histology Flashcards
(23 cards)
What is meristematic tissue
Function: to enable growth through rapid cell division (mitosis)
Structure: small cells with dense cytoplasm
Found: tips of shoots and roots (the apical meristem) for growth in length; sides of shoots and roots (lateral meristem or cambium) for growth in width.
what is dermal tissue
DERMAL TISSUE
Function: protection + outer covering of leaves, stems and roots
Structure: usually only 1 cell thick, closely packed with no intercellular spaces, transparent epidermal tissue in leaves and stems also has a waxy cuticle to prevent water loss
Found: outer covering of leaves, stems and roots
what is Collenchyma
Collenchyma
Function: support
Structure: thickened corners of cell walls (triangles)
Found: stems and branches just under epidermis
what is Sclerenchyma
Sclerenchyma
Function: support (the tissue which makes the plant hard and stiff).
Structure: very thick cell, may be elongated to form fibres or rounded stone cells (called sclereids).
Found: where extra support required, fruit
what are Parenchyma and chlorenchyma
Parenchyma and chlorenchyma
Function: packing tissue (fill up space), support (when full of water), gaseous exchange through intercellular spaces, photosynthesis (when containing chloroplasts)
Structure: thin walls, very large vacuoles, isodiametric (length and width are the same), intercellular spaces present
Found: throughout the plant forming the “filler” tissue in the soft parts of plants
what is Xylem
[VASCULAR TISSUE]
Xylem
Two types: tracheids and vessels
Structure: non-living, elongated cells joined end to end cells walls are thickened: either annular, spiralor or pitted
Vessels: end walls are perforated to form one long tube
Tracheids: end walls are tapered and there are pits down the sides
Found: throughout the plant in vascular bundles
Function: transport water & minerals from roots to other parts of the plant
what is Phloem
[VASCULAR TISSUE]
Phloem
Two components: sieve tubes & companion cells
Structure: living, elongated cells with thin cell walls
sieve tubes: have no nuclei, but are living; end walls are perforated to make sieve plates
companion cells: have nuclei, always lie next to a sieve tube to control it
Found: throughout the plant in vascular bundles
Function: transport food & nutrients e.g. from leaves to the rest of the plant
what is EPITHELIAL TISSUE
EPITHELIAL TISSUE
Epithelial tissues are formed by cells that cover surfaces (e.g. skin) and line tubes and cavities (e.g. digestive organs, blood vessels, kidney tubules and airways). Epithelial tissue usually consists of a single layer of cells, however in certain cases there may be more than one layer (stratified). All epithelial tissues are tissue surfaces that are attached to the underlying layers of a basement membrane.
what is Squamous epithelium
Squamous epithelium
Location: found lining capillaries, the alveoli (in lungs) and in a stratified form in skin.
Structure: these are thin and flat cells that are elliptically shaped and lie on basement membrane. Simple squamous epithelium is one-cell thick. Stratified squamous epithelium consists of many layers.
Function: these thin cells are permeable and allow for diffusion. Thin structure allows for movement of substances across the cells. When stratified, they provide protection and prevent friction.
what is Cuboidal epithelium
Cuboidal epithelium
Location: found lining various ducts (tubes) e.g. kidney tubules or glands - generally regions of the body responsible for excretion.
Structure: these cells are cube-like in structure. They may occasionally have structures called microvilli on surface to aid absorption.
Function: they serve a protective function against bacteria and the wearing away of certain organs by lining various structures. They also prevent water loss.
what is Columnar epithelium
Columnar epithelium
Location: digestive tract, reproductive organs
Structure: Elongated cells, nuclei located at the base of the cell. Cells connected by tight junctions and receive their nutrients from the basement membrane. Often they have structures called microvilli on surface.
