Human Physiology Chapter 12: the study of how living things work

Human PhysiologyHuman PhysiologyChapter 12: the study of how living things workChapter 12: the study of how living things work

Barron’s Essential 5: #3Barron’s Essential 5: #3

Molecules, cells, and organs coordinate activities for the fitness of the organism as a whole.

DigestionDigestion

A.) DigestionIs the breakdown, whether mechanical or chemical, of our food,

macromolecules, into smaller useable and absorbable form

B.) Absorption

Diffusion of broken down molecules into body cells

C.) Egestion

Removal of undigested waste

Digestive SystemDigestive System

http://resources.teachnet.ie/farmnet/Digestive.htm

1. Mouth

2. Esophagus

3. Stomach

4. Duodenum

5. Latter Small Intestines

6. Large Intestines

7. Rectum

8. Anus


1. MouthMechanical breakdown of food with

chewingChemical breakdown with initiation of

starch breakdown by salivary amylase secreted by salivary glands

Note: Specialization of teeth; Incisorsfor cutting, Canines for tearing, Premolars and Molars for grinding

2. EsophagusMovement of chewed food (Bolus)to stomach by involuntary muscle contractions known as Peristalsis


3. StomachMechanical digestion in churningChemical digestion of proteins

Note: Different types of cells in theStomach that coordinate for proteindigestion:

i.) Chief cells secrete inactive Pepsinogen

ii.) Parietal cells secrete hydrochloricacid in which providing a pH of2-3 in the stomach environmentto activate pepsinogen into pepsin

.

.

.iii.) And a third type of cell that secretes mucus for stomach lining...


4. DuodenumComplete digestion of moleculesin first 12 inches of small intestines

Note:

Pancreatic amylases hydrolyze starch and glycogen in maltose

Bile, from liver, stored in gall bladder emulsifies fat into fat droplets for further digestion

Lipases breaks down fat completely

Peptidases, such as trypsin or chymotrypsin breaks down proteins

Nuclease hydrolyzes nucleic acids


5. Small IntestinesAbsorption of molecules by villi and microvilli fingerlike projections to optimize surface area

Note: Amino acids, vitamins, and monossacharides are absorbed into capillary network of villus

Fatty acids and glycerol go into lacteal which leads into the lymphatic system as a small vessel

6. Large IntestinesResponsible for egestion, vitamin production and removal of excess water (approx. 90%)

Note: Undigested waste is stored in rectum and eliminated through anus as feces

Hormones Regulating Digestive System

Hormones Regulating Digestive System

Hormone Site of Production Effect

Gastrin Stomach wall Stimulates sustained secretion of gastric juice

Secretin Duodenum wall Stimulates pancreas to release bicarbonate to neutralize acid in duodenum

CCK (Cholecystokinin) Duodenum wall Stimulates pancreas to release pancreatic enzymes and gall bladder to release bile into small intestine

Respiratory SystemRespiratory System

http://antranik.org/the-respiratory-system/

Main function is for Gas Exchange (of O2 and CO2 for cell use)

Air Pathway:

1.Nasal Cavity-moistens, warms, andfilters air2.Larynx3.Trachea4.Bronchi5.Bronchiole6.Alveoli- diffusion of respiratory gases

Note: Rib cage expands, diaphragm contracts and lowers, and chest cavity (thoracic cavity) expands which draws air in bynegative pressure

Detouring... To fully understand the respiratory system itself and its role within the body, we must take recall the Circulatory System

http://blog.vixra.org/2012/02/07/stop-rumours/

Circulatory SystemCirculatory SystemA closed circulatory system in humans has the function of transporting nutrients, gas exchange, and taking away toxic waste through the medium of blood circulation.

Note: The system consists of the heart, arteries, veins, and capillaries

Arteries-carry blood away from heart; thick walls of elastic smooth muscle

Veins-carry blood back to heart by valves and skeletal muscle contractions thatpropels blood to move

Capillaries-allow for diffusion of nutrients and wastes between cells and blood

Content of BloodContent of Blood

Fight infection; formed in the bone marrow; die fighting infection, pus; B lymphocytes produce antibodies

Cell fragments; formed in bone marrow; clots blood

Carries hemoglobin and oxygen; no nucleus, 120 day life span; formed in bone marrow and recycled in liver

Liquid portion; contains clotting factors, hormones and antibodies, dissolved gases, nutrients, and wastes. Maintains proper osmotic potential.

