Human Biology Units 3 and 4 PDF

Chapter 1: Science inquiry 3 Types of investigations: - Observations - Controlled experiments - Surveys What are controlled experiments? - Controlled experiments are also called fair tests and investigate the relationship between variables. +-----------------------------------+--...

Chapter 1: Science inquiry 3 Types of investigations: - Observations - Controlled experiments - Surveys What are controlled experiments? - Controlled experiments are also called fair tests and investigate the relationship between variables. +-----------------------------------+-----------------------------------+ | Syllabus dot points | Content | +===================================+===================================+ | - the hypothalamus, pituitary, | Exocrine glands- A part of | | thyroid, parathyroid, | endocrine glands\ | | pancreas, thymus, gonads, | Secrete into a duct that carries | | pineal and adrenal glands, | the secretion to the body | | are endocrine glands found in | surface/ cavity | | the human body. | | | | E.g Mucous, sweat | | | | | | Endocrine- Secretes into the | | | extracellular fluid. | | | | | | Purely Endocrine glands secrete | | | hormones E.g Hypothalamus | | | | | | Partly endocrine glands are | | | partly endocrine partly exocrine | | | e.g Kidneys | | | | | | The pituitary gland | | | | | | - Lies under the hypothalamus | | | | | | - Joined to the hypothalamus by | | | a stalk called the | | | infundibulum | | | | | | - Not much bigger than a large | | | pea (about 13cm) | | | | | | - Consists of the anterior lobe | | | and the posterior lobe | | | | | | Pineal gland | | | | | | - In children, it is about the | | | size of a pea | | | | | | - It secretes the hormone | | | melatonin (involved in the | | | regulation of sleep patterns) | | | | | | - Melatonin- Stimulated by | | | darkness | | | | | | - Inhibited by the light | | | | | | Thyroid gland | | | | | | - Located in the neck | | | | | | - Secrete 2 hormones: | | | Thyroxine(T4) and | | | thiidothyroxine (T3) | | | | | | - Releases Calcitosin- | | | regulates levels of calcium | | | and phosphate in blood | | | | | | - Calcium and phosphate are | | | absorbed in the kidneys). | | | | | | Parathyroid glands | | | | | | - Secrete parathyroid hormone | | | | | | - Increases calcium levels in | | | the blood and phosphate | | | excretion in the urine. | | | | | | Thymus: | | | | | | - Secrete hormones called | | | thymosins | | | | | | - These hormones influence the | | | maturation of | | | disease-fighting lymphocytes. | | | | | | Adrenal glands | | | | | | - Made up of outer adrenal | | | cortex | | | | | | - Inner Adrenal medulla | | | | | | Adrenal medulla | | | | | | - Produces adrenaline | | | (concerned with fight or | | | flight responses) and | | | noradrenaline (increases the | | | rate of the heartbeat) | | | | | | Adrenal cortex | | | | | | - Produces | | | glucocorticoids(cortisol)- | | | Helps the body to withstand | | | stress | | | | | | - Aldosterone- Acts on the | | | kidney to reduce the amount | | | of sodium and increase the | | | amount of potassium in the | | | urine | | | | | | - Aldosterone Increases the | | | amount of potassium in the | | | urine | | | | | | Pancreas | | | | | | - Exocrine- secretes digestive | | | enzymes into the small | | | intestine through the | | | pancreatic duct | | | | | | - Endocrine- Made up of special | | | cells called the islets of | | | Langerhans: | | | | | | - Beta cells: Insulin (Decrease | | | BGL) | | | | | | - Alpha cells: Glucagon | | | (Increase BGL) | | | | | | Gonads | | | | | | - The gonads are the testes and | | | the ovaries | | | | | | - They are a part of the | | | reproductive system and the | | | endocrine system due to the | | | production of their hormones: | | | | | | - Androgens- (produced by the | | | testes) E.g Testosterone | | | | | | - Oestrogen and Progesterone- | | | Produced by the ovaries | +-----------------------------------+-----------------------------------+ | - Hormones secreted from the | | | hypothalamus, pituitary, | | | thyroid, parathyroid, | | | pancreas and adrenal glands | | | are involved in homeostasis | | | by affecting specific target | | | organs. | | | | | | | | | | Gland | | | Hormone | | | Target cell< | | | /th> | | | Main effects | | | | | | | | | | | | | | | | | | Hypothalamus | | | | | | Inhibits