The Human Nervous System: Structure and Function
Central Nervous System
The central nervous system (CNS) is formed by the brain and spinal cord. It is responsible for processing received information and controlling body functions.
Peripheral Nervous System
The peripheral nervous system (PNS) is formed by a set of nerves that connect the CNS with the rest of our body organs. Its function is to transmit information and conduct the CNS’s orders to the organs responsible for executing them.
Brain
The brain is located in the skull. It consists of the cerebrum,
Read MoreGenetics: Key Concepts and Heredity Principles
Gene: A gene is the basic unit of heredity, transmitting genetic information.
Genotype: The complete set of genes within an individual.
Phenotype: The observable characteristics of an individual, resulting from the interaction of genotype and environment.
Homozygous: Having two identical alleles for a particular gene.
Heterozygous: Having two different alleles for a particular gene.
Dominant Allele: An allele that expresses its trait even when paired with a recessive allele.
Recessive Allele: An allele
Read MoreImmune System Defenses: Types and Processes
Nonspecific Defenses
The immune system employs various nonspecific defenses to protect the body from pathogens.
Phagocytes
Phagocytes are leukocytes responsible for removing microorganisms and foreign substances from tissues through phagocytosis.
Phagocytes move via amoeboid movements.
Types of Phagocytes
- Granulocytes: These cells contain abundant granules with enzymes and antimicrobial compounds.
- Monocytes: These cells lack granules and have a lobulated nucleus. They are larger than granulocytes.
Phagocytic
Read MoreAnimal Breeding and Genetics: Concepts and Applications
True/False Questions in Animal Breeding and Genetics
General Concepts
1. Animal domestication processes are exclusively based on artificial selection (False)
2. All quantitative traits present more than 20 phenotypic classes (False)
3. Highly inbred lines can be used to analyze the environmental contribution to a given trait (True)
4. The breeding value of an animal is always constant, independently of the environment (False)
5. The breeding value of the offspring of an individual can be half of its breeding
Human Reproduction: Gametes, Fertilization, and Development
Human Reproduction: From Gametes to Birth
In sexual reproduction, women produce gametes called ova (eggs), and men produce gametes called sperm. These gametes join during fertilization to form a zygote. This process occurs within the gonads: ovaries in females and testicles in males. Fertilization is internal, meaning the egg and sperm unite within the female reproductive tract. Humans are viviparous, meaning the development of the new being occurs inside the mother.
Key Processes in Reproduction
Reproduction
Read MoreHuman Digestion: Defecation, Vomiting, Saliva Synthesis
Defecation
Defecation is a reflex involving the rectum and anus, triggered by the parasympathetic nervous system (PSNS), but subject to voluntary control. The rectum, a muscular tube 12-15 cm in length, is normally empty. When a mass movement forces stool into the rectum, the person feels the urge to defecate.
The anal canal is closed by two sphincters:
- Internal anal sphincter (IAS): Composed of smooth muscle, contracted by the sympathetic nervous system (SNS) via noradrenaline (NA). It is involuntary.