tissues (animals) Flashcards
tissues and the cells that they consist of
what are tissues?
tissues are groups of specialised cells that work together to perform a specific function in the organism.
how many types of tissue are found in animals?
there are four general types of tissue found in complex animals.
epithelial tissue, connective tissue, muscle tissue & nervous tissue.
what is epithelial tissue?
epithelial tissue is a tissue that covers body surfaces, protects organs and forms glands.
what is the structure of epithelial tissue?
epithelial tissue is made up of densely packed cells, occurring in sheets or layers.
it doesn’t contain blood vessels and relies on connective tissuer for nutrients.
what are the two distnict surfaces that epithelial tissue is found?
- surfaces exposed to the exterior or the body cavity.
- ither side is exposed to the adjacent tissue.
where is epithelial tissue found?
it is found in the skin and surface of organs in the digestive, repiratory, and many others.
it can also be specialised for absorption or secretion.
for example; epithelial tissue that lines the larynx secretes mucus to keep the surface moist.
what is connective tissue?
connective tissue supports, binds, and connects other tissues and organs. it is vital for providing structurasl support, protecting organs, storing energy, and facilitating the transportation of substances in the body.
what are the different types of connective tissue?
fibrous
loose
adipose
cartilage
blood and bone
what is the extracellular matrix (ECM)?
the ECM is a non-living material that surrounds the cells of the connective tissue and gives it its strength and flexibility.
it is made up of:
protein fibres : collagen, elastin, and reticular fibres
ground substances: a gel like material that fills the space between cells and fibres, composed of water, proteins, and polysaccharides.
what is fibrous connective tissue?
fibrous connective tissue is a type of connective tissue that has a lot of densly packed fibres, mainly collagen, which provide support and elasticity.
the fibres can eoither be arranged in a regular or irregular pattern depending on the specific function and use.
where is fibrous connective tissue primarily found?
dense regular fibrous tissue is arranged in parallel fibres, found in tendons and ligaments, while dense irregular fibrous tissue has a more disorganised fibre arrangement, found in the skin dermis and organ capsules.
what is loose connective tissue?
loose connective tissuye is a type of connective tissue that is characterised by loosely arranged fibres and an abundant ECM, providing flexiblity and cushioning to the body.
it acts as a filler material between organs, tissue and structures, supporting and binding them while allowing for nutrient exchange and waste removal.
what are the cells that make up loose connective tissue?
fibroblasts
macrophages
adipocytes
mast cells
what are fibroblasts?
fibroblasts are responsible for producing fibres and ground substance <- ECM.
they are the main connective tissue cells present in the body.
what are macrophages?
they are a type of white blood cell, playing a role in immune responses, helping to phagocytize pathogens and debris.
what are adipocytes?
adipocytes are fat cells that store energy and provide insulation.
what are mast cells?
mast cells are found throughout the body in loose connective tissue, playing a role in inflammatory response by releasing histamine and other chemicals during allergic reactions.
what are some types of loose connective tissue?
areolar tissue
adipose tissue
reticular tissue
what is areolar tissue?
function, structure, location
loose connective tissue
it provides support, strength and elasticity to tissues, also playing a role in nutrient and waste exchange between the blood and cells.
it contains a mix of collagen and elastic fibres in a loose irregular arrangement. it has a soft, gel-like matrix that allows flexibility.
areolar tissue is found widely throughout the body, including: beneath the skin (subcutaneous tissue), around blood vessels, nerves and organs, in the muscous membranes lining the respiratory, digestive, and urinary tracts.
what is adipose tissue?
function, structure, location
loose connective tissue
adipose tissue is specialised for stroring fat (energy), insulating the body, and providing cushioning to organs.
it is composed of large adipocytes (fat cells) that store lipids, with very little ECM.
it’s found beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow, and in breast tissue.
what is reticular tissue?
function, structure, location
loose connective tissue
it provides a supportive framework for soft organs, particularly those involved in flitering or immune functions.
it contains a network of reticular fibres (thin collagen fibres) that form a scaffold to support the cells within the tissue.
it’s found in lympoid organs (e.g. lymph nodes, spleen, bone marrow, liver).
what are the types of adipose tissue and where are they found?
white adipose tissue is the most common for, primarily for energy storage, insulation, and cushioning.
brown adipose tissue is found mainly in newborns and some adults, it helps generate heat through non-shivering thermogenesis.
what is cartilage?
it is a type of connective tissue that is firm yet flexible, providing structure and support to various parts of the body.
what is the function of cartilage?
it provides flexible support, reduces friction in joints, and absorbs shock. it also plays a role in the formation of bones during development.
what is the structure of cartilage?
it is composed of chondrocytes (cartilage cells) embedded in a firm but flexible ECM made up of collagen fibres and chondroitin sulfate.
it lacks blood vessels, so nutrients and waste must diffuse through the matrix, leading to slower healing.
what are the main types of cartilage?
three
hyaline cartilage
elastic cartilage
fibrocartilage
what is hyaline cartilage?
it is the most common type of cartilage, and has a smooth, glassy appearance due to fine collagen fibres.
it is found in the nose, trachea, and at the ends of long bones where joints form.
what is elastic cartilage?
it contains more elastic fibres, giving it greater flexibility.
is found in the external ear and the epiglottis.
what is fibrocartilage?
it contains a high density of collagen fibres, making it tougher and more resilient.
is found in areas requiring strong support and shock absorption, like the invertebral discs and the menisci in the knee.
what is blood?
function & structure
fluid connective tissue
blood serves as the body’s primary transportation system for oxygen, nutrients, hormones, and waste products. it also plays a key role in immune response and clotting.
it consists of cells suspended in a liquid ECM called plasma.
what is plasma?
plasma is a liquid extracellular matrix (ECM).
it’s made up of mostly watr and contains proteins, electrolytes, and dissolved gases.
what are the different types of blood cells?
three
red blood cells
white blood cells
platelets
what are red blood cells (RBCs)?
function, structure, lifespan
also called Erythrocytes
they transport oxygen from the lungs to tissues and carry carbon dioxides from tissues back to the lungs.