and releases hormone | | | s | | | Pituitary gland | | | Plays a role in inhibiting an | | | d releasing hormones from the pit | | | uitary gland | | | | | | | | | Thyroid | | | Thyroxine (T4) and triiodo | | | thyronine | | | Calcitonin (T3) | | | Most body cells | | | Bones, Kidney | | | | | | Increases metabolic rate a | | | nd therefore, oxygen consumption | | | and heat production. | | | Decreases calcium and phos | | | phate levels in the blood | | | | | | | | | | | | Parathyroid< | | | /td> | | | Parathyroid hormone | | | Boneys, kidneys | | | Increases levels of calcium i | | | n blood | | | | | | | | | Pancreas | | | Insulin | | | Glucagon | | | Most body cells | | | Liver and fat storage cells | | | Stimulated uptake of gluco | | | se; lowers blood glucose levels.< | | | /p> | | | Stimulates breakdown of glycog | | | en and fat; increases blood gluco | | | se level. | | | | | | | | | Adrenal cortex | | | Corticosteroids, including | | | Aldosterone | | | Cortisol | | | Kidneys | | | Most body cells | | | Increases reabsporption of | | | sodium ions and excretion of pot | | | assium ions. | | | Promotes normal metabolism; he | | | lps the body deal with stress; pr | | | omotes repair of damaged tissues. | | | | | | | | | | | | Adrenal Medulla | | | Adrenaline and noradrenaline< | | | /td> | | | Most body tissues | | | Prepares the body for fight o | | | r flight responses; reinforces th | | | e effects of the sympathetic nerv | | | ous system | | | | | | | | | | | | | | | **Pituitary gland:** | | | | | | **Posterior lobe of the Pituitary | | | gland- not a real endocrine gland | | | as it does not secrete hormones, | | | it only releases them.** | | | | | | +---------+---------+---------+ | | | | **Hormo | **Targe | **Main | | | | | ne** | t | Effects | | | | | | organ** | ** | | | | +=========+=========+=========+ | | | | **Anter | | | | | | | ior | | | | | | | lobe:** | | | | | | +---------+---------+---------+ | | | | **FSH** | Ovaries | Growth | | | | | | | of | | | | | | Testes | follicl | | | | | | | es | | | | | | | | | | | | | | Growth | | | | | | | of | | | | | | | sperm | | | | +---------+---------+---------+ | | | | **Lutei | Ovaries | Ovulati | | | | | nising | | on | | | | | hormone | Testes | and | | | | | ** | | mainten | | | | | | | ance | | | | | | | of | | | | | | | corpus | | | | | | | luteum | | | | | | | | | | | | | | Secreti | | | | | | | on | | | | | | | of | | | | | | | testost | | | | | | | erone | | | | +---------+---------+---------+ | | | | **Growt | All | Growth | | | | | h | cells | and | | | | | Hormone | | protein | | | | | ** | | synthes | | | | | | | is | | | | +---------+---------+---------+ | | | | **Thyro | Thyroid | Secreti | | | | | id- | gland | on | | | | | stimula | | of | | | | | ting | | hormone | | | | | hormone | | s | | | | | : | | from | | | | | TSH** | | the | | | | | | | thyroid | | | | +---------+---------+---------+ | | | | **Adren | Adrenal | Secreti | | | | | ocortic | cortex | on | | | | | otropic | | of | | | | | hormone | | hormone | | | | | (ACTH)* | | s | | | | | * | | from | | | | | | | the | | | | | | | adrenal | | | | | | | cortex | | | | +---------+---------+---------+ | | | | **Prola | Mammary | Milk | | | | | ctin** | glands | product | | | | | | | ion | | | | +---------+---------+---------+ | | | | **Poste | | | | | | | rior | | | | | | | lobe:** | | | | | | +---------+---------+---------+ | | | | **ADH | Kidneys | Reabsor | | | | | (Antidi | | ption | | | | | uretic | | of | | | | | hormone | | water | | | | | )** | | | | | | +---------+---------+---------+ | | | | **Oxyto | Uterus | Contrac | | | | | sin** | | tions | | | | | | Mammary | of | | | | | | glands | uterus | | | | | | | during | | | | | | | childbi | | | | | | | rth | | | | | | | | | | | | | | Release | | | | | | | of Milk | | | | +---------+---------+---------+ | | | | | | **Hormones secreted:** | | | | | | **Remember them by GOAT FLAP:** | | | | | | \- Growth Hormone | | | | | | \- Oxytosin | | | | | | \- ADH- Antidiuretic hormone | | | | | | \- Thyroid stimulating hormone | | | | | | \- Follicle stimulating hormone | | | | | | \- Luteinising hormone | | | | | | \- ACTH | | | | | | \- Prolactin | +-----------------------------------+-----------------------------------+ | - | | +-----------------------------------+-----------------------------------+ | - hormones