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Showing posts with label Biology. Show all posts
Showing posts with label Biology. Show all posts

TISSUE

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TISSUE
Epithetical Tissue
(i) On the basis of cell layers
(a) When an epithelium has a single layer of cells it is called a simple epithelium.
(b) Where as a multiple tier of cells are known as stratified epithelium.
(ii) On the basis of simple shape of cells:
Ø  Cuboidal : its occurrence is in kidney tubules, salivery glands, inner lining of the cheek. Its main function is to give mechanical strength.
Ø  Columnar : its occurrence is in sweat gland, tear gland, salivary gland its main function is to gives mechanical strength concerned with secretions.
Ø  Squamous : when it forms a living as that of blood vessels, it is called endothelium.
Its main function is to protect the underlying parts from injury, entry of germs, etc.
Ø  Connective tissue : Its main function is to bind and support other tissues.
There are a few types of connective tissue.

Connective Tissue
Arelor
(i) Tendon
(ii) Ligament

Adipose Skeletal
(i) Bone
(ii) Cartilage

Fluid
(i) Blood
(ii) Lymph

A. Areolar tissue : It fills spaces inside organs found around muscles, blood vessels and nerves. Its main function is to joins skin to muscles, support internal organs, help in the repair of tissues. Whereas tendon’s main function is to connect muscles to bones and ligament is connects bones to each other.

B. Adipose tissue : Its occurrence is below skin, between internal organs and in the yellow bone Marrow. Its main function is to storage of fat and to conserve heat.

C. Skeletal tissue : Bone & cartilage occurrences is in nose, epigotis and in intervertebral disc of mammals. Its main function is to provide support and flexibility to body part. Whereas bone protects internal delicate organs provides attachments for muscles, bone marrow makes blood cells.

D. Fluid tissue : Blood & Lymph blood transport O2 nutrients, hormones to tissues and organs. Whereas leucocytes fight diseases and platelets help in cloting of blood. Lymph transport nutrients into the heart and it also forms the defense system of the body.

Muscular Tissue
It is specialized for ability to contract muscle cells.
Types of Muscular tissue:
A. Skeletal muscle: It attached primarily to bones. Its main function is to provide the force for locomotion and all other voluntary movements of the body.
B. Cardiac muscle: It occurs only in the heart. The contraction and relaxation of the heart muscles help to pump the blood and distribute it to the various parts of the body.
C. Smooth muscle: It can be found in stomach, intestines, and blood vessels these muscles cause slow and prolonged contractions which are involuntary.
D. Nervous tissue: This tissue is specialized with a capability to conduct electrical impulses and convey
information from one area of the body to another. Most of the nervous tissue (98%) is located in the central nervous system. The brain and spinal cord.
Types of Nervous Tissue
Ø  neurons
Ø  neuroglia

Important facts regarding animal tissue:-
Ø  Muscles contain special protein called contractile protein. Which contract and relax to cause
Ø  Fat storing adipose tissue is found below the skin and between internal organs.
Ø  Two bones are connected to each other by a tissue called ligament. This tissue is very elastic.
Ø  The skin, the living of the mouth, the living blood vessels, kidney tubules are all made up of epithelial tissue.
Ø  Voluntary muscles and cardiac muscles are richly supplied with blood whereas involuntary muscles are poorly supplied with blood.

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CELL

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CELL

Cell: It is the basic structural unit of life.
Cells were first discovered by Robert Hooke.
Note: The smallest cell is 0.1 to 0.5 micrometre in bacteria. The largest cell measuring 170 mm ×130 mm, is the egg of an ostrich.
Amoeba acquires its food through endocytosis.
1.       Prokaryotes cells - cells that have no defined nucleus
Eg: Bacteria & Blue-green Algae
2.       Eukaryote - cells which have definite nucleus
Eg: Other than Bacteria & Blue-green Algae
Compounds called proteins and phospholipids make up most of the cell membrane.

Diffusion-It is a process of movements of substance from a region of high concentration to a region where its concentration is low. Water also obeys the law of diffusion.
Eg: Substances like Co2 and O2 can move across the cell membranes by a process called diffusion.

Osmosis: The movement of water molecules is called osmosis. Osmosis is a special case of diffusion through a selectively permeable membrane.

Types of Osmosis:
1.       Hypotonic: more water will come into the cell than will leave. The cell is likely to swell up.
2.       Isotonic: the amount going in is the same as the amount going out of the cell.The cell will stay the same size.
3.       Hypertonic: more water leaves the cell than enters it. Therefore the cell will shrink.
When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.

