Biology Exam 2

Central Nervous System (CNS)

Consists of the brain and spinal cord.

Peripheral Nervous System (PNS)

Includes all peripheral nerves connecting the CNS.

Somatic vs. Autonomic

Parts of (PNS)

Muscular system vs. Organs and glands…

Parasympathetic = rest and digest

Sympathetic = fight or flight

Corpus Callosum

left and right hemisphere communication

Cerebellum

Coordinates balance and movement.

Frontal Lobe

Involved in cognitive thinking and voluntary movement.

Occipital Lobe

visual processing area

Cerebrum

muscle function and temperature regulation

Parietal lobe

sensory perception of the 5 senses

Temporal lobe

auditory stimuli, memory, emotion

Brain Stem

Connects the brain to the spinal cord and controls primitive functions.

Midbrain

reflexes and fight or flight response

Pons

regulates sleep and breathing

Medulla Oblongata

Controls heart rate, breathing, and blood pressure.

Frontal, Parietal, Temporal, and Occipital

The 4 brain lobes

CSF

Fluid protecting brain and stored in ventricles

Dendrites

Receive signals from other neurons.

Axon

Conducts electrical impulses away from the cell body.

Cell body

Central part of neuron containing nucleus

Neurotransmitter

Chemical messengers across synapses.

Synapse

The junction between two neurons where communication occurs.

Afferent Neurons

Sensory neurons that carry signals to the CNS (Quick reflexes)

Efferent Neurons

Motor neurons that carry signals away from the CNS to muscles (More time)

Antigen

Any substance that triggers an immune response. All cells have unique antigens. (Antigen is lock and antibody is key)

Antibody

Protein produced by human immune system to tag and destroy invasive microbes (B-cells) -But don’t directly kill pathogen

Antibiotic

Various chemicals produced that are toxic to bacteria. Some we use as medicines.

Pathogen

Microorganisms that cause diseases, including viruses and bacteria.

Allergic Response

An immune response to allergens typically involving IgE antibodies.

Adaptive Immunity

The immune response that involves the formation of memory cells.

Innate Immunity

The non-specific defense mechanisms present from birth.

Phagocytes

White blood cells that engulf and destroy pathogens.

Darwin’s Observation of Nature

1. Genetic Variation: within a species, no two individuals are exactly alike. Some of this variation is heritable.

2. Limited Resources: Every habitat contains limited supplies of the resources required for survival.

3. Overproduction of Offspring: More individuals are born than survive to reproduce

Darwin’s Inferences from observations

1. Struggle for existence: individuals compete for the limited resources that enable them to survive. (Competition)

2. Unequal Reproductive success (natural selection): the inherited characteristics of some individuals make them more likely to obtain resources, survive, and reproduce.

• Struggle, heredity, variation in traits

3. Descent with modification: over many generations, a population’s characteristics, can change by natural selection, even giving rise to new species. (Vertical evolution with mutations)

Evolution

Genetic change over time gene distribution changing

Population

Evolution occurs here because allele frequencies change from one generation to the next over time (Scandinavian vs. Asian)

Gene

code for different traits (genes on chromosomes)

Mutation

Change in DNA sequence causing evolution to occur -creates genetic diversity

Allele

Version of a gene

Allele Frequency

Vary between populations (isolated populations are high)

3 Reasons for Natural Selection

Variation in traits

Heredity

Difficulty surviving

Process of Natural Selection

Natural selection requires genetic variation- since more individuals are born than resources available, there is a struggle to survive. Some individuals in a population are better at surviving and reproducing.

Speciation

Formation of a new and distinct species through evolution (Gradual or punctuated)

Microevolution

Small-scale changes in allele frequencies within a population.

Macroevolution

Evolutionary change that results in the formation of new species.

Descent with Modification

The principle that species change over time, giving rise to new species.

Speciation

The process by which new species arise through evolution.

Evidence of Evolution 4 things

1. Fossils -lower is older (Law of Superposition)

2. Anatomical Comparisons -Homologous and Analogous

3. Molecular Data -Cytochrome C

4. Embryology

Homologous Structures

Body parts that are similar due to shared ancestry.

Analogous Structures

Body parts that are similar due to convergent evolution but do not share a common ancestor.

Convergent

Slowly got more similar and had similar feature but not related

Divergent

species divided by geography and slowly get further apart with different environments

Embryological Development

The study of embryos to understand evolutionary relationships.

Steps in Nerve Impulse and Synaptic Transmission

1. Dendrite receptors receive neurotransmitters.

2. Signal travels down the neuron

3. To the axon.

4. Signal crosses the synapse.

5. Neurotransmitters are broken down by reuptake.

Dopamine

A neurotransmitter associated with the pleasure and reward center of the brain.

