Biology (FYJC) Ch. 10 Animal Tissues PDF

1 Biology (FYJC) Ch. 10 Animal tissues Cells (multicellular organisms) Somatic cells...

1 Biology (FYJC) Ch. 10 Animal tissues Cells (multicellular organisms) Somatic cells Germ cells Body cells that make up different These cells are concerned with the tissues. reproduction. E.g., Sperm and ovum  Tissue is a group of cells having same embryonic origin, structure and function. Unit 10.1 Histology  Histology: The study of the structure and arrangement of tissue.  Marie Francois Xavier Bichat is known as “Father of Histology”. Tissues (types) Epithelial tissue Connective tissue Muscular tissue Nervous tissue Unit 10.2 Epithelial Tissue Location  It covers the outer surface of body and organs.  It lines the cavities of hollow organs of the body. Characteristics  Cells are polygonal, cuboidal or columnar in shape with a single nucleus.  The cells are compactly arranged with little intercellular matrix.  Cells rest on non-cellular basement membrane.  Cells are avascular i.e., lack their own blood supply. These cells get their nutrition from blood capillaries present in the underlying connective tissue.  It has good capacity of regeneration due to presence of basement membrane which acts as substratum.  Protection of skin from microorganisms Functions  Absorption of nutrients from intestine.  Secretion from epithelial glands.  Transportation  Filtration and secretion of lymph from blood capillaries. Types A) Simple epithelium is made up of single layer of cells. B) Compound Epithelium is made up of two or more layers of cells.  2 Biology (FYJC) A) Simple Epithelium tissue 1) Squamous epithelium 2) Cuboidal epithelium  Location – in blood vessels, alveoli, coelom,  Location – in lining of pancreatic duct, etc. salivary duct, proximal and distal convoluted  Cells – flat, thin and polygonal with serrated tubules of nephron. margin.  Cells – cuboidal in shape. *Cells fit together like tiles of footpath, hence  Nucleus – spherical nucleus at the centre of also called as pavement epithelium. cell.  Nucleus – spherical or oval nucleus at the  Function – absorption, secretion centre of cell.  Function – protection, absorption 4) Ciliated epithelium  Location – Inner lining of trachea, lining 3) Columnar epithelium buccal cavity of frog, oviduct of vertebrates.  Location – Inner lining of intestine, gall  Cells – Cells are columnar or cuboidal. Inner bladder, gastric gland and intestinal gland. ends are narrow & rests on basement  Cells – Cells are tall, pillar like. Inner ends of membrane. Free ends are broad & has cilia. cell are narrow. Free ends are broad, flat and  Nucleus – oval & placed at basal end of cell. has microvilli.  Function – to create a movement of  Nucleus – oval and present in lower half of materials in contact in specific direction, cell. prevent entry of foreign material in trachea,  Function – absorption, secretion push ovum through oviduct. 5) Glandular epithelium  Location – in the glands  Cells – Cells are columnar, cuboidal or pyramidal in shape with secretory granules in the cytoplasm.  Nucleus – Large and towards the base of cell.  Function – Secretion of enzymes, hormones, mucus, etc. Glands (depending on number of Cells) i) Unicellular - E.g., Goblet cells of Intestine ii) Multicellular - E.g., Salivary Gland Multicellular glands (mode of secretion) (i) Exocrine Glands - pour their secretions at specific site. E.g., Salivary gland, sweat gland. (ii) Endocrine Glands - release their secretions directly in blood. E.g., Thyroid, Pituitary gland. Pancreas acts as an endocrine as well as exocrine gland. 6) Sensory epithelium 7) Germinal epithelium  Location – in nose (olfactory), ear (auditory hair  Cells divide meiotically to produce haploid cells), eye (photoreceptors) gametes.  Cells – Modified columnar cells and elongated  Location – Lining of seminiferous tubules, neurosensory cells. Sensory hairs are present at inner lining of ovary. free ends of cell.  Function – Cells perceive external and internal stimuli.  3 Biology (FYJC) Compound epithelium Characteristics  It is made up of two or more layers of cells.  The lowermost layer lies on the basement membrane.  Cells of stratum germinativum are nucleated. Cells of free surface become flat and lack nucleus called stratum corneum. Types b. Transitional Epithelium a. Stratified Epithelium  The cells can undergo a change in their shape  Location: epidermis of skin, and structure depending on degree of stretch. oesophagus, cornea, vagina  Location: Urinary bladder  Functions: Protection  Function: distension of organ Cell Junctions  Epithelial cells are connected to each other laterally as well as to the basement membrane by junction complexes called as Cell Junction.  Types – Tight junction, Gap junction, Adherens junction, Desmosomes and Hemidesmosomes  4 Biology (FYJC) Unit 10.3 Connective tissue Characteristics  Most widely spread tissue in the body.  They comprise of fibres and various cells embedded in the matrix.  They are highly vascular in nature (except cartilage). Types 1. CT Proper 2. Supporting CT 3. Fluid CT  Loose CT  Cartilage  Blood  Dense CT  Bone  Lymph 1. Connective Tissue Proper a) Loose CT: Areolar and Adipose tissue  It consists of semisolid viscous matrix made up of gelatin in which fibres and cells are dispersed. i) Areolar CT Location  below skin, between muscles & bones, around organs, blood vessels and peritoneum.  