Cells & Tissues Flashcards
Cytoskeleton
Microtubules: small tubular proteins which maintain cell structure and move organelles around the cell
Microfilaments: repeating units of actin, responsible for cell movement, changes in shape and make muscle contraction possible
Centrioles
A pair of organelles that organise microtubules during cell division to create spindle fibres
Cytoplasm
Viscous fluid containing proteins, other organic molecules and organelles
cytosol: where chemical reactions occur
Golgi apparatus
modifies and packages proteins.
made of flattened sacs called cisternae
contains enzymes that allow processing and excretion of lipids and proteins
Plasma membrane
a phospholipid bilayer that contains cholesterol, glycoproteins and glycolipids. it surrounds the cell and enables it to communicate and detect changes in the environment
Mitochondria
site of aerobic respiration - produces ATP
the most active cells have lots of mitochondria
What does catabolism mean
process of releasing energy
Nucleus
DNA is stored
Nuclear envelope: double membrane that separates the contents of the nucleus from the cytoplasm
Nuclear pores: gaps in nuclear envelope
nucleolus: produces ribosomes
DNA is stored as chromatin, but during cell division the chromatin forms distinct structures called chromosomes
Endoplasmic reticulum
RER: has ribosomes attached and is responsible for the synthesis of proteins
SER: synthesis and lipids and steroids. In muscle cells it releases calcium ions that trigger contraction
Ribosomes
Protein synthesis - attaches amino acids using. Ribosomes are composed of two subunits containing rRNA
Cilia
hairlike projections which allow movement of substances over the cell surface
Phospholipids
Hydrophilic heads and hydrophobic tails
What is the role of cholesterol in the plasma membrane?
stabilises the membrane
What is the role of channel proteins in the plasma membrane?
let larger molecules in - such as polar molecules
What is the role of receptor proteins in plasma membranes?
communicate with the environment outside the cell. molecules bind to them and a message is sent in. some have a carbohydrate molecule attached to them giving them immunological identity
Examples of passive processes in cells
simple diffusion
osmosis
facilitated diffusion
these do not require ATP as molecules move from a high concentration to a low concentration
Examples of active processes in cells
Active transport
Endo/exocytosis
these require ATP as molecules move from a low concentration to a high concentration
Types of cells in connective tissue
Fibroblasts: make collagen and elastic fibres.
Fat cells
Macrophages: important in the body’s defence mechanism since they are phagocytic
Leukocytes: WBC - Migrate in large numbers during infection
Mast cells: histamine is responsible for inflammatory responses and heparin prevents coagulation
What are mast cells?
WBC that play a role in the body’s immune system and inflammatory responses
Examples of connective tissue
Elastic tissue: allows considerable extension and recoil
Fibrous tissue: closely packed collagen, found in ligaments, periosteum, protective coverings
Hyaline Cartilage: chondrocytes arranged in small groups within cell nests and the bluish white matrix is solid
Where is epithelial tissue found?
covering surfaces, lining cavities, forms glands
Simple epithelium
single layer of cells.
squamous epithelium: single layer of flattened cells, found in endocardium, alveoli and collecting ducts
Cuboidal epithelium: forms walls of kidney tubules and is found in the thyroid gland
Columnar epithelium: single layer of tall and thin cells on a basement membrane. Found in the stomach, small intestine and trachea
Stratified epithelium overview
several layers of cells of various shapes
continual cell division in the lower layers pushes cells nearer to the surface. main function is to protect underlying structures from wear and tear.
stratified squamous epithelium
in the deepest layers the cells are mainly columnar
keratinised: dry surfaces. no nuclei. provides tough and waterproof layer
non-keratinised: protects moist surfaces
Transitional epithelium
pear shaped cells that allow stretching
present in the urinary tract
Skeletal muscle
moves bones
striated and is under voluntary control
fibres are cylindrical and contain multiple nuclei
Smooth muscle
non striated and involuntary
has lots of mitochondria
regulates the diameter of blood vessels
Cardiac muscle
not under conscious control
striated
each fibre has one nucleus
intercalated discs are significant for heart contraction
Types of nervous tissue
Excitable: neurones which initiate, receive, conduct and transmit info
non excitable: glial cells which support neurones
3 types of membranes
Cutaneous
Mucous
Serous
Mucous membranes
Lines hollow organs
lines the alimentary, respiratory and genitourinary tracts
epithelial cells secret mucus - which protects the membranes from drying
Serous membranes
Closed cavities
double layer of loose areolar connective tissue lined by simple squamous epithelium
parietal = lines a cavity
Visceral = surrounds an organ
cell cycle overview
Interphase: growth and replication
Prophase: chromatin condenses and becomes visible. spindle fibres form, centrioles go to opposite poles
Metaphase: chromosomes line up on the metaphase plate attached by their centromeres
Anaphase: centromeres become separated, one of each pair of chromatids migrate to each end of the cell. spindle fibres shorten
Telophase: spindle fibres disappear, chromosomes decondense, plasma membrane splits
Apoptosis
genetically programmed cell death. shrinks and remaining fragments are phagocytosed without an inflammatory reaction
Necrosis
Cell death as a result of lack of oxygen due to injury or pathological process
Common causes of tumours
spontaneous changes in DNA or exposure to carcinogens such as: chemicals, ionising radiation and oncogenic viruses
3 ways in which tumours can spread
Local spread: benign tumours grow and cause pressure damage
Lymphatic spread: group of tumour cells can break off and be carried to lymph nodes where they may lodge into secondary tumours, this may cause further spread into the lymphatic system because lymph drains into subclavian veins
Blood spread: thrombus may form, blocking blood vessels causing infarcts and the development of metastatic tumours
Effects of tumours
Pressure effects: compression of adjacent structures can cause ischaemia, necrosis, blockage of ducts and pain
Hormonal effects: well differentiated tumours can secrete uncharacteristic hormones such as lung tumours secreting insulin
Cachexia: severe weight loss, weakness and lack of appetite
Common causes of death in malignant disease
Infection: predisposition of infection is increased by prolonged immobility or bedrest and due to chemo or radioactivity
Organ failure
Carcinomatosis: widespread metastatic disease
Haemorrhage: Tumour ruptures
