Unit 1 Nervous System and Endocrine Sytem Flashcards
What hormones are secreted from the hypothalamus
- hypothalamus = oxytocin, adh
How are the hormones secreted from the hypothalamus involved in homeostasis affecting specific target organs
The hormones secreted form the hypothalamus (oxytocin and ADH) are specialized for the uterus, breast and the kidneys. Oxytocin stimulates the contraction of the uterus and also stimulates the mammary glands, resulting in breast milk. ADH causes the kidneys to remove water from urine that is forming
how are the secretions of the pituitary gland controlled by the hypothalamus through transport of hormones?
The hypothalamus secretes releasing factors which stimulates the secretion of a hormone, or inhibiting factors which slow down the secretion of a hormone. These factors travel through blood vessels to the anterior lobe of the pituitary gland
How can hormones be lipid-soluble and able to cross cell membranes to bind with and activate intracellular receptors?
Steroids are lipid soluble and their mode of action follows the following four steps;
1. Hormone diffuses across the cell membrane (lipid soluble)
- Hormone attaches to the receptor in the cytoplasm/ on the nucleus (hormone-receptor complex formed)
- Hormone-receptor complex enters the nucleus
- Hormone receptor complex activates genes/transcription of mRNA (complex binds to DNA)
how can hormones be water-soluble and able to bind with and activate receptors on cell membranes, and require secondary messengers to affect cell functioning
Protein or amine hormones are water-soluble and follows the following four steps;
- Hormone stays on the outside of the cell membrane (water soluble)
- Hormone attaches to the receptor on the surface of the cell membrane (hormone-receptor complex forms)
- Secondary messenger is activated which diffuses through the cytoplasm
- Activates enzymes in the cytoplasm
whats the difference between endocrine and exocrine glands
Exocrine - secrete into a duct that carries the secretion to the body surface or to one of the body cavities
I.E - sweat glands, mucous glands, salivary glands
Endocrine - secrete hormones into the extracellular fluid that surround the cells that make up the gland
I.E - hypothalamus, pituitary, thyroid, parathyroid, adrenals, pineal
where are each of the endocrine glands located within the body (Hypothalamus, Pineal, Pituitary, Thyroid, Parathyroid, Thymus, Adrenal, Pancreas)
Hypothalamus - brain
Pineal - brain
Pituitary - brain
Thyroid - throat
Parathyroid - throat
Thymus - chest
Adrenal - kidney
pancreas - itself
whats the difference between a paracrine and hormones
Paracrine - relating to or denoting a hormone which has effect only in the vicinity of the gland secreting it.
Hormones - a chemical that is secreted by the endocrine gland that affects the functioning of a cell or organ; often carried in the blood
label and state the function of a neuron (Nucleus, axon, dendrite, cell body, neurilemma, node of ranvier, myelin sheath)
Label the; nucleus, axon, dendrite, cell body, neurilemma, node of Ranvier, myelin sheath
Function - functional units of the nervous system. Highly specialised cells which are perfectly designed for rapid communication of messages in the body
explain the transmission of a nerve impulse (4 Marks) write as paragraph answer in onenote
1) Polarisation
- At a resting, potential the membrane is polarised-inside of the cell and has a net negative charge and the outside of the cell has a net positive charge. A Na/K pump allows these ions to move across the membrane: sodium into the cell and potassium out
2) Depolarization
- the sudden increase in membrane potential
- This occurs if the level of stimulation exceeds 15mV
- Once they are open, more sodium ions move into the cell. this makes the intracellular fluid less negative, increasing the potential difference
- If the stimulus is strong enough to increase the potential to -55mV then voltage-gated sodium channels open
- This produces a movement of sodium ions into the cells
- The size of the response is not related to the strength of the stimulus, this is also known as the all or none response
3) Repolarization
- The sodium channels close, which stops the influx of sodium ions
- At the same time, voltage-gated potassium channels open, increasing the flow of potassium ions out of the cell
- This makes the inside of the membrane more negative than the outside and decreases the membrane potential
- The membrane is repolarized
- The potassium channels remain open longer than what is needed, this results in the membrane potential dropping lower than the resting membrane potential, and the membrane is hyperpolarised
- This process is called hyperpolarization
4) Refractory Period
- Once the sodium channels have opened they quickly become inactivated
- Thus being unresponsive to stimulus
- Therefore, for a brief period after being stimulated, the membrane will not undergo another action potential
What hormones are secreted from the pituitary
- pituitary = fsh, lh, gh, tsh, acth, prl
What hormones are secreted from the thyroid
- thyroid = Thyroxine and T3
What hormones are secreted from the pancreas
- pancreas = Insulin and glucagon
What hormones are secreted from the parathyroid
- parathyroid = PTH
What hormones are secreted from the adrenal gland
- adrenal = Adrenaline and corticosterioids
How are the hormones secreted from the pituitary involved in homeostasis affecting specific target organs
The hormones secreted from the pituitary (FSH, LH, GH, TSH, ACTH & PRL) are specialized for the testes, adrenal cortex, thyroid gland and mammary glands. The have many effects namely;
LH - stimulates sperm production, growth of skin and muscles
TSH - increases metabolic rate
ACTH - promotes normal metabolism and stimulates the reabsorption of sodium ions in the kidney
How are the hormones secreted from the thyroid involved in homeostasis affecting specific target organs
thyroxine and T3 or Triiodothyronin - affects metabolic rate, directly impacting the liver and kidneys
How are the hormones secreted from the parathyroid involved in homeostasis affecting specific target organs
PTH specialized for bones and kidneys and it increases the calcium levels in the blood
How are the hormones secreted from the pancreas involved in homeostasis affecting specific target organs
the pancreas secretes insulin and glucagon.
