Biology 110

Columbia College, Fall 2003

Immunity, Respiration, Development

Chapters 35, 36, 39

Chapter 35 - Immunity

I- Nonspecific Surface Barriers
II-Immune System Nonspecific Responses
III-Immune System Specific Responses

A. Antigen

B. Cells

C. Antibody Mediated Response

D. Cell Mediated Response

IV-Other

I-Nonspecific Surface Barriers

Mechanical Barriers

Chemical Barriers

II-Immune System Nonspecific Responses

A. Introduction

If pathogens breach physical and chemical barriers, -> kill or damage cells
Body actively seeks pathogens & try to eliminate them
Must clean up the injured area & repair damage

B. Cells

1. Phagocytes

2. Natural killer cells

C. Chemicals

1. Inflammatory response

Triggered by injured tissue
Symptoms - redness, warmth, swelling, pain.
Injured cells release chemicals

1. blood vessels & capillaries leaky, -> fluids & cells can reach injured tissue, increased blood flow
2. activates pain receptors, -> immobilize area, -> rest
3. attracts phagocytes & white blood cells

Cells clean up

2. Blood clotting protein -> fibrin

walls off area to protect rest of body
fibrin mesh also provides scaffold for permanent repair

3. Complement System

holes in & lysis of foreign cells
also aids antibody & inflammatory response

4. Interferon

released by virus infected cells
stimulate the production of proteins that interfere with viral reproduction
protects uninfected cells

D. Fever

III-Immune System Specific Responses

1. Antigen specific
2. Systemic
3. Memory

A. Antigen = Any substance, including toxins, foreign proteins, or bacteria, that, when introduced to the body, is recognized s foreign and activates the immune system

Antigen-presenting cells - Macrophages, B cells, dendritic cells

Process & display antigen
Ingest, digest antigen. Present fragments of antigen to T cells so that T cells can direct specific immune response.
Activate T cells with a chemical signal

B. Cells - Lymphocytes - Each original lymphocyte can only bind one antigen, genetically determined.

1. B cells

Mature in bone marrow
Responsible for antibody-mediated immunity
-> Antibodies

Antibody = a protein molecule released by a B cell of a plasma cell that binds to a specific antigen T cells

Antibody specificity
Each antibody is unique for its antigen

Variable region of both sides of binding site have many versions
When mix & match possibilities, -> at least a billion possible combinations, -> match for everything body can encounter
(Variable region is site where antigen binds.)

Antibody functions

1. fixes & activates complement, -> holes in cells, -> lysis & chemicals aiding inflammation, enhances phagocytosis
2. neutralizes or masks exotoxins & block harmful effects

3. agglutinates cell, -> easier clean up by phagocytes
4. precipitates antigen, -> easier clean up by phagocytes

2. T cells

Mature in thymus
Cells that react with self are sorted out

Several types of T cells

Helper T cells - Central role in immune response

C. Antibody Mediated Response

Antibodies circulate throughout the body. Most effective against viruses, bacteria, foreign molecules that are soluble in blood & lymph

1. antigens presented to B lymphocytes in lymphoid organs
2. B lymphocytes divide, -> cloned colony
3. Most become plasma cells, -> specific antibody
4. Some B cells -> memory cells, -> mobilize fast response if encounter same antigen

D - Cell Mediated Response

Most effective against parasites, bacteria, viruses, fungi, cancerous cells, & cells perceived as foreign (tissue transplants)

Must be mutual recognition between macrophage & T cell

Several types of T cells with different functions

1. helper T cells
2. killer T cells
3. suppresor T cells
4. memory cells
5. delayed hypersensitivity T cells

V-Other

A-Immunization

1. Active acquired immunity
2. Passive acquired immunity

B-Allergies

C-Autoimmune Disorders

D-Deficient Immune Responses

 

Chapter 36 - Respiration

I-Anatomy
II-Gas Laws
III-Ventilation
IV-Gas Exchange & Transport
V-Regulation of Ventilation

Introduction

Function of the respiratory system is to deliver O2 to blood and remove CO2, the gaseous waste product of metabolism.

Reminder: O2 necessary for aerobic respiration -> greatest ATP yield from food

Respiratory system includes the lungs, several passageways leading from outside to the lungs, and the muscles that move air into & out of lungs.

4 distinct events must occur to exchange respiratory gases between air and body cells:

1. pulmonary ventilation = process of taking air into & out of lungs
2. external respiration = process of gas exchange between the air in lung alveoli & blood within lung capillaries
3. respiratory gas transport = process of movement of O2 and CO2 in the blood
4. internal respiration = exchange of gases between body cells & blood in the surrounding capillaries

Primary functions of respiratory system

1. exchange of gases between the atmosphere & the blood
2. homeostatic regulation of body pH
3. protection from inhaled pathogens & irritating substances
4. vocalization

I-Anatomy

A. Nose-air warmed, moistened, filtered.

B. Palate divides air from mouth

C. Pharynx = throat

D. Larynx

Passageway between pharynx & rest of respiratory tract. Leads to sound for speaking & singing.
Epiglottis
Vocal folds, vocal cords

E. Trachea-windpipe

F. Bronchi

G. Lungs

made of alveoli
red blood cells go through capillaries single file. Lungs contain about 1L blood

H. Bones & Muscles

Diaphragm – muscle at floor of thoracic cavity
Intercostals – between ribs, -> expansion, contraction of volume

II-Gas Laws

1. Gases move from areas of higher pressure to areas of lower pressure

More O2 in atmospheric gases than in blood in lung -> O2 into blood
More CO2 in blood in lung from body -> CO2 into lung

2. changes in gas volume -> changes in pressure

P1V1 = P2V2
Changes in thoracic volume -> changes in thoracic pressure – basis of ventilation. Lungs mostly passive via volume change.