RBCs are biconcave discs, which increases their surface area for gas exchange. they lack a nucleus in their mature form, allowing more space for haemoglobin, the protein responsible for oxygen transport.
RBCs live for about 120 days in humans, after which they’re broken downin the spleen and liver.
what are white blood cells (WBCs)?
function, types, lifespan
also called leukocytes
they play a key role in the immune system, helping to defend the body against infections, foreign invaders, and abnormal cells (like cancer).
the lifespan of WBCs varies depending on the type, some last a few hours while others can last for years.
WBCs are classified into several subtypes, each with specialised roles.
-neutrophils
-lymphocytes
-monocytes
-eosinophils
-basophils
what are platelets?
function, structure, lifepspan
also called thrombocytes
they are small, cell fragments (not full cells) derived from a larger cell called a megakaryocyte in the bone marrow.
platelets are essential for blood clotting. when a blood vessel is injured, platelets adhere to the site of injury, clump together, and release chemicals that initiate the formation of a blood clot, preventing further blood loss.
lifespan is about 8-10 days.
what are neutrophils?
WBC
the most common type of white blood cell, important in fighting bacterial infections.
what are lymphocytes?
WBC
they’re involved in the production of antibodies (B cells) and attacking infected or cancerous cells (T cells)
what are monocytes?
WBC
they transform into macrophages, which engulf and digest pathogens and dead cells.
what are eosinophils?
WBC
they are white blood cells that help combat parasitic infections and play a role in allergic reactions.
what are basophils?
WBC
white blood cells that release histamine and play a role in inflammatory responses.
what is bone (osseous connective tissue)?
it is a specialised type of connective tissue that forms the skeletal framework of the body, providing structure, support, and protectin for vital organs.
it plays a key role in mineral storage, blood cell production, and movement.
what is the function of bone?
it provides structual support, protects internal organs, facilitates movement by serving as attachment points for muscles, stores minerals (e.g. calcium and phosphate), and houses bone marrow, which produces blood cells.
what is the structure of bone?
it is composed of osteocytes (bone cells) embeddd in a rigid extracellular matrix that contains collagen fibres and mineral salts (mainluy calcium phosphate), which provides strength and hardness.
it is highly vascularised, which means that it has a strong blood supply, allowing for quick healing and repair.
what are the types of bone?
two
compact bone and spongy bone.
what is compact bone?
it is dense and strong, found on the outer surfaces of bones, providing structural support and protection.
what is spongy bone?
it is found inside bones, and has a porous structure that makes bones lighter, housing bone marrow, where blood cells are produce.
what is nervous tissue?
it is a specialised tissue found in the nervous system, which comprises of the brain, spinal cord, and peripheral nerves.
it is responsible for transmitting and processing information throughout the body, playing a crucial role in controlling and coordinating bodily functions.
what makes up nervous tissue?
nervous tissue consists of neurons and neuroglial cells.
what are neurons?
function & structure
they are nerve cells, and are the primary functional units of nervous tissue. they transmit electrical signals (nerve signals) to communicate with other neurons, muscles, or glands.
neurons are made up of; the cell body (soma), dendrites (branch-like extensions), axon (a long extension), and synapse (the junction between the axon of one neuron and the dendrite or cell body of another neuron).
what are the types of neurons?*
three
sensory neurons
motor neurons
interneurons
what are neuroglial cells?*
function & types
they are a part of nervous tissue,and provide support, protection, and nourishment to neurons.
they don’t transmit electrical impulses but are essential for maintaining the health and efficiency of neurons.
the types of glial cells are; astrocytes, oligodendrocytes, schwann cells, microglia, and ependymal cells.
what are the types of nervous tissue?
central nervous tissue and peripheral nervous tissue.
what is central nervous tissue?
it is found in the brain and spinal cord, which make up the central nervous system (CNS).
the CNS processes and intergrates information, controls most functions of the body, and coordinates responses.
what is the peripheral nervous tissue?
it is found in the nerves that extend from the brain and spinal cord to the rest of the body, forming the peripheral nervous system (PNS).
the PNS is responsible for transmitting signals between the CNS and the rest of the body, incuding many sensory inputs and motor outputs.
what is muscle tissue?
muscle tissue is a specialised tissue that is able to contract and produce movement in the body. it is responsible for voluntary movements like walking or lifting, and involuntary movements like pumping the heart or moving food through the digestive tract.
what is the structure of muscle tissue?
muscle tissue consists of muscle cells and muscle fibres that are highly specialised for contraction.
what are the different types of muscle tissue?
skeletal muscle tissue
cardiac muscle tissue
smooth muscle tissue
