Tag: Connective tissues

Introduction

The smallest structural and functional units in all living things are cells. Together, several cells make up tissues. Plants and animals both have eukaryotic cells and hence all cells contain many membrane cell organelles such as the nucleus, nuclear membrane, endoplasmic reticulum, etc. Organs are made up of tissues that perform the same functions. To carry out specific tasks, tissues are organized in a specific way. Animals and plants are made up of several tissues. Meristematic tissue and permanent tissue are the two types of tissues found in plants. Epithelial, connective, muscle, and nerve tissue are the four different types of tissues found in animals. Animal tissues solely include living cells, but plant tissues contain both living and dead cells.

Plant tissues

Organs are made up of tissues that are united to carry out certain functions. These organs and tissues work together and help in growth, development, and reproduction. Plant organs include leaves, roots, flowers, fruits, and stems, which are made of many types of tissues.

The majority of plant tissues are composed of dead cells, and they give the plants their structural stability and defense against extreme environmental changes. Plant tissues can be divided into two kinds, such as permanent and meristematic tissue.

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Types of plant tissues

• Meristematic tissue: Meristematic tissues support the plant’s primary growth. These tissues’ cells regularly divide, and they can be found at the root and stem tips. Spherical, tightly packed cells with no interstitial space are a common feature of meristematic tissues. These cells contain a thick cytoplasm surrounding the nucleus. Depending on where they are, meristems can be divided into
  • Apical meristems-At the growing tip of the stem and roots apical meristems are present. They help increases the length of the plant.
  • Lateral meristems- Lateral meristems are located at the lateral portion of the root or stem. These cells help in increasing the girth of the plant. They include cork cambium and vascular cambium which assist in secondary growth.
  • Intercalary meristems-These tissues are usually located in the internodes, nodes, or base of the leaves. They help in the growth of the leaves in the direction of light also they help in increasing the height of the plant.

• Permanent tissue: Permanent tissues are those that have fully developed and lost the capacity to reproduce. The permanent tissues are formed by the division and differentiation of the meristematic tissues.
  • Simple permanent tissues- Cells are identical and simple in simple tissues. These tissues are made up of cells that share a common origin, a similar structure, and related functions. Further, these tissues are divided into the parenchyma, collenchyma, and sclerenchyma.
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• Complex permanent tissues: These tissues are made up of various cells which are complex in nature. Phloem and xylem are examples of complex permanent tissues. These tissues aid in the transportation of  food, water, and mineral throughout the plant body.
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• Animal tissues are constructed from a collection of the animals’ cells. Animals have a range of tissues that each carry out a specific function for the organism. Organs are created when the tissues come together. Organisms are composed of organs. So, with the aid of tissues, a multicellular creature is created as a whole structure. The animal body contains four main types of tissues: epithelium tissues, muscular tissues, nerve tissues, and connective tissues. These tissues have various origins and functions.

Types of animal tissues

• Epithelial tissues
  • These were the first to arise during evolution and can be single or multilayered.
  • Covers both the body’s interior and exterior organs. They are very tightly packed and lack an intercellular matrix.
  • The cells may regenerate. 
  • Major functions of these tissues are to protect layers of organs, absorb, and secrete various fluids.
  • Based on the structure of the cells, there are four different types of epithelial tissues: squamous, cuboidal, stratified, and columnar epithelium.

Muscle tissues: 

• Muscle tissues are the tissues that surround the muscles.
• They aid in the body movement of the animal by contraction and relaxation.
• Skeletal muscle, smooth muscle, and cardiac muscle are the three different types of muscles found in an animal body.

• Connective tissues:
  • These tissues assist in connecting organs, other tissues, and various other body parts.
  • They also assist in the transportation of various materials throughout the body.
  • There are six different types of connective tissues: cartilage, adipose, lymph, bone, and blood.

• Nervous tissues:
  • The electrochemical impulse transmission between various neurons is carried out by these cells.
  • They help in the control and coordination of the entire body.
  • Nervous tissues are made up of nerve cells like neurons and neuroglia.

Differences between plant and animal tissue

Plant tissues	Animal tissues
They are defined as groups of cells performing the same task in plants.	They are defined as groups of cells performing the same task in animals.
The tissues here are comparatively simple.	The tissues here are comparatively more complex.
They have two types of tissues- Permanent and Meristematic tissues.	They are of 4 types-  Epithelial, Connective, Nervous, and Muscle tissues.
Differentiation is seen in both permanent and meristematic tissues.	No such differentiation is seen in animal cells.
These include living as well as dead tissues.	It mostly includes living tissues.
Maintenance of plant tissue requires less energy.	Maintenance of animal tissue requires more energy.
The cells of these tissues have cell walls.	The cells of these tissues are devoid of cell walls.
They provide mechanical support to the plants.	They help in movement and locomotion.