[Side] Blood Clotting[Side] Blood Clotting

• Clotting factors from platelets

• Anticlotting factors in plasma to prevent thrombus formation

Damaged Tissue->Thomboplastin + Ca2+->Prothrombin (inactive) -> Thrombin (active) ->Fibrinogen (inactive)->

Fibrin (Clot) (Active)

HeartHeart

http://www.heartandstroke.com/site/c.ikIQLcMWJtE/b.3532069/

Composed of 4 chambers: two atria,two ventricles; right or left ventricle or atrium

Note: Cardiac muscle cells can contract even when removed from heart

--Own innate pacemaker, sinoatrial node

S A A V

SA node then to atrioventricular (AV) node to contract

Note2: Electrical impulses travel through cardiac and body tissues, where can be detected by electrocardiogram (EKG)

Pathway of BloodPathway of BloodRight atriumRight atrioventricular valve(tricuspid)Right ventriclePulmonary semilunar valvePulmonary arteryLungs (Pulmonary circuit)Pulmonary veinLeft atriumBicuspid (left AV) valveLeft ventricleAortic semilunar valveAortaSystemic circuit

Note: Systemic circuit consists of coronary circulaiton, renal circulation, and hepatic circulation.

http://www.tutorvista.com/content/biology/biology-ii/transportation/circulation.php

Going back...Going back...The medulla in the brain contains the breathing control center—sets rhythm ofbreathing and monitors CO2 levels in blood by sensing changes in pH.

CO2 is the by-product of cellular respiration, dissolves in blood to form: Carbonic Acid

Therefore, higher [CO2], lower pHBlood pH <7.4 causes medulla to increase rate of breathing--There are O2 sensors (chemoreceptors) to a lesser degree

Continuing Internal RespirationHemoglobin

Continuing Internal RespirationHemoglobin

Oxygen loosely carries 4 oxygen molecules

Unique in having allosteric properties butalso exhibits cooperativity

Once binds to an O2 molecule, it changesconformation to allow other oxygen moleculesto better bind

A drop in pH alters affinity

for oxygen. This is known as the Bohr shift. CO2 emitted by actively respiring cellsinduces an acidic environment as CO2 dissolves to form carbonic acid. As the hemoglobin approaches to a a more acidic environment, it will release its oxygen into the cell where needed.

Transport of Carbon DioxideTransport of Carbon DioxideReversible blood buffering carbonic acid-bicarbonate ion system

Excretory SystemExcretory System• Functional unit of the kidney is the nephron• Consists of a cluster of capillaries, the glomerulus, sits inside Bowman’s capsule, and connects to the renal tubule• Nephron carries out filtration, secretion, reabsorption, and excretion• Filtration is passive and nonselective.• Specialized cells in Bowman’s capsule modified into podocytes and along with slit pores, increase the rate of

filtration• Everything small enough to diffuse out of the glomerulus includes glucose, salts, vitamins, waste such as urea,

and other small molecules• Filtrate travels into the proximal tube• Secretion is active and highly selective• Occurs in proximal and distal tubules• Uptake of certain drugs and toxic molecules, secretes ammonia to neutralize the acid• Reabsorption is passive, active, and selective.• Water and solutes are transported back into the body• Process occurs in the proximal convoluted tubule and loop of Henle and collecting tubule• Loop of Henle acts as countercurrent exchange mechanism to maintain steep salt gradient surrounding the loop• Excretion is removal of metabolic wastes, urines passes through the ureter to the urinary bladder and passes out

the body via the urethra.• Aldosterone is hormone released by the adrenal glands in response to a decrease in blood pressure.• ADH, vasopressin, produced by the hypothalamus is stored and released from the posterior pituitary in response

to dehydration.