III-Ventilation

A. Inspiration-air enters lungs-requires energy

B. Quiet Expiration-depends on elastic recoil of lungs & costal cartilage & relaxation of muscles-passive-no energy required

C. Forced expiration during strenuous exercise

D. Surfactant - detergent that decreases surface tension of fluid lining inside of alveoli

IV-Gas Exchange & Transport

Via pressure gradients.

A. partial pressure (concentration) gradient

1. Gas exchange requires pressure gradients, i.e., gases flow from regions of higher partial pressure to regions of lower partial pressure.

a. in lungs

Higher O2 pressure in lung than red blood cells -> O2 binding to red blood cells.
Higher CO2 pressure in blood than in lungs, so CO2 -> lungs. Gases diffuse down concentration gradient.

b. in tissues

Higher O2 pressure in red blood cells than in tissues -> O2 release from red blood cells -> tissue cells
Higher CO2 pressure in tissues than in plasma, so CO2 -> blood

B. Gas Transport in Blood

1. Most O2 transported on hemoglobin (hb) in red blood cells, -> bright red blood

Factors influencing hb binding

1. partial pressure of O2

O2 binds at pressures likely to be found in arterial blood
O2 released from hb at pressures likely to found in tissues

2. temperature
increased temp. -> more O2 release

3. pH
more acid -> more O2 release

4. CO2 levels
increased CO2 -> more O2 release

Factors 1-4 correlate with metabolically active tissue, ie, hardworking tissues: 1-use O2, 2. produce heat, 3. produce lactic acid, 4. produce CO2

2. CO2 mostly carried in plasma

a. CO2 produced in tissues & diffuses into blood
b. CO2 + H2O -> HCO3- + H+
c. Blood goes to lungs where CO2 pressure low
d. H+ + HCO3- ->H2O + CO2

CO2 diffuses into lungs & is expelled during breathing.

V-Regulation of Ventilation

CO2 most important factor in regulating breathing. Example of negative feedback loop.
If CO2 concentration goes up, changes pH (CO2 + H2O -> H2CO3 -> H+ + HCO3-) -> stimulation of diaphragm & intercostal muscles -> increased breathing rate & depth

Opposite happens if decreased CO2 concentration - Respiratory center sends message to decrease breathing movements of rib muscles & diaphragm

Chapter 39 - Development

I- Fertilization
II- Stages of Development
III- Specialization & Pattern Formation
IV-Birth

I- Fertilization

Sperm swim into uterine tubes to meet oocyte.
Sperm binds to receptor site on ovum & acrosome digests covering of ovum.
Plasma membranes of ovum fuses with acrosome.
Sperm nucleus released inside ovum.
Nuclei of the female and male sex cells unite to form the nucleus of the 1st cell of a developing individual (zygote). Zygote begins to grow via cell division, even before it becomes implanted in uterus.

II- Stages of Development

A. Cleavage. Zygote undergoes a series of mitotic cell divisions.

Forms blastula = hollow ball of cells

B. Implantation. Blastula starts to implant into uterus about 6 or 7 days after fertilization

Many celled embryo attaches to the endometrium of the uterus. Burrows into & becomes embedded in endometrium
Blood vessels, placenta, umbilical cord develop. Inner lining of placenta connects to embryo via umbilical cord.
No direct contact between 2 circulations, except accidentally at birth

Placenta:

1. transports materials between mother & embryo/fetus-nutrients, hormones, antibodies, wastes, drugs, infectious agents
2. Produces hormones to maintain pregnancy.

III- Specialization & Pattern Formation

3rd-8th week of life.
Organs & body shape develop.
Most body systems become functional.

A. Gastrulation –Cell divisions, migrations and rearrangements produce two or three primary tissues, the forerunners of specialized tissues and organs. Begins day 15.

3 germ layers form different part of body

ectoderm -> skin, nervous system
endoderm -> gut, respiratory system, bladder
mesoderm -> organs between ectoderm & endoderm, i.e. muscle, gonads, blood vessels, parts of kidneys, gonads.

B. Organ formation

Cell differentiation- All cells in body have complete set of DNA to make any type of cell in body. Starting with gastrulation, only the information needed for a particular type of cell is utilized. Cell selectively activates genes and synthesizes proteins not found in other cell types.

Morphogenesis-the evolution and development of form, as the development of the shape of a particular organ or part of the body.

1. Cells migrate, change shape. Migration & shapes are response to local chemical factors.
2. Whole sheets of cells expand and fold inward and outward.
3. Apoptosis- programmed cell death removes cells, sculpts body.

Theory of Pattern Formation

1. Original egg has two poles that predetermine planes of division, head & tail end
2. Cells signal each other chemically. Influence of signal decreases with distance.
3. Master genes activate blocks of genes, -> overall body plan
4. Once block of tissues programmed to become certain type of tissue, it will develop into that tissue or organ even if transplanted to another area of the body

2nd trimester-fetus grows, ossification.

3rd trimester-growth.

Refinement, maturation & growth of organ systems & of body form.

Teratogens.

IV-Birth

Pressure of baby on cervix dilates it, producing uterine contractions & secretion of oxytocin.

Positive feedback loop ends with birth.