Transcript Unit VII: Animal Structure and Function, Part I

Unit VII: Animal Structure and
Function, Part I
Animal Nutrition, Circulation and
Gas Exchange, and Immunity
Unit Objectives
• Observe how animals adjust to the
environment over the long term by
adaptation due to natural selection and over
the short term by physiological responses.
+ How do animals obtain energy from the
environment?
+ How do animals obtain O2 for cell
respiration while disposing of the waste gas
CO2?
+ How do animals respond to pathogens?
Epithelial Tissue
The Cell
• basic unit of structural organization
for all living things
+ tissue (Latin, weave)
- groups of cells with a
common structure and
function
• Epithelial Tissue
+ surface tissue- covers every
surface of the body
- squamous
- cuboidal
- columnar
Connective Tissue
Live cells in a non-living matrix
Connective Tissue (con’t)
Blood
• RBC/WBC in water based fluid plasma
Bone
• osteocytes living in calcified hard matrix
Ligaments
• fibroblasts in a matrix of collagen fibers
+ bone-to-bone connection
Tendons
• fibroblasts in a matrix of less elastic fibers
+ muscle-to-bone connection
Cartilage
• chondrocytes in a soft/pliable matrix
Adipose tissue
• mostly cells (little matrix)
Loose connective tissue
• tissue glue of the body
Muscle Tissue
Muscle Tissue
• muscle fibers capable of
contracting when stimulated
by nerve impulses
+ Skeletal Muscle
- striated (striped)
- voluntary movements
- multinucleated
+ Smooth Muscle
- branched, tapered
- involuntary actions
+ Cardiac Muscle
- striated, branched
- no neurons
Muscle Contraction
Skeletal Muscle
• two kinds
+ fast-twitch (white meat)
- tend to go anaerobic
+ slow-twitch (dark meat)
- myoglobin-rich
• “twitch”
+ contraction of protein filaments causes
muscles to shorten
- thin (actin) and thick (myosin) bands
- interleaved with each other
+ myosin grabs actin and pulls
- sliding filament theory of muscle
contraction
Muscle Contraction
Sliding Filament Theory
• relaxed muscle
+ length of each sarcomere is greater
- Z-line to Z-line
• Contracting Muscle
+ actin/myosin slide past each other
- shortening the sarcomere
• Contracted Muscle (maximum)
+ actin filaments overlap each other
- sarcomere is very short
Nervous Tissue
Organ Systems
• Digestive System: mouth … anus
• Circulatory System: heart, blood vessels, blood
• Respiratory System: lungs, trachea, other breathing tubes
• Immune and Lymphatic System: marrow, lymph nodes, spleen, WBC
• Excretory System: kidneys, ureters, bladder, urethra
• Endocrine System: hormone-secreting glands
• Reproductive System: ovaries, testes, etc.
• Nervous System: brain, spinal cord, nerves
• Integumentary System: skin and its derivatives
• Skeletal System: bones, tendons, ligaments, cartilage
• Muscular System: skeletal muscles
Bioenergetics
Overview
• animals derive chemical energy from
the environment in food
• digestion breaks down food into
nutrient molecules
+ some energy returns to
environment as feces
• nutrient molecules enter body cells
+ convert to useful form (ATP)
• use ATP for cellular work and
biosynthesis
+ some energy lost as heat
• metabolic rate
+ amount of energy an animal uses
in a unit of time
+ BMR
Energy Content of Food
Calorimeter
• instrument used to measure the amount
of energy in a food sample
+ food sample is burned, and the
heat produced is measured
• calorie
+ unit commonly used in measuring
energy content of food
- amount of heat that is needed
to raise the temperature of 1 gram
of water 1ºC
+ 1 calorie = 4.2 joules
+ 1 Calorie = kilocalorie (1000 calories)
Regulating the Internal
Environment
Homeostasis
• the process of controlled and regulating the internal environment
+ interstitial fluid
Homeostasis
Feedback Mechanisms
• negative/positive
+ receptors detect a change
in a variable
- response depends on the
type of change
• thermometer (receptor)
• variable (room temperature)
• response (heat produced)
Human Digestive System
Alimentary Canal
• “tube-within-a-tube”
+ mouth
+ pharynx
+ esophagus
+ stomach
+ small intestine
+ large intestine
+ rectum
+ anus
• 27 feet long!!!