Cytoplasm: It is the fluid that fills a cell. Scientists used to call the fluid protoplasm.

Ribosomes: It synthesis protein, and Endoplasmic reticulum sent these protein in various part of the cell. Whereas Smooth Endoplasmic reticulum helps in the manufacture of fats. It a made up of ribonucleic acid.

Functions of these proteins and fats:
·         Protein and fat (lipid) help in building the cell membranes. This process is known as membranes biogenesis.
·         Smooth Endoplasmic reticulum plays a crucial role in detoxifying many poisons and drugs.

Golgi apparatus :  It is another packaging organelle like the endoplasmic reticulum functions:
·         It is the organelle that builds lysosomes  (cells digestion machines).

Lysosomes(suicidal bag): It is a kind of waste disposal system of the cell.

Mitochondria(power house):  The energy required for various chemical activities headed for life is released by mitochondria in the form of ATP (adenosine-tri-phosphate) molecules.
Ø  ATP is known as the energy currency of the cell.
Ø  Mitochondria are strange organelles in the sense that they have their own DNA and ribosomes, therefore mitochondria are able to make their own protein.
Ø  Mitochondria is absent in bacteria and the red blood cells of mammals and higher animals.

Centrioles:  centrioles are concerned with cell division. It initiates cell division.

Plastids: These are present only in plant cells.
Types of plastids:-
Ø  Chromoplast(colour plastides)  impart colour to flowers and fruits.
Ø  Leucoplasts(white or colourless plastids) present  in which starch, oils and protein are stored.
Ø  Plastids are self-replicating. i.e. they have the power to divide, as they contain DNA, RNA and ribosomes.
Ø  Plastides contains the pigment chlorophyll that is known as chloroplast. It is the site for photo synthesis.
non –living parts with in the cell :-

Vacuoles: it is a fluid filled spaces enclosed by membranes. Its size in animal is small and in plant it is big.
Amino acids and sugars are stored in vacuoles.

Granules: It is not bounded by any membranes. It store fats, proteins and carbohydrates.

Cell nucleus: The cell nucleus acts like the brain of the cell. It helps control eating, movement
and reproduction. Not all cells have a nucleus.
The nucleus contain, the following components :
(a) Nuclear envelope (nuclear membrane)
(b) Chromatin : When the cell is in resting state there is something called chromatin in the nucleus. Chromatin is made up of DNA, RNA and nucleus protein. DNA and RNA are the nucleus acids inside the cell. When the cell is going to divide, the chromatin become very compact. It condenses when the chromatin comes together we can see the chromosomes.
(c) Chromosomes: Chromosomes make organisms what they are. They carry all the information used to help a cell grow, thrive and reproduce.
Ø  Chromosomes are made up of DNA.
Ø  Segments of DNA in specific patterns are called genes.
Ø  In prokaryotes, DNA floats in the cytoplasm in an area called the nucleoid.
Ø  Chromosomes are not always visible. They usually sit around uncoiled and as loose shards called chromation.
Ø  Chromosomes are usually found in pairs.
Ø  Human Beings probably have 46 chromosomes (23 pairs).
Ø  Peas only have 12, a dog has 78 chromosomes.
Ø  The number of chromosomes is not related to the intelligence or complexity of the creature.
(d) Nucleolus: It is a dense spherical granule contained within the nucleus.It stores proteins.

Cell Division
Organisms grow and reduce through cell  division.
There are two methods of replication mitosis and meiosis.
(a) Mitosis: It duplicates its DNA and the two new cells (daughter cells) have the same pieces and generic code. There are five steps in this process. You should remember the term PMATI. It breaks down to :
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
5. Interphase.
The main theme of meiosis is that there are two cell division. Mitosis has one division

Some important facts regarding cells :
Ø  Nerve cells in animals are the longest cells.
Ø  Smallest human cell is red blood cell.
Ø  Largest human cell is female ovum.
Ø  The single largest cell in the world is of an ostrich.
Ø  The smallest cells are those of the mycoplasma.
Ø  Every minute about 3 million cells in our body die.
Ø  Sieve tube in plants and the mature mammalian red blood cells do not have a nucleus.
Ø  The red blood cell carries respiratory gases.
Ø  Sieve cells in plants transport nutrients in plants.
Ø  The lysosomal enzymes of the sperm cells digest the limiting membranes of the ovum (egg). Thus the sperm is able to enter the ovum.
Ø  During the transformation of tadpole into frog. The embryonic tissues like gills and tail are digested by the lysosome.
Ø  Mitochondria contain DNA, hence capable of replication.
Ø  Matrix is a transparent, homogenous semi-fluid substance. In its active state. It remains saturated with water.