Summary 

The cells that makeup tissues collaborate to carry out various functions of the body. Meristematic and permanent tissues are the two categories of plant tissues. Epithelial, connective, neuronal, and muscle tissues are the four different types of tissues found in animals. Plant tissues support nutrient delivery and plant growth, whereas animal tissues support body movement or locomotion. This is the major distinction between plant and animal tissues. The healthy development and functioning of both plants and animals depend on both plant and animal tissues respectively.

Frequently Asked Questions

1. What are the similarities between plant and animal tissue?
Ans: Following are the similarity between plant and animal tissues-

• Cells of both tissues are eukaryotic i.e. they contain all cell organelles such as the Nucleus, nucleolus, RNA, DNA, Endoplasmic reticulum, etc.
• These tissues lead to the formation of organs and organ systems.
• Cells of these tissues release ATP which is used as an energy source to carry out all cellular activities.

2. Give the components of the xylem and phloem.
Ans: Phloem tissue aids in transporting materials throughout the plant body and is made up of sieve tubes, companion cells, phloem parenchyma, and phloem fibers. The xylem transports water and nutrients throughout the plant body and is made up of tracheids, vessels, xylem parenchyma, and xylem fiber.

3. Describe sclerenchyma.
Ans: Sclenechyma is simple permanent tissue found in plants. It provides mechanical support to plants and is made up of dead cells. These dead cells are highly lignified. Sclerenchyma is mostly found in the mature parts of the plants such as barks, thick stems, etc. It is made up of long and narrow cells. Cells are usually without protoplasts.

Introduction

The essential building blocks of living things are cells. There are billions of cells that make up the human body. A group of specialized cells which perform one or more similar functions are referred to as a tissue. They combine to produce several organs, such as the skin, kidney, lungs, liver, and heart. An organ system is made up of two or more organs that perform the same tasks. Each of these contributes to the overall body’s survival.

Types of animal tissues

Animal tissues are classified into four kinds based on their origins, structures, and functions. Animal tissues are of the following types-

• Muscular tissues
• Nervous tissues
• Epithelial tissues
• Connective tissues

Muscular tissue

Muscular tissue, which is considerably longer and has the ability to contract and expand, which causes motion. These tissues have a lot of blood vessels since they help in activities like running, walking, swimming etc.

Features of Muscular tissues

• Muscular tissues contract in response to stimuli to produce motion.
• They can be stretched more than their length.
• These tissues are elastic in nature because they can expand and then contract to their original length.
• They can adapt to their surroundings.

Types of Muscular Tissues

Types	Location	Function
Cardiac muscle	Heart	Continuous blood pumping
Skeletal muscle	Skeletal bone	Movement
Smooth muscle	Eyes, uterus, blood vessels, and digestive tract	Maintain blood flow and blood pressure

Nervous tissues

Nervous tissues make up the central nervous system (CNS) and peripheral nervous system (PNS). By sending nerve impulses, the neural or nervous tissue is in charge of control and coordination of  numerous bodily functions. The spinal cord, the brain, and the nerves are part of nervous system and that stimulate muscle contraction and regulate emotions, memory, and reasoning.

Neurons

Axon, dendrites, and cell bodies make up a neuron, and they are responsible for transmitting and receiving signals throughout the body.

Types of neurons– According to their functions, neurons can be divided into the following types:

• Sensory neurons– Short axons and lengthy dendrites are characteristics of unipolar sensory neurons. They are also referred to as afferent neurons since they transport action potential from the sensory receptor to the CNS and brain.
• Motor neurons– Motor neurons are multipolar and operate as efferent neurons because they transport the action potential from the central nervous system to activate muscles.
• Associated neurons-Associated neurons help the brain learn, make decisions, and regenerate new neurons. They are multipolar neurons which connect sensory and motor neurons.

Neuroglial cells 

It is responsible for supporting and maintaining the nervous system and they are of following types-Astrocytes, Ependymal cells, Microglial cells, Oligodendrocytes, Satellite cells and Schwann cells.

Epithelial tissues

All of the body’s inner and outer surfaces are lined and covered with epithelial tissue. The cells form single or several layers and are tightly packed together.

