Cells Tissues Organs Flashcards
What percentage of water in the body is found in cells?
38%
What percentage of body mass is made up of water?
60%
What is the plasma membrane composed of?
Two layers of fatty substances called phospholipids
What makes the plasma membrane partially permeable?
Hydrophilic phosphate heads (interact with water) and hydrophobic fatty acid tails (don’t interact with water and shielded in by phosphate heads.
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
What is osmosis?
It is the net movement of water from an area of low concentration to an area of high concentration against a concentration gradient
What is active transport?
The movement of substances moving from an area of low concentration to an area of high concentration against the concentration gradient using energy in the form of ATP
What is a cell?
The fundamental unit of all living organisms
What is a plasma membrane?
It is also known as the cell surface membrane that coats a cell controlling what enters and exits the cell
What is the cytoplasm?
Jelly-like substance that makes the matrix of the cell
It is where all chemical reactions take place
What is the nucleus?
It is an organelle that controls the activities of the cell and is also involved in cell division
What is the rough endoplasmic reticulum?
It is continuous with the nucleus and produces and packages proteins to be transported to the Golgi apparatus
What are ribosomes?
It is tiny granules composed of RNA and protein
They make proteins from amino acids and are involved in metabolism in the cell
What is the smooth endoplasmic reticulum responsible for?
Synthesis lipids, steroid hormones, detoxification of harmful metabolic by-products and storage and metabolism of calcium ions within the cell
What is the Golgi apparatus responsible for?
Folded membranous sacks that package proteins into secretory vesicles which are either released out of the cell from the CSM or remains in the cell as lysosomes if it contains hydrolytic enzymes
Also modifies proteins during protein synthesis by adding carbohydrates
What is the mitochondria responsible for?
Aerobic respiration carried out and adenine triphosphate (ATP) is produced
What are the tiny protein fibres that make up the cytoskeleton?
Microfilaments
Microtubules
Centrosomes
Cell extensions
What are the actin filaments (aka microfilaments) responsible for?
Helps maintain the cell shape also helping in cell movement
What are the microtubules responsible for?
They are large proteins responsible for the movement of organelles by creating tracks and is involved in cell division in the metaphase and anaphase where the cell chromosomes first line up in the metaphase plate and is then pulled to either side of the cell to the poles separating them.
What are the intermediate filaments responsible for?
Rigidity of the cell and the positioning of the organelles within
What is a differentiated cell?
A cell that has the ability to differentiate/change into any cell type to carry out a particular function
Where are goblet cells found?
In the bronchi and bronchioles
What do goblet cells do and why?
They secrete mucous which captures and traps invading pathogens and foreign particles within the respiratory pathway
What are cilia responsible for?
They are hair-like structures that move in a rhythmic manner and woft the mucous containing foreign partciles up and out of the respiratory pathway into the mouth where it is swallowed and digested
Where is the islets of Langerhans found?
In the pancreas
What cells are in the islets of Langerhans?
Alpha and beta cells
What is the alpha cells responsible for?
Production and secretion of glucagon in order to raise blood sugar levels
What is the beta cells responsible for?
Production and secretion of insulin in order to reduce blood sugar levels
What is a neuron?
A specialised cell that transmits information in the form of nerve impulses or action potentials from one area to another through saltatory conduction where the electrical impulse jumps across the axon in the gaps known as the Node of Ranvier
What is the function of the cell body?
integrate synaptic information and transmit information to other cells via the axon
What is the function of the axon?
Transmits nerve impulses away from the cell body
What are the dendrites responsible for?
They are projections of a neuron that receive signals from other neurons and transmit impulses towards the cell body
What is the function of the myelin sheath?
It is a lipid-rich substance that surrounds parts of the axon insulating it and increases the rate of nerve impulse transmission along the axon
What is the function of the Schwann cell?
It is in the centre of the myelin sheath and is known as a myelin-secreting glial cell
They form the myelin sheath
They support nerve regeneration
What is the Node of Ranvier?
It is the gap in-between each individual myelin sheath
It is involved in saltatory conduction
What is multiple sclerosis?
It is a progressive disease causing damage to the myelin sheath of the nerve cells in the brain and spinal cord
What are erythrocytes (RBC) responsible for?
Transport of oxygen and carbon dioxide
Why do RBC have no nucleus (enucleated)?
To maximise surface area to ensure maximum oxygen capacity
Where are RBC formed and destroyed?
Made in the bone marrow and destroyed in the spleen
What is passive transport?
Substances move down a concentration gradient without the use of energy needed to facilitate the movement of substances
What are the three types of passive transport?
Diffusion
Facilitated diffusion
Osmosis
What does DNA stand for?
Deoxyribonucleic Acid
What is the DNA structured?
Double helix
Sugar-phosphate backbone
4 nitrogenous bases - A, T, C, G
What do the A, T, C, G bases stand for?
Adenine
Thymine
Cytosine
Guanine
What is DNA composed of?
Condensed chromosomes
How many chromosomes do humans have?
46
How many pairs of chromosomes do humans have?
23
What causes genetic variation in DNA?
Crossing-over, mutations and replication errors in DNA replication and division process
What is mitosis?
It is the division of a cell resulting to the production of genetically identical diploid daughter cells
What is the four stages of mitosis?
Prophase Metaphase Anaphase Telophase Cytokinesis
What is the role of mitosis?
Produce body cells
What is the role of interphase in mitosis?
Growth
DNA replication
Cell functions
How are chromosomes in DNA counted?
The number of centromeres
How many chromosomes is there before and after mitosis?
46 before and after mitosis
How many chromatids is there before and after mitosis?
46 before and 92 after mitosis
What is the process of prophase?