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Vitamins and Their Sources

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We usually talk about vitamins but do we know what are vitamins? The vitamins are important as they perform various functions in the body. The deficiency of vitamins may take place as the food which you intake might not have enough of vitamin contents. This deficiency of vitamins hampers proper body functioning. To have a balanced diet enriched with the vitamins we need to know about the vitamins, their importance and sources. Read this article to know about different Vitamins and their sources and their importance.

Vitamins and Their Sources

There are 13 essential vitamins that are important for a human body. These vitamins are divided into two categories, fat-soluble and water-soluble vitamins. Given below in the table are the Different vitamins and their sources.
Fat-Soluble VitaminsWater-Soluble Vitamins
It is stored in the body’s fatty tissue.It is not stored in the body.
Fat-soluble vitamins are – A,D,E, KWater-soluble vitamins are – B1, B2, B3, B5, B6, B7, B9, B12, Vitamin C

Vitamins and Their Sources: What are Fat-Soluble Vitamins

The fat-soluble vitamins are similar to oil and do not dissolve in water. Fat-soluble vitamins are most abundant in high-fat foods and are much better absorbed into your bloodstream when you eat them with fat. Given below is the table with the list of different vitamins and their sources from which you can get, their importance for the body.
VitaminsImportanceSources
Vitamin A
  • This vitamin is vital for vision.
  • This vitamin provides healthy skin and mucous membranes.
  • It also improves bone and tooth growth.
  • It is vital for improving immunity.
  • Fortified milk
  • Cheese
  • Cream
  • Butter
  • fortified margarine
  • Eggs
  •  Liver
  • Leafy vegetables
  • Apricots
  •  Carrots
  • Sweet potatoes
  • Pumpkin.
Vitamin D
  • It is essential in proper absorption of calcium stored in bones.
  • Egg yolks
  • Liver
  • Fatty fish
  • Fortified milk
  • Fortified margarine
  • Sunlight.
Vitamin E
  • It protects cell walls.
  • Soyabean, corn e.t.c.
  • Leafy green vegetables
  • Wheat germ
  • Whole-grain products
  • Liver
  • Egg yolks
  • Nuts and seeds.
Vitamin K
  • It essential for proper blood clotting.
  • Kale
  • Collard greens
  • Spinach
  • Broccoli
  • Brussels sprouts
  • Asparagus
  • Produced in the intestinal tract by bacterias.

Vitamins and Their Sources: What are Water-Soluble Vitamins

Water-Soluble Vitamins are vitamins that can dissolve in water. These vitamins are carried to the body’s tissues but are not stored in the body. They are found in animal foods and plants or dietary supplements and should be taken daily. Both Vitamin C and members of the vitamin B complex are water-soluble. To know more about Water-Soluble Vitamins and their Sources, refer to the table given below.
VitaminsImportanceSources
Thiamine (vitamin B1)
  • The part of an enzyme which is required for energy metabolism.
  • It is significant in nerve functioning.
  • Pork
  • Whole-grain
  • Enriched breads
  • Cereals
  • Legumes
  • Nuts and seeds.
  • It is found in all nutritious food in moderate amounts.
Riboflavin(vitamin B2)
  • The part of an enzyme is needed for energy metabolism.
  • It is important for normal vision & skin health.
  • Milk and milk products
  • Leafy green vegetables
  • Whole-grain
  • Enriched  breads
  • Cereals.
Niacin (vitamin B3)This vitamin helps in maintaining:
  • healthy skin
  • nerves
  • digestive system.
  • Meat
  • Fish
  • Whole-grain
  • Enriched breads
  • Cereals
  • Mushrooms
  • Leafy green vegetables
  • Peanut butter.
Pantothenic acid
  • This vitamin is essential for the metabolism of food.
  • It is widespread in almost all food.
Biotin
  • Important in metabolism of proteins and carbohydrates.
  • It also helps in the production of hormones and cholesterol.
  • It is widespread in food.
  • It is produced in the intestinal tract by bacteria.
Pyridoxine (vitamin B6)
  • The part of an enzyme needed for protein metabolism.
  • It helps in making red blood cells.
  • Meat
  • Fish
  • Poultry
  • Vegetables
  • Fruits.
Folic acid
  • The part of an enzyme is needed for making DNA.
  • This also required for new cells i.e. red blood cells.
  • Leafy green vegetables
  • Legumes
  • Orange juice
  • Liver
  • It is now added to most refined grains.
Cobalamin (vitamin B12)
  • The part of an enzyme needed for making new cells.
  • It is important for nerve functioning.
  • Meat
  • Poultry
  • Fish
  • Seafood
  • Eggs
  • Milk and milk products
  • It is not found in plant foods.
Ascorbic acid (vitamin C)
  • This promotes healthy teeth & gums.
  • It is needed for healthy immune system.
  • The part of an enzyme is needed for protein metabolism.
  • It helps in iron absorption.
  • Citrus fruits
  • Cabbage family
  • Cantaloupe
  • Strawberries
  • Peppers
  • Tomatoes
  • Potatoes
  • Lettuce
  • Papayas
  • Mangoes
  • Kiwifruit.
Hope this article on vitamins and their sources was informative and helpful in your exam preparation. If you have any queries related to the article, do mention in the comments section.

