C3.1 - Internal Systems and Regulation

Organ Systems

• Human body cells arranged in a hierarchy
• tissue: group of specialized cells that work together to perform a specific task
• organ: structure composed of different tissues specialized to carry out a specific function
• organ system: group of organs that have related functions

flowchart TD
	a["`**Specialized Cells**
	(i.e. cardiac muscle cells)`"] --> b
	b["`**Tissues**
	(i.e. cardiac tissue)`"] --> c
	c["`**Organ**
	(i.e. heart)`"] --> d
	d["`**Organ System**
	(i.e. circulatory system)`"]

Human Organ Systems

mindmap
	[Human Organ Systems]
		(Digestive)
		(Circulatory)
		(Respiratory)
		(Reproductive)
		(Excretory)
		(Locomotion)
		(Endocrine, horm.)
		(Nervous)

4 Types of Tissue

• epithelial tissue forms protective structures in body
  • lines outer layer of skin and many organs
  • form glands in body to produce hormones, enzymes, and sweat
• connective tissue supports and protects structures in the body
  • also connects two structures together
  • found in
    • tendons (connect muscle to bone)
    • ligaments (connect bone to bone)
    • bones
    • cartilage (stops bones from rubbing on each other)
    • blood
    • fat
• muscle tissue allows for movement in body
  • skeletal muscle: muscle located in arms, legs, and areas with bones to help us move
  • smooth muscle: muscle located in digestive tract to help food move through the digestive system
  • cardiac muscle: muscle located in the heart to help the heart move to pump blood
  • smooth and cardiac muscles allow the organs to move
• nervous tissue responds to stimuli and sends signals throughout body
  • stimuli: factor that causes the body to react to it —> change of bodily activities
  • found in brain, spinal cord, nerves

Respiration and Gas Exchange

• Essential for all organisms
• Oxygen in → carbon dioxide out
• Different organisms have different gas exchange systems
• All rely on moist respiratory surfaces
• breathing: ventilation of respiratory system with air

Respiratory Surfaces

• respiratory surface: special, moist membrane where gas exchange occurs
• cellular respiration: process that produces energy needed to fuel all cell activities
  • glucose + oxygen → water + carbon dioxide + ATP
• Characteristics of Respiratory Surface
  • very thin and moist → permeable to gases being diffused
  • large surface area to maximize diffusion
  • diffusion gradient must be maintained
    • diffusion: high conc. → low conc.
    • relative difference in concentration of oxygen and carbon dioxide in both sides required

Membrane Diffusion Only

• Found in single-celled and some multi-celled organisms
• Rely on simple diffusion
• Concentration gradient
  • high concentration → low concentration
• i.e. bacteria, protists, flatworms, hydra

Specialized Respiratory Systems

• Larger organisms require more complex respiratory systems
• Simple diffusion effective only to thickness of few cells
• Systems include:
  • respiratory surface
  • passageways
  • muscular structures associated w/ respiratory surfaces

I. Skin Respiration

• Moist surface
• Tissue lined w/ capillaries
• Occurs across all of body surface
• Species relying on skin respiration generally small or have flat bodies to have large surface area
• i.e. earthworms

II. Gills

• gills: folds in the body surface specialized for gas exchange
  • feathery tissues in aquatic animals
  • high surface area
  • ventilated w/ oxygen-rich water
  • enables water to flow so that gases can diffuse from water and across respiratory membranes
  • may be combined w/ other functions like feeding (bivalves) and locomotion (octopus)
• i.e. fish

III. Tracheal Respiration

• tracheal system: system of tubes that extend through their bodies
  • tracheae: larger entry tubes
  • tracheoles: smaller branching tubes from tracheae
• Internal system in insects
• Open to exterior by spiracles
• spiracle: valved pores used for breathing
• Internal network of tracheae
• Ventilated through muscular contractions
• Generally, insects don’t need circulatory system for gas exchange (diffusion enough)
• Larger insects sometimes pump in more air through rhythmic body movements
  • … compressing and expanding the air
• i.e. grasshopper

IV. Lungs

• lungs: internal, thin-walled sacs with a large surface area
• Internal structures connected to exterior by specialized passageways
• 3 components
  • lungs w/ moist respiratory system
  • circulatory system
  • ventilation system
• i.e. terrestrial vertebrates, arachnids (book lungs)
• Inside lungs, oxygen gas diffuses into blood and is transported via vessels across body
• Carbon dioxide diffuses out of blood, enters lungs, and moved out