Chapter 1-6 Flashcards
Define Homeostasis
Maintenance of stable internal environment regardless of outside changes
Name 5 components of Control Mechanism
- Stimulus - change in external environment
- Receptor - senses the change and sends a message via afferent pathway (sensory neuron) to the control centre
- Control Centre - analyses and decides on response and sends msg to effector via efference pathway (motor neuron)
- Effector - the muscle or gland that responds to the command from the control centre
- Response - the action carried out by the effector
Describe Negative Feedback and give an example
Response that reduces or shuts off the original stimulus. If stimulus is decreased then response is increased.
EG. regulation of blood volume
1. Receptor senses a decrease on blood volume
- Control Centre in hypothalumus detects the loss of blood and sends a msg to the pituitary gland to release ADH hormone
- ADH causes kidneys (effector) to return more water to the blood
- Response is increased blood volume
- Return to normal volume sensed by receptors.
- Control centre stops stimulation of pituitary gland.
- Pituitary gland stops release of ADH.
Describe positive feedback and give an example
Response increases or exaggerates original stimulus. If there is an increase in stimulus, response is increased.
This type of feedback is otherwise normal self limiting (childbirth) or can result in an abnormal disease condition (heart failure)
EG. Childbirth:
stretching of cervix -> oxytocin -> contraction of uterus -> more oxytocin -> more contractions -> more oxytocin, etc… then once baby is born the cycle will end
Describe a positive feed back that ends heart failure
EG. Heartfailure
plaque build up in vessels -> decreased diameter of vessels -> inflammation of vessels -> more plaque build up -> increased restriction of flow -> increased blood pressure -> stress on heart -> heart failuretion
What is the function of the plasma membrane and what is it made of?
- Plasma membrane separates intercellular fluid from extracellular fluid and plays a major part in cellular activity
- Constantly changing fluid mosaic
What is the fluid mosaic made up of?
- 75% phosophlipid bilayer
- 5% glycolipids
- 20% cholesterol
What is the phospholipid bilayer made up of?
- phosphate heads that are polar (hydrophilic)
2. fatty acid tails that are non polar (hydrophobic)
What are the glycolipids and where are they located?
- Glycolipids are lipids with attached sugar groups
2. They are attached to the outer surface of the membrane.
What is the function of cholesterol in the membrane?
stabilizes the membrane, regulates fluidity
List the 6 functions of the membrane protein
TRAEIC
- Transport (ATP - Active Transport)
- Receptors - sites for chemical messengers to bind on (eg. hormones)
- Attachment - cytoskeleton and extracellular matrix
- Enzymes - catalysts (speed up reactions)
- Intercellular joining - anchor cells to each other
- Cell to cell recognition - identify cells, self or foreign (eg. WBC’s can tell whether to attach or not)
Name the 3 membrane proteins, location and function
- Integral - located firmly into the membrane and transport proteins, enzymes or receptors
- Peripheral - loosely attached to integral proteins either inside or outside the membrane. They act as enzymes, motor proteins, cell-to-cell links, support on intracellular surface
- Glycoprotein - proteins with sugar groups attached. They function in cell identification and form part of the glycocalyx (sugar coating)
Name two special structures of the cell membrane
- Glycocalyx - sugar coating on cells, composed of glycolipids and glycoproteins and plays a part on cell recognition
- Microvilli - outfoldings on the apical cell membrane, increase surface area (eg. digestive tract)
Name the 3 membrane junctions
- Tight junction
- Desmosome
- Gap junction
What is the function of the tight junction and where in the body where it might be useful?
Prevents fluids and molecules from moving between cells.
These would be useful in the stomach
What is the function of the desmosome?
They act like rivets that anchor cells together. They resist tension and resist cells from being separated.
What is the function of the gap junction?
Permit quick spread of ions between cells.
What are the 3 functions of the plasma membrane?
- selectively permeable - only lets certain molecules through
- controls movement of materials in and out
- maintains homeostasis
Name the 2 types of membrane transport and describe
- Passive process - no ATP required, substance moves down its concentration gradient
- Active process - ATP energy required, proteins required, substances move against concentration gradient
Name 3 characteristics that determine whether or not a substance can passively penetrate a membrane
- its solubility
Lipid soluble - substance can diffuse through the bilayerWater soluble - must use channels or carriers - its size - large molecules cannot get through
- suitable carrier proteins - carriers are specific, can only bind to certain molecules
Name 4 types of passive procceses
- Filtration
- Simple Diffusion
- Facilitated Diffusion
- Osmosis
Describe Filtration
Materials are carried along with fluid from an area of high fluid pressure to an area of low fluid pressure
Describe Simple Diffusion
Diffuse directly through the phospholipid bilayer following a concentration gradient. Kinetic energy causes them to move - random movement
Describe Facilitated Diffusion
- Uses carriers or channel proteins
2. substances can only move with a concentration gradient from high to low.
Describe Osmosis
Diffusion of water across a selectively permeable membrane.
Describe carrier proteins
Integral proteins transport specific polar molecules. Binding of substrate causes shape change in carrier.
Describe channel proteins
aqueous channels formed that selectively transport ions or water
Name two types of channel proteins
- Leakage - always open
2. Gated - controlled by chemical or electrical signals
Name the two ways water diffuses through the plasma membrane during osmosis
- through the lipid bilayer - wiggling between phospholipids
- through protein channels calls aquaporins
What does water respond to when it diffuses?
It responds to concentration gradients from higher water concentration to areas of lower water concentration
What happens when osmosis occurs?