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The Human Nervous System

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The nervous system is a complex connection of nerves and unique cells (neurons) that are responsible for transmitting signals to and from various body parts.

Classification Of the Human Nervous System

The nervous system is basically classified into Central nervous system and Peripheral nervous system. The central nervous system manages the whole body and the nervous system. It is only because of the nervous system’s efficient coordination between the different organ systems that we can feel sensations like pain or cold.

Broadly, the nervous system can be classified into:
  1. The central nervous system (CNS) consisting of the brain, spinal cord.
  2. The peripheral nervous system (PNS) consisting of sensory neurons, ganglia (a cluster of neurons) and nerves.

The Human Nervous System - Testbook

The nervous system is also classified on the basis of functionalityinto:

  1. The somatic nervous system(SNS) responsible for conscious perception and voluntary motor response. For example, getting startled when someone sneaks up on you. That was not decided by you, nonetheless, it is a motor response involving skeletal muscle contractions.
  2. The autonomic nervous system( ANS) responsible for involuntary body movements usually with the objective of maintaining body homeostasis. For example, sweating when your body is hot is to cool the body down.
  3. The enteric nervous system(ENS) responsible for controlling smooth muscle and glandular tissue in the digestive system.

Let’s understand in detail the Central Nervous system and the Peripheral Nervous System –

Central Nervous System

So far you know that the nervous system is classified into Central and Peripheral nervous system. Neurons are the basic unit of the nervous system. These neurons are classified into three types – Sensory, motor and association/connecting neurons. The main function of the central nervous system is to keep control over the entire body and the nervous system. The Central Nervous consists of two main parts – Brain and Spinal Cord. These two parts are covered by three membranes mentioned below:

  • Durameter which is the outer layer/membrane.
  • Arachnoid membrane is the middle layer.
  • Piameter is the innermost membrane

Let’s study in details the two main parts of the central nervous system i.e. brain and spinal cord –

Human Nervous System - Testbook

Brain

It is entirely covered by a protective layer called meninges. To protect the brain from injuries it is covered by a bony box termed as the cranium. Furthermore, the brain is divided into three parts Forebrain, Midbrain, and Hindbrain.

  • Forebrain

The forebrain is made up of the Cerebrum, Thalamus, and Hypothalamus. The Cerebrum is associated with memory, wisdom, knowledge, will power and thinking. Thalamus regulates cold, heat and pain. Whereas, the Hypothalamus controls the sweat, blood pressure, secretion of hormones, thirst, hunger, etc.

  • Midbrain

Midbrain manages the main function of hearing and vision.

  • Hindbrain

Hindbrain includes parts like Cerebellum, Pons and Medulla. The human body posture is managed by Cerebellum. The Pons acts as a bridge between the spinal cord and brain. Medulla regulates important functions like respiration, heart rate, sneezing, and coughing, etc.

Spinal Cord

  • The spinal cord starts from the medulla oblongata and extends towards the neural canal of the backbone/vertebral column.
  • There are 31 pair of spinal nerves that arises from the side of the spinal cord.
  • The function of the Spinal cord is to control all the reflexes that take place below the neck.
  • Furthermore, the spinal cord conducts the sensory impulses arising from the muscles and skin to the brain.
  • Vertebrae protect the spinal cord from any kind of injuries.
  • The spinal cord also conducts the motor responses from the brain to the muscles present in the limbs and trunk area.

Peripheral Nervous

The peripheral nervous system consists of the nerves that arise from the brain and spinal cord. The human body has 31 pairs of spinal nerves and 12 pairs of cranial nerves. The peripheral nervous system is divided into the somatic nervous system and autonomic nervous system.

Somatic Nervous system

Somatic Nervous system includes the peripheral nerve fibers that convey the sensory information to the motor nerve fiber and central nervous system.