The nucleus is still present
Chromosomes are visible as they coil and condense
What is the process of metaphase?
Nucleus no longer present
Nuclear envelope disintegrates
Chromosomes line up in the centre of the metaphase plate
What is the process of anaphase?
The chromosomes are pulled to either side of the cell to the poles where the sister chromatids are separated
This happens when the spindle fibres attach to the centromeres of the chromosomes dragging them along the cytoplasm to either centrioles
What is the process of telophase?
Chromosomes are now on two sides of the cell
Nucleus begins forming on both sides
Two identical nuclei are produced
What is the process of cytokinesis?
Here the cytoplasm begins splitting forming a cleavage furrow
This then produces two genetically identical diploid daughter cells
What are the four types of body tissue?
Epithelial
Connective
Nervous
Muscle
Where is epithelial tissue located?
It covers and lines membrane surfaces, so is protective in nature
What two properties can epithelial tissue have?
Simple or stratified
What is simple epithelial tissue?
Composed of single layer of identical cells
Not in areas of wear and tear
Found mostly in areas of absorption and secretion
What is simple squamous epithelial tissue?
Flattened
Efficient diffusion pathway
Commonly found in endocardium of the heart, blood vessels and the alveoli of the lungs
What is simple cuboidal epithelial tissue?
Involved in secretion, absorption and excretion
Most commonly found in kidney tubules and some glands
What is simple columnar epithelial tissue?
Found lining many organs
There is two types which is ciliated and non-ciliated
What is ciliated columnar epithelial tissue?
Cilia on outer surface that wafts mucus in one direction in the respiratory tract and transports it to the mouth where it is swallowed and digested
What is stratified squamous epithelium tissue?
Several layers of cells and continuous cell division pushes the lower layers of cells closer to the surface
Protects underlying structures from damage
Skin is an example
What is transitional epithelial tissue?
Pear-shaped and found in urinary tract
Allows foe stretching
What are the two types of glands?
Endocrine and exocrine gland
What is the role of an endocrine gland?
Secretes hormones directly into the bloodstream
What is the role of an exocrine gland?
Secretes enzymes and mucus onto a free surface via ducts
What organs is both endocrine and exocrine?
Pancreas
How is the pancreas endocrine?
Production of hormones such as insulin and glucagon
How is the pancreas exocrine?
Production of enzymes used in digestive tract used to breakdown proteins, lipids, carbohydrates and nucleic acids etc
What is connective tissue?
Most abundant tissue
What is the primary functions of connective tissue?
Binding and structural support
Protection
Transport
Insulation
What are some examples of connective tissue?
Blood Bone Cartilage Adipose tissue Lymphoid tissue
What are the five cells found in connective tissue?
Collagen and elastic fibres formed by fibroblasts
Adipose or fat cells
Macrophages engulf and digest cell debris
Leukocytes (WBC)
Mast cells involved in inflammatory response
What is loose connective tissue?
Found all over the body and supports and connects other tissues
What are some examples of where loose connective tissue can be found?
Under skin Between muscles Supporting blood vessels and nerves In the alimentary canal (passage for food) In glands supporting secretory cells
What is dense connective tissue?
More fibres and less cells than loose connective tissue
What are the two types of dense connective tissue?
Fibrous tissue
Elastic fibres
What is fibrous tissue?
A dense connective tissue found in ligaments, periosteum (the outer layer of the bones), protecting covering of organs, such as the brain and in muscle sheaths and tendons
What is elastic fibre tissue?
Found in large blood vessels, the trachea and the bronchi
Extension and recoil
What is cartilage?
More solid than any other tissue
What is cartilage composed of?
collagen and elastic fibres
What is adipose tissue?
Collection of fat cells
Where is cartilage found?
Bone Airways Joints Blood vessels In the ear
What is the two types of adipose tissue?
White and brown
What is white adipose tissue?
Accounts for 20-25% of body weight
Supports organs such as the kidneys and the eyes
Where is white adipose tissue stored?
Between muscle fibres and under the skin (subcutaneous)
What is brown adipose tissue?
Present only in the new-born
When metabolised, produces less energy but much more heat, so keeps infants warm
What is blood?
A connective tissue used to transport substances around the body
What are bone cells also known as?
Osteocytes
What are bone cells surrounded by?
Collagen fibres
What does muscle tissue need to contract?
Oxygen
Calcium
Nutrients
What is the main property of muscle tissue?
Contract and relax
Why does muscle tissue need adequate blood supply?
To remove waste products
What are the three types of muscle?
Smooth
Skeletal
Cardiac
What is the main property of smooth muscle?
Non-striated
What is smooth muscle?
Involuntary
Stimulated by ANS and some hormones
Where is smooth muscle located?
Areas where dilation and constriction occurs
such as the blood vessels, alimentary tract (digestive tract) and the urinary bladder
What is the main property of skeletal muscle?
Striated and generally voluntary
Where is the skeletal muscle found?
Skeleton
Where is cardiac muscle found?
In the heart and not under conscious control (ANS)
What is an important characteristic of cardiac muscle?
Cells are branched so that nerve impulses can radiate across the heart
What are nerve cells also known as?
Neurons
What are the two types of membranes?
Epithelial and synovial
What are epithelial membranes made of?
Epithelial tissue and connective tissue
Where is epithelial membranes found?
lining internal structures
What are the two types of epithelial tissue?
Mucous membranes and serous membranes
What is serous membranes?
Secretes watery fluid called serous fluid in areas of high friction, such as between the layers of pleura (in the lungs) and between the layers of pericardium in the heart
Where is synovial membranes located?
found within moveable joints which lubricate and nourish
