Biology unit 3 Flashcards
What are stem cells?
the animal version of meristematic cells; more are produced to allow for growth of animal - sometimes allows for regrowth of limbs
What are totipotent stem cells?
they are found in early development human embryos and can become any type of cell (ex. zygotes [fertilized egg] and early embryonic cells)
What are pluripotent stem cells?
they are found in later embryonic development and are less versatile than totipotent stem cells: can become almost any cell (ex. late embryonic cell)
What are adult stem cells?
found late in development or after birth and can only produce specific cells: multipotent - differentiate into a closely related family of cells; oligopotent - differentiate into a few cells; unipotent - produce only own type
What determines cell specialization?
genes get turned on or off which determines what specific cell type will be produced: genes are activated or deactivated by other cells and environmental conditions
What 3 main factors influence cell specialization?
contents of the cytoplasm, environmental conditions (temperature and nutrients) and neighbouring cells
How do the contents of the cytoplasm affect cell specialization?
depends on what organelles it has and how many of each (partly cause of early cell specialization)
How do environmental conditions affect cell specialization?
Some cells are only produced in certain temperatures (can determine sex of turtle, crocodile and alligator eggs); the presence and absence of certain nutrients can turn a certain gene on or off, hormones
How do neighbouring cells affect cell specialization?
cells produce substances that diffuse out of the cell and affect nearby cells
What do groups of neighbouring cells form?
tissues
What harmful environmental substances have affected human embryos?
chemical contaminants, heavy metals, pollution, parasites, diseases
When do cells stop dividing and live as mature specialized cells?
when enough of their genes are turned off
What is epithelial tissue?
it lines the surfaces of the body (skin and lining of organs): it is made of cells with strong connections in their membrane to form a barrier
Define skin epithelia
thin and flat epithelial cell that acts as a semi-permeable membrane between external and internal environment
Define columnar epithelia
columns of cells lining the small intestine, stomach and glans (not all glands)
What is muscle tissue?
it changes shape by shortening or lengthening
Define skeletal muscle
muscular tissue: cells line up in the same direction, striated appearance, they attach to bone and allow the body to move
Define smooth muscle
muscular tissue found in blood vessels and walls of internal organs; contracts slowly so an action can be sustained
Define cardiac muscle
muscular tissue: contracts as a unit, found only in heart
What is nervous tissue?
nerve cells: made up of neurons with projections for receiving and transmitting signals to coordinate bodily activities
What is connective tissue?
strengthens, supports, protects, binds or connects cells and tissues: found in blood ligament and bone
Define bone tissue
connective tissue: cells surrounded by calcium hardened tissue through which blood vessels run: assists movement, support and protection
Define fat tissue
connective: large tightly packed cells found under skin and around organs that store energy, provide padding and insulation
Define blood tissue
connective: platelets and red and white blood cells; transports nutrients and oxygen, clots after injury, attacks foreign invaders
What is the ethical problem with stem cells?
in order to get totipotent cells, you have to destroy the embryo - totipotent cells are invaluable to research and treatment purposes
What is the organizational hierarchy of the body?
System - organs work together to perform a specific function; organs - tissues work together to perform a specific function; tissues - specialized cells that work together to perform a specific function
What is the role of the digestive system?
to mechanically and chemically breakdown food in order to facilitate absorption of nutrients
What does the mouth do in digestion?
glands release enzymes in saliva (amylose) (chemical); teeth (mechanical)
What does the esophagus do in digestion?
a muscular tube that performs peristalsis (mechanical breakdown): involuntary contractions of smooth muscles that forces food down into stomach
What does the stomach do in digestion?
partially digested food is broken down into a liquid; contracts to mix its contents (mechanical); gastric acids break down food (chemical)
What does the small intestine do in digestion?
most of digestion takes place in the first segment, the duodenum (only chemical: duodenum has ducts that release digestive enzymes)
What does the large intestine do in digestion?
includes colon, rectum and anus: absorbs nutrients from digested foods, eliminates waste through feces, (only chemical breakdown: contains bacteria that finish breaking down food and produce essential nutrients like vitamin k)
Describe arteries
- carry oxygenated blood throughout the body (except for pulmonary)
- thick, elastic muscle layer to handle high blood pressure
- carry blood away from heart
- arteriosclerosis and peripheral vascular disease
Describe veins
- carry deoxygenated blood from the body to the heart (except for pulmonary)
- thin, elastic muscle (less pressure than arteries)
- blood vessels carry blood towards the heart
- varicose veins and deep vein thrombosis
Describe capillaries
- connect arteries and veins
- extremely small, thin-walled blood vessels
- bring blood in close contact with the tissues of the body (villi and microvilli for nutrients, close to lungs for oxygen)
- one epithelial cell thick, allowing them to pick up nutrients from digestive system and oxygen from lungs via diffusion
- release CO2 into lungs
- deliver nutrients and oxygen to all cells in the body while collecting CO2 and other waste
What are the three lines of defence in the body?
- SKIN attempts to prevent pathogens from entering the body
- IMMUNE SYSTEM attacks and destroys harmful invaders: body sends white blood cells and antibodies (attack antigens)
- BONE MARROW produces white blood cells and antibodies - prevent invaders from harming the rest of the body and identify and signal the presence of other intruders for the rest of the immune system
What is the role of the immune system?
destroys and removes invading microbes and viruses from the body
What causes disease?
pathogens (viruses, bacteria, fungi)
What is angioplasty?
TO UNCLOG ARTERIES: a surgeon inserts a plastic tube through an artery in the arm or leg all the way to the heart. When it reaches the blockage, a balloon or lader is used to open the clogged artery/break open the blood clot
What causes heart disease and stroke?
hypertension (high blood pressure) and atherosclerosis (thickening of arterial walls): both cause blood clots that obstruct flow. In coronary artery = heart attack, in brain = stroke
What happens in the alveoli?
Red blood cells contain haemoglobin which attaches to oxygen: deoxygenated blood passes the alveoli, haemoglobin picks up oxygen, releases CO2
What is SARS?
Severe Acute Respiratory Syndrome: causes fluid to fill the lungs, preventing absorption of oxygen. It is airborne and spreads quickly
What is AIDS?
Acute Immunodeficiency Syndrome: caused by HIV (human immunodeficiency virus) which attacks the immune system, preventing it from being able to attack invaders
Describe the West Nile Virus
mostly no symptoms, but sometimes can result in death or serious illness, transferred through mosquitoes
Example of how the contents of the cytoplasm affects cell specialization
If one daughter cell has more mitochondria, it would allow the cell to use more energy as it grows
Example of how the environmental conditions affect cell specialization
Temperature - Siamese cats gets their colouration because only cells that develop at cold temperatures produce dark hair colours (parts of the cats body that are cold)
Nutrients - protein FGF4 in mice causes a cell to become a muscle cell
Example of how the neighbouring cells affect cell specialization
Chick embryo cells develop into eye cells mainly
What is the role of the circulatory system
transports nutrients and oxygen to cell and carries waste to organs responsible for eliminating them
Describe the heart
most important organ in circulatory system: contracts to pump blood throughout the body - atria and ventricles contract simultaneously, two contractions needed to pump blood through 4 chambers of heart
Describe the journey of deoxygenated blood
(cells use up oxygen and produce CO2) - (lower body) vena cava > right atrium > right vetricle > pulmonary artery > lungs (alveoli)
Describe the journey of oxygenated blood
(lungs reoxygenate blood and the o blood travels back to the heart) pulmonary veins > left atrium > left ventricle > aorta (upper and lower body)
