Tissues and homeostatis Flashcards
Describe the order of organization
atomic
molecular
organelle
cell
tissue
organ
organ system
organism
What are the 4 tissue types?
Muscular, connective, epithelial and nervous
Describe the structure, importance and function of epithelial tissue
There are 2 types of epithelial tissue (stratified and simple)
Stratified refers to many layers whereas simple refers to a single layer of cells. Epithelial tissue is involved in protection, filtration, excretion, secretion, and absorption. It covers the organs and lines the blood vessels. 2 forms of epithelium glandular (secretion) and covering and lining (BV’s)
What are the 4 shapes of the epithelial tissue
Columnar, cuboidal and squamous, these tissues all have differently shaped nuclei and are all attached to basement membranes
Describe squamous epithelium
It is a single thin permeable flat layer of cells, normally found in places where diffusion is required e.g., alveoli. It contains disc-shaped nuclei & sparse cytoplasm. involved in filtration e.g., kidney, secretion. epithelium supported by a basement membrane
Describe cuboidal epithelium
it is cube-shaped with a large central spherical nucleus, involved in secretion and filtration (kidneys), found in kidney tubules and ovaries
Describe columnar epithelium
Highly specialized cells with oval nuclei, tall cells, found with goblet cells in the trachea, which secrete mucus, also found in digestive tract
Describe pseudostratified columnar epithelial cells
These are single layers of cells that differ in height, and so the nuclei are at different levels to the adjacent cell, which may contain goblets cells and cilia. Involved in mucus secretion e.g., in digestion, the ciliated type propels the mucus in a direction.
Describe the role of connective tissue
It’s main function is to support and bind the organs e.g., cartilage found in lungs
What are the functions of connective tissue?
heat production, transport, binding of organs, immune protection, physical protection, support, storage, movement
Describe the common characteristics of connective tissue
Connective tissue is the most abundant in the body, it has an extracellular matrix, which enables it to bear weight
Give examples of connective tissues
Blood, cartilage, adipose tissue, elastic tissue, bone tissue etc
What are the 3 main tissue types of connective tissue?
Areolar, adipose and dense connective tissue
Describe areolar tissue
it has elastin and collagen fibres with a loose arrangement, it provides support, connects organs and tissues, and acts as cushioning and packing between organs. found beneath the skin surrounding organs and blood vessels, defends against infections
Describe adipose tissue
This is fat tissue, involved in insulation, cushioning of organs & protection. Brown adipose in infants produces heat, contains lots of fatty acids, and is used for energy, 90% of mass in cells is adipose, richly supplied with nerve tissue
Describe dense connective tissue
a dense tissue containing lots of collage fibres, irregular pattern, very strong and contain fibroblast nuclei. it creates fibrous coverings around organs and joints for protection
Difference between clasts and blasts cells
Clast cells breakdown connective tissue
blast cells are mitotically active and secrete fiber and matrix
What is a lacuna
a space/cavity
what are the 3 types of cartilage?
hyaline cartilage, fibrocartilage and elastic cartilage
Describe hyaline cartilage
Most abundant in the body
involves in structural support and flexibility
Has spherical chondrocytes
Only fibre is collagen fibres
It covers the end of most movable joints (articular cartilage)
Connects the ribs to sternum (costal cartilage) aids in respiring
Supports the nose (nasal cartilages) and the respiratory system (respiratory cartilage)
Contain perichondrium which surrounds cartilage
Describe elastic cartilage
Contains more elastic fibres than hyaline cartilage
Able to stretch and recoil e.g., in blood vessels, prevents bursting from high BP
Are involved in repeated bending movements
Found only in external ear and epiglottis
Describe fibrocartilage
very fibrous lots of thick collagen fiber bundles, less matrix, fibers spread in all directions, resistant to impact, shock absorbent, found in knees and pubic bone
Consist of parallel rows of chondrocytes which alternate with thick collagen fibres
What are collagen fibres?
made of the protein collagen, assemble and cross-link together, and bundle together to form thick collagen fibres, due to linkage they are extremely strong, and tough and can resist being pulled apart
What are elastic fibres?
long & thin elastic fibres form branching networks, contain protein elastin, enabling stretch and recoil, found where elasticity is needed e.g., lungs and blood vessels
What is ground substance?
Known as the matrix contains proteins which trap water to make it a gel-like substance, site of protein synthesis and movement of organelles
Define Homeostasis
the ability to maintain an optimum internal environment within narrow limits, it is a dynamic equilibrium which is adapts due to changes in external environments
Examples of homeostatis
Temperature control- controlled by the hypothalamus, thermoreceptors on skin’s surface can detect a stimulus (temp change) and sends signals to the hypothalamus for it to coordinate a response to bring body temperature back to optimum condition
Define negative feedback and give and example
Negative feedback is the most common homeostatic mechanism it prevents further deviation from optimum conditions e.g., sugar levels in the blood, need to be regulated, if too high, insulin is released storing excess glucose as fat, if too low glucagon is released to breakdown glycogen and release glucose into the bloodstream
Define positive feedback
This is when the response to the stimulus involves a greater deviation from set point, it is positive as it moves in the same direction and not a loop
e.g., in labour, contractions are intensified by oxytocin as labour continues more oxytocin is released in increasing frequency and power of contractions. This continues until the baby is born
What is a cell
smallest functional unit of an organism
Purpose of nucleus
Holds DNA, controls activities of the cell
Purpose of plasma membrane
acts as a barrier, contains bulk of cell, involved in endo and exocytosis, controls what enters and exits cell
Cytoplasm function
gel-like substance, serves a site for enzyme reactions
What is chromatin
contains DNA, encodes the proteins, found in the nucleus
what is the nucleolus
involved in synthesis of ribosomes
What are ribosomes
responsible for making proteins through transcription and translation, ribosomes read RNA, cause AA’s to bulk together and build proteins
What is RER
site of protein production,
what is the golgi apparatus>
site where protein is modified and packaged, becomes enzymes or glycoproteins
what is a vesicle
responsible for transporting proteins, can be exported outside of the cell via exocytosis
Cytoskeleton function
anchors organelles in place, provides a network in which vesicles travel along
SER
smooth endoplasmic reticulum involved in detoxfication, synthesis and packaging of lipids
