Science 10

Central Nervous System

• acts as the body’s control center

• coordinates the body’s activities

• made up of the brain and spinal cord

Impulses travel through the neurons in your body to reach the brain.

Peripheral Nervous System

• made up of all the nerves that carry messages to and from the Central Nervous System

• Central Nervous System and Peripheral Nervous System work together to make rapid changes in your body in response to stimuli

2 parts of the Peripheral Nervous System

• Somatic Nervous System

• Autonomic Nervous System

Somatic Nervous System

• relay information between the skin, skeletal muscles, and Central Nervous System

• you consciously control this pathway by deciding whether or not to move a muscle (except reflexes)

• Responsible for carrying motor and sensory information

• Is made up of nerves that connect to the skin, sensory organs, and skeletal muscle movements

• Processes sensory information from external stimuli (hearing, touch, and sight)

Autonomic Nervous System

• relays information from the Central Nervous System to the organs

• Involuntary: you cannot consciously control these

Sympathetic Nervous System

• controls in times of stress, such as the fight or flight response

Parasympathetic Nervous System

• controls the body in times of rest

Neurons

• the basic unit of structure and function in the Nervous System

• cells that conduct impulses

• made up of dendrites, cell body, and axons

  

Dendrites

• receive impulses from many other axons

• branch-like extensions which the receiver impulses and carry them toward the cell body

Axons

• single extension of the neuron that carries impulses away from the cell body

• branches out an ending to send impulses to many different neurons

Cell Body

• also called the soma, is the spherical part of the neuron that contains the nucleus

• connects to the dendrites, which bring information to the neuron, and the axon, which sends info to other neurons

• when information is received from another neuron, the dendrites pass the signal to this

Types of Neurons:

Sensory Neurons

• carry impulses from inside and outside the body to the brain and spinal cord

Interneurons

• found within the brain and spinal cord, process incoming impulses and pass them onto motor neurons

Motor Neurons

• carry impulses away from the brain and spinal cord

Six Main Sections of the Brain

• Cerebrum

• Cerebellum

• Diencephalon

• Midbrain

• Pons

• Medulla Oblongata

Cerebrum

• controls memory, intelligence, muscles, conscious activities

• divided into 4 lobes which are:

  • Frontal Lobe - reasoning and thought

  • Temporal Lobe - processes auditory information from the ears

  • Parietal Lobe - integrates sensory information

  • Occipital Lobe - processing visual information from the eyes

Cerebellum

• controls balance, posture, coordination, memory of physical skills

• when injured, movements become jerky

Diencephalon

• Is found between the cerebrum and the midbrain

Two Structures:

• Thalamus - directs sensory impulses to the cerebrum

• Hypothalamus - controls and regulates temperature, appetite, water balance, sleep, and blood vessel constriction and dilation

• Also controls emotions

Brainstem

• Made up of medulla oblongata, pons, ad midbrain

• controls involuntary activities such as breathing

• Also called the reptilian brain

Cerebral Cortex

• Wrinkled countless folds and groove

Medulla Oblongata

• involuntary activities such as heart rate and breathing

• The lowest part of the midbrain

• Regulates heart and blood vessel function

• Center for respiration

Pons

• located below the midbrain (in the brainstem)

• Responsible for certain reflex actions such as chewing, tasting, and saliva production

Regulates

• Heart and blood vessel function

• Digestion

• Swallowing

• Coughing

• Sneezing

• Blood pressure

Spinal Cord

• The link between the brain and the nerves in the rest of the body

• Divided into 4 regions:

  • Cervical

  • Thoracic

  • Lumbar

  • Spinal nerves

Afferent Spinal Nerves

• Carries information from the body to the brain

Efferent Spinal Nerves

• Carries information from the brain to the body

Afferent Sensory Neurons and Efferent Motor Nerves

• Allows communication to happen between the nerves in the body in the central nervous system

Afferent Sensory Neurons

• Conducting inward

• Takes information from the nerves to the central nervous system

Efferent Motor Neurons

• Conducting outward

• Takes information from the central nervous system to the muscle nerves throughout the body

Nervous System

• Coordinates all activities of the body

• Responds and adapts to change

Spinal Cord

• The link between the brain and the nerves in the rest of the body

4 Regions:

• Cervical

• Thoracic

• Lumbar

• Spinal nerves

Endocrine System

• Collection of glands that produce hormones, that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep

• Includes endocrine glands and hormones

Hormones

• Produces notable effect

• Chemicals secreted by endocrine glands

• Chemical messenger which targets a specific group of cells

Exocrine glands

• Release their secretions into ducts or tubes

• Secrete sweat, tears, saliva, milk, and digestive

• Liver - bile released into the gall bladder > duct > small intestine

• Pancreas - releases pancreatic juice into the small intestine via duct

Endocrine glands

• Are called ductless glands

• Releases hormones directly into the bloodstream

• Each hormone acts only on a certain kind of tissue called its target tissue

Parts of the Endocrine System:

• Pituitary

• Thyroid

• Parathyroid

• Adrenal

• Pancreas

• Thymus

• Testes and Ovaries

Pituitary gland

• At the base of the brain and is no bigger than a pea, located behind the bridge of the nose

• Often called the master gland

• Stimulates growth and controls function of other glands

• Hormones released are oxytocin, vasopressin, growth hormone, ACTH (adrenocorticotropic), prolactin

• Round organ, the size of a pea (1cm in diameter)

• Secretes different hormones

  • Growth

  • Blood Pressure

  • Regulation of Pregnancy, etc.

• Oversecretion of growth hormones - Gigantism

• Undersecretion of growth hormones - Dwarfism

Thyroid

• Stimulating hormone ~ Stimulates thyroid

• Follicle-stimulating hormone ~ regulates puberty

• Luteinizing hormone ~ stimulates the production of estrogen & testosterone

• Bowtie size

• In the neck

• Release hormone thyroxin

• Regulates metabolism

• Oversecretion - weight loss and nervousness

• Under secretion - cretinism (mental retardation, small size)

• Iodine deficiency in your diet results in goiter

Parathyroid

• Control metabolism of calcium

• Necessary for normal nerve and muscle function, blood clotting, healthy bones, and teeth

• Back of thyroid gland

• Releases hormone (Parathyromone)

• Under secretion - results in nerve disorder, brittle bones, and blood clotting

Adrenal Glands (Kidney Hat)

• Located at the top of each kidney

• Release cortisone and adrenaline

• Cortisone - regulates carbohydrate, protein, and fat metabolism

• Adrenaline - raises blood sugar levels, increases heartbeat, and breathing rates

• Under secretion - results in the inability to deal with stress

Islet of Langerhans (Pancreas)

• Located in the pancreas

• Secretes hormones - insulin and glucagon

• Insulin - stimulates glucose uptake by cells

• Glucagon - promotes the conversion of glycogen (animal-based carbohydrates) to glucose

• Under secretion - results in high blood sugar which leads to diabetes

Diabetes Type 1

• Found in children and young adults; the body does not make enough insulin

• Frequent urination, unusual thirst, extreme hunger, unusual weight loss, extreme fatigue, and irritability (symptoms)

Diabetes Type 2

• The body does not produce enough insulin

• Any type 1 symptoms, frequent infections, blurred vision, cuts/bruises that are slow to help, tingling/numbness of hand (symptoms)

Feedback Mechanism

Endocrine System

Input > Process > Output

Positive Feedback

• Controls events that can be out of control and do not require continuous adjustment

• Rarely used to maintain homeostasis negative feedback

• Act like a thermostat in a home

• Often used to maintain homeostasis

Testicle

• Pair of sperm-producing organs that maintain the health of the male reproductive system

• Testes are known as gonads

• Their female counterpart is the ovaries

• Also, have the distinction of being an endocrine gland because it testosterone - a hormone that is vital to the normal development of male physical characteristics

• Located at the lower abdomen

• Hormones secreted: androgen, testosterone

Slow

• Endocrine System

• Long Term

Rapid

• Nervous System

• Short Term

2 Types of Pituitary Gland:

Anterior - inside

Posterior - outside

Pineal Gland

• Mainly connects the endocrine and nervous system

Hypothalamus

• Controls the pituitary gland by producing chemical

Parathyromone

• Hormones released by the parathyroid

Thymus

• Enables the body to produce antibodies

• Under secretion - inability to deal with stress

In adulthood, testosterone maintains libido, muscle strength, and bone density

Disorders of the testes are caused by too little testosterone production

Ovary

• Girl sex organ

• Primary girl/woman reproductive organs

• Are a pair of ova-producing organs (produce egg cells) that maintain the health of the female reproductive system

• Produces or secrete hormones, estrogen, and progesterone – that are vital to normal reproductive development and fertility

• Ovaries are the female gonads

• Located in the lower abdomen

• Maintain the health of the female reproductive system

Primary Organ

• Testes

• Ovary

Diseases associated with the ovary are ovary cancer, dysmenorrhea, and myoma.