+ Take the tour!
• accessory organs
+ salivary glands
+ liver
+ pancreas
Mouth and Pharynx
Mechanical Digestion
• teeth and tongue
Chemical Digestion
• salivary glands
+ two types
- thin, watery
- thick, mucous
+ salivary amylase
- digests starch
Swallowing Reflex
• tongue pushes bolus to
pharynx
• epiglottis closes off
trachea
Esophagus
Peristalsis
• alternate waves of relaxation and contraction
+ moves food through alimentary canal
• sphincter
+ ring of muscle
- cardiac sphincter
- pyloric sphincter
The Stomach
Thick-walled, muscular sac
• bolus is stored temporarily
+ 2+ liters of food/liquid
+ 20 minutes or less
• mechanical breakdown
+ churning and contracting
• chemical digestion of proteins
+ gastric juices
- hydrochloric acid (ulcers)
- pepsin
• bolus changed into chyme
+ thin, soup liquid
The Small Intestine
Small Intestine
• 6.5 meters long,
2.5 centimeters diameter
+ coiled, folded
+ lined with villi
• three regions
+ duodenum, jejunum,
ileum
• site of chemical digestion
and absorption
+ pancreatic juice
- amylase, protease,
trypsin, lipase
+ bile
+ intestinal juice
- peptidase, maltase
Stomach Secretions
How does our body know when to secrete these
enzymes?
Feedback Mechanisms
Intestinal Secretions
Large Intestine
Large Intestine
• 1.5 meters long, 6 centimeters diameter
• four regions
+ ascending, transverse, descending,
and sigmoid colon
• three functions
+ reabsorption of water
- diarrhea/constipation
+ absorption of vitamins from bacteria
- E. coli bacteria produce vit. K
+ elimination of feces
• appendix
+ vestigial structure with no function
Circulation and Gas Exchange
Transport Systems
• functionally connect the organs
of exchange with the body cells
+ diffusion alone is not
adequate
+ circulatory system solves
this problem
- chemicals are
transported b/n the blood
and interstitial fluid
+ O2/CO2,
nutrients/waste
Open and Closed Circulatory Systems
+ animals having many layers of cells
- open: no distinction b/n blood and interstitial fluid
+ hemolymph
- closed: blood is confined to vessels and is distinct from
interstitial fluid
Vertebrate Circulatory System
Cardiovascular System
• heart, blood vessels, and
blood
+ heart
- atria (1 or 2) and
(1 or 2) ventricles
+ blood vessels
- arteries/arterioles:
carry blood away from the heart
- veins/venules:
carry blood towards the heart
- capillaries:
microscopic vessels with very
thin, porous walls
+ capillary beds:
networks of capillaries
infiltrating tissue
Single circuit flow in fish: blood must pass through two capillary beds
Double circuit flow in amphibian: blood is pumped through two circuits
Double circuit flow in mammals: O2-rich blood segregated from O2-poor
The Mammalian Heart
Atria
• thin-walled collection chamber
Ventricles
• thick-walled pumping chamber
Heart Valves
• atrioventricular (AV) valve
+ b/n each atria/ventricle
- tricuspid/bicuspid
• semilunar valves
+ at the each exit of heart
The LEFT side of the heart services O2-rich blood only
• pumps blood through systemic circulation
The RIGHT side of the heart services O2-poor blood only
• pumps blood through pulmonary circulation
(1) Right Ventricle
+ semilunar valve
(2) Pulmonary arteries
+ right/left
(3) Lungs (Pulmonary Circulation)
+ pulmonary veins
(4) Left Atrium
+ bicuspid valve
(5) Left Ventricle
+ semilunar valve
(6) Aorta
(7) Systemic Circulation
+ head/forelimbs
(8) Systemic Circulation
+ abdominal organs/legs
(9) Anterior Vena Cava
(10) Posterior Vena Cava
(11) Right Atrium
+ tricuspid valve
“Lub-dup”
The Cardiac Cycle
• caused by the closing of
valves
+ lub: AV valves
+ dup: semilunar valves
- heart murmur
Pulse
• rhythmic stretching of the
arteries caused by the
pressure of blood driven by
heart’s contractions
+ heart rate
- cardiac cycle
+ systole/diastole
The Cardiac Cycle (con’t)
Sinoatrial (SA) node
• specialized muscle tissue that sets the rate at which all cardiac
muscle cells contract
+ atrioventricular (AV) node
- relay point: delayed for about 0.1 sec.
