Biology 101 Chapter 22 & 28 Body Tissues & Nervous System

Anatomy

study of body's internal and external structures and their relationships

Physiology

study of how these structures work as an integrated whole

Anatomy

study of body's internal and external structures and their relationships

Physiology

study of how these structures work as an integrated whole

Homeostasis

maintain a constant stable internal environment

How does Homeostasis work

- Negative Feedback: a form of regulation in which the result of a process inhibits that same process (ex., thermoregulation)

- Positive Feedback: ex., a mother who breastfeeds hears a baby crying, increases milk production

Thermoregulation in the human body

- 5 components (Set point, stimulus, sensor, control center and response) example:

1. Set Point: 37 C

2. Stimulus: Body Temperature

3. Sensor: Temperature sensors on the skin

4. Control Center: Brain

5. Response: either cold (constriction of blood vessels, shivering and increase metabolic rate) or hot (dilate blood vessels, sweat, decrease metabolic rate)

Levels of physical organization

1. Tissues: groups of cells

2. Organs: groups of different tissues with distinct functions

3. Systems: several organs working together

4. Organisms: several organ systems (humans have 11 systems)

Physical organization refers to

- internal organization of an individual allows transport of nutrients/wastes, movement and support

What are the 4 basic body tissue types

1. Epithelial

2. Connective

3. Muscle

4. Nervous

Epithelial Tissue function

- cells always in contact with external environment

- Function:

Protection: keeps body heat, waterproof

Secretory:

exocrine glands: sweat glands (sweat), salivary glands (saliva)

endocrine glands: produce hormones to regulate growth. metabolism (thyroid)

Connection to other tissues

Cell organization (Epithelial tissue)

1. Simple Squamous: capillaries

2. Stratified Squamous: skin, mouth, vagina

3. Simple Cuboidal: kidney

4. Stratified Cuboidal: lining of sweat glands

5. Simple Columnar: small intestine

6. Stratified Columnar: lining of mammary glands

Basement membrane

- supporting non-cellular layer, anchors to connective tissue

Junctions

- Tight Junction: leak-proof (digestive tract)

- Desmosomes: flexibility (skin, heart)

- Gap Junctions: exchange of ions/water (epithelium of liver, heart, pancreas)

Connective Tissue

- Cells produce ground substance

- two types: fibrous and specialized

- Function: flexibility, insulation, cushion, energy storage, strength, transport

What is fibrous tissue

- Loose: collagen and elastin, most common, flexibility

- Dense: collagen, in tendons, ligaments, lower skin layers, strongest

- Elastic: organs that change shape(stomach)

what is specialized tissue

- Cartilage: protects/cushions joints, collagen and chondroblasts in lacunae, no capillaries

- Bone: few living cells, mostly mineral deposits of calcium and phosphate, contains blood vessels

- Blood: cells suspended in plasma, RBC carry oxygen/CO2, WBC involved in immunity, platelets involved in clotting

- Adipose: adipocytes, amount no ground substance, protection, insulation

Muscle Tissue

- power movement, contractile proteins within cells allow them to shorten

- 3 types: Skeletal, Cardiac, Smooth

Ligament

Connects bone to bone

Tendon

Connects muscle to bone

Skeletal

- Striated (stripe-like looking)

- regular arrangement of actin and myosin fibers

- voluntary control

- connects to tendons

- fused young cells into long one long cell

- peripherally located nuclei

- example Biceps and hamstrings

Cardiac

- found only in the heart

- Striated, but under the influence of its own pacemaker cells

- involuntary

-short, blunt-ended cells with one nucleus/cell

- connected by gap junctions for electrical connections

- example: heart

Smooth

- surrounds hollow organs and tubes (blood vessels(except capillaries), digestive tract, uterus, and urinary bladder)

- non-striated

- involuntary

- small parallel cells with one nucleus

- tapered cells

-gap junctions

Nervous Tissue

- generate and transmit electrical impulses.

- Located in the brain, spinal cord and nerves

- 2 types: Neurons and Neuroglia

Neurons

- transmit nerve signals

- 3 basic parts:

1. Cell body contains nucleus

2. Dendrites are several cytoplasmic extensions from the cell body and receive signals from other neurons

3. Axons are long extensions that transmit electrical impulses over long distances

Neuroglia

- non-neuronal cells surround neurons and hold them in place

- for support, nourishment, insulation and to destroy pathogens