Female Reproductive System

Vulva

• the external female reproductive organs

External Female Structures

• Mons Pubis.

• Labia Majora

• Labia Minora.

• Clitoris.

• Vestibule.

• Perineum

Mons Pubis

• rounded, soft fullness of subcutaneous fatty tissue, prominence over the symphysis pubis that forms the anterior border of the external reproductive organs.

• is covered with varying amounts of pubic hair.

Labia

• Rich in nerve endings and blood vessels (similar…)

• Protects internal organs against pathogens

• Functions in sexual arousal

Labia Majora

• is two rounded, fleshy folds of tissue that extend from the mons pubis to the perineum.

• protects the labia minora, urinary meatus, and vaginal introitus.

Labia Minora

• located between the labia majora, are narrow.

• lateral and anterior aspects are usually pigmented.

• inner surfaces are similar to the vaginal mucosa, pink, and mois.

• rich vascularity.

Clitoris.

• the term comes from a Greek word meaning key.

• erectile organ.

• it’s rich in vascular, highly sensitive to temperature, touch, and pressure sensation

• small knob of tissue above & in front of the vaginal opening

• rich supply of nerve endings & blood vessels

• important in sexual arousal

• Similar in sensitivity & number of nerve endings to the head of the penis

Vestibule

• is an oval-shaped area formed between the labia minora, clitoris, and fourchette?

• contains the external urethral meatus, vaginal introitus, and Bartholins glands.

Perineum

• is the most posterior part of the external female reproductive organs.

• extends from the fourchette anteriorly to the anus posteriorly.

• composed of fibrous and muscular tissues that support pelvic structures.

Internal Female Structures

• Vagina

• Uterus

• Fallopian tubes

• Ovaries

Fallopian tubes

• The two tubes extended from the corner of the uterus to the ovary.

• runs in the upper free border of the broad ligament.

• length 8 to 14 cm average 10 cm

• divided into 4 parts.

• Fimbriae are fingerlike processes, one of these is longer than the other and adherent to the ovary.

• The fimbriae become swollen and almost erectile at ovulation.

Functions:

• Gamete transport (ovum pickup, ovum transport, sperm transport).

• Final maturation of gamete post ovulates oocyte maturation, sperm capacitation.

• Fluid environment for early embryonic development.

• Transport of fertilized and unfertilized ovum to the uterus.

Ovaries

• oval solid structure, 1.5 cm in thickness, 2.5 cm in width, and 3.5 cm in length respectively. Each weighs about 4–8 gm.

• is located on each side of the uterus, below and behind the uterine tubes

Functions of the ovary

• Secrete estrogen & progesterone.

• Production of ova

Uterus

• is a hollow, pear-shaped muscular organ.

• measures about 7.5 X 5 X 2.5 cm and weighs about 50 – 60 gm.

• normal position is anteverted (rotated forward and slightly anti-flexed (flexed forward)

• divided into three parts

• Cervix

• a part of the uterus

• lowermost position of the uterus “neck”.

• length is about 2.5 t0 3 cm.

• the os is the opening in the cervix that runs between the uterus and vagina.

• the upper part of the cervix is marked by the internal os and the lower cervix is marked by the external os.

• Vaginal Opening

• Hymen

• Located just inside the vaginal opening

• Thin tissue stretching across the opening

• No known function; not always present

• Some females may be born w/o; usually has several holes

• Allows passage of menstrual flow

• 1st-time w/intercourse – female may experience pain & bleeding, NOT ALWAYS true with all females!

• Tissue is very flexible & may stay intact during intercourse!

• b/c it has openings, sperm released at the vaginal opening can swim into the vagina and up to the ovum

• Can get pregnant & still have the hymen intact!

Vagina

• An elastic fibro-muscular tube and membranous tissue about 8 to 10 cm long or 4 - 5” long

• Lying between the bladder anteriorly and the rectum posteriorly

• Connects the uterus above with the vestibule below

• “Birth canal”

Function

• To allow discharge of the menstrual flow

• As the female organs of coitus

• To allow passage of the fetus from the uterus