Photosynthesis: Process, Phases, and Pigments
Autotrophic and Heterotrophic Anabolism
Autotrophic anabolism is the synthesis of complex molecules from simple inorganic molecules such as glucose or glycerol. Heterotrophic anabolism is the transformation of simple organic molecules into more complex ones, like starch. There are two types of autotrophic anabolism based on the energy source: photosynthetic anabolism, which uses light energy (e.g., photosynthesis in plants, cyanobacteria, and photosynthetic bacteria), and chemosynthetic anabolism,
Read MoreHuman Digestive System: Functions and Processes
Mouth
Digestive Functions
- Mechanical Decomposition: Chewing
- Chemical Digestion: Salivary glands secrete enzymes.
- Serous (watery): Contains ptyalin or amylase for starch digestion.
- Mucosa: Lubricates food, protects oral mucosa, and facilitates swallowing.
Saliva Functions
- Protects dental mucosa
- Cleans teeth
- Starts carbohydrate digestion
- Helps form the bolus
- Lubricates the oral cavity and pharynx
- Dissolves chemical substances for taste perception
- Immune function
Salivary Glands
- Major Glands: Parotid, submaxillary,
Nervous System: Coordination, Impulses, and Synapses
At the synapse, a neurotransmitter is released into the synaptic cleft and diffuses to the postsynaptic membrane. It then binds to specific receptors, which determines a potential change of the membrane (postsynaptic potential). If this potential reaches the threshold of excitation, it is propagated through the entire postsynaptic neuron. Once the neurotransmitter has acted, it is inactivated enzymatically, and the stimulation disappears.
Types of Synapses
Chemical Synapses
The arrival of the electrical
Read MoreHuman Reproduction: System, Fertilization, Pregnancy, and Delivery
Item 7: Human Reproductive System
Sexual Reproduction
Humans reproduce sexually. Women produce gametes called eggs, and men produce male gametes called sperm. These two cells combine to form a zygote.
Fertilization is internal; the sperm and egg bind within the female reproductive system. Humans are viviparous.
- Gamete Production: In specialized reproductive organs.
- Fertilization: The union of two gametes within the female reproductive tract, forming a single-celled zygote.
- Zygote Development: Within the
Nucleic Acids: Composition, Structure, and Function
Composition of Nucleic Acids
Nucleic acids are essential biological macromolecules responsible for storing, transmitting, and expressing genetic information in all living organisms. They include DNA and RNA, both of which are composed of nucleotides. Nucleotides consist of a nitrogenous base, a five-carbon sugar (pentose), and a phosphoric acid molecule.
Nitrogenous Bases
Nitrogenous bases are heterocyclic compounds containing carbon and nitrogen, with a flat structure. There are two types:
- Purines:
Human Digestive System: Functions, Anatomy, and Diseases
Digestive System Physiology
Gastrointestinal Tract Function
The gastrointestinal tract, a 10-12 meter tube with associated glands, digests food, transforming complex molecules into simple, usable substances for the body.
The Digestive Process
Digestion starts in the mouth where food mixes with saliva, is crushed by chewing, and formed into a bolus for swallowing.
Stomach Functions
The stomach, a muscular bag, secretes gastric juice, mixing food into chyme. This semi-fluid mass then passes to the duodenum.