Insulin regulates the body’s energy supply, whilst glucagon stimulates the breakdown of glycogen and fat
How are the hormones secreted from the adrenal glands involved in homeostasis affecting specific target organs
the adrenal gland secretes cortisol and adrenaline
Cortisol promotes normal metabolism and adrenaline prepares the body for fight or flight responses
Define Homeostasis
The maintenance of a relatively constant internal environment despite fluctuations in the external environment
How do thermoreceptors detect changes in the internal and external environments?
Internal - core temperature
- detected by thermoreceptors within the hypothalamus, detecting the temperature of the blood flowing through the brain
External - changes in temp outside the body
- skin thermoreceptors inform the brain of changes
what is the structure and function of the central and peripheral nervous system
Central
Structure - brain and spinal chords - protected by bone, meninges and cerbrospinal fluid
Function - receives and processes incoming messages and outgoing messages are initiated
Peripheral
Structure - cranial nerves and spinal nerves
Function - takes messages from receptors to the CNS and from the CNS to muscles and glands
what is the structure and function of the afferent and efferent nervous system
Afferent
Structure - nerves and neurons
Function - carry impulses into the CNS
Efferent
Structure - nerves and neurons - carry away from the CNS - divided into somatic and autonomic
Function - carry impulses away from the CNS
What is the structure and function of the autonomic and somatic nervous system
Autonomic
Structure - groups of nerve cells in the medulla oblongata, hypothalamus and cerebral cortex
Function - controls the body’s internal environment and is involved in many of the mechanisms that keep it constant
Somatic
Structure - nerves and neurons
Function - responds to the external environment
what is the structure and function of the sympathetic and parasympathetic nervous system
Parasympathetic
Function - generally produces responses that maintain the body during relatively quiet condition
Sympathetic
Function - produce responses that prepare the body for strenuous physical activity
Compare how the afferent and efferent nervous system detects and responds to changes in the internal and external environments
Afferent
- Internal
carries impulses into the CNS from receptors in the skin
- External
notifies internal of impulses
Efferent
- Internal
carries impulses away from the CNS
- External
takes impulses from the somatic and autonomic PNS
Compare how the autonomic and somatic nervous system detects and responds to changes in the internal and external environments
Autonomic
- Internal
adjustment of the internal environment - affects heart muscles, involuntary muscle, and glands
- External
No detection
Somatic
- Internal
no detection
- External
responds to the external environment - effects skeletal muscles
Compare how the sympathetic and parasympathetic nervous system detects and responds to changes in the internal and external environments
Parasympathetic
- Internal
Heart, lungs, stomach and intestines, liver, iris, salivary gland, and urinary bladder
- External
no detection
Sympathetic
- Internal
everything from above and blood vessels of skin, skeletal muscle and internal organs
- External
no detection
what specific parts of the central nervous system have roles in the co-ordination of body functions and are protected by the bones of the skull, the meninges and cerebro-spinal fluid
Brain - cerebrum, cerebellum, medulla oblongata, hypothalamus, corpus callosum
Spinal cord
what specially structured neurons are in the reflex arc and are used to transmit information from the receptor to the effect
Sensory (PNS)
Interneurons (CNS)
Motor (PNS)
why do the transmissions of nerve impulses occur?