Autonomic Nervous system

The autonomic nervous system consists of three sections namely, the sympathetic, parasympathetic and the enteric nervous system. It regulates the smooth muscle of the viscera (internal organs) and glands.

What is the Function of the Nervous System?

  • Essentially, the primary function of the nervous system is to send signals either from one cell to another or from one body organ to another.
  • There is more than one way in which cells send signals. The broadcast method of signaling is done through the endocrine system where the hormones are released into the circulatory system. Through the nervous system, the signaling is done “point to point”. Hence, the nervous system entails advantages of being more specific, accurate and speedy.
  • The human nervous system controls the human body. The body reacts to stimulus because the nervous system extracts these external signals via sensory receptors and the central nervous system processes these signals and decides on an appropriate response and then sends an output signal to the concerned body part to activate the response.
Human nervous system - Testbook

Diseases Associated with the Nervous System

Diseases occurring in the nervous system are mainly due to a genetic defect, a result of traumatic experiences, infections, or ageing. Diseases associated with the peripheral nervous system are mainly due to stoppage in nerve conduction. Illustrated below is the list of diseases along with their symptoms, treatment and precautionary measures.

Name of

disease

SymptomsTreatmentPrevention
Alzheimer’sAssociated with failing memory and deterioration in reasoning ability.Treatments exist only to slow down the symptoms because the death of brain cells cannot be reversed.Regular physical exercise can reduce the risk of Alzheimer’s by at least 50%. We should keep a check on our thyroid and sex hormone levels and eat healthy fats.
Leprosy– Infectious disease and is associated with skin lesions and no sensation to touch

– numbness in hands, feet and legs

– Muscle weakness, as evident from symptoms such as foot drop.

 Early recognition is important as early treatment limits the damage. Medications exist to kill the microorganisms and reduce symptoms.Doctors recommend annual examinations for at least five years after the last contact with an infectious person.
PolioFever, headache, vomiting, diarrhoea, fatigue, neck stiffness, muscle stiffness, abnormal sensations in an area, muscle spasmsThe motive of the treatment is to control the growth of symptoms while the infection runs its course.Polio can be completely prevented and immunised against through vaccination. The polio vaccine needs to be given at age 2 months, 4 months, and between 6 and 18 months of age with a booster between 4 and 6 years of age.
RabiesPreliminary symptoms are mild and varied. The victim alternates between moods of agitation and calm; experiences muscle spasms of mouth and pharynx.Injections or immunoglobulin vaccine.Rabies can be prevented by vaccinating dogs and cats as required by law. We should not keep wild animals as pets and stay away from strays.
EpilepsyEpilepsy is a sudden rush of electrical activity in the brain. Mild seizures may be difficult to recognise and could span a few moments wherein you lack awareness. Stronger seizures will lead to spasms and uncontrollable muscle twitches. Victims either become confused or lose consciousness.The treatment plan depends on the severity of seizures. Some options are anti-epileptic medications, ketogenic diet, vagus nerve stimulator and even brain surgery of the affected area.We should keep away from alcohol and drugs and maintain a regular sleep schedule. Vitamin D tablets can be consumed and regular exercising would also be beneficial. A head injury can be prevented by wearing helmets while riding at all times. Regularise your sleep cycle and ensure you stick to it.
Parkinson’s diseaseParkinson’s disease commences usually with a tremor in the hand. Other symptoms include slow movement, stiffness, loss of balance, speech impairment.Treatments prevent symptoms from aggravating. In more advanced cases, surgery is advised. A speech pathologist will correct the problems associated with speech.Consume organic products which do not contain pesticides and insecticides. Have green tea and also incorporate Vitamin D3 and Omega 3 Fatty Acids in our diet. Regular aerobic exercise can also be beneficial.
Cerebral PalsySymptoms of cerebral palsy start to show in the first three years of life. These include overdeveloped or underdeveloped muscles, leading to stiff or floppy movements; crawling abnormally, limited movement, preferring one side of the body to another, lying down awkwardly.The treatment varies from individual to individual. A care plan addresses the needs of the child and the parents. As the child gets older, the plan is reviewed and revised. The aim is to provide maximum possible independence to the child.Unfortunately, cerebral palsy cannot be completely prevented during pregnancy or delivery. However, expecting mothers should try to deliver a healthy baby through regular visits to their gynecologist. Identifying potential Rh incompatibility between mother and child can also help prevent cerebral palsy in the unborn child.

This note on one of the most vital systems of the human body will help you in your static GK preparation. However, it is important for the candidate to be prepared with the other human body processes as all work hand-in-hand. 

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