can be lipid-soluble | Protein vs Steriod hormones | | and able to cross cell | | | membranes to bind with and | +--------------+--------------+ | | activate intracellular | | Protein/ | Steroid | | | receptors or, water-soluble | | amine | hormones | | | and able to bind with and | | hormones | | | | activate receptors on cell | +==============+==============+ | | membranes, and require | | - Water | Lipid | | | secondary messengers to | | soluble | Soluble | | | affect cell functioning. | | | (easily | | | | | | travel | | | | | | through | | | | | | membranes) | | | | +--------------+--------------+ | | | | - Quick to | Slow to have | | | | | cause a | an affect | | | | | response | but the | | | | | and the | affect is | | | | | affect | long-lasting | | | | | is short | | | | | | lasting | | | | | +--------------+--------------+ | | | | - They are | - Once | | | | | unable | released | | | | | to | into the | | | | | diffuse | blood, | | | | | across | they | | | | | the cell | bind to | | | | | membrane | transpor | | | | | because | t | | | | | they are | proteins | | | | | not | , | | | | | lipid-so | enabling | | | | | luble | to | | | | | | travel | | | | | - They | in the | | | | | Bind | bloodstr | | | | | with | eam. | | | | | receptor | | | | | | s | | | | | | on cell | | | | | | membrane | | | | | +--------------+--------------+ | | | | - Causing | - When | | | | | a | they | | | | | secondar | reach | | | | | y | the | | | | | messenge | target | | | | | r | cells, | | | | | to | the | | | | | diffuse | steroid | | | | | through | hormone | | | | | the cell | separate | | | | | | from the | | | | | | transpor | | | | | | t | | | | | | proteins | | | | | | and | | | | | | diffuse | | | | | | across | | | | | | the cell | | | | | | membrane | | | | +--------------+--------------+ | | | | - Activate | - Inside | | | | | s | the | | | | | particul | cell, | | | | | ar | they | | | | | enzymes | combine | | | | | | with a | | | | | | receptor | | | | | | protein | | | | | | in the | | | | | | cytoplas | | | | | | m | | | | | | or the | | | | | | nucleus. | | | | | | | | | | | | - The | | | | | | hormone- | | | | | | receptor | | | | | | complex | | | | | | activate | | | | | | s | | | | | | the | | | | | | genes | | | | | | controll | | | | | | ing | | | | | | the | | | | | | formatio | | | | | | n | | | | | | of | | | | | | particul | | | | | | ar | | | | | | proteins | | | | | |. | | | | | | | | | | | | - It does | | | | | | this by | | | | | | binding | | | | | | to the | | | | | | promoter | | | | | | section | | | | | | of a | | | | | | certain | | | | | | gene. | | | | | | | | | | | | - This | | | | | | stimulat | | | | | | es/ | | | | | | inhibits | | | | | | transcri | | | | | | ption | | | | | | and | | | | | | therefor | | | | | | e, | | | | | | protein | | | | | | synthesi | | | | | | s. | | | | +--------------+--------------+ | | | | | | Hormone receptors | | | | | | - Hormone receptors are | | | specific | | | | | | | | | | | | - Each type of receptor will | | | bind with only one specific | | | molecule | | | | | | - The lock and key analogy can | | | be used to describe this | | | interaction | | | | | | - The lock, the receptor | | | protein will only work with | | | the correct key, the binding | | | molecule. | | | | | | Enzyme amplification | | | | | | - The hormone triggers a | | | cascading effect in which the | | | number of reacting molecules | | | involved is increased | | | hundreds or thousands of | | | times. | | | | | | Hormone clearance | | | | | | - Once a hormone has produced | | | the required effect, it must | | | be turned off | | | | | | - This is done by breaking down | | | the molecule | | | | | | - [Some] hormones | | | are broken down in the target | | | cells | | | | | | - [Most] are broken | | | down in the liver and Kidneys | | | | | | - The degraded hormones are | | | excreted either in the bile | | | or in the urine | | | | | | Control of hormone secretions | | | | | | - To maintain homeostasis, the | | | amount of hormone secreted | | | must be very closely | | | regulated | | | | | | - Any oversecretion/ | | | undersecretion of a hormone | | | will cause the body to | | | function | | | [abnormally.] | | | | | | - Hormones are regulated by | | | negative feedback | | | | | | - Response is the opposite to | | | the stimulus | | | | | | - E.g