Nervous System and Brain Function

• The nervous system is the major control system of homeostasis.
• It monitors, responds, and regulates all systems in the human body and other organisms.

Central Nervous System (CNS)

• The main "processing center" for the entire nervous system.
• Includes the brain and spinal cord.

Peripheral Nervous System (PNS)

• Connects the brain and spinal cord to other body parts
• It's primarily made up of nerves.

Brain

• Organ that controls the body's functions, including movement, thought, and memory.
• Consists of three main parts:
  • Cerebrum: the largest part, responsible for thinking, learning, memory, and speech.
  • Cerebellum: Located under the cerebrum to maintain balance, posture, and fine motor movement.
  • Brain stem: Connects the brain to the spinal cord and responsible for breathing, heart rate, seeing, hearing, talking, walking, and eating.
• The nervous system detects stimuli and coordinates responses.

Stimulus

• Stimulus: A change in the environment that causes a living organism to respond.
• Types of stimuli:
  • External: Changes outside an organism like sound, light, heat, smells, temperature changes, and touch.
  • Internal: Changes within an organism such as hunger, thirst, pain, or blood pressure.

Response

• Response: An action or reaction to a change in the environment (stimulus).
• Two types of responses:
  • Positive: moving toward a stimulus
  • Negative: moving away from a stimulus

Examples of Response to Stimulus

• Plants demonstrate phototropism, geotropism, and thigmotropism.
• Animals show pupil dilation, reflexes, and muscle contraction.
• Humans exhibit eye response, temperature regulation, hearing, touch response, and muscle response.

Neuron (Nerve Cell)

• The basic unit of the nervous system.
• Parts of a neuron:
  • Dendrites: Branch-like structures that receive messages for the cell.
  • Cell Body: Contains the nucleus, Golgi body, endoplasmic reticulum, mitochondria, and other components.
  • Axon: A long, thin nerve fiber, carries electrical impulses from the cell body to another neuron/nerve cell.
• Neurotransmission: the transfer of information between neurons.
• Neurotransmitter: A chemical substance produced by the neurons.

Reproductive System

• The reproductive system also known as the genital system.
• It's is the biological system made up of all anatomical organs involved in sexual reproduction.
• Male reproductive system functions to produce and deposit sperm
• Female reproductive system functions to produce egg cell, and to protect and nourish the fetus until birth.

Male Reproductive System

• External Structures:
  • Penis: Used for sexual intercourse to expel or ejaculate semen.
  • Scrotum: Contains the testicles.
  • Testicles (Testes): Responsible for making testosterone and producing sperm.
  • Epididymis: Carries, stores, and brings the sperm to maturity.

Male reproductive system Internal organs

• Vas Deferens: Transports mature sperm to the urethra for ejaculation.
• Ejaculatory Ducts: Formed by the fusion of the vas deferens and the seminal vesicles.
• Urethra: Carries urine from the bladder and semen to outside of the body.
• Seminal vesicles: Produces a sugar-rich fluid (fructose) that provides sperm with a source of energy and helps with the sperm's motility.
• Prostate gland: Contributes additional fluid to the ejaculate, and helps to nourish the sperm.
• Bulbourethral glands or Cowper's gland: Produces a clear, slippery fluid that serves to lubricate the urethra and to neutralize any acidity due to residual drops of urine in the urethra.
• Pathway Of Sperm Cells: Testicles - Epididymis – Vas deferens - Ejaculatory duct – Urethra

Female Reproductive System

• External structures:
  • Labia majora: Encloses and protects the other external reproductive organs
  • Labia minora: Surrounds the openings to the vagina and urethra.
  • Bartholin's glands: Located besides the vaginal opening and produce mucus secretion.
  • Clitoris: covered by a fold of skin called prepuce.

Female reproductive system Internal organs

• Vagina: Joins the cervix to the outside of the body.
• Uterus (womb): Home to a developing fetus.
  • Cervix: the lower part that opens into the vagina.
  • Corpus: Main body of the uterus that easily expands to hold a developing baby.
• Ovaries: Produces eggs and hormones.
• Fallopian tubes: serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus.

Fertilization

• The process of a sperm and egg uniting to create a zygote, which is the first stage of pregnancy.

Menstruation

• The process in which blood and other tissues are shed from the uterus and leave the body through the vagina.
• Also called a menstrual period or menses
• An ovary releases only one egg every 28 days.
• Menarche (the first menstrual cycle): normally occurs between the ages of 11 and 15
• Menopause- between the ages of 45 and 55.
• Menstrual Cycle phases:
  • Menstruation Phase: The thickened uterine lining falls away
  • Follicular Phase: Hormones creation of follicles on the ovaries, one follicle matures.
  • Ovulation Phase: The egg is released from the follicle.
  • Luteal Phase: If there is no fertilized egg, the body prepares to shed the thickened lining, cycle begins again.