- Water enters or leaves a cell
What is tonicity?
Terms used to describe concentration solutes in two different solutions
What are isotonic solutions?
Two solutions with the same solute concentrations
What are hypertonic solutions?
A solution having a greater solute concentration than some other solution
What are hypotonic solutions?
A solution with a lower solute concentration than some other solution
What is the effect of an isotonic solution on a red blood cell?
no change - osmosis happens equally in both directions
What is the effect of a hypertonic solution on a red blood cell?
Cell will shrink (crenated)
What is the effect of a hypotonic solution on a red blood cell?
Cell will swell (lyses).
Name 2 types of active processes
- Active transport pumps
2. Vesicular transport
Name 3 characteristics of Active Transport
- requires carrier proteins
- moves solute against a concentration gradient
- requires ATP energy
Name 3 types of active transport
- Primary transport
- Secondary transport
- Cotransport
Describe primary active transport
Energy comes directly from hydrolysis of ATP. Causes shape change on transport protein so that ions are pumped across the membrane. (eg. sodium/potassium pump)
Describe secondary active transport
Depends on ion gradient created by primary active transport.
Describe cotransport
Always transports more than one substance at a time.
Name the two systems used by contransport
a. Symport system - two substances transported in the same direction
b. Antiport system - two substances transported in opposite direction
Describe vesicular transport
transports large molecules, macromolecules and fluids across plasma membrane..requires ATP.
Name 3 types vesicular transport
- Exocytosis - transport out of cell
- Endocytosis - transport into cell
- Transcytosis - transport into, across, and then out of cell
Name 3 types of endocytosis
- Phagocytosis - solid materials are engulfed and brought into interior of cell, carried out by some types of white blood cells
- Pinocytosis - liquids and solutes brought into cell by infolding of plasma membrane
- RME - specific endo and trans cytosis. Main mechanism for the movement of most macromolecules.
What type of molecules help cells stick together?
Cell adhesion molecules (CAMs)
Name 3 things that CAMs do.
- anchor cells to extracellular matrix or to each other
- assist in movement of cells past one another
- CAMs of blood vessel lining attract white blood cells to injured or infected areas
What is the cytoplasm?
The cytoplasm is the cell contents outside the nucleus and is the major site of most activities carried out by the cell.
What is the fluid part of the cytoplasm called?
The cytosol.
What parts of the cell carry out specific activities for the cell as a whole?
The organelles
Define nucleus
Control centre of the cell. Is the site for genetic material - DNA.
When the cell is not dividing what is the genetic material in a threadlike form called?
Chromatin
When the cell is dividing the chromatin coils and condenses to form what?
Chromosomes
What function does the nucleoli play?
Nucleoli is the assembly sites for ribosomes.
What is the double layered membrane that surrounds the nucleus called?
Nuclear envelope
Define smooth ER
Site of lipid synthesis
Define Mitochondrion
Powerhouse of the cell, produces ATP energy
Define Lysosome
Digest worn out cell organelles and foreign substances that enter the cell
Define Centrioles
Direct the formation of the mitotic spindle during cell division
Define Microvilli
Fingerlike projections that greatly increase the surface area of the cell
Define microfilaments
Anchor the organelles and moving them within the cell
Define microtubule
Give cell shap and form. Move materials within the cytoplasm of cell.
Define intermediate filaments
Resist mechanical forces acting on cells
Peroxisome
Detoxify alcohol, hydrogen peroxide and other harmful chemicals.
Golgi Apparatus
Packages proteins or other substances that will be exported by the cell.
Ribosomes
Made of RNA and protein. Sites of protein synthesis…they are free floating or attached to a the rough ER.
Rough ER
Studded with ribosomes associated with protein synthesis. Ribosomes making these proteins will be secreted.
Name the 6 steps in mitosis.
- Interphase
- Early prophase
- Late prophase
- Metaphase
- Anaphase
- Telephase (cytokinesis)
What is the difference between mitosis and cytokinesis?
Mitosis - nuclear division
Cytokinesis - division of the cytoplasm
What happens during interphase?
Period from cell formation to cell division. Nuclear material called chromatin.
Name for 4 phases of interphase
- G1 - (gap 1) vigorous growth and metabolism
- G0 - gap phase in cells that permanently cease dividing
- S(synthetic) - DNA replication
- G2 - gap 2 - preparation for division
What is the importance of cell division?
Necessary for growth and cell repair.
What is the difference between mitosis and meiosis?
- Mitosis - daughter cells are diploid (have 46 chromosomes)
- Meoisis - occurs only in germ cells and results are haploid cells (23 chromosomes)
What are the largest molecules in the body?
Nucleic acids
What two major molecules are included in nucleic acids?
- Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
What are the structural units of nucleic acids called?
Nucleotides
What are the 3 components nucleotides consist of?
- nitrogen-containing base
- pentose sugar
- phosphate group
What are the major cell sites for DNA and RNA?
- DNA - the nucleus
2. RNA - cytoplasm
What is the major function of DNA vs RNA?
- DNA - genetic material, directs protein synthesis, replicates itself before cell division
- RNA - carries out the genetic instructions for protein synthesis
What are the sugars in DNA vs RNA?
- DNA - deoxyribose
2. RNA - ribose
What are the bases in DNA vs RNA?
- DNA - adenine, guanine, cytosine and thymine
2. RNA - adenine, guanine, cytosine and uracil
What are the base pairings in DNA?
A always bonds to T
G always bonds to C