Human Physiology

By Chelsea Finn

The Nervous System

There are 100 billion neurons in the human brain

The Nervous System Standards

Students know how the nervous system and endocrine systems regulate conditions in the body.

Students know the functions of the nervous system and the role of neurons in transmitting electrochemical impulses.

Students know the role of sensory neurons, interneurons, and motor neurons in sensation, thought, and response

Components of the Nervous System

Includes: Central Nervous System

includes brain and spinal cord brain has three parts:

cerebrum, cerebellum, and medulla oblongata

the cerebrum is conscious, while the other two parts are part of the unconscious brain

Peripheral Nervous System responsible for involuntary

actions such as heart beat and the digestive system

divided into sympathetic and parasympathetic systems

these two systems check on each other to create a balance

Nervous System Functions

Receives and compares input of external conditions and the body’s external state

Acts as a control system for all actions

Responds to stimuli

Parts and Types of Neurons (Nerve Cells)

Parts of Neurons: Dendrite: receive and transmit

information from another nerve cell into cell body

Cell Body: contains nucleus, mitochondria, and other organelles typical to eukaryotic cells

Axon: guides electrochemical messages away from the cell body

Types of Neurons: Sensory Neurons: usually have short

axons and long dendrites, carry messages from receptors to the central nervous system

Interneurons: found only in the central nervous system

Motor Neurons: have a long axon and a short dendrite, transmit messages from the central nervous system to muscles

How Nerves Function

Receives sensory input in various forms from electrochemical impulses

These impulses travel along the the lengths of cells up to 250 miles per hour

Body Regulation through loops: Signals from senses go to the neurons. Depending on the impulse, the nerve

cell will either send the impulse to the brain, or react immediately

For example, if a person steps on a nail, an impulse will go to a nerve and the neuron will automatically pick up the foot, without sending the impulse to the brain.

Another example is if a person starts to feel cold, a neuron will send that impulse to the brain and then the person will choose what to do, because it’s not that important to get warmer

The Circulatory System

Students know how the complementary activity of major body systems provides cells with oxygen and nutrients and removes toxic waste products such as

carbon dioxide

Circulatory System

Includes: Red blood cells that carry

oxygen from the lungs to other parts of the body

Arteries that carry blood away from the heart

Veins that carry blood back to the heart

Capillaries that are the point of exchange of blood and the tissues

two pumps in the heart Specialized organs for the

exchange of acquired materials, such as oxygen from the external environment

Circulatory System Functions

Delivers oxygen, nutrients, and hormones to cells in the body

Removes waste such as carbon dioxide, ammonia, and other metabolic wastes

The Heart

Heart has two pumps: One to pump deoxygenated

blood to the lungs The other to pump

oxygenated blood to all other organs and tissues

Contracts in a rhythm to pump blood

Skeletal System

The body has 206 bones

Functions of the Skeletal System

Forms and shapes our bodies with 206 bones

Supports, protects, and allows bodily movement

Produces blood for the body Stores minerals such as

calcium and phosphorus Protects vital organs inside

body

Parts of the Skeleton

Axial Skeleton Consists of bones that

protect organs of the head, neck, and trunk

Forms the axis of the body Contains the skull, sternum,

ribs, and spine

Appendicular Skeleton Attaches limbs to axial

skeleton Contains upper extremities

(arms), lower extremities (legs), the shoulder girdle, and the pelvic girdle

Types of BoneShort Bones: Short and cube-shaped Found in ankles and wristsLong Bones: Longer than they are wide Work as levers Ex. Femur, HumerousFlat Bones: Broad Surfaces for:

Protection of Organs Attachment of Muscles

Ex. Ribs, Bones in the SkullIrregular Bones: Bones that don’t fall into other

categories Ex. Bones in the Vertebra

Bone CompositionMany bones contain both spongy

bone and compact bone.Compact bone: Dense and hard Forms the protective outer layer of

all bones

Spongy Bone: Inside the compact bone Has many tiny holes like a sponge

or sponge cake (porous) Is in most bones

The bone cells are imbedded in inorganic salts like calcium and phosphorus for strength

Collagen fibers give the bone flexibility

Muscular System

Students know the cellular and molecular basis of muscle contraction, including the roles of actin,

myosin, Ca+2, and ATP.