Osmoregulation | +-----------------------------------+-----------------------------------+ | - the secretions of the | - The pituitary gland is | | pituitary gland are | connected to the hypothalamus | | controlled by the | via an Infundibulum | | hypothalamus through | | | transport of hormones, either | - Hypothalamus- Posterior | | via nerve cells or the | Pituitary gland=Nerve fibres | | vascular link between them. | that come from nerve cell | | | bodies that pass through the | | | infundibulum | | | | | | - The posterior lobe is not a | | | true endocrine gland as it | | | does not secrete substances, | | | it simply stores and releases | | | hormones | | | | | | - Hypothalamus- Anterior | | | pituitary gland= Blood | | | vessels lying in the | | | infundibulum | +-----------------------------------+-----------------------------------+ | - Transmission of nerve |  | | impulses is via | | | electro-chemical changes that | **Transmission of the nerve | | occur at the generation of | impulse:** | | the impulse, the propagation | | | of the impulse along the | - A single action potential | | nerve fibre, and the transfer | occurs in one section of a | | of the impulse across the | membrane. | | synapse. | | | | - However, it triggers an | | | action potential in the | | | adjacent membrane. | | | | | | - The action potential does not | | | travel along a nerve fibre, | | | it is the message or nerve | | | impulse that travels along a | | | nerve fibre. | | | | | | **Conduction along unmyelinated | | | fibres:** | | | | | | - Depolarisation of one area of | | | the membrane causes a | | | movement of sodium ions into | | | the adjacent areas. | | | | | | - This movement stimulates the | | | opening of voltage-gated | | | sodium channels in the next | | | part of the membrane, which | | | initiates an action potential | | | in the area of that membrane | | | | | | - This process repeats itself | | | along the length of the | | | membrane so the action | | | potential moves along the | | | membrane away from the point | | | of stimulation. | | | | | | - The nerve impulse is | | | prevented from going | | | backwards along the fibre by | | | the refractory period. | | | | | | - During the refractory period | | | of an action potential, | | | another action potential | | | can't be generated at that | | | point on the fibre and so the | | | nerve impulse is unable to | | | travel in that direction. | | | | | | - In an unmyelinated fibre, the | | | maximum speed of transmission | | | is 2 m/s. | | | | | | **Transmission along myelinated | | | fibres:** | | | | | | - The Myelin sheath insulates | | | the nerve fibre from the | | | extracellular fluid. | | | | | | - This does not occur at the | | | node of Ranvier because the | | | myelin sheath is absent from | | | the nodes. | | | | | | - Where the nerve fibre is | | | surrounded by myelin, ins | | | cannot flow between the | | | inside and outside of the | | | membrane and an action | | | potential cannot form. | | | | | | - The action potential jumps | | | from one node of ranvier to | | | the next. | | | | | | - This jumping conduction is | | | known as "saltatory | | | conduction." | | | | | | - A large myelinated fibre can | | | conduct impulses at the speed | | | of 140 m/s. | | | | | | **Size of a nerve impulse:** | | | | | | - A nerve impulse that travels | | | along a nerve fibre is always | | | the same size, regardless of | | | of the size of the stimulus. | | | | | | - A weak stimulus, provided is | | | exceeds the threshold, | | | produces the same action | | | potential as a strong one. | | | | | | - This is called an | | | **all-or-nothing response**- | | | a stimulus is either strong | | | enough to trigger an impulse, | | | or it's not. | | | | | | - A strong stimulus causes | | | depolarisation of more nerve | | | fibres than a weak stimulus. | | | | | | - A strong stimulus produces | | | more nerve impulses in a | | | given time than a weak | | | stimulus. | | | | | | **Transmission across a | | | synapse:** | | | | | | 1. When the nerve impulse | | | reaches the axon terminal, it | | | activates voltage- gated | | | calcium ion channels. | | | | | | 2. As there is a higher | | | concentration of calcium ions | | | in the extracellular fluid, | | | they flow into the cell at | | | the pre-synaptic axon | | | terminal. | | | | | | 3. This causes synaptic vesicles | | | to fuse with the membrane, | | | releasing special chemicals | | | called neurotransmitters by | | | exocytosis. | | | | | | 4. The neurotransmitters diffuse | | | across the gap and attach to | | | receptors on the membrane of | | | the next neuron. | | | | | | 5. 