SciOly Anatomy and Physiology

Exocrine gland

discharge
secretions through a duct to a targeted
tissue such as digestive glands

Endocrine Glands

release secretions
directly into the blood stream so they
are ductless.

Stimulus

change in homeostatic environment causes a signal sent to CNS

Response

signal sent from CNS
; produce effect & body returns to homeostasis

Hormones

body's chemical messengers

Glands

Groups of cells that produce chemical products
for our body to use.

negative feedback

"turnoff" process used to stop hormones production when not needed; Most common control mechanism

Negative feedback exmples

body temperature and sugar
metabolism

Positive Feedback

reinforces the original change - an increase in A will cause an increase in B

Examples of positive feedback

lactation and labor contractions

OXYTOCIN

Hormones that causes contractions

hypothalamus

controls the secretions of the
pituitary gland

Neurosecretory cells

specialized neurons that
synthesize & secrete hormones

Pituitary gland

Located at the base of the brain and is no larger than the size of
a pea

"master gland"

Pituitary

endorphins

chemicals that reduce sensitivity to
pain

Follicle stimulating hormone (FSH) and luteinizing hormone (LH)

regulate
production of estrogen and progesterone

Thyroid stimulating hormone (TSH)

stimulates the thyroid to release thyroxin

Adreno-corticotropic hormone (ACTH)

stimulates release of chemicals from the
adrenal cortex

Growth hormone (GH)

stimulate cell growth ( cell division)

Melanocyte-stimulating hormone (MSH)

increases production of the skin pigment
melanin

Prolactin

n stimulates production of milk in nursing mothers

Oxytocin

stimulates contractions of the uterus

Antidiuretic hormone (ADH)

stimulates the kidneys to reabsorb more water from the
collecting ducts in the kidneys so there is more water in the blood

Pineal

secretes melatonin, which regulates our internal clocks and any
rhythmic activities; circadian rhythm

Thyroid gland

wraps around the trachea at the base of the neck

thyroxine

regulates the metabolic rates of almost all the cells in
the body;As the thyroxine levels in the blood increase so does the rate of
cellular respiration;The thyroid gland needs iodine to create thyroxine, that is why
salt is iodized now

Parathyroid

four little glands are embedded in the thyroid
gland

parathyroid hormone

regulates the
amount of calcium in the blood and its absorption by
bones

parathyroid hormone

regulates the
amount of calcium in the blood and its absorption by
bones

Thymus

Secretes thymosin which stimulates T-cell (that is
a type of white blood cell) production in
children.

Adrenal

There are two located on top of the kidneys; secretes epinephrine, norepinephrine, cortisol, aldosterone

epinephrine (adrenaline) and norepinephrine

regulate our fight or flight response at times of extreme stress

aldesterone

regulates reabsorption of
nutrients from the kidney

cortisol

controls the rate of metabolism of
carbohydrates, fats, and proteins

Pancreas

Secretes insulin which tells the liver and muscles
to remove sugar from the blood and store it as fat; Also secretes glucagon which tells the liver to
break down fat stores and release sugar back into
the blood

Ovaries

Secrete estrogen and progesterone which regulate the
female menstrual cycle

Testicles

secrete testosterone

Pituitary Gland Disorders

Pituitary dwarfism \= hyposecretion of GH
• Giantism \= hypersecretion of GH during childhood
• Acromegaly \= hypersecretion of GH during adulthood
• Diabetes insipidus \= hyposecretion of ADH which causes excretion of
large amounts of dilute urine and subsequent dehydration and thirst

Thyroid Gland Disorders

Cretinism \= hyposecretion of thyroid hormones during fetal life or infancy.
• Myxedema \= hypothyroidism during adult years
• Grave's Disease \= an autoimmune disease which is the most common
form of hyperthyroidism
• Goiter \= enlarged thyroid gland

Parathyroid Gland Disorders

Hypoparathyroidism results in muscle tetany
• Hyperparathyroidism produces osteitis fibrosa cystica which results in demineralization of the
bone.

Adrenal Gland Disorders

Cushing's Syndrome \= hypersecretion of cortisol by the adrenal cortex
• Addison's Disease \= hyposecretion of glucocorticoids and aldosterone
• Tumors of the adrenal medulla can cause hypersecretion of medullary hormones and a prolonged
"fight or flight" response.

Pancreatic Disorders

Diabetes mellitus \= a group of disorders caused by an inability to produce or use insulin
• Type I or insulin-dependent diabetes mellitus is caused by an absolute deficiency of insulin
• Type II or insulin-independent diabetes is caused by down-regulation of insulin receptors
• Hyperinsulinism results when too much insulin is present and causes hypoglycemia (low blood
sugar) and possibly insulin shock.

