BSC1010 Lecture 6

Chp 6 - Cellnoanimation

Digestive System Overview

• Mouth:

  • Teeth: Reduce food size, increasing surface area for enzyme action.

  • Saliva enzymes begin carbohydrate digestion.

• Pharynx (Throat):

  • Epiglottis: Flap that blocks windpipe to direct food to the esophagus instead of lungs.

• Esophagus:

  • Transports food to the stomach using peristalsis (rhythmic muscle contractions).

• Stomach:

  • Acidic gastric juices initiate food breakdown.

  • Pepsin: Enzyme that breaks down proteins.

  • Mucous: Protects stomach lining from digestion.

  • Pyloric sphincter: Regulates food movement to small intestine.

• Small Intestine:

  • Main site for digestion of carbohydrates, proteins, fats, and nucleic acids.

  • Nutrients are absorbed into the bloodstream here.

• Pancreas:

  • Produces digestive enzymes and buffers neutralizing stomach acid.

• Large Intestine (Colon):

  • Absorbs water from undigested materials; produces feces.

Nutrient Absorption

• Villi:

  • Small finger-like projections in the small intestine that absorb nutrients into the bloodstream.

Transport of Nutrients

• Nutrients, along with oxygen, are dissolved in the plasma and transported via capillaries to all cells in the body.

Purpose of Eating

• Animals eat to:

  1. Ingest food for energy.

  2. Digest food so nutrients can be absorbed.

  3. Transport food molecules to cells for cellular respiration.

  4. Produce ATP, the energy currency of the cell.

Cardiovascular System

• Function: Enables the transport of nutrients, gases (O2, CO2), hormones, and wastes to and from cells throughout the body.

Respiratory System

• Function: Facilitates gas exchange, supplying blood with oxygen and removing carbon dioxide through structures such as trachea, bronchi, and lungs.

Excretory System

• Function: Eliminates liquid wastes and regulates water balance through organs like kidneys, ureters, bladder, and urethra.

Summary of Basic Life Functions

1. We eat to provide cells with nutrients.

2. We breathe to supply cells with oxygen.

3. We urinate to excrete cellular wastes.

4. Blood carries nutrients and oxygen to all cells and removes wastes and carbon dioxide.

Cellular Respiration

• Energy Production:

  • After digestion, nutrients are absorbed from the small intestine into the bloodstream.

  • Nutrients enter cells to produce energy through cellular respiration, generating ATP.

Cell Structure and Definition

• Cells: The smallest unit of life.

• Cytology: The study of cells; initiated by Robert Hooke’s work with microscopes.

Types of Microscopes

• Compound Light Microscopes:

  • Magnification up to 1,000 times, useful for viewing human cheek cells and other specimens.

• Electron Microscopy:

  • Higher magnifications (up to 100,000), allows the study of fine cellular structures.

Importance of Cell Size

• Small Size: Cells need to maintain a manageable size for adequate transport of nutrients and waste across the cell membrane. Larger volumes lead to a decreased surface area to volume ratio, which impairs cellular functions.

Prokaryotic and Eukaryotic Cells

• Prokaryotic Cells: Bacteria, typically with simpler structure and smaller size.

• Eukaryotic Cells: Larger, more complex cells with membrane-bound organelles and a nucleus.

Unique Structures in Eukaryotic Cells

• Endoplasmic Reticulum (RER & SER): Synthesizes proteins (RER) and lipid synthesis (SER).

• Golgi Apparatus: Processes and modifies proteins and synthesizes polysaccharides.

• Mitochondria: Site of ATP production via cellular respiration.

• Lysosomes: Digest macromolecules and recycle cellular components.

• Cytoskeleton: Provides structural support and facilitates movement within cells.

Plant Cell Structures

• Chloroplasts: Site of photosynthesis, containing chlorophyll.

• Central Vacuole: Storage center for nutrients, waste products, and allows cell expansion.

• Cell Wall: Provides structure and protection (made of cellulose in plants).

Intercellular Junctions in Animal Cells

1. Tight Junctions: Prevent leakage of extracellular fluid between cells.

2. Desmosomes: Anchor cells together and provide structural integrity.

3. Gap Junctions: Allow communication between adjacent cells by providing cytoplasmic channels.