They interconnect different organs and protect vital organs. Functions  This tissue acts as packing material and helps in healing. Structure  The semisolid matrix contains fibres and various cells. Fibres are of two types i.e., White and Yellow fibres.  White fibres are made up of collagen. They give tensile strength to tissue.  Yellow fibres contain elastin and are elastic in nature. Cells in the matrix are of following four types: Large flat cells with branched processes. Fibroblasts They produce fibres and secrete polysaccharides which forms the matrix. Oval cells that secrete heparin and Mast cells histamine. Macrophage Amoeboid phagocytic cells. Cells with eccentric nucleus that store Adipocytes fats.  5 Biology (FYJC) ii) Adipose tissue Location  Present in sole, palm region, around kidneys. Functions  Acts as a good insulator, shock absorber and good source of energy.  Adipose tissue consists of large number of adipocytes. Structure  Matrix is less with few fibres and blood vessels.  Cells are rounded or polygonal with nucleus at periphery.  Fats are stored in the form of droplets. Adipose tissue is of two types: These appear opaque due to presence of large number of i) White AT adipocytes. They are commonly seen in adults. Reddish brown in colour due to ii) Brown AT presence of large number of blood vessels. b) Dense CT: Regular and Irregular CT.  In this tissue fibres and fibroblast are compactly arranged. i) Dense regular connective tissue  Collagen fibres are arranged in parallel manner.  Types: Tendon and Ligaments  Tendons connect skeletal muscles to bones.  They are composed of bundles of white Tendon fibres.  It provides tensile strength.  E.g., Achilles tendon, Hamstring tendon  Ligaments connect bones with one another.  They are composed of yellow fibres making Ligaments them elastic.  They prevent dislocation of bones.  They are present at joints. ii) Dense irregular connective tissue  Fibres and fibroblast are not arranged in orderly manner.  They are found in dermis of skin.  6 Biology (FYJC) 2. Supporting CT: Cartilage and Bone  It is characterized by presence of hard matrix. a) Cartilage Location  It is widely distributed in vertebrate animals and forms endoskeleton of cartilaginous fishes. Structure  Pliable yet tough tissue  Abundant matrix i.e., chondrin is delimited by a collagenous sheath of perichondrium.  Below perichondrium, chondroblast (immature) cells are present. Chondrocytes (mature cells) are seen scattered in matrix.  Chondrocytes are enclosed in lacunae. Each lacuna contains 2 to 8 chondrocytes. Based upon the nature of the matrix there are four types of cartilage. 1. Hyaline cartilage  Chondrin is bluish white gel like. 2. Elastic cartilage  Matrix contains elastic fibres and few chondrocytes. 3. Fibrocartilage  Matrix contains bundles of collagen fibres and few chondrocytes. 4. Calcified cartilage  Rigid cartilage due to deposition of salts in matrix.  7 Biology (FYJC) b) Bones Structure  Periosteum is the outer tough membrane and encloses the matrix.  Blood vessels and nerves pierce through periosteum.  Matrix is hard and is called as Ossein, which is made up of mineral salt hydroxy apatite.  Matrix is arranged in the form of concentric layers called lamellae.  Each lamella contains fluid filled cavity called lacunae.  In the lacunae osteoblast (active bone cells), osteocytes (inactive bone cells) and osteoclasts are present. Lacunae gives off canaliculi. Canaliculi of adjacent lamellae connect with each other. Haversian System  Mammalian bone shows structural unit called as Haversian system.  A single Haversian system shows Haversian Canal in the centre enclosing an artery, vein and nerves. Haversian canal is surrounded by lamellae containing lacunae.  According to presence of matrix there are two types of bones in human body: i) Spongy bones ii) Compact bones  Haversian system is absent.  Matrix shows haversian system  Matrix is arranged in the form of without any space between trabeculae. lamellae.  It contains red bone marrow.  8 Biology (FYJC) Unit 10.4 (A) Muscular tissue Characteristics  Muscular tissue is known as contractile tissue as the muscle fibres can contract upon stimulation.  It is vascular and is innervated by nerves.  Cells are elongated and are called as muscle fibres or myofibres.  A muscle fibre has sarcoplasm (cytoplasm) covered by sarcolemma (plasma membrane.  In the sarcoplasm, large number of myofibrils (contractile fibrils), mitochondria and one or many nuclei are present.  Myofibrils are made up of proteins – actin and myosin. Actin filaments are thin and light coloured, while myosin filaments are thick and dark coloured. Types 1. Skeletal muscle 2. Smooth muscle 3. Cardiac muscle Also called as  Striated muscle  Non striated muscle  Visceral muscles 1. Skeletal muscles / Striated muscles Location  They are found attached to the bones.  These muscles perform quick, strong and voluntary contractions and Functions thus brings about voluntary contractions in body. Structure Structure of a muscle fibre:  Sarcolemma delimits the sarcoplasm.  