Biological Control and Coordination

Biological Control and Coordination

• Control and coordination in living organisms are essential for maintaining homeostasis and responding to stimuli.
• Two main systems are involved:
  • Nervous system: rapid responses to stimuli using nerve impulses.
  • Endocrine system: slower, longer-term responses using hormones.
• Nervous system: composed of neurons that transmit electrical signals.
  • Neurons have three main parts: dendrites to receive signals, a cell body for processing, and axons to transmit signals to other cells.
  • Neurotransmitters are chemicals that transmit signals across synapses (gaps between neurons).
  • The brain is the central processing center of the nervous system, receiving, interpreting, and responding to information. The spinal cord connects the brain to other parts of the body.
  • Reflex arcs are rapid, automatic responses to stimuli, with minimal brain involvement.
• Endocrine system: uses hormones to regulate bodily functions.
  • Hormones are chemical messengers transported in the bloodstream to target organs or cells.
  • Each hormone has a specific effect on its target cells.
  • Examples include insulin, glucagon, and adrenaline.
• Human Nervous System:
  • Central Nervous System (CNS) comprises the brain and spinal cord.
  • Peripheral Nervous System (PNS) comprises nerves that transmit signals to and from the CNS.
  • The PNS is further divided into the Somatic Nervous System (voluntary actions) and the Autonomic Nervous System (involuntary actions).

Reproduction

• Reproduction is the process by which living organisms produce offspring to ensure the continuity of their species.
• Asexual Reproduction:
  • Simple, rapid method.
  • Offspring are genetically identical to the parent.
  • Examples: binary fission, budding, fragmentation.
• Sexual Reproduction:
  • Involves the fusion of gametes (sperm and egg) from two parents.
  • Offspring show genetic variation due to the combination of genetic material from the parents.
  • Examples: flowering plants and animals.
• Reproductive Systems: specialized structures and organs for sexual reproduction in animals.
  • Male reproductive system: produces and delivers sperm.
  • Female reproductive system: produces eggs and supports development.

Heredity

• Heredity is the passing on of traits from parents to offspring.
• Genetics: The scientific study of heredity.
• Genes: The units of heredity, located on chromosomes within the nucleus of cells. Genes are responsible for all traits and characteristics.
• Chromosomes: Structures containing DNA, the genetic material. Chromosomes come in pairs, one from each parent.
• DNA: Deoxyribonucleic acid, a double helix structure that carries the genetic code. DNA is the blueprint that controls all the functions within a cell.
• Mendel's Laws of Inheritance:
  • Law of segregation: each parent contributes one allele for each trait to its offspring.
  • Law of independent assortment: different traits segregate independently of each other during gamete formation.
• Types of Inheritance:
  • Dominant: one allele masks the effect of another.
  • Recessive: an allele only expresses its effect if it is present in both copies.
  • Incomplete dominance: neither allele is totally dominant; the phenotype shows a blending of traits.
  • Codominance: both alleles are fully expressed, with both traits visible.
• Genetic Variation:
  • Caused by mutations, sexual reproduction, and gene shuffling during meiosis. Genetic variation is beneficial for adaptation and evolution.
• Methods of Studying Heredity:
  • Pedigree analysis: tracking the inheritance of traits across generations.
  • Karyotyping: visualizing chromosomes to identify abnormalities.
  • Genetic testing: determining the genetic makeup of an individual.
  • Genetic engineering and modification are increasingly important tools.