vessels.

• This vessel again drains out the blood into sinuses; hence it is kept in CIRCULATION.

CLOSED CIRCULATORY SYSTEM:

• In mammals there is a closed circulatory system, because the blood during flowing always remains inside the blood vessels and never comes in direct contact with the cells.

• The materials enter and exit the blood vessels through the walls.

• The blood flows in the blood vessels under high pressure such that it reaches all the parts of the body in good time.

COMPONENTS OF CLOSED CIRCULATORY SYSTEM:

There are three main components of the closed circulatory system in ma are:

BLOOD: A fluid that can carry all the materials to be transported (blood).

HEART: A pumping organ that can push the fluid through the body.

BLOOD VESSELS: Many tubes through which the fluid can flow through the body.

There are three types of blood vessels:

• Arteries.                      

• Veins.

• Capillaries.

ARTERIES:

• The blood vessel that carry blood from the heart to various organs are called arteries.

• They carry oxygenated blood (except pulmonary artery that carries de-oxygenated blood) and lie deep in the body.

• The colour of fresh blood drawn from the arteries is bright red.

• When an artery enters in the corresponding organ, it divides up into smaller branches or arterioles which eventually divides in to fine capillaries.

• The walls of an artery is composed of three layers; an inner layer layer of endothelial cells, a thick middle layer of smooth muscles and elastic fibres, and an outer layer of elastic fibers and connective tissues.

VEINS:

• Veins carry deoxygenated blood except for pulmonary vein that carries oxygenated blood from the lungs.

• The blood drawn from the veins is dark red in colour. 

• The capillaries join together to form venioles.  
• The venioles join together to form veins.
   
• The walls of the veins are not a thick as those of arteries.
   
• All the veins of the upper body joins, except the pulmonary vein, and form the inferior vena cava.
   
• The pulmonary veins bring the blood to the heart from the lungs.
  

• Thus, the blood vessels that brings the blood to the heart are called the veins. 

CAPILLARIES:

• These are microscopic vessels where exchange of various substances occurs between blood and the surrounding tissues

• Each capillary is composed of only a single layer of endothelial cells.

• Internally, its diameter is slightly larger that of Red Blood Cells.

• They are connected on one side and venioles on the other side.

STRUCTURE OF HEART

EXTERNAL STRUCTURE OF HEART:

• Externally the human heart is a muscular, cone-shaped, hollow organ about the size of a fist (about 12cm in length and 9 cm in breadth).

• The heart is situated behind the sternum, between the lings in the thoracic cavity.

• The major part of the heart is made up of muscles and is called MYOCARDIUM.

• The inner lining of the heart is called the ENDOTHELIM.

• The heart is covered by a membrane called PERICARDIUM.

• The pericardium encloses the PERICARDIAL CAVITY that houses the heart.

INTERNAL STRUCTURE OF HEART:

• Internally the human heart is four- chambered.

• The upper chambers are called the atria or the auricles and the lower two chambers are called the ventricles.

• The two atria are separated by the INTER-ATRIAL SEPTUM.

• The two ventricles are separated from each other by the INTER-VENTRICULAR SEPTUM. 

 

•  The ventricles have more muscular walls than the auricles.

• An AURICULO – VENTRICULAR aperture connects the ATRIUM with VENTRICLES of its own side.

• In between the right atrium and right ventricle lies a TRICUPSID CAVITY.

• Similarly a BICUPSID CAVITY guards the opening between left atrium and left ventricle.

• The tricuspid and bicuspid valves prevent back flow of blood into the auricles from the ventricles.

• The two ATRIA contracts simultaneously to push the blood into the respective ventricles.

• The blood from the right ventricle is pumped through PULMONARY ARCH to the lungs for OXYGENATION while blood from the left ventricle is pumped through aorta to all parts of the body.

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ENDOCRINE GLANDS:

''In the body of vertebrates, there is a system of glands which are ductless and their secretion is directly poured into blood known as ENDOCRINE GLANDS. Their secretion is called as HORMONES.'' 