DNA

• DNA - a molecule which contains all the instructions that an organism requires to develop, live and reproduce.
• Nucleotides are the basic building blocks of DNA.
  • sugar group: deoxyribose
  • phosphate group: a chemical group made up of one phosphorus atom and four oxygen atoms
  • nitrogenous base: adenine (A), cytosine (C), guanine (G), thymine (T)

DNA nitrogenous bases

• Adenine (A) pairs with Thymine (T)
• Guanine (G) pairs with Cytosine (C)
• The shape of the DNA is a double helix, like a twisted ladder.
• Each side of a ladder is composed of alternating sugar molecules and phosphate molecules.

RNA

• RNA: RNA is single stranded found mainly in the cytoplasm of the cell.

RNA building blocks

• Nucleotides are the basic building blocks of DNA.
  • sugar group: ribose
  • phosphate group: A chemical group made up of one phosphorus atom and four oxygen atoms
  • nitrogenous base: adenine (A), cytosine (C), guanine (G), uracil (U)

RNA nitrogenous bases

• Adenine (A) pairs with Uracil (U)
• Guanine (G) pairs with Cytosine (C)

RNA major types

• Messenger RNA (mRNA)
• Ribosomal RNA (rRNA)
• Transfer RNA (tRNA)

Replication

• The process of copying a cell's DNA before it divides to produce two identical DNA molecules
• each molecule is composed of one half of the original DNA strand and one half of the old DNA strand that are complementary with each other.
  • Unzipping: DNA molecule unzips and the enzyme called helicase breaks down the hydrogen bonds between the complementary base pairs.
  • Priming: Create short sequences of RNA called primers, which are synthesized by primase
  • Elongation: An enzyme called DNA polymerase is used to form new strands when the complementary nucleotides are added to each strand
• ENZYMES: Proteins that speed up biological reactions.

DNA Replication Keyplayers

• Helicase: unzipping enzyme that separates the double helix
• Primase: RNA initializer
• DNA Polymerase: builder enzyme
• Ligase: gluer enzyme
• Codon: A three-letter genetic sequence found in both DNA and RNA.

Protein synthesis

• The process where a sequence of DNA is used to build a protein from individual amino acids.
  • Transcription: converted to messenger RNA (mRNA). The mRNA goes to a ribosome in the cell's cytoplasm.
  • Translation: Converts messenger RNA (mRNA) into proteins.

Mutation

• A change in the DNA sequence of an organism alters individual genes.
• Mutations can be caused by errors in DNA replication, exposure to chemicals or radiation, or viral infections.
  • Point Mutation: a change a single base pair occurs.
  • Insertion mutation: occurs when an extra base pair is added to a sequence of bases.
  • Deletion mutation: occurs when a base pair is deleted from a sequence.
• With one or two bases added or deleted, all of the three-base codons change. This is called a frameshift mutation.

Genetic disorders

• Caused by an abnormality in the genetic makeup of an individual.
• Monosomy: Individual is missing one copy of a chromosome
• Trisomy: Having an extra copy of a chromosome
• Polyploidy: Extra set of chromosomes.

Genetic disorders examples

• "Down's syndrome" or Trisomy 21- a person has three copies of chromosome 21
• “Edwards' syndrome” or Trisomy 18- a person has three copies of chromosome 18
• "Patau syndrome” or Trisomy 13- a person has three copies of chromosome 13
• "Klinefelter syndrome”- Individual has one or two extra sex chromosome(s)

Evolution

• The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of earth.
• Organisms inhabiting the earth have changed over time, their structures, traits, and abilities allowed them to adapt and survive in their environment

Evidence for Evolution

• Fossils: Traces of organisms that lived in the past and were preserved by natural process or catastrophic events.
  • Imprints: shallow external molds left by animal or plant tissues with little or no organic materials present
  • Compression: preserved in sedimentary rock and is formed with more organic material
• Determine The Age Of Fossils
  • Relative Dating: age of rock is compared to the other rock layer
  • Radiometric Dating: using the decay of radioactive isotopes of Carbon-14 which is present in rocks when the organism died.
• Comparative Anatomy: Study of the similarities and differences in the structures of different species
  • Homologous structures: Refer to the body parts of an organisms that may perform different functions but of the same origin. This type of evolution is called divergent evolution.
  • Analogous structures: Body parts of an organism that may perform the same function but of different origin This type of evolution is calles Convergent Evolution

Theories of Evolution

• Darwin's Theory of Natural Selections
  • Darwin believed that organisms evolved from common ancestors
  • organisms reproduce and increase in number, compete for resources, and struggle for their existence.
  • organisms with favorable traits would be better able to survive and reproduce than organisms with unfavorable traits Nature selects the survivors, and the result is evolution.
• Lamarck's Theories on Evolution
  • organisms evolved in response to their environment
  • Lamarck's further explained that organisms developed specialized characteristics by the use and disuse of organs
  • expalined that an animal developed these adaptations as acquired traits, and these traits are passed on from parents to offspring.

This quiz covers the nervous system, how the brain functions, and stimulus response. Questions cover components of the nervous system, brain areas affecting functions like speech and balance, and the concept of stimulus.