Cell Structures, Digestion, and Heart Flashcards

Cell Organelles

• All cells have organelles, each with a specific function.

Nucleus

• Found in both animal and plant cells.
• Large, circular object within the cell.
• Contains the nucleolus, where ribosomes are produced.
• Contains chromatin (long strands).
• Chromatids wind up tightly during cell replication, forming DNA chromosomes.

Endoplasmic Reticulum (ER) & Ribosomes

• Found in both animal and plant cells.
• Two types of ER: rough and smooth.
• Rough ER: covered in ribosomes, giving it a rugged appearance.
• Smooth ER: contains enzymes, proteins, and lipids for use in different areas of the cell.

Golgi Body and Lysosomes

• Golgi body: found in both plant and animal cells, packages proteins.
• Lysosomes: found only in animal cells, release contents outside the cell.

Mitochondria

• Found in both animal and plant cells.
• Powerhouse of the cell.
• Converts energy stored in glucose into ATP when the cell needs to work (move or divide).

Centrioles

• Found only in animal cells.
• Made of thick protein tubes called microtubules.
• Help the cell divide through mitosis and meiosis.

Cytoplasm and Cell Membrane

• Found in both plant and animal cells.
• Cytoplasm: liquid that holds organelles in place.
• Cell membrane: outermost limit of the cell, selectively permeable (controls what goes in/out).

Vacuoles

• Found in both animal and plant cells.
• Store water and nutrients, filled with fluid, and remove waste products.

Cell Walls

• Found only in plant cells.
• Surround the cell membrane.
• Provide strength, support, and protection, helping plants maintain their shape even when thirsty.

Chloroplasts

• Found only in plant cells.
• Absorb light to make sugar through photosynthesis.

Animal Cells

• Contain lysosomes.
• Typically round in shape.
• Have many small vacuoles.
• Nucleus is usually in the center.

Plant Cells

• Typically rectangular and pointier.
• Have one central vacuole.
• Nucleus is visually pushed to the side.
• Contain cell walls and chloroplasts.

Digestive System

Parts

• Mouth, esophagus, stomach, small intestine, large intestine, anus.

Accessory Organs

• Liver, pancreas, and gallbladder.

Purpose

• To break large molecules into smaller subunits.

Stages of Digestion

• Ingestion: food is taken into the body via eating.
• Digestion: food is broken down physically (mastication) and chemically (enzymatic hydrolysis).
• Absorption: digested food products are absorbed into the bloodstream and transported to cells.
• Assimilation: digested food products are converted into fluid & solid part of a cell/tissue.
• Elimination: undigested food residues are egested from the body as semisolid feces.

Methods of Digestion

1. Mechanical:
   • Food is physically broken down into smaller fragments via chewing (mouth), churning (stomach), and segmentation (small intestine).
2. Chemical:
   • Food is broken down by the action of chemical agents (enzymes, acids, bile, etc.).

Key Terms

• Macromolecule: A very large molecule made up of smaller molecules linked together.
• Hydrolysis: A chemical reaction in which water breaks apart macromolecules into smaller molecules.

Part 1: The Mouth

• Salivary glands secrete saliva, which begins chemical digestion.
• Teeth begin mechanical digestion, and the tongue helps turn food into a soft bolus (food + saliva).

Part 2: The Esophagus

• The bolus is swallowed, entering the esophagus.
• The epiglottis at the top of the trachea closes to ensure the bolus does not enter the trachea.
• Lined with epithelial tissue.
• Glands in the lining produce mucus to keep the tube moist and facilitate food movement.

Part 3: The Stomach

• The bolus enters the stomach through the esophageal sphincter.
• Food triggers the secretion of gastric juice—a mixture of salts, enzymes, hydrochloric acid, water, and mucus.
• Gastric juice kills harmful substances and denatures proteins.
• Mucus protects the stomach from the acid.
• Pepsin: a protease secreted in an inactive form, activated by acid, breaks down proteins into smaller polypeptides.
• Food is digested for several hours and turned into a creamy paste called chyme.

Part 4: The Small Intestine

• Most digestion and absorption of nutrients occur here.
• Has 3 parts: duodenum, jejunum, and ileum.
• Digestive enzymes are secreted to further break down food.
• Nutrients diffuse through the intestinal wall into the bloodstream for transport and use by the body.
• Contains villi, which increase the surface area for absorption.

Part 5: The Pancreas (Accessory Organ)

• Pancreatic juice containing enzymes is released into the duodenum via the pancreatic duct.
• When acidic food enters the small intestine, the pancreas releases bicarbonate to neutralize it and prevent damage to the intestinal walls.
• The pancreas secretes insulin and glucagon to control blood sugar levels.

Part 6: The Liver (Accessory Organ)

• Synthesizes bile, which is stored in the gallbladder.
• Bile is composed of cholesterol, bile salts, and bilirubin, and emulsifies fats.
• Converts glucose to glycogen and vice versa.
• Processes and stores nutrients for release into the bloodstream (glycogen, vitamins, etc.).
• Detoxifies harmful substances and excretes them via urine (bacteria, old red blood cells).

Part 7: The Gallbladder (Accessory Organ)

• Stores bile from the liver.
• Releases bile into the small intestine when needed.

Part 8: The Large Intestine

• Also known as the colon, reabsorbs fluids and electrolytes.
• Smooth and does not contain villi.
• Absorbs approximately 90% of water back into the blood.
• Parts: Cecum (blind pouch), Colon (longest part), Rectum (stores feces), Anus (opening for waste egestion).
• Food is pushed through by peristalsis to the rectum, where feces is produced and eventually egested.

Chambers of the Heart

Atria

1. Right Atrium:
   • Receives blood returning to the heart via the superior/inferior vena cava.
   • Deoxygenated blood from the body.
2. Left Atrium:
   • Receives blood via the pulmonary veins.
   • Oxygenated blood from the lungs.

Ventricles

1. Right Ventricle:
   • Receives blood from the right atrium.
   • Pumps deoxygenated blood to the lungs.

Arteries of the Heart

• Pulmonary Artery: carries deoxygenated blood to the lungs
• Aorta: Carries oxygenated blood away from the heart to the rest of the body (largest artery).

Veins of the Heart

• Inferior Vena Cava: carries deoxygenated blood from the bottom of the body to the heart.
• Superior Vena Cava: carries deoxygenated blood from the top of the body to the heart.
• Pulmonary Vein: carries oxygenated blood from the lungs to the left atrium.