These signals convey, to the spinal cord and brain, information about the body and about the outside world
how do the nervous and endocrine system differ in the speed of action
Nervous - rapid within milliseconds
Endocrine - slower within minutes to days
how do the nervous and endocrine system differ in their duration of action
Nervous - short lasting
Endocrine - long lasting
How do the nervous and endocrine system differ in their nature and transmission of the message
Nervous - utilises electrical impulses
Endocrine - utilises hormones
how do the nervous and endocrine system differ in their specificity of message
Nervous - specific part of the body - influence one effector
Endocrine - all parts of the body - affect a number of different organs
how does the central nervous system relay neurons
Through its interneurons, which as the same suggest connects sensory and motor neurons by going in between them.
what type of nerves are the peripheral nervous system composed of
Sensory (Afferent) -
Motor (Efferent) - further divides into the
- somatic
- autonomic - divides into the;
- sympathetic and parasympathetic nervous system
How do osmoreceptors detect changes in the internal and external environments?
Internal - determines osmotic pressure
- determined by the concentration of substances dissolved in the water of the blood plasma
- located in the hypothalamus and are sensitive to even very small changes
How do chemoreceptors detect changes in the internal and external environments?
Internal
- sensitive to the pH of the blood and to the concentrations of oxygen and CO2
External
-Present in nose, causing smell and present in mouth causing taste
How do touch receptors detect changes in the internal and external environments?
External
- nerve endings send impulses to the brain
How do pain receptors detect changes in the internal and external environments?
External and Internal
- stimulated by damage to the tissues
- occurs everywhere but brain
explain the transmission across a
- Nerve impulse reaches axon terminal, voltage-gated calcium channels open
- Higher concentration of calcium ions in extracellular fluid - causes them to flow into the cell at the pre-synaptic axon terminal
- Causes synaptic vesicles to fuse with the membrane, releasing special chemicals called neurotransmitters by exocytosis
- The neurotransmitters diffuse across the gap and attach to receptors on the membrane of the next neuron
- This stimulates ligand-gated protein channels to open, which allows the influx of sodium ions and initiates an action potential in the post-synaptic membrane
Label the endocrine system
see onenote
label the pituitary gland
see onenote
label the brain
see onenote
label the spinal chord
see onenote
define hormone
a chemical that is secreted by an endocrine gland and that affects the functioning of a cell or organ; often carried in the blood
Why is the pituitary gland considered the master gland
The pituitary gland is considered the master gland because it controls the functions of many of the other endocrine glands.
function of each of the neurons components (Myelin Sheath, cell body, dentrite and axon)
Dendrite - carry nerve impulses into cell body
Axon - carries nerve impulses away from cell body
Myelin Sheath - insulates, protects, speeds up movement of nerve impulse
Cell Body - controls the cell
Schwann Cell - produces the myelin sheath around cells
types of neurons based on structure
(SEE ONENOTE FOR DIAGRAMS)
Unipolar - cell body on end - axon terminals on the other end
Bipolar - cell body in center, sensory receptor on one end and axon terminal on other
Pseudounipolar- no dentrites, branched axons
Multipolar - cell body with dendrite on one end and axon terminal on other
types of neurons based on function
- Sensory - afferent
- Motor - efferent
- Interneurons - connect neurons
Structure and location of different types of meninges
- Pia Mater - inner layer - delicate sticks closely to the surface of brain and spinal cord
- arachnoid mater - middle layer -loose mesh of fibres
- Dura Mater - outer layer - tough and fibrous,
Function of
- Cerebrum
- Corpus Callosum
- Cerebellum
- Medulla Oblongta
- Cerebrum - responsible for thinking, reasoning, learning, memory and sense of responsibilty.
- Corpus Callosum - allows the two sides of the cerebrum to communicate to one another
- Cerebellum - controls posture, balance and fine coordination
- Medulla Oblongta - regulates cardiac, respiratory and vasomotor centres of the body
how does the sympathetic division effect its target organs
Heart - increases rate and strength of contraction
Lungs - dilates bronchioles
Stomach - decreases movement
Liver - increases breakdown of glycogen and release of glucose
Iris - dilates pupil
Sweat Glands - increases sweat secretion
Salivary glands - decreases secretion of saliva
skin blood vessels - constricts vessels
Skeletal muscle blood vessels - dilates
Internal organ blood vessels - constricts
Urinary bladder - relaxes muscles of wall
Adrenal medulla - stimulate hormone secretion
How does the parasympathetic division effects its target organs
Heart - decrease rate and strength of contraction
Lungs - constricts bronchioles
Stomach, intestines - increases movement
Liver - increases uptake of glucose and synthesis of glycogen
Iris - constricts pupil
Sweat - no effect
Salivary glands - increases secretion of saliva
Blood vessels - little to no effect
Urinary bladder - constricts muscles of wall
Adrenal medulla - no effect