Features of Epithelial Tissues

• Without intercellular gaps, cells are tightly grouped together to form a sheet.
• Gap junctions, tight junctions, and adherent’s junctions connect the cells.
• Despite being non-vascular, or lacking a blood supply, these are innervated (supply nerves to organs or parts of the body).
• These tissues regenerate rapidly.
• Although they lack a blood supply, they receive nutrition from substances that diffuse from the blood vessels of the underlying tissues.
• At the basal surfaces, the epithelial tissues are joined to the connective tissues to forming  basal membranes.
  Types of Epithelial Tissues

Types	Location	Function
Simple squamous	Blood vessels, capillary walls, air sacs, linings of lymph	Transport the selective material to pass through osmosis, diffusion, filtration, and absorption
Simple cuboidal	Lining of ducts, tubular linings of kidneys, surfaces of ovary	Absorption and secretion
Simple columnar	Linings of the respiratory tract, digestive tract and uterus	Mucous secretion, absorption and protection
Transitional epithelium	Inner linings of the ureter, urethra and urinary bladder	Prevent reabsorption of toxic materials
Pseudostratified columnar	Linings of respiratory passage	Secretion, movement of mucous and protection
Stratified squamous	Throat, linings of the mouth, vagina, and the outer surface of skin	Protection
Stratified cuboidal	Salivary glands, mammary glands, pancreas and sweat glands	Protection
Stratified columnar	Parts of the pharynx and male urethra	Secretion and protection

Connective tissues
Connective tissues connects and supports the body’s all the other tissues and organs. These tissues have the capacity to store fat and aid in the flow of nutrients and other substances between the tissues and organs throughout the body. This transport of nutrients is done thorough the process of diffusion.

Features of Connective tissues

• Extracellular matrix and cells make up the connective tissue.
• Mast cells, macrophages, plasma cells, adipocytes, chondrocytes, fibroblasts, osteoblasts, and osteocytes are the cells that present in the connective tissue.
• Extracellular matrix is made up of tissue fiber and the ground substance.
• Collagen, elastic, reticular, and fibrillin are the tissue fibers present in the connective tissue. Glycoproteins, glycosaminoglycans, and proteoglycans are ground substances present in the connective tissue.
  Types of Connective tissues

Types	Location	Function
Non-fibrous connective tissues- Blood and adipose tissue.	Blood was found throughout the body. Adipose tissue found in association with areolar tissue.	Provides nutrition and oxygen to the body. Adipose tissue is a good insulator and source energy reserve.
Collagen fibers	Tendon, Ligament, Skin, Cartilage, Bone etc.	Binding bones and other tissues
Elastic fibers	Extracellular matrix	Give elasticity to the organs and helps to retain original position post stretching.

Summary

Animal tissues are categorized according to their shape and function. Tissues are groups of cells having similar functions. Epithelial tissue is present on the upper skin surfaces which have intercellular substances and densely packed cells. Epithelial tissues include squamous, cuboidal, columnar, stratified, transitional, and pseudostratified tissue types. Muscle tissues can contract the muscles to perform particular functions in the heart, skeleton, blood vessels, eyes, and digestive tract. Connective tissues support the placement of organs to enable optimal internal organ form and function. It consists of adipose, areolar, blood, lymph, tendon, ligament, cartilage, bone, and lymphatic tissues. Nervous tissue contains neurons and neuroglial cells that are present  in the brain and spinal cord to control the CNS and PNS and helps entire bodily control and coordination.

Frequently Asked Questions

1. How are various tissues derived?
Ans: All tissues come from one of three distinct germ layers. During embryonic development, these germ layers are formed. They are as follows-

• The epidermis and nervous system are formed from the ectoderm (outer layer).
• The middle layer, or mesoderm, eventually forms connective tissue and lines the body’s cavities.
• The inner layer, or endoderm, gives rise to a number of internal organs, including the pancreas and liver, as well as the lining of the digestive tract, respiratory system, and reproductive system.

2. Give the classification of neurons based on their structure.
Ans: Based on their structural characteristics, neurons can be divided into the following types:

• Bipolar neurons- Axons and dendrites are two of the extensions seen on bipolar neurons.
• Unipolar neurons- There is only one extension from the body of a unipolar neuron (one axon).
• Multipolar neurons- One axon and several dendrites characterize multipolar neurons.

3. What are bones?
Ans: Bones are connective tissue with abundant collagen and calcium, they provide support for the joints that make up the skeletal system of the body. These are places where various lymphocytes of the immune system develop and help in protection of the body.