+ electrocardiogram (ECG/EKG)
Structure of Blood Vessels
Arteries and Veins and Capillaries
• arteries: thick layer of smooth muscle and elastic connective tissue
+ carry blood AWAY from the heart
• veins: thin layer of smooth muscle
+ valves promote unidirectional flow of blood
- varicose veins
• capillaries
+ site of exchange; only epithelial tissue
- thin-walled; 1 RBC pass through at a time
• blood pressure
+ blood travels 1000x faster in the aorta than the capillaries
- law of continuity: if a pipe’s diameter changes over it’s
length, a fluid will stream through narrower segments of
the pipe faster than the wider segments
+ but, with so many capillaries…
Blood Pressure
• Systolic/diastolic
+ measured in mm of mercury
- sphygmomanometer
+ systolic pressure created
when ventricles contract
+ diastolic pressure is the
background pressure
- blood is constantly under
some pressure in a
closed circulatory system
Lymphatic System
Lymph
• plasma leaks out of capillaries
+ some of it reabsorbed by blood vessels (veins)
- body’s drainage system
+ lead back to vena cava through network similar to veins
+ WBC fight infection
+ filaria infection
Blood
Components of Blood
• Plasma (55%)
+ water (91%)
+ dissolved ions,hormones,
proteins, nutrients
- fibrinogen, albumin,
prothrombin, globulin
• RBC
+ erythrocytes (no nucleus)
- transport O2/CO2
• WBC
+ leukocytes
- defense/immunity
• Platelets
+ thrombocytes
- blood clotting
Stem Cells
• bone marrow or embryo
+ stem cell research
+ luekemia
Blood Clotting
Red Blood Cells
Hemoglobin
• 2.8 x 108 per RBC
+ each hemoglobin can carry 4 O2
• uptake of O2 affected by pH
+ CO2 combines with H2O in plasma
- carbonic acid (H2CO3)
+ muscles produce a lot of CO2
- pH around muscles is low (acid)
+ lower pH causes hemoglobin to let
go of O2
Why do we need to carry these gases?