Peptides and Amines

Protein hormones (1st messengers) - bind to receptor
on target cell triggering 2nd messenger to affect cell's
activity

Steroid hormones

- fat-soluble hormones - bind to
receptors within target cell and influence cell activity
by acting on specific genes

peptides

- short chains of amino acids (most hormones)
pituitary, parathyroid, heart, stomach, liver & kidneys

amines

derived from tyrosine and secreted by thyroid and adrenal cortex

steroids

lipids derived from cholesterol secreted by the gonads, adrenal cortex, and placenta

eicosanoid

produced from 20-carbon fatty acid, arachadonic acid, produced in all cells except
RBCs -Prostaglandins and leukotrienes

Peptide/Protein

Hydrophilic
• Large
• Can't fit through membrane
• Second messenger mechanism of action
• Most common hormone
Example: Insulin

Amine

Synthesized from a single amino acid
• Melatonin from tryptophan

Eicosanoid

Produced from 20-carbon fatty acid, arachadonic acid
• Produced in all cells except RBCs
• 2nd messenger
• Prostaglandins and leukotrienes
• inflammation

Steroid Hormones

Small
• Hydrophobic/Lipophilic
• Travel in blood w/carrier
• Cytoplasmic or nuclear receptors
• change protein synthesis
• Example: estradiol

Neuron

Basic functional cell of nervous system
• Transmits impulses (up to 250 mph)

Dendrite -

receive stimulus and carries it impulses
toward the cell body

Cell Body

- nucleus & most of
cytoplasm

Axon

fiber which carries impulses away from cell body

Schwann Cells

Glial cells that are located in the peripheral nervous system and that form the myelin sheath around the axon of a neuron

Myelin sheath

A layer of electrical insulation that surrounds the axon.

Node of Ranvier

gaps or nodes in the myelin sheath

Sensory neurons

Neurons that carry incoming information from the sense receptors to the central nervous system.

Motor neurons

Neurons that carry outgoing information from the central nervous system to the muscles and glands.

Interneurons

Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs

stimulus

change in the environment with sufficient
strength to initiate a response

Excitability

ability of a neuron to respond to the stimulus and convert it into a nerve impulse

All of Nothing Rule

- The stimulus is either strong enough to start and impulse or nothing happens

Synapse

Gap between neurons

Neurotransmitters

Chemical messengers that cross the synaptic gaps between neurons.

Reflex Arc

A. Receptor - reacts to a stimulus
B. Afferent pathway (sensory neuron) - conducts impulses to the CNS
C. Interneuron - consists of one or more synapses in the CNS (most are in the spine)
D. Efferent pathway (motor neuron) conducts impulses from CNS to effector.
E. Effector - muscle fibers (as in the Hamstring muscle) or glands responds by contracting or secreting a
product.

Reflex arc

CNS

Brain and spinal cord

Peripheral nervous system

A division of the nervous system consisting of all nerves that are not part of the brain or spinal cord.

Somatic nervous system

A subdivision of the peripheral nervous system. Enables voluntary actions to be undertaken due to its control of skeletal muscles

autonomic nervous system

A subdivision of the peripheral nervous system. Controls involuntary activity of visceral muscles and internal organs and glands.

sympathetic nervous system

The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

Parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy

Meninges

three layers of connective tissue in which the brain and spinal cord are wrapped

dura mater

thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord

arachnoid

Weblike middle layer of the three meninges

pia mater

thin, delicate inner membrane of the meninges

cerebrospinal fluid

buffers, nourishes, and detoxifies the brain and spinal cord, flows through
the subarachnoid space, between the arachnoid mater and the pia mater

Cerebellum

Balance and coordination;
A large structure of the hindbrain that controls fine motor skills.

Cerebrum

conscious activity including
perception, emotion, thought, and planning

Thalamus

A structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex. Brain's switchboard

Medulla

vital reflexes as heart beat and respiration

Brainstem

medulla, pons, and midbrain

Hypothalamus

involved in regulating activities
internal organs, monitoring information from the
autonomic nervous system, controlling the pituitary gland and its hormones, and regulating sleep and
appetite

brain

Know labels

Cerebrum

largest portion of the brain

cerebral cortex

gray matter; NO myelin, lack the
insulation or white fatty myelin sheath that
makes most other parts of the brain appear
to be white.

gyri

ridges or SULCI of the cerebral cortex

Medullary body

the white matter of the cerebrum and consists of myelinated axons

Basal ganglia

masses of gray matter in each hemisphere which are involved in the control of
voluntary muscle movements

Lobes of the Cerebrum

Know picture

Lobes of the Cerebrum

Frontal - motor area involved in
movement and in planning &
coordinating behavior
• Parietal - sensory processing, attention,
and language
• Temporal - auditory perception, speech,
and complex visual perceptions
• Occipital - visual center - plays a role in
processing visual information

Broca's area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

Wernicke's area

controls language reception - a brain area involved in language comprehension and expression; usually in the left temporal lobe

Limbic System

A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions. Includes the hippocampus, amygdala, and hypothalamus.

Brain waves

wave patterns may vary in frequency they also vary in amplitude

electroencephalogram (EEG).

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.