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bio ct1 flashcards

Excretion

Definition:

Waste removal process known as excretion.

Waste Products:

Includes carbon dioxide (from cellular respiration) and urea (from protein metabolism).

Organs Involved:

  • Lungs: Excrete carbon dioxide.

  • Kidneys: Main excretory organs, above the waist at the back of the body, excreting urea.

Function of the Kidneys

Primary Role:

Remove urea, water, and other unwanted substances from the blood.

Blood Pathway:

  • Renal artery: Carries 'dirty' blood (contains waste) to the kidneys.

  • Renal vein: Carries 'clean' blood away from the kidneys.

Urination:

  • Ureters: Tubes carrying urine to the bladder.

  • Bladder: Stores urine until disposal.

  • Urethra: Tube that carries urine out of the body.

  • Kidneys: Remove urea and other wastes from blood and excrete in a liquid called urine

  • Sphincter: A ring of muscle which keeps the bladder closed until you go to the toilet

Kidney Functionality

Blood Cleaning Process:

Kidneys filter blood 300 times a day through over a million tiny tubes (nephrons).If kidneys fail, artificial kidney machines can filter blood, or a kidney transplant may be necessary.

Anatomy of the Kidneys

Kidney Structure:

Diagram shows a kidney cut in half to reveal a nephron.

Nephron Components:

  • Glomerulus: Cup-shaped structure where 'dirty' blood is filtered.

  • Urine formation begins in nephron tubes.

  • Urine from many nephrons drains into the collecting duct (ureter i think)

How Nephrons Work

Filtration:

Blood is filtered, allowing nearly all components except red blood cells to enter the nephron.

Selective Reabsorption:

Useful substances (glucose, water) reabsorbed back into the blood.

End Product:

Remaining liquid in nephron is urine, consisting of urea and water.
SO URINE CONSISTS OF UREA AND WATER

Digestion

Purpose:

Breaks food into soluble molecules to be absorbed by the blood.

Alimentary Canal:

A coiled tube over seven meters long that processes food.

Stages of Digestion:

  1. Ingestion: Food taken into the mouth, broken down by teeth, and mixed with saliva.

  2. Digestion: Enzymes in the gut break food down into liquid form.

  3. Absorption: Digested food passes into the bloodstream through the gut wall (mainly in the small intestine).

  4. Assimilation: Cells use food for repair growth energy etc

  5. Defecation: Undigested substances like dietary fibre exit the body as feces through the anus.

Digestive Enzymes

Roles:

Each food type requires specific enzymes.

  • Carbohydrase: Breaks down carbohydrates (starch -> glucose).

  • Lipase: Breaks down fats into fatty acids and glycerol.

  • Protease: Breaks down proteins into amino acids.

Enzymatic Breakdown:

Example: Carbohydrase enzymes convert starch into glucose.

Absorption and the Liver

Absorption:

Takes place primarily in the small intestine (6m long) via structures called villi, which increase the surface area for optimal nutrient uptake.

Liver Functions:

Chemical factory, food store, and heat production center.

  • Handles glucose storage and conversion to glycogen.

  • Stores vitamins and minerals (copper, potassium, iron).

  • Converts excess amino acids into urea.

  • It takes poisons from blood and makes them harmless, these poisons come from germs alcohol and drugs

  • Produces bile which is needed for digestion

  • Makes fibrinogen which needed for blood to clot in wounds

  • These jobs and many other jobs done in the liver produce heat, which heat blood carries around the body to keep the body warm