Lecture 5: Cell Phy 1 Flashcards
How much of the human body is fluid?
50-70%
How much of the human body fluid is intracellular?
2/3
How much of the human body fluid is extracellular?
1/3
What fluid is the internal environment of the body?
extracellular fluid
What is in intracellular fluid?
Potassium, magnesium,
phosphate
What is in extracellular fluid?
electrolytes and nutrients for cells’ function (also: sodium, chloride, bicarbonate, oxygen, glucose, fatty acids, amino acids, and CO2 for excretion)
What is homeostasis?
Maintenance of nearly constant conditions in the internal environment
True/False: Even in disease, homeostasis continues, but at decreased performance
True
What is one way a cat or sheep in renal failure will get tipped
over the edge?
Infection
Where does blood travel?
Through blood vessels
Where does extracellular fluid move?
between capillaries and cells
How often does blood move through circulation in humans while resting vs activity?
Once per minute or six times per minute when active
How does diffusion occur in cells?
Continual exchange of ECF between plasma in blood and interstitial fluid between cells
How does our body maintain oncotic pressure?
large plasma proteins stay in the blood
True/False: Capillaries are permeable to most molecules except large
plasma proteins
True
True False: Most cells are located more than 50 micrometers from a
capillary
False usually 50 mm or less
What is the function of the lungs?
obtain oxygen in alveoli by diffusion and lose CO2
What is the function of the GI tract?
breaks things down to obtain carbohydrates, fatty acids, aa
What is the function of the kidneys?
- Remove substances for excretion
- Filter plasma at glomeruli and reabsorb glucose,
amino acids, water (as needed) - Poorly absorbed substances are excreted
How are poorly absorbed substances excreted in the body?
through the kidneys
What is a cell?
The cell is the “basic living unit of the body.”
Each tissue or organ is “many different cells held
together by intercellular supporting structures.”
True/False: The circulatory system is divided into two parts?
True
Explain the cytoplasm.
- Separated by a nuclear membrane
- Cytoplasm is separated from fluid by cell membrane
What percentage of cells is water?
70-85% (except fat cells)
Give examples of ions in the cell.
potassium, magnesium, phosphate, bicarbonate, sodium, chloride, calcium
What is the function of ions in the cell and give an example?
ions provide chemicals for cellular reactions (e.g. ions at cell membrane are needed to transmit impulses in nerve and muscle fibers)
What percentage of cells is protein?
10-20%
What is the structure of proteins?
long thin filaments provide contraction, cytoskeleton
What is the function of proteins (general)?
- peripheral proteins enzymes, often adhere to inside cell membrane and catalyze reactions
- Provide pores to allow water and water-soluble substances through cell membrane (e.g. ions)
- Also act as Carrier proteins to transport substances that could not penetrate lipid bilayer, also provide active transport
- Also serve as Receptors for water-soluble chemicals such as peptide hormones
What percentage of the cells is lipid?
2%
What is the function of lipids in the cell?
Insoluble in water so it forms the cell membrane and intracellular membrane barriers
What are adipocytes?
fat cells
What are examples of lipids that form the cell membrane?
Phospholipids
Cholesterol
Triglycerides
What is the function of triglycerides?
energy stores
What is the function of carbohydrates in the cell
stored for energy
What is the function of intracellular glycogen?
longer storage backup system that can be used rapidly if needed.
What is the structure of the Cell Membrane?
-Water-insoluble barrier made of lipids and protein
- Thin film of lipid 2 molecules thick continuous over entire surface of cell
- Has a lipid bi-layer prevents water penetration,
interspersed with proteins
What is the function of the cell membrane?
- Cover the cell and internal organelles such as mitochondria, nucleus, endoplasmic reticulum
- Structure
Explain the structure of a phospholipid molecule.
- Hydrophilic ends cover outside in contact with water
- Hydrophobic ends are in center (soluble only in fats)
What substances can penetrate the hydrophobic layer of a phospholipid molecule?
Can be penetrated by fat-soluble substances such as
oxygen, CO2 and alcohol
What molecules provide specificity to a membrane?
Proteins
What is the function of integral proteins?
- Provide pores to allow water and water-soluble substances through cell membrane (e.g. ions)
- Also act as Carrier proteins to transport substances that could not penetrate lipid bilayer, also provide active transport (highway)
- Also serve as Receptors for water-soluble chemicals such as peptide hormones (epinephrine)
- channels, pores, carriers, enzymes, etc.
What is the function of peripheral proteins?
enzymes (usually catalyze reactions), intracellular signals, mediators
What is another name for aquaporins?
water channels
What is the function of aquaporins?
- Transport water across the cell membrane via water-permeable channels
- Increases water permeability, so more water is reabsorbed from the collecting duct, back into the body (and urine is then concentrated)
What is the function of Vasopressin?
vasopressin binds to receptors on the cells of the collecting duct in the kidneys, it activates a signaling pathway that results in the translocation of aquaporin channels (responsible for the absorption or excretion of water)
How do the lungs maintain homeostasis for the body?
supply constant source of oxygen
How does the GI tract maintain homeostasis for the body?
supplies nutrients
How do the kidneys maintain homeostasis for the body?
maintain ion concentration
Does disease develop fast or slow?
slow
What is the function of dissolved glucose in the extracellular fluid?
readily available energy to the cell
True/False: Protein molecules form pores through membrane for passage of specific substances
True