Function: Protective by preventing against bacterial infection. They can also secrete mucus to protect surface from damage. Mucus and microvilli can trap dirt and transport this away e.g. sinuses and trachea. Also very important for absorption of digested nutrients in the small intestine.
goblet vs stirated epithelium
Goblet cells:
Mucous secretions
lubricate
Striated epithelium:
Layered epithelium
e.g. cheek lining, skin
what is CONNECTIVE TISSUE
CONNECTIVE TISSUE
Connective tissue is a biological tissue that is important in supporting, connecting or separating different types of tissues and organs in the body. All connective tissue is made up of cells, fibres (such as collagen) and extracellular matrix. The type of intercellular matrix differs in different connective tissues e.g. forming a solid in bone and a liquid in blood.
what is Adipose tissue
Adipose tissue
Location: Surrounding organs and under the skin.
Structure: consisting of lipid-rich cells called adipocytes, a thin matrix with a few fibres.
Function: Energy storing, hormone production, thermal insulation.
what is Dense connective tissue
Dense connective tissue
Location: the tissue making up tendons and ligaments. Tendons connect skeletal muscles to bones a ligaments connect bones in joints.
Structure: Tendons are inelastic with lots of collagen fibres. Ligaments are elastic with lots of elastin fibres. Between this dense network of fibres are cells called fibroblasts.
Function: allows skeletal muscles to pull on bones to enable movement as well as allows joints to bend.
what is Cartilage
Cartilage
Location: Surrounding the bones of joints, the nose, the sternum, the trachea
Structure: a semi-solid matrix with cells called chondrocytes
Function: part of the endoskeleton, for flexible structures e.g. the ears
what is Bone
Bone
Location: Forms the bones of the endoskeleton
Structure: a solid matrix made up of collagen fibres that have been mineralised with calcium and phosphates to make it solid. Cells called osteocytes are scattered throughout the solid matrix in concentric rings called osteons.
Function: provides strength and support and allows for movement
what is Blood
Blood
Location: Formed in the red bone marrow of the body and located in the blood vessels and heart.
Structure: a liquid matrix called blood plasma. Blood is composed of red blood cells, white blood cells and platelets (thrombocytes).
what is MUSCLE TISSUE
MUSCLE TISSUE
Muscle tissue is made up of cells that can contract and shorten the length of the cell. This brings about movement. Skeletal and cardiac muscle are striated. Striated muscle cells are striped, with regular patterns of proteins responsible for contraction. Striated muscle contracts and relaxes in short bursts, whereas smooth muscle contracts for longer.
what is Skeletal muscle tissue
Skeletal muscle tissue
Skeletal muscle is a voluntary muscle. It is striated in appearance. Skeletal muscle tissue has regularly arranged bundles. It is anchored by tendons and is used to effect skeletal muscle movement, such as locomotion, and maintain posture. The muscles have a reflex action but can also respond to conscious control.
what is Cardiac muscle
Cardiac muscle
Cardiac muscle is the major tissue making up the heart. It is an involuntary muscle that is striated in appearance. However, unlike skeletal muscle, cardiac muscle connects at branching, irregular angles. The connected branches help with coordinated contractions of the heart.
what is Smooth muscle tissue
Smooth muscle tissue
Smooth muscle is an involuntary, non-striated muscle with tapered ends. It is found within the walls of blood vessels such as arteries and veins. Smooth muscle is also found in the digestive system, urinary tract and in the trachea. It is responsible for involuntary rhythmic contractions of peristalsis, required for moving food down the alimentary canal, and for the dilation and construction of blood vessels to control blood pressure.
what is NERVOUS TISSUE
NERVOUS TISSUE
The function of nerve tissue is to transmit nerve impulses around the body. Nerves consist of a cell body (soma), dendrites, which receive impulses, and axons which send impulses. The axons of neurons are surrounded by a myelin sheath. The myelin sheath consists of layers of myelin, a white fatty substance. The myelin sheath’s main function is to insulate nerve fibres and it also increases the speed of the impulses transmitted by the nerve cell. There are three types of nerve cells: sensory neurons, interneurons and motor neurons.