Serotonin

A neurotransmitter that regulates mood, well-being, sleep, and memory; low levels are linked to depression.

Epinephrine

Also known as adrenaline, it is involved in the fight-or-flight response, raising heart rate and shutting down non-essential systems.

Acetylcholine

Muscle contraction and is influenced by substances like tobacco.

Melatonin

A hormone that regulates sleep cycles and is produced by the pineal gland.

Depressants

blocked neurotransmitters

Stimulants

more dopamine produced

Somatic Nervous System

Part of the peripheral nervous system that controls voluntary movements and the muscular system.

Sensory (Afferent) Neurons

Neurons that carry signals towards the CNS from sensory receptors.

Motor (Efferent) Neurons

Neurons that carry signals away from the CNS to muscles.

Thalamus

Part of the limbic system that processes sensory information.

Hypothalamus

Regulates homeostasis in the body.

Amygdala

Associated with fear responses and emotional regulation.

Multiple Sclerosis (MS) Symptoms

Include difficulty walking, fatigue, numbness and tingling, muscle spasms, weakness, and vision problems.

Multiple Sclerosis Causes

Occurs when the immune system attacks the CNS, specifically targeting the myelin sheath.

MS Diagnosis 3 requirements

1. Damage in 2 separate areas of CNS

2. Problems at least 2 different times

3. Rule out everything else

MS Treatment 3 ways

1. Limit entry of T cells into CNS

2. Interfere with T cell activation

3. Limiting immune system activity (inflammatory response)

Viruses

Non-living, need host, so they hijack cells to reproduce and can only survive by immune system. (Creates colds and influenza)

Bacteria

Living and can reproduce on their own, can be killed by antibiotics

Pathogen

Any microorganism that can cause disease, including viruses, bacteria, and fungi.

Immune System

A complex network of cells and tissues that helps the body fight infections and diseases.

Infectious Disease

Disorders caused by organisms that spread from one person to another, usually through pathogens.

Innate Immune Response

The body's first line of defense that is non-specific and present from birth.

External: skin, mucus, cilia

Internal: Fever, Inflammation, WBC’s=Phagocytes-Neutrophils, macrophages, NK cells, Dendritic cells

Non-specific defenses are designed to prevent infections by viruses and bacteria, including…

1. Intact skin: acidic and oily -kills things

2. Mucus and cilia

3. Phagocytes (WBC’s) -Inside=certain white blood cells -Neutrophils and macrophages

Adaptive Immune Response

Specific response developed after exposure to pathogens, involving memory cells. Give us immunity to certain diseases.

Humoral Response

Pathogens, lymphatic system

B cells=Antibodies

1. Clump

2. Block receptor sites

3. Signal phagocytes

   helper T cells in charge, fights extracellular pathogens

Cell Mediated

All T cells. Helper T cells activate and direct other T cells and phagocytic cells

• Helper T -direct immune response, Memory -remember past illness, Regulatory -tells cells to stop and shut down (part of autoimmune disease), Cytotoxic -they kill bad things with enzymes

• Memory cells, regulatory cells, travels through blood, infected cells and cancer

Phagocytes

White blood cells that engulf and destroy pathogens. Attracted by inflammatory response of damaged cells

WBC’s -4 of them

Neutrophils: most basic defender, fight all

Macrophages: blood ⇾ tissue

Natural killer cells: early cancer cells

Dendritic cells: antigen presenting cells.

Fever as a Defense Mechanism

Raises body temperature to help fight infections by making the environment less hospitable for pathogens.

Mucus as a Defense Mechanism

Contains enzymes that destroy pathogens and trap them, preventing them from entering the body.

Cilia's Role in Defense

Move mucus out of the lungs to expel bacteria and viruses.

Cell-Mediated Immune Response

Involves T cells without antibodies; focuses on infected or cancerous cells.

Antigen Recognition

Cells of the immune system are trained to distinguish self from non-self proteins; macrophages present non-self proteins to helper T cells for identification.

Role of Antibodies

What B-cells make but don’t directly kill pathogens

1. Signal macrophages to come and destroy

2. Clump pathogens together

3. Block receptor sites on pathogen

B Cells

In general produce antibodies, Memory cells and plasma cells (kill)

T Cells

Helper T cells stimulate B cell division while Killer T cells seek and destroy any antigens in the system.

Types of T Cells

Helper T cells stimulate B cell division; Killer T cells destroy tagged antigens; Cytotoxic T cells can also target cancer cells.

Antibiotics work

Antibiotics help destroy bacteria by weakening cell walls and slowing bacterial reproduction.

Vaccines work

Vaccines, made from killed or weakened pathogens, prepare the immune system to recognize and mount a defense against the actual pathogen.

Antivirals work

aren’t many out there