Types of Muscle

Skeletal Muscle: Responsible for moving limbs,

trunk, and face Responsible for voluntary

movement Made up of elongated cells

called muscle fibers Mostly controlled by Central

Nervous System

Cardiac Muscle: Only found in heart Involuntary

Smooth Muscle: Usually not voluntary Spindle-shaped Found in stomach, intestines,

and walls of blood vessels Can contract without nervous

stimulation

Functions of Muscular System

Determines the shape of our bodies and how we move

40 to 50 percent of our mass Allows motion and movement

of our bodies Maintains our posture Produces heat

Muscle Structure

Attached to bones by tendons that are made of connective tissue Skeletal muscles have bundles called fasicles Fasicles are made up of many muscle fibers Muscle fiber contains many myofibrils

Muscle Contraction

1. An action potential, or wave of electrical discharge, reaches the muscle cell via T tubules

2. The action potential causes calcium to leak out and immediately combine with thin myofilamints

3. This exposes the active site on the actin molecules4. The active site on the actin molecules are now free to bind with the

cross-bridges of the mysoin molecules of the thick myofilament5. After this attachment, stored energy is released as the cross-bridges

pivot, using a power stroke o move toward the middle of the contracting unit. All of the contracting units of a cell move together to make the cell contract

6. Calcium ion concentration in the cytoplasm quickly returns to normal due to the active transport of calcium ions into the extracellular fluid and into the sarcoplasmic reticulum.

7. As calcium detaches from the troponin, the actin active sites become blocked, breaking the bridge connections, and the cell relaxes

Integumentary System

Students know the role of the skin in providing nonspecific defenses against infection.

Skin Function and How it Functions

Protects the body: Serves as barrier

against infection on injury

Helps regulate body temperature through sweat

Removes waste products through the air

Serves as protection against UV light from the sun

Produces vitamin DSweat Pore

Parts of the Integumentary System

Epidermis The outer layer Composed of many sheets of flat

epithelial cells Made of mostly dead cells Most cells under go rapid cell division Newer cells push outward and older cells

loose their content and start to produce keratin

Keratin is a tough protein that makes up calluses, hair, and nails

Does not contain blood vessels

Dermis Contains blood vessels, nerve endings,

glands, sense organs, smooth muscles, and hair follicles.

Helps control body temperature by expanding and shrinking blood vessels

Hair and Nails

Hair is produced by cells called hair follicles

Nails grow from rapidly dividing cells in the nail matrix located near the tips of fingers and toes

Hair protects and insulates the body

Nails grow .5 to 1.2 mm per day

Respiratory System

Students know how the complementary activity of major body systems provides cells with oxygen and nutrients and removes toxic waste products such as

carbon dioxide.

Functions of Respiration

Functions Get oxygen into the body and carbon dioxide and waste gases out of the

body helps maintain body temperature and eliminate excess water from the body

Parts of the Respiratory System

Parts Nose- a passage way for air and also a sense Pharynx- (throat) passage way for air and food Larynx- the voice box, lined with mucus membrane Trachea- windpipe, tube composed of cartilage, lined with mucus membrane,

lies in front of esophagus Bronchi- C shaped rings of cartilage, sweeps out dust particles Lungs- main organ of respiration, millions of alveoli and blood capillaries

exchange oxygen and carbon dioxide

Gas Exchange

1. Gas exchange happens in the alveoli

2. The alveoli are the tiny sacs found in the lungs

3. Their walls are extremely thin, enough to allow gas to diffuse through them

4. The alveoli are lined with pulmonary capillaries, which have walls thin enough to permit gas exchange.

5. The inhaled gases diffuse from the alveoli to the blood in the capillaries, while carbon dioxide diffuses in the opposite direction from the capillaries to the alveoli

6. Now, pulmonary blood has oxygen and the lungs are holding carbon dioxide.

7. Then, exhalation occurs and gets rid of the carbon dioxide

Excretory System

Students know the homeostatic role of the kidneys in the removal of

nitrogenous wastes and the role of the liver in blood detoxification and glucose

balance.

Parts of the Excretory System

Kidney- bean-shaped organ, made up of tiny units called nephrons, it filters the blood, re-absorbs the blood, and secrets the waste

Ureter- the waste that has been filtered out is secreted through this tube

Bladder- a hollow organ, walls are made of muscle, where the ureters empty into

Urethra- receives the urine from the urinary bladder and disposes it

Function of the Excretory System

Disposes of waste such as toxins, excess water, other solutes, and normal components of the blood that are present in greater-than-normal concentrations

Regulates blood pressure, metabolism, and blood compisition and volume

How the Excretory System Functions

1. The kidney filters out blood of its small molecules and ions. It reclaims needed amounts of useful materials.

2. The kidney secretes blood through ureters

3. Ureters empty out into the bladder

4. The urethra receives the urine from the bladder and disposes of it

Endocrine System

Students know how feedback loops in the nervous and endocrine systems regulate conditions in the

body.

Parts of the Endocrine System

Hypothalamus and Pituitary Gland- both found in brain, both produce growth hormone or growth horrmone-releasing hormones

Thyroid Gland- found in the neck

Liver- produces insulin like growth factor

Pancreas- produces insulin Adrenal Glands- produce

testosterone and adrenoline Stomach- produce gastrin Ovaries- produce estrogen Testes- produce testosterone

Functions of the Endocrine System

Regulates mood, tissue function, metabolism, sexual function, and reproductive processes

Controls glands that secrete hormones that circulate through the body through the bloodstream to affect cells in specific organs

Regulates growth and development

Helps nervous system in regulating the body through loops

How the Endocrine Functions

Endocrine glands secrete their products into the blood or interstitial fluid without storing the product.

