Nutrient Processing: Digestion and Respiration

• Nutrients Procurement & Processing - Q4 Week 2

Digestion

• It is the process of breaking down food into simpler substances.

Sugar/Glucose

• It is one of the products of photosynthesis.

Bulk-Feeding

• A feeding mechanism that a lion uses to eat a large amount of meat.

Gas Exchange

• This includes the uptake of molecular oxygen from the environment.
• It also includes the discharge of carbon dioxide into the environment.
• It is also called respiratory exchange or respiration.
• Oxygen is needed in tissues for aerobic cellular respiration to occur and extract ATP from food.
• Carbon dioxide must be released to prevent physiological pH in tissues from being very acidic.

Aerobic Respiration

• Uses oxygen to produce energy from food.
• Its reactants are glucose and oxygen, and the organisms include plants and animals.
• The energy yield is high at 36-38 ATP.
• Products include CO2 and H2O.
• This occurs in the cytoplasm and mitochondrion.

Anaerobic Respiration

• Does not use oxygen to breakdown food molecules.
• Its reactants are glucose, and the organisms include bacteria and fungus.
• The energy yield is low at 2 ATP.
• Products include lactic acid in animals and ethanol + CO2 in yeast.
• This occurs in the cytoplasm.

Gas Exchange vs. Cellular Respiration

• Plants inhale oxygen and exhale carbon dioxide during cellular respiration.
• Carbon dioxide, released as a by-product of cellular respiration, can be used in photosynthesis.
• During photosynthesis, carbon dioxide is absorbed, and oxygen is released.

Oxygen Cycle

• Plants create oxygen via photosynthesis.
• Animals breathe in oxygen.

Gas Exchange in Plants

• Plants obtain the gasses needed through their leaves.
• Oxygen is required for respiration, and carbon dioxide is required for photosynthesis.
• Gasses diffuse into intercellular spaces of leaves through pores called stomata.

Structures for Gas Exchange in Plants

• Stomata in leaf surfaces have guard cells that open or close the stomatal pore.
• Carbon dioxide enters and oxygen is released here.
• Stomata are abundant on the lower surface of the leaf and typically open during the day when photosynthesis rates are highest.
• Each stoma is surrounded by two specialized guard cells that are attached at each end.

Photosynthesis

• Occurs only in plants and some photosynthetic bacteria.
• Takes place in the presence of sunlight and occurs in the chloroplast and is dependent on light.
• Raw materials are CO2 and water.
• Light energy is fixed in the form of chemical energy and stored in carbohydrates.
• Oxygen is liberated, and carbon dioxide is utilized.

Respiration

• Occurs in all living organisms and takes place throughout the day.
• Aerobic respiration occurs in the cytoplasm and mitochondria and is independent of light.
• Uses carbohydrates or organic substances and oxygen.
• Chemical energy stored in carbohydrates burns to release energy.
• Oxygen is utilized, and carbon dioxide is released.

Cellular Respiration

• The process through which organisms convert glucose to a form that may be used by cells for energy.
• The formula is C6H12O6 + O2 → CO2 + H2O + ATP.

Respiratory System of Plants

Roots

• Aerial roots are adventitious roots above-ground, often found in orchids and other epiphytes.
• Some aerial roots have root hairs for increased surface area.
• In mangroves, pneumatophores, or lateral roots, are specialized aerial roots for waterlogged soil.
• Roots carry oxygen from the air, water, and nutrients.

Stem

• Stems have porous tissues.
• Porous tissues aid in gas exchange, especially on thickened barks and stems, and are called lenticels.
• Lenticels are small openings in the bark of a tree where gas exchange happens.
• Stems are used as a passageway for air, water, and nutrients.

Stomata

• It is the opening into the leaf that allows oxygen and carbon dioxide to diffuse.

Guard Cells

• Guard cells regulate transpiration happening in the stomata.
• Transpiration is the evaporation of water from plants through stomata.

Gas Exchange in Animals

• Animals have external gills, internal gills, lungs, and tracheae.

Gas Exchange System of Animals

Skin System

• Animals like amphibians in damp environments breathe in oxygen through their moist body surface.

Gills System

• Animals like fish take in dissolved oxygen from water using gills.

Tracheal System

• Animals like insects enable gas exchange using tracheae.

Lung System

• Terrestrial animals have lungs, which are a pair of organs inside cavities separated into small chambers packed with capillaries.

Respiratory Organs of Invertebrates

Integumentary Exchange

• Refers to the general body surface or skin used by animals with a high surface-to-volume ratio.
• Examples include a flatworm and earthworm.
• Amphibians like frogs and salamanders also use their moist skin in addition to lungs.

External Gills

• Used by invertebrates that live in aquatic habitats.
• Highly folded, thin-walled, vascularized epidermis that projects outward.
• Examples include annelids, aquatic insects, crayfish, lobster, sea star, and nudibranch.
• Most crustaceans and mollusks such as clams and oysters utilize internal gills.

Tracheal System in Arthropods

• Utilizes fine air-conducting tubules called spiracles where air enters and exits.
• Examples include insects and spiders.

Respiratory Organs of Vertebrates

External Gills

• Thin, vascular projections from the body surface of a few amphibians.
• Example: larval salamander.

Internal Gills

• Rows of slits or pockets in adult fishes positioned at the back of the mouth.
• Water flows over the gills, and blood circulates through them in opposite directions.
• This mechanism, called countercurrent flow, efficiently extracts oxygen from water.

Lungs

• Internal respiratory surfaces shaped as a cavity or sac.
• Lungs provide a membrane for gaseous exchange and require a circulatory system to transport gases.
• Found in birds, reptiles, and mammals.

Respiratory System Functions

• Facilitate the exchange of gases between air and blood.
• Supply oxygen to blood and the entire body.
• Remove and dispose of carbon dioxide away from the body.

Respiratory System Breakdown

Upper Respiratory Tract:

• Nasal Cavity
• Pharynx
• Larynx.

Lower Respiratory Tract:

• Trachea
• Bronchi and Bronchioles
• Lungs.

Respiratory System Parts

• Mouth & Nose: The opening where air enters into the respiratory system.
• Pharynx: The tube that brings air into the trachea.
• Larynx: The part of the respiratory system that produces sounds.
• Trachea: Connects the larynx and bronchi and contains the epiglottis (that covers the larynx).
• Bronchi: Connects and brings air inside the lungs.
• Lungs: Contains alveoli where the exchange of carbon dioxide and oxygen takes place.

How the System Works

• Oxygen enters through the mouth & nose -> pharynx & larynx -> trachea -> bronchi -> lungs -> alveoli (where exchange of gases takes place).
• Carbon dioxide is then released outside the body.

The Human Respiratory System

• Nasal Cavity: Located behind the nose, it warms, humidifies, and filters inhaled air, also housing chemoreceptors for the sense of smell and taste.
• Pharynx: A passage behind the nasal chamber and serves as the common passageway for both air and food.
• Larynx: Known as the voice box as it houses the vocal chords, which are paramount in the generation of sound.
• Epiglottis: A flap-like structure that covers the glottis and prevents entry of food into the windpipe.
• Trachea: Also known as the windpipe, it is a long tube passing through the mid-thoracic cavity.
• Bronchi: The trachea divides into left and right air tubes called bronchi which connect to the lungs.
• Bronchioles: Each bronchus is further divided into finer channels known as bronchioles.
• Alveoli: The bronchioles terminate in balloon-like structures known as the alveoli.
• Lungs: Humans have a pair of lungs, which are sac-like structures covered by a double-layered membrane known as pleura.