Nervous SystemNervous System

• Central nervous system consists of the brain and spinal cord.

• Peripheral nervous system consists of all nerves outside the CN

• Neuron consists of a cell body which contains the nucleus, dendrites and axons

• Dendrites are sensory and receive oncoming messages

• Axons transmit an impulse outward to another cell• Axons wrapped in a fatty myelin sheath formed by

Schawnn cells

• Sensory neurons receive initial stimulus

• Motor neuron stimulates effectors

• Internueron transfers information directly to the motor neuron or to the brain for processing

• Reflex arc is inborn, automatic, and protective

• Sensory neuron transmits an impulse to the interneuron in the spinal cord

NeurotransmittersNeurotransmitters

http://txtwriter.com/Backgrounders/Drugaddiction/drugs1.html

• All living cells exhibit a membrane potential

• Cytoplasm(negatively charged) and extracellular fluid(positively fluid)

• Stimulus must be enough to overcome the resting potential

• Sodium ion-gated channel, results in depolarized and easier for the nerve to fire

• Potassium ion-gated channel results in hyperpolarization, harder for neuron to fire

• Action potential generated in the axon of the neuron

• Sodium channels and potassium channels open

• Wave of depolarization reverses the polarity of the membrane

• Sodium-potassium pump restores the membrane to its original polarized condition, refractory period, neuron cannot respond to stimulus

• The body distinguishes strong and weak stimulus by the frequency of action potentials

• Impulse crosses a synapse chemically• Cytoplasm at the terminal branch of the presynaptic neuron

contain many vesicles that contain molecules of neurotransmitter

• Depolarization cause Ca++ ions to rush through calcium-gated channels

• Neurotransmitter released by exocytosis, and bind with receptors on the postsynaptic side

• Neurotransmitter release into the synapse is destroyed by esterase

• Neurotransmitter at neuromuscular junction is acetylcholine, others are serotonin, epinephrine, norepinephrine, and dopamine

• Cerebrum• Learning, emotion, memory, perception• Cerebellum• Coordinates movement and balance• Receives sensory information • Brainstem• Controls several automatic homeostatic functions, breathing, heart and blood vessel

activity• Integrates sensory information• Sensory phase of vision• Photons of light pass through the lens which focuses light on retina• Light is absorbed by photoreceptors when it strikes the retina in neurons – rods( black

and white) and cones( color vision)• Stimulation of retinal activates a G protein-signaling mechanism that alters the

membrane potential and closes Na+ channels• Each molecule of photoexcited rhodopsin activates enzyme molecules which activate

cGMP closing Na+ channels and causing impulse to be sent to the optic nerve and cortex of the brain where messages are interpreted

• Another opsin molecule has evolved by means of gene duplication and has generally enhanced our colour vision. However when the gene is nonfunctional it results in red-green colour blindness in men

Chemical SignalsChemical Signals

Two major regulatory chemicals: Hormones and Neurotransmitters--as seen, neurotransmitters regulated by nervous system while hormonescontrolled by excretory system

HormonesHormones

produced in ductless (endocrine glands)

moves through blood to a target cell

short-lived response

*Refer to Barron’s page 235 Overview of Hormones

HypothalamusHypothalamus

http://www.studyblue.com/notes/note/n/limbic-system/deck/1241563

Bridge between the endocrine and nervoussystems– ultimately two functions.

Stress- Nervous function, sends outelectrical signals to adrenal gland to releaseadrenaline

Nervous, when releasing gonadotrpoic-releasing hormone(GnRH) to stimulateanterior pituitary to secret FSH and LH.

Endocrine, when releasing oxytocin and antidiuretic hormones

Ways Hormone StimulateWays Hormone Stimulate

1. Lipid or Steroid HormoneDiffuse directly through the plasma membrane and bind to receptorin nucleus to trigger cell response

2. Protein or peptide hormone (nonsteroidal)cannot dissolve in the plasma membrane, so they bind to a receptor onof cell, triggering secondary messenger c-AMP inside cell to convertextracellular chemical signal to a specific response.

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Human Physiology Chapter 12: the study of how living things work