Hormones are carried in the bloodstream to different cells in the body and act as messengers

The cells interpret the messages and act on them

Digestive System

Students know the individual functions and sites of secretion of digestive enzymes (amylases, proteases,

nucleases, lipases), stomach acid, and bile salts.

Functions of the Digestive System

Uses enzymes to Process and break down the chemical compounds in food into molecules that can be absorbed and used by the cells as energy

Builds and replaces cells and tissues that are constantly dying

Parts of the Digestive System

Mouth: Food is partially broken

down here by chewing and salivary enzymes

Esophagus: Food is pushed down this

tube by rhythmic muscles

Stomach: Food is bathed in gastric

acid

Small Intestine: Food is broken down by bile,

pancreatic enzymes, and other digestive enzymes.

Large Intestine: Water and electrolytes are

removed from food

The Digestive Process

1. Food is partly broken down by chewing in the mouth and salivary enzymes that break down the starches in smaller molecules

2. Food goes through the esophagus using rhythmic movements that allow humans to eat or drink up-side down

3. In the stomach, food is churned in gastric acid

4. Food then passes through the duodenum, the jejunum, and the ileum in the small intestine. Bile, pancreatic enzymes, and other digestive enzymes help break down the food.

5. The food then passes through the large intestine where water and electrolytes are removed from the food.

6. At the end of the process, solid food is stored in the rectum until excreted by the anus

Digestive Enzymes

Amylases- digests starch into small segments of multiple sugars and into individual soluble sugars

Gastric Amylase- degrades starch (little significance) Pancreatic Amylase- degrades most hydrocarbons besides

starch, glycogen, and celluloseNucleases- degrade nucleic acidsLipases- found in the first part of the small intestine, break down

fatty acidsPepsin- the main gastric acid in the stomach, breaks down

proteins in smaller peptide fragments

The Reproductive System

Students know how hormones (including digestive, reproductive, osmoregulatory) provide internal

feedback mechanisms for homeostasis at the cellular level and in whole organisms.

Functions of the Reproductive System

To ensure the survival of the species by

Producing egg and sperm cells

Transporting and sustaining these cells

Nurturing the development of offspring

Producing hormones

Parts of the Reproductive System

Females: Fallopian Tubes- eggs travel through

these Uterus- where baby matures Cervix- bottom end of the uterus Ovaries- where eggs are produced Vagina- repository for sperm

Males: Testes- where sperm is produced Scrotum- sac where testes are held Epididymis- where sperm is stored,

where sperm mature Vas deferens- tubes which carry sperm

from scrota to urethra Prostate Gland- the largest of the

accessory glands which puts its secretions directly into the urethra

Penis- where the urethra goes through

How the Reproductive System Functions

Uses hormones There are 2 types of hormones:

Steroids Protein and Polypeptide hormones

Reproductive System uses estrogen, a steroid, to mature females

Estrogen is responsible for: development of breasts further development of the uterus and

vagina broadening of the pelvis growth of pubic and axillary hair increase in adipose (fat) tissue

Reproductive system uses testosterone to mature males

Testosterone is responsible for: Development of sex organs Deepening of voice Facial Hair Etc.

Immune System

Immune System Standards

Students know the role of the skin in providing nonspecific defenses against infection.

Students know the role of antibodies in the body's response to infection.

Students know how vaccination protects an individual from infectious diseases.

Students know there are important differences between bacteria and viruses with respect to their requirements for growth and replication, the body's primary defenses against bacterial and viral infections, and effective treatments of these infections.

Students know why an individual with a compromised immune system (for example, a person with AIDS) may be unable to fight off and survive infections by microorganisms that are

usually benign.

Students know the roles of phagocytes, B-lymphocytes, and T-lymphocytes in the immune system.

Functions of the Immune System

Detects and eliminates pathogens such as viruses or parasitic worms using an intricate network of tissues, organs, cells, and chemicals

Even though the immune system is highly effective, humans use vaccination processes to further protect humans from infectious diseases

Parts of the Immune System

Bone Marrow- where all immune system cells originate

Thymus- produces mature T cellsLymphatic System- network of vessels

carrying lymph, or tissue-cleansing fluid, from the tissues into the veins of the circulatory system, it absorbs nutrients from the small intestines,

Tonsils- found in throat, act as a filter against disease organisms

Spleen- lies under diaphagm, acts as a filter against foreign organisms that infect the bloodstream, filters out old red blood cells from the bloodstream

Skin- acts as physical barrier of defense

How the Immune System Functions

leukocytes circulate through the body between the organs and nodes by means of the lymphatic vessels

There are 2 types of leukocytes: lymphocytes and phagocytes

Phagocytes chew up invading organisms

Lymphocytes allow the body to remember and recognize previous invaders

The two types of lymphocytes are called B lymphocytes (B cells) and T lymphocytes (T cells).

B cells produce antibodies in response to foreign proteins of bacteria, viruses, and tumor cells.

Bibliography

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