Sarcoplasm contains parallelly arranged myofibrils.  Each myofibril is made up of repeated functional units of contraction called as Sarcomeres.  Fibres are syncytial i.e., multinucleated with nuclei Striated muscles towards the periphery. Structure of a Sarcomere: A sarcomere shows following regions:  A band – dark band in the centre of sarcomere, made up of actin and myosin.  H zone – light area in the centre of A band.  M line – a dark line in the centre of H zone.  I band – light band on both sides of A band, made up of actin.  Z line – separates adjacent light bands.  Dark and Light bands on neighbouring fibres corresponds with each other to give striated appearance. Sarcomere  9 Biology (FYJC) 2. Smooth Muscle or Non-Striated Muscles Location  Found in the walls of visceral organs. Functions  These muscles undergo slow and sustained involuntary contractions. Structure  Muscle fibres are present in the form of sheets or layers.  Each muscle fibre is unbranched and spindle shaped (fusiform).  Sarcoplasm shows a single central nucleus, myofibrils and is without any striations.  Muscle fibres are innervated by Autonomic nervous system (ANS). Smooth muscles 3. Cardiac muscles Location - Myocardium of heart wall. Function - Acts as striated involuntary muscles. Structure  Cardiac muscles show characteristics of both striated and non-striated muscles.  Muscle fibres are uninucleate but appear multinucleate. Adjacent fibres join to give branched appearance.  Sarcolemma is not distinct.  Point of adhesion of muscle fibres are formed by transverse thickening of sarcolemma and are called as intercalated disc. Hence quick transfer of stimulus takes place in cardiac muscles.  Myogenic heart – Mammalian heart can generate impulse of contraction on their own.  Neurogenic heart – Cardiac muscles need neural stimulus to initiate contraction.  10 Biology (FYJC) Unit 10.4 (B) Nervous tissue Nervous tissue is composed of neuroglia and neurons. A) Neuroglia  Non nervous supporting cells, fills inter neuronal space.  They are capable of regeneration and division due to presence of centriole. B) Neuron Characteristics  Neurons are structural and functional units of nervous system.  Neuron cannot divide and regenerate due to absence of centriole.  Neuron is an impulse generating and impulse conducting unit. They bring about quick communication within body.  Neuron change action potential of their membrane on receiving any external stimulus. This property of neuron is called Excitability.  Wave of impulse is carried from dendron to axon, this is called Conductivity. Structure of neuron  A Neuron is made up of cyton (cell body) enclosing neuroplasm (cytoplasm) and gives out two processes; dendron and axon.  Neuroplasm – It is granular due to presence of Nissl’s granules made up of RNA. It also contains a central nucleus, mitochondria, golgi complex, RER, etc.  Dendrons – These are many short-branched processes given out by cyton. The fine branches given out by dendrons are called as dendrites. They carry impulses towards cyton.  Axon – It is a single, elongated process given out by cyton from axon hillock. Axoplasm (cytoplasm) of axon is bounded by axolemma (membrane). It contains large number of mitochondria and neurofibrils. The terminal arborization of axon is called as telodendron.  Myelin sheath – The axon of myelinated neurons is enclosed in the insulating fatty myelin sheath which is secreted by Schwann cells. Myelin sheath prevents loss of impulse during conduction. The myelin sheath is absent at intervals along the axon, these intervals are known as Node of Ranvier.  Synapse – It is the functional contact between axonal ends and dendrites of adjacent neurons.  In myelinated neurons, impulse is conducted at a faster rate as the impulse jumps from one node to another. Such faster impulse transmission is called as Saltatory conduction.  11 Biology (FYJC) 1) On the basis of presence of Myelin sheath: Myelinated or Non-myelinated or Medullated nerve fibres Non medullated nerve fibres  Myelin sheath is present over axon.  Myelin sheath is absent over axon.  Nerve fibre appear white in colour.  Nerve fibres appear grey in colour.  Conduction of impulse is at faster rate.  Conduction of impulse is slower.  E.g., Cranial nerves of vertebrates  E.g., Nerves of ANS 2) On the basis of function: a) Afferent neuron  It carries impulses from sense organ to CNS. (sensory neuron) b) Efferent neuron  It carries impulses from CNS to effector organ. (motor neuron)  This neuron performs processing, integration of sensory c) Inter neuron impulses and activates motor neuron to generate motor (Association neuron) impulse. 3) On the basis of number of processes given out from cyton: a) Unipolar  A single process originating from cyton at one point. (monopolar neuron)  Both axon and dendron arise from the cyton at one point.  It has two processes. A single dendron and an axon are b) Bipolar neuron given off from opposite poles of cyton.  Cyton is star shaped and gives out many processes. c) Multipolar neuron  From the cyton, a single axon and many dendrons arise. ---------------X----------X----------X---------------