Compendium 2 - How do cells do what they do? Flashcards
Organelles of a cell
- plasma membrane
- cytoskeleton
- nucleus and nucleolus
- ribosomes
- golgi apparatus
- lysosomes
- mitochondria
- centrosome
- flagella
- microvilli
- cytoplasm and cytosol
- endoplasmic reticulum
Plasma membrane
- encloses and supports cellular contents
- composed of a lipid bilayer with phospholipids, cholesterol and some proteins embedded in the membrane
- controls entry and exit of substances, have a function in intercellular communication, cell recognition
Cytoskeleton
- provides shape and strength
* supports cell and organelles
Nucleus
- control centre of the cell, contains genetic information (DNA)
- regulates protein synthesis and chemical reactions of the cell
Nucleolus
•produces ribosomes
Ribosomes
• involved in protein synthesis
Golgi apparatus
• modifies, packages and distributes proteins and lipids for use within the cell, or to secrete them
Lysosomes
• vesicles with digestive enzymes that dispose of cellular waste
Mitochondria
• site of ATP synthesis, produces energy for the cell (when oxygen is available)
Centrosome
- where centrioles are found
- centrioles form the basal bodies of cilia and flagella
- centrioles assist in cell division (mitosis and meiosis)
Flagella
• one long extension of the plasma membrane which propels to move a cell (in humans, this is only found in sperm cells)
Microvilli
• increase the surface area of the plasma membrane for greater absorption and secretion
Cytoplasm and cytosol
• cytoplasm: thick fluid that all organelles are contained in, made of cytosol
• cytosol: the fluid portion of cytoplasm (ions and proteins in water)
- includes cytoplasmic inclusions (aggregates of chemicals) and cytoskeleton
Rough ER
- involved in manufacturing and modifying proteins
* transports proteins to golgi
Smooth ER
- produces steroids, fats and carbs
- involved in detoxification
- converts glycogen to glucose
What makes up the environment of a cell
- intracellular fluid: fluid inside the cell
- extracellular fluid: fluid outside of the cell
- intercellular fluid: fluid in between cells
- similar cells will surround a cell, making up part of their environment
- cell environment depends on cell type (e.g. stomach cells are surrounded by acid)
What happens to a cell if an organelle stops working
• if one organelle stopped working, the whole function of the cell would be disrupted
Are all the cells in the body the same
- yes, because most cells have a similar structure and the same organelles which have the same functions
- no, because different cells have different roles (e.g. cells in heart will have more ATP because they need more energy to keep pumping than other cells)
4 primary tissues
- epithelial
- connective
- muscular
- nervous
Functions and characteristics of epithelia
- covers and protects
- distinct cell surfaces
- avascular but innervated
- has the ability to regenerate
Location of epithelial tissues
- lungs, tubules of kidneys, serous membranes, Fallopian tubes, bladder
- almost every organ
Types of cell surface modifications in epithelia
- cilia: move substances across the surface of the cell
* microvilli: assist with absorption and secretion
Simple squamous epithelia
• simple squamous: one layer of thin, flat cell
- involved in diffusion, filtration and some secretion
- found in alveoli of lungs to help with CO2 and O2 diffusion
- found in tubules of kidney for filtration
- makes up serous membranes to secrete serous fluid to stop friction
• squamous cells are ideal because they are thin and allow for quick diffusion, filtration and secretion
Simple cuboidal epithelia
• simple cuboidal: one layer of cube shaped cells
- involved in absorption, secretion and movement
- found in tubules of kidneys (these cells have microvilli to assist with absorption)
- found in terminal bronchioles (these cells have cilia for movement of substances across surface)
Simple columnar epithelia
• simple columnar: one layer of column shaped cells
- function in absorption, secretion and movement
- found in duodenum for secretion of mucous to neutralise acid
- found in fallopian tubes for movement of egg
- found in gastrointestinal tract (these cells have microvilli for absorption)
2 types of stratified squamous epithelia
• keratinised:
- found on the soles of feet, palms of hands and skin on body
- acts to protect underlying tissue
- is waterproof
•non-keratinised:
- found in mouth, oesophagus, anus and vagina
- areas where there is lots of friction and waterproofing is not needed
General characteristics of connective tissue
- most abundant and widely distributed primary tissue
- has many functions (binding together, support, strengthen, protect, insulate, compartmentalise etc.)
- found in all organs (quantity and type is different in each organ)
- made of cells, ground substance and fibres
- 4 classes: connective tissue proper, cartilage, bone, blood
Classes of connective tissue
- connective tissue proper (loose and dense)
- cartilage
- bone
- blood
Loose connective tissue proper
- areolar
- adipose
- reticular
Dense connective tissue proper
- regular
- irregular
- elastic
Areolar connective tissue
- loose packing
- supports and binds other tissues
- connective tissue that epithelia of skin rests on
Adipose connective tissue
- loose
- nutrient-storing ability
- shock absorption and protection
- insulation
- fat beneath the skin, surrounding kidneys, breasts, abdomen and hips
Reticular connective tissue
- loose
- forms a framework to support free blood cells (white blood cells, mast and macrophage cells)
- located in lymph nodes, spleen, bone marrow
Regular connective tissue
- dense
- used for attachment
- in tendons to attach muscles to bones
- in most ligaments to attach bones to bones
Irregular connective tissue
- dense
- provides strength and stretching
- located on the dermis of the skin
- located on fibrous coverings surrounding bones, cartilages, muscles and nerves
Elastic connective tissue
- dense
- has high recoil and strength
- located in the walls of arteries and ligaments between spinal vertebrae
Composition of connective tissue
- cells make up ground substance and fibres
* ground substance and fibres make up the extracellular matrix
Composition of connective tissue (cells)
- adipose cells: energy source and cushioning
- fibroblasts: secrete fibres and ground substance
- mast cells: immunity
- white blood cells: repair injury and fight off infection (e.g. neutrophils)
- macrophages: phagocytose (eat up) foreign molecules
Composition of connective tissue (ground substance)
• fills the space between the cells of the connective tissue
Composition of connective tissue (fibres)
- collagen
- elastic
- reticular
Histology
• the study of tissues
Cell layers
- simple: a single layer of cells
- stratified: more than one layer of cells (top layers look more squashed)
- pseudostratified: one layer of cells that appears to look like more than one layer (all cells sit on the basement membrane)
Cell shapes
- squamous: thin, flat cells from a side view, look like paving stones when seen in a surface view
- cuboidal: cube shaped (square in most views), usually with large, round nuclei
- columnar: tall cells, usually with oval nuclei toward their base
- transitional: can change shape from columnar to cuboidal or squamous (only found in the bladder for expansion)
Characteristics of muscle tissue
- highly cellular, well vascularised and responsible for most body movement
- muscle tissue needs to be highly vascular as a lot of energy is used through the tissue and oxygen is needed for metabolic reactions
- skeletal, cardiac and smooth muscle
Characteristics of nervous tissue
- consist of brain, spinal cord and nerves
- nervous tissue is the main component of the nervous system
- neurons are nerve cells
- neuroglia are supporting cells
NEURONS
• cell body is called the soma
• dendrites: structures that receive signals from other cells, large surface area to receive as much info as possible
• axon: conduct or transmit info away from the soma