Respiratory System
Gas Exchange
• acquire O2, dispose CO2
+ cell respiration
- uses O2,
produces CO2
• respiratory medium
+ source of O2
- water vs. air
• respiratory surface
+ where O2/CO2 exchange
takes place
- must be moist
+ earthworm uses skin
- high ratio of surface
area to volume
Gills
• outfoldings of the body
surface specialized for gas
exchange for aquatic animals
• countercurrent exchange
+ blood flows in opposite
direction of water
- creates diffusion
gradient
Tracheal Systems
Tracheal Systems
• respiratory adaptations for
terrestrial animals
+ air tubes that branch throughout the body
- extend to the surface of nearly every cell
Lungs
Respiratory System
• nasal passages
+ filtered by hair
• through pharynx to trachea
+ rings of cartilage
+ larynx (voice box)
• trachea branches into two bronchi
• bronchi branch into many bronchioles
• bronchioles branch into bronchial tubes
• bronchial tubes end in alveoli
+ clusters of air sacs
- surrounded by blood vessels
- moist, thin-walled
Ventilating the Lungs
Breathing
• alternate inhalation and
exhalation of air
+ negative pressure
- suction pump
• inhalation
+ diaphragm pulls
downward
+ rib cage and muscles
pull upward
- increases lung volume
- decrease pressure in lungs
- fresh air rushes in
• exhalation
+ diaphragm/rib cage and muscles relax
- decreases lung volume
Automatic Control of Breathing
Breathing Control Centers
• medulla oblongata and pons
+ sets basic breathing rhythm
• monitors CO2 levels in blood
+ pH of blood
- drop in pH, increase
the rate/depth
• O2 sensors in aorta and carotid
arteries
+ sense severely depressed
levels of O2 (high altitude)
• hyperventilating
+ depletes CO2 and fools the
brain/body into thinking it
does not need to breath
Transport of Gases
Respiratory Pigments
• hemoglobin
+ four polypeptide subunits each with
a cofactor called a heme group
- iron atom at center of group
+ binds to gases reversibly
- most O2 carried by hemoglobin
+ loading and unloading dependent
on partial pressure of gases
- gases diffuse from a region of
higher partial pressure to a
region of lower partial pressure
Carbon Dioxide Transport
CO2 Transport
1. CO2 produced by tissues
2. CO2 diffuses into
interstitial fluid and plasma
3. >90% enters RBC
4. 23% binds to hemoglobin
5. Most reacts with H2O to
form H2CO3
6. H2CO3 dissociates into
HCO3- + H+
7. Hemoglobin takes away H+
8. HCO3- diffuses into plasma
9. Carried to lungs
10-13. Opposite happens
The Body’s Defenses
Nonspecific defense mechanisms
• not selective in their response
+ fight off everything the same way
Specific Defense Mechanisms
• Immune System
+ generates efficient and selective response
Nonspecific Defenses Against
Infection
1st Line of Defense
• physical and chemical barriers
+ skin and mucous membrane
+ acid and lysozyme
2nd Line of Defense
• phagocytosis
+ ingestion of invading organisms by certain types of WBC
- neutrophils and monocytes
- eosinophils and natural killer (NK) cells
• antimicrobial proteins
+ complement system
- serum proteins help to destroy (lyse) microbial cells
+ interferons
- secreted by virus-infected cells
+ limit cell-to-cell spread of viral infection
• inflammatory response
+ localized response to tissue damage (cut) or entry of microorganism
- increased blood supply (redness/swelling/warmth)
- histamine and prostaglandins
+ aid in delivering clotting elements and phagocytic cells
Specific Immunity
Immune System Response
• lymphocytes
+ B cells and T cells
- come from stem cells in bone marrow
+ mature in different locations before moving on to
lymphoid tissue (lymph nodes, spleen, blood, lymph)
- respond to specific antigens
+ clonal selection
- effector cells and memory cells
+ primary and secondary immune response
• self vs. non-self
+ autoimmune diseases
- Type I diabetes, Multiple sclerosis
Cell-Mediated Immune Response
T cells
• kill cells that have been infected, or parasites
• response initiated through contact with cell or macrophage
+ divides into four cell lines
- T memory cells
- cytotoxic “killer” T cells
- T4 helper cells
+ core of immune system; infected by HIV
+ “messenger”
- T suppressor cells
+ protect our own tissues
Humoral Immune Response
B cells
• fights infections of plasma (generally bacteria)
• “antibody-mediated response”
+ antibody is quaternary protein (multiple polypeptide chains)
- Y-shaped
- can bind to variety of antigens
+ response to foreign antigen
- divides into two different cell lines
+ memory cells
+ plasma cell
- antibody factory
- makes antigens easier to locate by phagocytes