Mammalian PhysiologyMammalian Physiology

You & me baby, we aint nothin’ but You & me baby, we aint nothin’ but mammals……mammals……

Animal CharacteristicsAnimal Characteristics• Multicellular,

heterotrophic eukaryotes

• No cell walls• Nervous & muscle

tissue present in most• Sexual reproduction,

diploid life cycle is dominant

• All have similar developmental stages

•

Our AncestorOur Ancestor

mammalsmammals

• Characteristics– Mammary glands

(milk)– Hair– Endothermic– Well developed

respiratory & circulatory systems

– Internal fertilization

MammalsMammalsmajor groupsmajor groups

• Monotremes– Egg layers

• Marsupials– Born early, complete

development while nursing

• Eutherians (placental)– Placenta, complete

internal development

Some vocab…Some vocab…

• Anatomy-structure• Physiology-function• Tissue-group of cells w/ common structure

& function– Most organs are made of several types of

tissues– Four categories:

1. Epithelial

2. Connective

3. Nervous

4. muscle

Homeostasis-maintained by self-regulating control Homeostasis-maintained by self-regulating control systems known as feedback mechanismssystems known as feedback mechanisms

• Negative feedback– Returns set point to normal,

or towards normal state– Response is opposite to that

of stimulus– Ex: body temp., blood

pressure, blood glucose– Most feedback mechanisms

in the body are negative

• Positive feedback– Moves away from normal

state– Response is in same

direction as that of stimulus, increases the change

– Ex: blood clotting, child birth– Positive feedback produces

instability in the body, and these reactions usually are short-lived

All feedback mechanisms involve three components:

1. Receptor-detects change2. Control center –processes info3. Effector-directs appropriate response to change

BioenergeticsBioenergetics• Metabolic rate-amount of energy an animal uses

in a given period of time– Calories or kilocalories– Inversely related to body size– NOT total calories consumed

• Ectotherms-fish, amphibians, reptiles– Do not maintain stable internal temp, it changes w/

surrounding– Measured as standard metabolic rte (SMR)-uses

specific temperature

• Endotherms-birds & mammals– Stable internal temp maintained by high metabolism– Measured as basal metabolic rate(BMR)-rest,

nonstressed, empty stomach

Epithelial TissueEpithelial Tissue• Tightly packed sheets

– Tight junctions important– “free” surface, & attached surface, known as basement membrane

• Cover outside of body, line organs & cavities within body• Functions

– Mechanical & biological barriers, prevent fluid loss• Classified by

– Number of layers• Simple• Stratified• Pseudostratified

– Shape• Squamous• Cuboidal• Columnar

– Ciliated (or not)– Glandular (or not)

• Mucous membranes

Simple SquamousSimple Squamous

Stratified SquamousStratified Squamous

Simple Cuboidal EpithelialSimple Cuboidal Epithelial

Stratified Cuboidal EpitheliumStratified Cuboidal Epithelium

Simple ColumnarSimple Columnar

PSUEDOSTRATIFIED COLUMNARPSUEDOSTRATIFIED COLUMNAR

Connective TissuesConnective Tissues

General characteristics • most abundant tissue type• many functions

• bind structures• provide support and protection• serve as frameworks• fill spaces• store fat• produce blood cells• protect against infections• help repair tissue damage

• fewer cells, separated by a matrix(secreted by cells)• have cells that usually divide

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Connective Tissue FibersConnective Tissue Fibers

Collagenous fibers• thick, nonelastic• composed of collagen protein• great tensile strength •hold structures together• tendons, ligaments

Elastic fibers• made of elastin protein•branched• elastic• vocal cords, air passages

Reticular fibers• very thin collagenous fibers• highly branched• form supportive networks 5-13

Connective Tissue Connective Tissue Major Cell TypesMajor Cell Types

Fibroblasts• fixed cell• most common cell • large, star-shaped• produce fibers

Macrophages• wandering cell• phagocytic• important in defense

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Osteoblasts & osteocytes•Found in bone

Chondrocytes•cartilage

Various blood cells

Types of connective TissueTypes of connective Tissue

• Loose• Adipose• Fibrous• Cartilage• Bone• Blood

Adipose TissueAdipose Tissue

• cells called adipocytes• forms beneath the skin, around organs• fat pushes nuclei & other organelles to one side• Functions:

- insulates and protects

- reserve energy supply– cushions

Loose (Areolar) TissueLoose (Areolar) Tissue• most widely distributed throughout body• soft, pliable, with semi-fluid matrix• composed of fibroblasts, macrophages, and adipocytes• Widely distributed• Functions:

- wraps & cushions organs, binds to other tissue

Fibrous Connective TissueFibrous Connective Tissue• fibroblasts in rows between bundles of parallel collagen fibers• great strength• forms tendons & ligaments • Avascular• Dense regular, dense irregular• Function:

- provides strong attachments between structures, resists tensile stress in one direction

Hyaline CartilageHyaline Cartilage

• firm matrix made of collagen• found on ends of long bones, nose, parts of larynx, trachea, bronchi,

bronchial tubes, and embryonic skeleton• Little flexibility• Functions:

- supports & reinforces, resists compressive stress, cushioning

BoneBone

• Hard, calcified matrix (hydroxyapetite)• consists of osteons (haversion systems)

– contain lamellae(concentric circles), with lacunae containing osteocytes

– Lamellae around central canal(blood vessel)– Lacunae (osteocytes) connected by canaliculi

• Functions– Support & protection, – levers for muscles, – stores calcium & fat, – site of hematopoiesis(bone marrow)

BloodBlood• contains red blood cells, white blood cells, and platelets in fluid

matrix(plasma)• plasma consists of water with dissolved nutrients, ions, hormones,

gasses, and plasma proteins• Functions

– Transport respiratory gases, nutrients, wastes, etc

Muscle TissueMuscle Tissue

General characteristics

• specialized to contract or shorten to produce movement

• three types• skeletal• smooth• cardiac

Skeletal Muscle (striated)Skeletal Muscle (striated)

• attaches to skeleton• Voluntary control• fibers contain alternating light and dark bands (striation)• multinucleated• fibers are cylindrical in shape, parallel (NOT branched)

Cardiac MuscleCardiac Muscle• found only in the heart• striated , involuntary• fibers are branched with usually only one nucleus• attached to each other through intercalated discs-help

conduct electrical impulses

Smooth MuscleSmooth Muscle

• found in walls of hollow organs- stomach, bladder, uterus, blood vessels

• fibers are tapered, one nucleus

• NO STRIATIONS• has ability to propel objects

through the organ via peristalsis - wave-like motion

Nervous TissueNervous Tissue• Two cell types:

- neurons- neuroglia

• Brain, spinal cord, peripheral nerves• neurons receive stimuli (sensory)and conduct electrochemical

impulses• neuroglia provide supporting structure of of nervous tissue