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. | | | | | | - The transmission of a nerve | | | impulse across a synapse | | | occurs only in one | | | direction-from axon to | | | dendrite or from axon to cell | | | body. | | | | | | **Effect of chemicals on the | | | transmission of nerve impulses:** | | | | | | - Stimulants such as caffeine | | | and Benzedrine stimulate | | | transmission at the synapse. | | | | | | - Other drugs such as | | | anaesthetics or hypnotics, | | | depress the transmission. | | | | | | - Venom from certain species of | | | snakes and spiders also | | | effect the neuromuscular | | | junction. | | | | | | - Nerve agents | | | (organophosphates) cause the | | | build up of acetylcholine at | | | the neuromuscular junction. | | | | | | - All the muscles in the body | | | then try to contract and the | | | loss of muscle control | | | prevents breathing. | +-----------------------------------+-----------------------------------+ | - Different receptors detect | Thermoreceptors: respond to heat | | changes in the internal and | and cold. | | external environments, | | | including thermoreceptors, | Peripheral thermoreceptors in the | | osmoreceptors, chemoreceptors | skin send messages about the | | and receptors for touch and | external/environmental | | pain | temperature to the hypothalamus | | | and cerebrum. | | | | | | Central thermoreceptors in the | | | hypothalamus monitor core body | | | temperature by the temperature of | | | the blood flowing through the | | | brain. | | | | | | Osmoreceptors: located in | | | hypothalamus and sensitive to | | | changes in osmotic pressure. | | | Osmotic pressure is determined by | | | the concentration of substances | | | dissolved in the water of the | | | blood plasma. | | | | | | Chemoreceptors: stimulated by | | | certain chemicals. Peripheral | | | chemoreceptors in the nose | | | (detect odours) and mouth (detect | | | taste). Internal chemoreceptors | | | sensitive to composition of body | | | fluids. In particular | | | chemoreceptors in blood vessels | | | that detect blood pH.and | | | therefore concentrations of | | | carbon dioxide and oxygen. | | | | | | Touch receptors: located mainly | | | in the skin. Surface receptors | | | are sensitive to light touch e.g. | | | lips and fingertips, whereas | | | others deeper in the skin are | | | sensitive to pressure and | | | vibration. | | | | | | Pain receptors: (also called | | | nociceptors) stimulated by damage | | | to the tissues (cuts or bumps), | | | poor blood flow to a tissue, or | | | excessive stimulation from heat | | | or chemical stimuli. | | | | | | Pain receptors are especially | | | concentrated in the skin and | | | mucous membranes. They occur in | | | most organs but not the brain. | | | | | | Pain is essential for our | | | survival and will persist as long | | | as the stimulus is present, | | | serving as a warning system that | | | damage is occurring.e sensitive | | | to pressure and vibration. | +-----------------------------------+-----------------------------------+ | - The reflex arc comprises of |  | | specially structured neurons, | | | including sensory, | **Dorsal root** -- contains axons | | interneuron and motor | of sensory neurons that have | | neurons, to transmit | their cell bodies in the small | | information from the receptor | swelling on the dorsal root known | | to the effector to respond | as the dorsal root ganglion. | | rapidly to stimuli | | | | **Ventral Root** -- contains | | | axons of motor neurons that have | | | their cell bodies in the grey | | | matter of the spinal cord. | | | | | | **The somatic division:** | | | | | | Is usually voluntary | | | | | | **The autonomic division:** | | | | | | - Operates without conscious | | | control | | | | | | - It is regulated by cells in | | | the medulla oblongata, | | | hypothalamus  and cerebral | | | cortex. | +-----------------------------------+-----------------------------------+ | - The nervous and endocrine | | | systems work together to | | | co-ordinate functions of all | | | body systems, but differ in | | | terms of: | | | | | | - speed of action | | | | | | - duration of action | | | | | | - nature and transmission of | | | the message | | | | | | - specificity of message | | +-----------------------------------+-----------------------------------+ | - structure and function of the |  | | divisions of the nervous | | | system can be observed and | **Dorsal root** -- contains axons | | compared at different levels | of sensory neurons that have | | in detecting and responding | their cell bodies in the small | | to the changes in the | swelling on the dorsal root known | | internal and external | as the dorsal root ganglion. | | environments including: | | | | **Ventral Root --** contains | | - § central-peripheral | axons of motor neurons that have | | | their cell bodies in the grey | | - § afferent-efferent | matter of the spinal cord. | | | | | - § autonomic­-somatic | **The somatic division:** | | | | | - § sympathetic-parasympathetic | Is usually voluntary | | | | | | **The autonomic division:** | | | | | | Operates without conscious | | | control | | | | | | It is regulated by cells in the | | | medulla oblongata, hypothalamus | | |  and cerebral cortex. | | | | | |  | | | | | |  | | | | | | **The peripheral nervous | | | system:** | | | | | | **Composed of:** | | | | | | - Nerve fibres that carry | | | information to and from the | | | CNS | | | | | | - Groups of cell bodies, called | | | ganglia, which lie outside | | | the brain and spinal chord | +-----------------------------------+-----------------------------------+ | - the parts of the central | **Cerebrum:** | | nervous system, including the | | | brain (cerebrum, cerebellum, | - The cerebrum is the largest | | medulla oblongata, | part of the brain | | hypothalamus, corpus | | | callosum) and spinal cord, | - The outer layer of the | | have specific roles in the | cerebrum, called the cerebral | | co-ordination of body | cortex: | | functions and are protected | | | by the bones of the skull, | is made up of **grey matter.** | | meninges and cerebro-spinal | | | fluid | - **Deep inside the cerebrum is | | | additional grey matter called | | | the basal ganglia.** | | | | | | - Cerebral cortex is 2.4mm | | | thick | | | | | | | | | | | | - Grey matter consist of neuron | | | cell bodies, dendrites and | | | **unmyelinated neurons.** | | | | | | - Below the cortex there is | | | **white matter:** | | | | | | - Made up of **myelinated | | | axons** | | | | | | - Cerebral cortex is folded | | | into patterns which greatly | | | increase its surface area. | | | | | | - The folding produces rounded | | | ridges called convultions: | | | | | | - Shallow downfolds called | | | **Sulci** | | | | | | - Deep downfolds called | | | **fissures** | | | | | | - **The deepest fissure, | | | longitudinal fissures | | | separates the cerebrum into | | | two halves- the left and | | | right cerebral hemispheres.** | | | | | | - Joining the two hemispheres, | | | at the base of the | | | longitudinal fissure, is an | | | area of white matter | | | consisting of transverse | | | fibres also known as the | | | corpus collosum. | | | | | | - The patterns of folding of | | | the cerebral cortex vary from | | | person to person. | | | | | | - However, certain fissures and | | | sulci are fairly constant nd | | | used to further subdivide | | | each cerebral hemisphere into | | | four lobes- Frontal, | | | Temporal, Occipital and | | | pariental lobes. | | | | | | **Functions of the lobes of the | | | cerebral cortex:** | | | | | | **Lobe** * | | | *Fuction** | | | ----------------------------- - | | | --------------------------------- | | | --------------------------------- | | | ---------------------- | | | **Frontal lobe** * | | | *Thinking, problem solving, emoti | | | ons, personality, language and co | | | ntrol of movement.** | | | **Pariental lobe** * | | | *Processing temperature, touch, t | | | aste, pain and movement.** | | | **Temporal lobe** * | | | *Processing memories and linking | | | them to senses; receives auditory | | | information** | | | **Occipital lobe** * | | | *Vision** | | | **Insula (the fifth lobe)** * | | | *Reognition of different senses a | | | nd emotions, addiction and phychi | | | atric disorders.