IB Bio: Topic 6 (Human Physiology) (6.1, 6.2, 6.3)

Peristalsis

Process involving wave-like involuntary muscle contractions to move and mix digested materials through the alimentary canal (digestive tract)

Circular Muscle

* Outer muscle of the muscularis
* Contracts behind the digested food to ensure a one-way direction.

Longitudinal muscle

* Inner muscle of the muscularis
* Contracts WITH the digested food.
* Pushes digested food along the digestive tract.

Gut Wall

Peristalsis speeds

Esophagus: FAST

Intestines: SLOW

Vomiting

* Digested food returns from the stomach to the mouth.
* Process involves abdominal muscles to push digested food back up to the mouth.

Pancreatic juice

* Digestive enzymes that the pancreas secretes into gut lumen.


* Consists of Amylase (starch), Lipase (fats) and protease (proteins)

Cellulose

* Poly-saccharide made of chained glucose molecules.
* Found in plant cell walls.

Villi and Surface area

Increased surface area helps to absorb nutrients quickly and efficiently.

Villi

* Tiny hair-like projections that line the inside of the small intestine. They contain blood vessels and help absorb nutrients.
* Villi are lined with Microvilli to increase surface area further.
* Villi absorb materials such as:
* Macromolecule building blocks (amino acids and monosaccharides)
* Nucleotide bases
* Minerals
* Vitamins

Methods of absorption in Villi

* Different nutrients are absorbed differently as it depends on size and polarity
* Nutrients such as amino acids and glucose are diffused into the blood vessels.
* Fatty acids and glycerol are diffused into the lacteal and will rejoin the blood stream later.

3 types of blood vessels

Arteries, Veins, and Capillaries.

Arteries

Send blood away from the heart (A for Away)

Veins

Returns blood back to the heart

Capillaries

* Smallest blood vessels
* connect arterioles and venules
* 1 cell thick, blood cells travel in a single file.
* Material exchange occurs here.

Artery Walls

* Work with heart to control blood flow
* Strong, tough tissue to withstand changing blood pressure.
* Elastin: enables arteries to stretch during maximum flow.
* Smooth muscle: contractions from muscle control diameter of lumen.

Arterial Blood Pressure

* Blood entering from pumping heart causes HIGH BLOOD PRESSURE in arteries.
* Arterial walls help to regulate blood pressure.

Systolic Pressure

* Maximum Arterial pressure
* Occurs when the heart pumps
* Vasoconstriction occurs

Diastolic Pressure

* Minimum Arterial pressure
* Occurs when the heart relaxes
* Vasodilation occurs

Veins and Blood Pressure

* Collects blood returning from capillaries at LOW BLOOD PRESSURE
* Blood flow is assisted by gravity and general body muscle movements

Veins and Valves

* Valves are ONLY found in veins
* They allow for a one-way movement of blood flow
* Stops deoxygenated blood from flowing in the wrong direction

Steps of blood vessels used:

1) Aorta

2) Arteries

3) Arterioles

4) Capillaries

5) Venules

6) Veins

7) Vena Cava

Systemic Blood Circulation

Supplying nourishment to all tissues in the body (everywhere)

Coronary Blood Circulation

Supplying nourishment to heart tissues (heart)

Pulmonary Blood Circulation

Movement of blood between the heart and lungs for gas exchange (heart and lungs)

Renal Blood Circulation

Movement of blood to and through the kidneys for filtration of wastes.

Heart Chambers

* Right Atrium and Right Ventricle
* Pumps deoxygenated blood to lungs


* Left Atrium and Left Ventricle
* Pumps oxygenated blood to body

Heart Valves

* 2 types
* Atrioventricular Valves
* Between Atria and Ventricles
* Tricuspid and Mitral
* Semilunar Valves
* Between ventricles and exiting the heart
* Pulmonary and Aortic

Cardiac Cycle

Rhythmic contraction of heart muscles to pump blood throughout the body (the heart beat)

Heart Beat

The sounds of heart beats come from valves opening and closing.

2 phases of Cardiac Cycle

Systole and Diastole

Systole Phase

* Pumping phase
* Atria relax and fill with blood from vena cava and lungs
* Ventricles contract and blood is being pumped into lungs and the rest of the body
* Valves
* Semilunar Valves: Open
* Atrioventricular Valves: Closed

Diastole phase

* Refilling phase
* Atria contract and pump blood into ventricles
* Ventricles relax and fill with blood
* Valves
* Semilunar Valves: Closed
* Atrioventricular Valves: Open

Nervous control of heart beat

* Heart beat normally controlled by electrical activity
* Consist of 3 main parts: Sinoatrial (SA) Node, Atrioventricular (AV) Node and the His-Purkinje System

Steps of nervous control of heart beat

* Blood fills right atrium
* SA node sends electrical signal
* Atria contract and start filling ventricles with blood.
* Signals reach AV node
* Blood continues to fill ventricles
* Signal reaches His-Perkinje System in ventricles
* Ventricles contract to pump blood.
* Signal finishes
* heart muscles relax
* Heart Muscles wait for next signal

Chemical control of heart beat

Controlled by Adrenaline, the hormone increases heart rate.

