HOMEOSTASIS HOMEOSTASIS Keeping an organisms internal environment stable
HOMEOSTASIS
HOMEOSTASIS Keeping an organism’s internal environment stable Blood pressure Examples Water balance 60% H 2 O Temperature p. H
FEEDBACK MECHANISMS Help the organism respond to stimuli and maintain homeostasis on a large scale (whole body) 1. 2. Negative Feedback Positive Feedback
NEGATIVE FEEDBACK When a situation causes a response that reverses the first condition Most common in the body skin cells detect cold brain gets message normal body temp response shiver, blood vessels constrict and lower blood flow to the skin
Soon after a meal Too High Pancreas secretes insulin Liver coverts glucose to glycogen normal blood glucose level Long after a meal Too Low Pancreas secretes less insulin Blood glucose level falls normal blood glucose level Liver converts glycogen to glucose Blood glucose level rises
POSITIVE FEEDBACK When a situation causes a response that amplifies (increases) the initial (1 st) condition Ex. Labor pains, milk production, digestive enzymes enzyme s es nzym e enzymes s enzymes yme z n e enzymes s yme enz
On a small scale, individual cells maintain homeostasis by controlling what gets into and out of a cell.
CELL TRANSPORT Cells move molecules in and out 2 ways: 1. PASSIVE TRANSPORT: does not use energy, moves from high to low concentration. 2. ACTIVE TRANSPORT: uses energy, moves from low to high concentration.
PASSIVE TRANSPORT ***Molecules move with the flow, from high to low concentrations. ***No Energy Required! ***3 Types: Diffusion Facilitated Diffusion Osmosis
PASSIVE TRANSPORT Diffusion: movement of anything from high to low concentration.
PASSIVE TRANSPORT Facilitated Diffusion: Movement of molecules from high to low concentration. A protein in the membrane helps make bigger spaces in the membrane.
Facilitated Diffusion Movement of larger molecules (ex. glucose) from high concentration to low concentration with the help of a carrier protein outside cell inside cell
PASSIVE TRANSPORT Osmosis: movement of water from high to low concentration across a membrane.
Osmosis Movement of WATER from high concentration to low concentration diffusion with WATER * When the cell is at equilibrium with its environment, equal amounts of water move into and out of the cell ISOTONIC SOLUTION 60% H 2 O
* When there is more water in a cell than outside of a cell, water will leave the cell HYPERTONIC SOLUTION this can cause a cell to shrink 75% H 2 O 2% H 2 O
* When there is more water outside a cell than inside of a cell, water will enter the cell HYPOTONIC SOLUTION this can be bad, if too much water enters then the cell may lyse (burst) 60% H 2 O 80% H 2 O CYTOLYSIS
Plant cells respond differently to osmosis because of their cell wall * When water leaves a plant cell, the cell wall’s shape does not change, but the cell membrane pulls away and creates an air pocket between the two. This causes the plant to WILT. 5% H 2 O 85% H 2 O This is called PLASMOLYSIS
* When water enters a plant cell, the cell membrane pushes against the cell wall and creates pressure. 98% H 2 O 85% H 2 O This is called TURGOR PRESSURE
ACTIVE TRANSPORT Move molecules against the flow, from low to high concentration. Uses ENERGY!
ACTIVE TRANSPORT For Multicellular Organisms: Uses a carrier protein, to carry them across the membrane
Active Transport For Unicellular Organisms VESICLE --> organelle that transports materials through, into, or out of a cell * ENDOCYTOSIS --> into the cell Pinocytosis --> fluids Phagocytosis --> foods vesicle
* EXOCYTOSIS --> out of the cell
CELLS REVIEW!!!
THE CELL Smallest unit of life that can carry on all processes of life Unicellular or multicellular Multicellular organization cells tissues organ systems tissue cell organism A group of similar cells is called a tissue. A group of similar tissues is called an organ. A group of organs working together form an organ system or organism
• The scientist Schwann, Schleiden, and Virchow contributed to what we call today the … CELL THEORY All living things are made of one or more cells Cells are an organisms’ basic unit of structure and function Cells only come from preexisting cells (mitosis)
THERE ARE TWO TYPES OF CELLS: Prokaryotic 2. Eukaryotic 1. YOU ARE EUKARYOTIC!
Prokaryotic DOES NOT have membrane bound nucleus – DOES NOT have organelles with a membrane –Smaller cells –ALWAYS unicellular
A prokaryotic cell 2. DNA 1. Ribosomes 3. Plasma membrane 4. Cell wall
Eukaryotic – HAS a membrane bound nucleus –HAS organelles with a membrane –LARGER cells –Unicellular or multicellular
A eukaryotic cell 1. Nucleus 2. Nucleolus 3. Chromosomes 4. Plasma membrane 5. Organelles
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