** | | | | | | **The fifth lobe:** | | | | | | - The insula is regarded as a | | | fifth lobe, but it is deep | | | inside the brain and not | | | visible from the outside. | | | | | | - Between the grey matter at | | | the surface of the cerebrum | | | and the grey matter deep | | | inside is white matter | | | composed of bundles of | | | myelinated nerve fibres | | | called tracts | | | | | | **Three types of tracts occur in | | | the white matter:** | | | | | | 1\. tracts that connect various | | | areas of the cortex within the | | | same hemisphere | | | | | | 2\. tracts that carry impulses | | | between the left and the right | | | hemispheres | | | | | | tracts that connect the cortex to | | | other parts of the brain or to | | | the spinal cord | | | | | | **Cerebrum functional areas:** | | | | | |  | | | | | | **Sensory areas:** | | | | | | interpret impulses from receptors | | | | | | **Motor areas:** | | | | | | control muscular movements, for | | | example, basal ganglia are | | | associated with the control of | | | skeletal muscles. They consist of | | | groups of nerve cell bodies | | | | | | **Association area:** | | | | | | are concerned with intellectual, | | | emotional processes and memory | | | | | | Left Vs Right cerebrum: | | | | | | **the left hemisphere-** controls | | | language ability | | | | | | **the right hemisphere-** | | | controls musical and artistic | | | abilities | | | | | | Cerebrum fuction: | | | | | | - Thinking | | | | | | - Reasoning | | | | | | - Intelligence | | | | | | - Memory | | | | | | - Learning | | | | | | - Sense of resposibility | | | | | | **Cerebellum:** | | | | | | **Function:** | | | | | | - **posture and balance** | | | | | | - **fine motor coordination of | | | voluntary muscle** | | | | | | - **subconscious movements** | | | | | | - **Allows smooth coordinated | | | movements such as those | | | required for writing and | | | writing** | | | | | | - To carry out these fuctions, | | | the cerebellum receives | | | sensory information from: | | | | | | - The inner ear for information | | | about posture and balance | | | | | | - Stretch receptors in the | | | skeletal muscles for | | | information about the length | | | of muscles. | | | | | | **Structure:** | | | | | | - Cerebrum lies under the rear | | | part of the cerebrum | | | | | | - It is the second- largest | | | part of the brain | | | | | | - It's surface is folded into | | | parallel ridges. | | | | | | - The outer folded part | | | consists of grey matter | | | | | | - Inside is the white matter | | | that branches to all parts of | | | the cerebellum, rather like | | | the branches of a tree. | | | | | | **Medulla oblongata:** | | | | | | - Is the continuation of the | | | spinal cord | | | | | | - It is about 3cm long | | | | | | - It extends from just above | | | the point where the spinal | | | cord enters the skull | | | | | | - **The medulla oblongata | | | contains:** | | | | | | - **The cardiac centre:** | | | | | | - Regulates the rate and force | | | of the heartbeat | | | | | | - **The respiratory centre:** | | | | | | - Controls the rate and depth | | | of breathing | | | | | | - **The vasomotor centre:** | | | | | | - Regulates the diameter of | | | blood vessels | | | | | | **Hypothalamus:** | | | | | | - The hypothalamus lies in the | | | middle of the brain and | | | cannot be seen from the | | | outside | | | | | | - It is mostly contained with | | | maintaining a constant | | | internal | | | environment-homeostasis. | | | | | | **Functions:** | | | | | | - Regulation of the autonomic | | | nervouse system includinf the | | | regulation of heart rate, | | | blood pressure, the | | | secretions of digestive | | | juices, movements of the | | | alimentary canal and the | | | diameter of the pupil of the | | | eye | | | | | | - Body temperature | | | | | | - Food and water intake | | | | | | - Patterns of walking and | | | sleeping | | | | | | - Contraction of the urinary | | | bladder | | | | | | - Emotional responses such as | | | ager, aggression, pleasure | | | and contentment | | | | | | - The secretion of hormones and | | | coordination of parts of the | | | endocrine system. | | | | | | **Corpus Collosum:** | | | | | | - Wide band of nerve fibres | | | that lies underneath the | | | cerebrum at the base of the | | | longitudinal tissues. | | | | | | - Nerve fibres in the corpus | | | collosum cross from one | | | cerebral hemisphere to the | | | other and