Artherosclerosis

* Hardening (plaques) and narrowing of the arteries
* slowly block arteries and blood flow
* Cause of heart attacks and strokes.
* Causes:
* Bad Cholesterol
* High blood glucose levels

Occlusion

Stoppage or blockage of a blood vessel

Surface Barriers

The first line of defence against infectious disease are the surface barriers that present the entry of pathogens into the body

Skin

* Protects external structures when intact (outer body area)
* Consists of a dry, thick and tough region composed of deadly cells.

Mucous Membranes

* Protects internal Structures
* Consists of a thin region of living surface cells that release fluids to wash away pathogens
* Mucus, saliva, tears, etc…
* Contacts biochemical defence agents.

Clotting

* Process to stop bleeding when skin is cut
* Liquid blood changes to semi-solid form
* seals injured wound
* stops further blood loss
* stops pathogen entry
* protects new tissue while healing

Scab

Hard and dried clot that is a protective crust forming over a wound during healing.

Platelets

* Blood cells that help with clotting process
* Gather at damaged area/blood vessel and create a plug.
* Releases clotting factors which begins clotting process.

Fibrin Production

* Clotting factors leads to the production of the enzyme Thrombin
* Changes soluble fibrinogen to insoluble fibrin.

Fibrin

Forms a mesh that traps more blood cells, hardening into a scab once oxidized.

Coronary Thrombosis

* Blood clots forming in coronary arteries of the heart
* Reduces heart function
* Reduces oxygen capacity of cells
* Reduces ATP synthesis for cells
* Causes:
* Smoking, high B.P, diabetes, obesity…

Phagocytes

* Part of the NONSPECIFIC immune response
* Destroy pathogens by ingesting them through phagocytosis (cell-eating)
* Chemicals released from damaged cells attract phagocytes to area.

Lymphocytes

* Part of the specific immune response
* Destroy pathogens by producing chemicals called ANTIBODIES
* Can distinguish between body cells (self) and foreign cells (non-self)

Phagocytic WBC

* Variety of WBC that eat pathogens by endocytosis.
* eat everything (nonspecific)
* digest using lysozyme

Pus

White liquid formed when large numbers of phagocytes are attracted to a wound.

WBC movement

WBC are able to squeeze through cells to get to an infected area.

Antibodies

* Proteins produced by special WBCs
* Lymphocytes
* Plasma cells (Clones of lymphocytes)
* Specific Immunity
* Attach to pathogen’s antigens
* Act as a marker that tells WBCs to “eat” pathogens by phagocytic endocytosis
* Inhibits pathogen from attacking to other healthy tissue cells; neutralizing it.

Antigens

* Protein/ carbohydrate coat surrounding cells
* specific shape of pathogenic antigens can be detected by the immune system.

Lymphocyte differentiation

* Lymphocyte attaches to antigen and either
* 1) changes into plasma cells and makes many clones of itself
* releases antibodies to help kill pathogens.
* 2) becomes a memory cell
* remembers pathogen and is ready for future invasions.

Antibody specificity

* lymphocytes can make different kinds of antibodies
* Shape of “variable region” of antibody determines what antigen it can attach to.

Virus

Reproduction:

* Cannot reproduce by itself
* needs help from living host cell

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Steps of viral infection

1) Virus attaches or goes inside the cell

2) Virus DNA replaces all DNA

3) Cell produces LOTS of virus copies

4) Cell dies (explodes) due to large amount of viruses

5) New viruses are released

HIV

* Human Immunodeficiency Virus
* Specifically targets lymphocytes (helper-T cells) and destroys them.
* Decrease in immune response
* Decreased antibody production, and number of active lymphocytes.
* Infection of HIV can lead to AIDS
* Opportunistic infections take advantage of weakened immune system.

Antibiotics

* Chemical that stops microorganism growth
* Usually specific for prokaryotes (bacteria)
* Eukaryotic cells are not affected.
* Processes stopped in bacteria:
* DNA replication
* Transcription
* Translation
* Ribosome function
* Cell wall formation

Antibiotics VS Virus

* Antibiotics have NO effect on viruses
* Viruses have no cellular metabolism
* uses a host cell’s own process for reproduction

Blood Type A

* Has “A” Antigens
* Has “B” Antibodies

Blood Type B

* Has “B” Antigens
* Has “A” Antibodies

Blood Type AB

* Has “A” & “B” Antigens
* Has NO antibodies

Blood Type O

* Has NO Antigens
* Has “A” & “B” Antibodies

rH factor

* A third kind of antigen found on RBC
* When you have an rH antigen
* rH positive (rH+)
* When you have NO rH antigens
* rH negative (rH-)

Agglutination

* Immune response
* Clumping of blood cells due to antibodies attacking antigens in blood.
* Leads to hemolysis (the destruction of blood cells)

Blood Typing

* Method used to figure out the blood type of a person
* Blood type depends on the observed combination of agglutination or non-agglutination