 HORMONES: 

A hormone is defined as;

''A special chemical substance which is poured by certain group of cell or organs, and are secreted directly into the blood and by its circulation they are carried to the place where they are required. ''
Hormones are also called as CHEMICAL MESSENGERS. 

FUNCTION: 

They are secreted in small amounts and help to co-ordinate processes such a metabolism, growth etc. Their influence in the body is often profound and long lasting.

IMPORTANT ENDOCRINE GLANDS:

1-PITUITARY GLANDS:

• Pituitary glands are situated at the lower region of hypothalamus (in brain) and attached by a small structure.

• Its size is like a pea-seed.

• It is a very important gland, and directly influence other endocrine glands, it is therefore, said to be MASTER GLAND.

FUNCTIONS: 

Pituitary gland has two parts, which perform different function.

ANTERIOR LOBE:

• They secrete number of hormones one of them is called GROWTH HORMONE.

• This hormone controls the growth of bones and other tissues, thus it affect the size of the body.

• Some other hormones secreted by this lobe helps to regulate other endocrine glands, such as thyroid, ovaries etc.

POSTERIOR LOBE:

This lobe produces two hormones, one of these hormones controls the excretion of urine by kidney and the other hormone causes contraction of smooth muscles in the urinary bladder.

2-THYROID GLANDS:

• Thyroid glands are present in the lower region of neck, in front of trachea.

• It is butterfly shaped, and consists of two lobes; one is located on each side of trachea.

• It’s important hormone is THYROXIN.

FUNCTIONS:

• Thyroxin affects many chemical reactions in the cells, and controls the rate of metabolic activities in cells that releases energy from nutrients.

• This hormone is essential for normal growth and mental development especially in children.

• In early age, failure of thyroid to produce its hormones can results in stunned growth and severe mental retardation, known as CRETINISM.

3- PARATHYROID GLANDS: (PTG)

• These glands are small sized and two paired glands, located adjacent to the two lobes of the thyroid glands.

• It secrets a hormone called PARATHORMONE.

FUNCTION:

• It controls the amount of sugar in the blood and helps to increase re absorption of Calcium in kidney.

• The PTH regulated the storage of minerals of mineral elements in bones and teeth.

• It also controls the excretion of these substances from the body.

• The over secretion of this hormone is also harmful as it produces stones in the kidney and causes rickets.

4- PANCREAS:

• Pancreas is located in the abnormal cavity near the stomach. It is a gland which secrets hormones as well as enzymes.

• In pancreas hormones are secreted by some cells called ISLETS OF LANGERHANS.

• In islets of Langer Hans two types of cells are present, which are called Alfa cells and Beta cells and perform two functions.

FUNCTIONS:

• ALPHA cells secrets GLYCOGEN hormone. It is produced when amount of glucose in blood is decreased. This hormone converts GLYCOGEN into GLUCOSE, to produce energy.

• BETA cells produce INSULIN hormone. It is responsible to keep the amount balanced form in blood.

• By the help of this hormone extra amount of glucose is converted into GLYCOGEN.

• It stimulates liver and muscles tissues to receive and store glycogen.

5- ADRENAL GLAND:

• Adrenal glands are two in number, each of which is present on the anterior end of a kidney.

• Each adrenal gland consists of two parts, ADRENAL CORTEX (outer part) and ADRENAL MEDULLA (inner part).

FUNCTIONS:

• ADRENAL CORTEX secrets number of hormones, which are collectively called CORTICOSTIROIDS.

• They regulate amino acids and concentration of certain minerals elements in the blood and tissues of the body.

• ADRENAL MEDULLA produces a hormone called ADRENALIN or EMERGENCY HORMONE.

• They prepare the body to face a situation of emergency, e.g. at the situation of FIGHT or FLIGHT.

6- GONADS:

Gonads i.e. TESTES and OVERIES are important reproductive organs, but they also act as endocrine glands and productive hormone.