allow the two sides | | | of the cerebrum to | | | communicate with each other. | | | | | | **Spinal Chord:** | | | | | | - The spinal cord I roughly | | | cylindrical | | | | | | - Abput 44cm in an adult | | | | | | - The cord is enclosed in the | | | vertebral canal, and inside | | | the ring of bone are the | | | three meningeal layers. | | | | | | - The grey matter of the spinal | | | chord is at the centre | | | | | | - Surrounded by the white | | | matter | | | | | | - The grey matter is roughly in | | | the shape of a letter H. | | | | | | - In the cross-bar of the H is | | | a small space called the | | | central canal. | | | | | | - This runs the length of the | | | spinal cord and contains | | | cerebrospinal fluid. | | | | | | - The myelinated nerve fibres | | | of the white matter are | | | arranged in bundle known as | | | ascending and descending | | | tracts. | | | | | | - **Ascending tracts:** | | | | | | - Are sensory axons that carry | | | impulses upwards, towards the | | | brain. | | | | | | - **Descending tracts:** | | | | | | - Contains motor axons that | | | conduct impulses down, away | | | from the brain | | | | | | **They are protected by the:** | | | | | | **Bone:** | | | | | | - The outer most protective | | | layer is bone | | | | | | - The brain is connected by the | | | cranium, the part of the | | | skull that houses the brain | | | | | | - The spinal cord runs through | | | the vertebral canal, opening | | | the vertebrae. | | | | | | - These bones provide a strong | | | rigid structure to protect | | | the structures underneath. | | | | | | **Meninges:** | | | | | | - Inside the bones | | | | | | - Covers the surface of the | | | brain and spinal cord (i.e | | | the central nervous system): | | | | | | - The **outer layer** is called | | | the **dura matter** and is | | | tough and fibrous. It | | | provides a layer of | | | protection for the brain. | | | | | | - The **middle layer** is | | | called the **arachnoid | | | mater**, it is a loose mesh | | | of fibres. | | | | | | - The **inner layer** is called | | | the **Pia matter.** | | | | | | - It is far more delicate and | | | contains many blood vessels | | | and sticks closely to the | | | surface of the brain and | | | spinal cord. | | | | | | **Cerebro-spinal fluid:** | | | | | | - Occupies a space between the | | | **middle** and **inner | | | layer** of meninges | | | | | | - It circulates through | | | cavities in the brain and | | | through a canal in the centre | | | of the spinal cord. | | | | | | - The CSF is a clear, watery | | | fluid containing a few cells | | | and some glucose, protein, | | | urea and salts: | | | | | | **The CSF has three functions:** | | | | | | **Protection:** | | | | | | - The CSF acts as a shock | | | absorber, cushioning any | | | blows or shocks the CNS may | | | sustain. | | | | | | **Support:** | | | | | | - The brain is suspended inside | | | the cranium and floats in the | | | fluid that surrounds it. | | | | | | **Transport:** | | | | | | - The CSF is formed from the | | | blood, and circulates around | | | and through the CNS before | | | eventually re-enterin the | | | blood capillaries. | | | | | | - During its circulation its | | | takes nutrients to the cells | | | of the brain and the spinal | | | cord and carries away their | | | wastes. | +-----------------------------------+-----------------------------------+ | - Homeostatic processes involve | | | nerves and hormones in | | | maintaining the body's | | | internal environment within | | | tolerance limits through the | | | control of metabolism and | | | physiological and behavioural | | | activities. | | +-----------------------------------+-----------------------------------+ | - Thermoregulation occurs by | | | the control of heat exchange | | | and metabolic activity | | | through physiological and | | | behavioural mechanisms | | +-----------------------------------+-----------------------------------+ | - Blood sugar levels are | | | maintained by controlling of | | | sugar uptake, its storage and | | | release by cells and use in | | | metabolism; these processes | | | involve the hormones of the | | | pancreas and adrenal glands | | +-----------------------------------+-----------------------------------+ | - homeostatic processes involve | | | nerves and hormones in | | | maintaining the body's | | |