FUNCTIONS:

• TESTES: Testes are male reproductive organs, and they secrete hormones, called ANDROGEN.

• Testosterone is one of the important hormones of androgen, which is responsible for the development of secondary sexual characteristics, such as deepening of voice, appearance of moustaches and beard etc.

• OVARIES: Ovaries are female reproductive organs, but they also act as endocrine gland, and secrete two hormones.

• They hormones control the development of secondary sexual characters in female.

• OESTROGENS are one of the two hormones, helps to develop and maintain the characters of female sex.

• PROGESTERONE is another hormone, which helps in the implantation of ova, maintains pregnancy and also in the development of mammary glands.

Structure of villi

VILLI: 

''The digested food in the form of soluble molecules of glucose, fructose, amino acid, fatty acids and glycerol etc is absorbed into body through very fine finger like projections called Villi''.

• Each Villus is about 1mm long.

• There are about 5 million villi in the ileum.

  

  INTESTINAL VILLI

• Inside each villus there is a dense network of blood capillaries and a single lymph vessel or lacteal(A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine).

• Both blood vessel and lacteal absorb the digested food.

• Nutrients other than fatty acids diffuse through the surface cells of villi and are taken to the blood flowing in capillaries of villi.

• These capillaries join together to form a larger blood vessel called hepatic portal vein which carries the absorb food to the lever.

• Some fatty acid, after they are absorbed by surface cells of villi; recombine to form fats which are passed onto the other side into lacteal rather than blood capillaries.

• Lacteal of villi join together to form lymph vessel which finally delivers the fats into blood stream through lymphatic system.

HUMAN DIGESTIVE SYSTEM:

DIGESTION:

The process of conversion of non-diffusible food molecules (complex food) into fusible food molecules (simple form) by the action of enzymes is called as DIGESTION. 

PROCESS/STAGES OF DIGESTION:

The entire process of digestion takes place in a long, coiled, muscular tube called ALIMENTARY CANAL which consists of the following:

• Mouth cavity.

• Oesophagus.

• Stomach.

• Small intestine.

• Large intestine.

The process of digestion involves following different stages:

• Ingestion.

• Digestion.

• Absorption.

• Assimilation.

• Egestion.

INGESTION: 

The process of taking of food into the mouth or body of an animal is called as ingestion.

DIGESTION OF FOOD IN MOUTH: 

• The process of mechanical and chemical digestion begins in mouth.

• Teeth are present in the mouth cavity.

• The food is crushed down into small pieces with the teeth, and this process is called as mechanical digestion.

• There are three pairs of salivary glands, which produce saliva.

• Saliva contains enzymes called PTYALIN, which converts starch into maltose.

• This process is called chemical digestion. Starch---------Ptyalin------------Maltose.

• Now the partially digested food takes the form of a ball called BOLUS, which is pushed into oesophagus.

OESOPHAGUS:

• It is a long tube like structure, which keeps the food moist with the help of alkaline juices, secreted by its walls.

• It also helps in transport of food into stomach.

DIGESTION OF FOOD IN STOMACH:

• Stomach is a bag like structure, which is elastic in nature.

• The gastric glands secrete gastric juices, and these juices perform chemical digestion.

• Gastric juices are:

-HCL: It softens the food and kills germs.

-RENIN: It helps to curdle milk in infants.

-PEPSIN: It acts on proteins to break them into PEPTONES.

After few hours the food become a thick fluid called chyme, and is released bit by bit in small intestine. 

DIGESTION OF FOOD IN SMALL INTESTINE:

Small intestine is a narrow tube which is divided into two parts:

a) Duodenum.                                                                    b) Ileum.

DUODENUM:

It is the first part of small intestine, which receives a common duct which formed by the fusion of a bile duct and pancreatic duct, and is called as hepato pancreatic duct.

(i) BILE DUCT comes from gall bladder of liver, and brings bile juice. Bile juice helps in breaking down large molecules of fats into small droplets. This process is called  EMULSIFICATION.

(ii) PANCREATIC DUCT comes from the pancreas, and contains sodium bicarbonate and many enzymes. Three important enzymes are as follows:

-AMYLASE breaks down starch into maltose.     Starch ------- Amylase ------- Maltose.

-TRYPSIN acts upon proteins into smaller peptides. Proteins-----Trypsin-----Peptides.

-LIPASE breaks fats into fatty acids and glycerol. 
                                                                  Fat droplets----Lipase---- Fatty acids+ Glycerol.

ILEUM:

• This is the second part of small intestine, where food enters from the duodenum.

•  Here the rest of the digestion is completed, by the enzymes present in intestinal juices secreted by the glands present in the walls of small intestine.

• The enzyme amino peptidase breaks down peptides into amino acids.

                    Peptides---------------Amino peptidase--------------Amino acid.

• The enzyme disaccharides break down maltose, lactose and sucrose into glucose.

                    Maltose/Lactose/Sucrose--------Disaccharides-------Glucose. 

ABSORPTION OF FOOD IN SMALL INTESTINE:

• After the process of digestion, the digested food in the form of soluble molecules of glucose, fructose, amino acid, fatty acids and glycerol etc. is absorbed into the blood vessel through VILLI.

• The digested food is now diffused in the blood and then taken to the liver.

• From liver it is taken to the heart through blood.

• From heart it is taken to the each and every cell of the body through blood.(circulatory system)

LARGE INTESTINE:

• The undigested food (roughage) along with pass from the ileum to large intestine.

• Large intestine is wide tube, consists of coecum, appendix, colon and rectum.
  
• In large intestine absorption of water takes place, so the undigested food becomes slightly hard. 

• During the process intestinal bacteria cause fermentation of the undigested matter, which is now termed as FAECES.

EGESTION:

•  The FAECES are stored in the rectum,(the last portion of alimentary anal) where it is stored for some time.

• From here the faeces pass outside the body through an opening called ANUS.

TOOTH

STRUCTURE OF HUMAN TOOTH:

Each tooth consists of three parts:

• Crown.

• Neck.

• Root.

CROWN:

Crown is the part of tooth projected above the gum level. It is the biting and chewing part surface of the tooth.

-Enamel: 

The outer surface of crown is covered by a very hard white substance called the enamel. It is non-living and protects teeth besides giving lustrous appearance to tooth.

NECK:

Neck is the part surrounded by gum.

ROOTS:

Root is the part embedded in bone. The parts of root are:

-Dentine: The root as well a portion inside the enamel is dentine. It is less harder than enamel.

-Pulp cavity: Inside the dentine, there is a cavity known as pulp cavity. It is filled by soft connective tissues called pulp. It also contains nerves and blood vessels that supply the growing tooth with food and oxygen.

-Cement: The root of each tooth is covered with another hard material called cement.

  PERIODONTAL MEMBRANE:

The tough fiber of periodontal membrane is attached with the cement to the jaw bone so that each tooth is fixed firmly in socket.

TYPES OF HUMAN TEETH:

According to the shape and function following type of teethes are present in our oral cavity:

-INCISORS.              -CANINES.              -PREMOLARS.              -MOLARS.

INCISORS: 

The flat chisel-shaped teeth present in front of oral cavity are incisors. They are eight in numbers, four in upper jaws and four in lower jaws. They are used in cutting.

CANINES:

Beside incisors lie canines in each side in both jaws. They are four in number and are pointed. They are used for tearing and pulling flesh. They are very long and prominent in carnivores such as loin. Herbivore animals usually do not have canines. 

PREMOLARS:

In both jaws each canine is followed by two premolars. They are six in number and each with the two distinct edges. They are involved in grinding the food.

MOLARS:

Premolars of each side of both jaws are followed by three molars. They are 12 in number. They also grind food. The last molar is called as WISDOM-TEETH.